NEWS NEWSVol. 17, No. 1 February 2007Global Energy and Water Cycle Experiment

World Climate Research Programme(A Programme of WMO, ICSU and IOC)

Illustration of the space-time distribution of rainfall over the Sahel and the African Monsoon Multidisciplinary Analysis(AMMA) Project mesosites in 2006, characterized by a very late start of the rainy season over the whole subcontinent. Themap on the left shows the seasonal rainfall anomalies computed as a percentage of the mean rainfall over the 1950–2005period, showing positive anomalies in the north and negative anomalies over the south of the region. These anomalies werecaused by suppressed convection conditions during the early stage of the rainy season, followed by an unusually northernlocation of the primary tracks of the mesoscale convective complexes. The graph on the right illustrates the large differencesin precipitation that occur at this scale. See article by T. Lebel, et al. on page 4.

GABLS INTERCOMPARISON SHOWS THAT MODELS DIFFERCONSIDERABLY AND UNDERESTIMATE DIURNAL CYCLE OF WIND SPEED

AMMA FIELD CAMPAIGN RESULTS

The GEWEX Atmospheric Boundary Layer Study (GABLS), using observations from CASES-99, shows that models produce verydifferent results in all parameters and that they all differ substantially from observations. The left panel shows sensible heatflux at the surface (Wm-2), and the right panel shows the diurnal amplitude of the 10-m wind speed (ms-1), where the blacksolid line is the averaged amplitude for the entire month of October and the dashed line is for October 23. Single Column Modelresults, first order closures (black and red) and turbulence models (blue and cyan). The models with the first calculation levelabove 5 m are indicated with circles and the ones above with diamonds. See article by G. Svensson and B. Holtslag on page 9.

February 20072

Welcome to a new year. I wish all readers ofthis Newsletter peace and prosperity, and I alsowish the same for GEWEX. This year will be animportant one for GEWEX and we will need thesolidarity of the community to be successful in movingGEWEX forward and realizing the goals that wehave outlined in our GEWEX Phase II Roadmap. Iwould like to give you some reasons why 2007 willbe critical for GEWEX.

GEWEX is streamlining its operations. At itsrecent meeting, the GEWEX Scientific Steering Group(SSG) approved the merger of the GEWEX Hy-drometeorology Panel (GHP) and the CoordinatedEnhanced Observing Period (CEOP) into a singlepanel activity—the Coordinated Energy and WaterCycle Observations Project (CEOP). This restruc-turing will allow the former Continental-ScaleExperiments (now Regional Hydroclimate Projects)to more fully exploit the on-going data collectionand archival activities of CEOP and will bring morescience to the new CEOP and all of the programswith which it interacts. Since these two activitieshave accounted for more than half of the scientistsinvolved in GEWEX, I think it is incumbent on allof us to do all that we can to make this mergera success.

Research in the Earth sciences is at a criticalcrossroads. Over the past 2 years we have seen arefocusing of priorities within the National Aero-nautics and Space Administration (NASA). TheDecadal Survey recently issued by the NationalAcademy of Sciences outlines a path whereby NASAand the space community can move forward toensure that the Earth observation program remainsstrong. There are legitimate concerns that if Earthscience in NASA falters, then it may falter in otherspace agencies, and the focus on Earth observa-tions that seemed so promising only a few shortyears ago will be lost. Since GEWEX relies onspace agency support, data, and inspiration, anyloss of focus on the Earth sciences can only hurtour program. In the meantime, the good news isthat support for GEWEX and its scientific agendaremains at an all time high by almost all agenciesat an international level. The important scientific

COMMENTARY

2007 WILL BRING NEWCHALLENGES TO GEWEXSoroosh Sorooshian, Chairman

GEWEX Scientific Steering Group

contributions that GEWEX and its panels are mak-ing are well recognized by our supporters.

As most of you have heard the World ClimateResearch Programme (WCRP) is also at a cross-roads. It is launching some ambitious new crosscutsunder its strategic framework. These include mon-soons, extremes, the International Polar Year,anthropogenic climate change, seasonal predictionand atmospheric chemistry and climate. GEWEXhas a vested interest in each of these topics, how-ever, we must remain diligent to ensure that it is aviable contributor in these activities. These ambi-tious new activities are coming at a time whenWCRP seems to have reached a budget crisis andthe level of future support to its projects has be-come uncertain. Furthermore, WCRP is facing areview by the International Council for Science (ICSU)in the next year which may have implications for itsrelationship with WCRP and the InternationalGeosphere-Biosphere Programme (IGBP). GEWEXmust help WCRP chart a path through these wa-ters to ensure that both GEWEX and WCRP remainviable and independent of the winds that may seekto blow them off course.

During my 6 years as the GEWEX SSG ChairI have faced many challenges, but I feel that thisyear will be the most challenging. In previous yearsit has been the good will, common sense and sup-port of the community that have carried the day.There is no reason to expect it to be otherwise thisyear. I look forward to your support and collabora-tion in addressing these challenges.

Contents PAGE

Commentary: 2007 Will Bring New Challenges 2to GEWEX

Recent News of Relevance to GEWEX 3

AMMA Field Campaigns in 2005 and 2006 4

Land- Use and Climate Identification of 6Robust Impacts (LUCID) Project

Global Land-Atmosphere Coupling 7Experiment – Phase 2

The Diurnal Cycle – GABLS Second 9Intercomparison Project

19th Meeting of the GEWEX Scientific 10Steering Group

Workshop/Meeting Summaries:– First GEWEX Aerosol Products 12

Assessment Workshop– GEWEX Radiation Panel Meeting 13

GEWEX/WCRP Meetings Calendar 15

3February 2007

RECENT NEWS OF RELEVANCE TO GEWEX

U.S. NATIONAL RESEARCH COUNCILDECADAL SURVEY REPORT RELEASED

The Space Studies Board report, "Earth Sci-ence and Applications from Space: NationalImperatives for the Next Decade and Beyond,"provides a review of priorities for Earth observa-tions for the next decade. The report can bepurchased or viewed at http://www.nap.edu/cata-log/11820.html.

GEWEX DATA APPLICATIONS FORSOLAR AND OTHER RENEWABLE

ENERGY APPLICATIONS

GEWEX Surface Radiation Budget (SRB) Projectand Global Precipitation Climatology Project (GPCP)meteorological data sets have proven to be highlyvaluable to engineers, architects, and planners inthe renewable energy sector. These data sets aremade available on the NASA Surface Meteorologyand Solar Energy web site (http://eosweb.larc.nasa.gov/sse/RETScreen/) using RETScreen soft-ware (http://www.retscreen.net/ang/home.php), adecision support tool that is available free of chargethat can be used worldwide to evaluate the energyproduction and savings, life-cycle costs, emissionreductions, financial viability, and risk for varioustypes of energy efficient and renewable energytechnologies (RETs). The software also includesproduct, cost and climate databases, and a detailedonline user manual. Since these data sets becameavailable 7 years ago, there have been over 1 milliondata document downloads and 100,000 registeredusers. A new version of the Retscreen softwarein 21 languages is scheduled to be released soon.

CAPACITY BUILDING WORKSHOPHELD IN BUENOS AIRES

On 16–17 November 2006, Argentina's ComisiónNacional de Actividades Espaciales (CONAE) hostedthe Group on Earth Observations (GEO)/IntegratedGlobal Water Cycle Observations (IGWCO) Themecapacity building workshop in Buenos Aires. Repre-sentatives from a number of space agencies as wellas other programs such as the International ResearchInstitute (IRI) participated in the workshop. The con-cept for a capacity building program that emergedfrom these discussions foresees space agencies andother data providers, and in some cases researchers,developing techniques for using Earth observations insupport of decision making in the water resourcessector. The next step in this development is to com-plete a draft proposal for comment and review by theend of March 2007. Anyone wishing to have moreinformation about the proposal is invited to contactRick Lawford at lawford@umbc.edu.

WCRP DIRECTOR ATTENDS MEETINGSIN WASHINGTON, DC

On 30 November – 1 December 2006 the Direc-tor of the World Climate Research Programme (WCRP),Dr. Ann Henderson-Sellers attended a WCRP Round-table at a meeting of the Board on Atmospheric Sciencesand Climate of the National Academies Climate Re-search Committee. A workshop was also held withgovernment representatives on the plans of results ofthe WCRP stakeholders survey.

While in Washington, DC, she met with Gen. JackKelly, National Oceanic and Atmospheric Administra-tion (NOAA) Assistant Administrator for Weather,Dr. Chet Koblinsky, Director, NOAA Climate Office,and Dr. Peter Schultz, Deputy Director, U.S. ClimateChange Science Program. She also met with Dr. MaryCleave, Associate Administrator, National Aeronauticsand Space Administration (NASA) Science Director-ate and other NASA senior staff, including Dr. MichaelFreilich, Director of the Earth Science Division. Dr.Henderson-Sellers expressed her appreciation forNASA’s long-term support for WCRP programs,especially for GEWEX, for which NASA serves asthe major international sponsor. Dr. Cleave empha-sized the important role of GEWEX in NASA'sresearch on Earth system science issues, in particu-lar, water and energy processes associated withglobal climate variability and change.

GEWEX SCIENTISTS HONOREDAT THE ANNUAL AMS MEETING

At the 87th Annual Meeting of the AmericanMeteorological Society, Dr. Ulrike Lohmann re-ceived the Henry G. Houghton Award "for pioneeringcontributions to the representation and quantifica-tion of the effects of cloud-aerosol interactions onclimate." Dr. Anthony D. DelGenio, National Aero-nautics and Space Administration (NASA)/GoddardInstitute for Space Studies (GISS), Dr. Randal D.Koster, NASA/Goddard Space Flight Center, andDr. Michael I. Mischenko, NASA/GISS, werehonored as new AMS Fellows.

February 20074

AMMA FIELD CAMPAIGNSIN 2005 AND 2006

T. Lebel1, D. J. Parker2, B. Bourles3, A. Diedhiou1, A. Gaye4, J. Polcher5,

J.-L. Redelsperger6, and C. D. Thorncroft7

1LTHE, IRD, Niger, 2University of Leeds, UK,3LEGOS, IRD, France, 4LPA, UCAD, Sénégal,5LMD, CNRS, France, 6CNRM/GAME, CNRS,

France, 7 SUNY at Albany, USA

The African Monsoon Multidisciplinary Analysis(AMMA) field campaign is the largest and most ex-tensive of its kind ever undertaken in Africa. Its firstcomponent, the long-term observation period (LOP) isbased on operational networks and specific field projects,covering the period 2001–2010. In 2005, AMMA be-gan its Enhanced Observing Period (EOP) which willlast 3 years and is characterized by a widespreadintensification and coordination of existing networks.The peak of activity occurred in 2006 with four Spe-cial Observing Periods (SOPs) based on the deploymentof extensive observation platforms, including researchaircraft and vessels, balloons, and an array of groundinstruments.

The scientific diversity of the measurements em-braces oceanic, hydrological and atmospheric studies,in physical, chemical and socio-economic disciplines.As described by Redelsperger et al. (2006, 2007), theobservation strategy includes three spatial scales: re-gional, meso and local. Preliminary results indicatethat 2006 was characterized by a very late onsetof the monsoon over the continent (around 10July compared to 20–25 June, on average).

EOP monitoring of the atmosphere at the re-gional scale and SOP intensification. The main sourceof in situ atmospheric measurements was the existingoperational network, which was considerably upgradedusing AMMA funding. The infrastructure at 15 syn-optic existing stations was extensively refurbished, andfour new stations were created, thus providing a basicnetwork of 19 up-to-date stations. The sounding fre-quency was increased from two to four per day atseven key stations from June to September 2006. Fortwo periods totaling 25 days, a subnetwork of sixstations made eight soundings per day. The “fixed”profiling network was also supplemented by soundingsfrom “mobile” platforms. In total, 510 dropsondes werereleased from research aircraft and 129 from driftsondegondolas over the continent and the tropical Atlantic.Fifteen boundary layer pressurized balloons launchedfrom Cotonou moved generally north-eastward, sam-

pling the monsoon flow during the onset. In addition,six GPS stations, one VHF profiler and one UHFprofiler were used to obtain upper air observations.The outcome of the upper air programme has beenthe acquisition of a remarkably dense, high-qualityupper-air data set for West Africa.

Aerosol campaigns. West Africa is the world’slargest source of biomass burning aerosols and min-eral dust; satellite sensors consistently indicate thatthe West Africa aerosol plumes are the most wide-spread, persistent and dense on Earth. The effect ofthe dust and carbonaceous aerosols on climate changeis one of the greatest uncertainties in the Earth radia-tive budget. The EOP focuses on studying the mineraldust content and its transport toward the North Atlan-tic Ocean. This transport can take place at differentaltitudes within the Saharan Air Layer (SAL), andalso within the surface layer. The altitude of the dusttransport layer significantly modulates its radiative effectand also induces different deposition patterns, thusimpacting the regional dust budget. A Sahelian DustTransect made of three stations located in M’Bour(Senegal, 16.96°W), Cinzana (Mali, 5.93°W) andBanizoumbou (Niger, 2.66°W) provided precise localscale measurements as well as a regional view of thesurface concentration and aerosol optical thicknessassociated with several huge dust storms that affectedall of western Africa in 2005 and 2006. To the ex-treme north (Tamanrasset, 22°48N), the TransportableRemote Sensing Station was deployed to measureaerosol and cloud radiative properties through a syn-ergy of backscatter lidar, radiometry and in situ samplingin the Sahara. In the central Sahel, the AtmosphericRadiation Measurement Program (ARM) Mobile Fa-cility (AMF), equipped with high quality radiation andsounding sensors operated from the Niamey airport,while the Banizoumbou site was equipped with twoisokinetic samplers equipped with seven sampling out-lets and a similar set-up was deployed in a region ofdominant biomass burning aerosols.

The AMF and satellite instruments performed thefirst simultaneous observations of a major dust stormfrom space and the ground, allowing researchers totest their understanding of how dust affects the radi-ant energy budget of the atmospheric column (A.Slingo, et. al., 2006). Researchers used measurementsof atmospheric temperature and humidity profiles, andground-based retrievals of aerosol optical properties—such as aerosol optical thickness and reflectivity—asinput to radiation models to assess their ability tosimulate the impact of the dust on solar radiationbalance. The results indicate major perturbations tothe energy balance at both the surface and top of the

5February 2007

atmosphere. When compared with the satellite andground-based observations, the models did a good jobof reproducing the radiative energy balance at thesurface during the dust storm, but they underestimatedthe solar absorption within the atmosphere, indicatingthat scientists need to refine their understanding of theabsorbing properties of dust (see figure below).

Continental surfaces and water cycle. The landsurface EOP is intended to provide more appropriatedata for the study and estimation of water budgetsfrom the local scale to the mesoscale. Surface fluxes(latent and sensible heat, and carbon dioxide) and soilmoisture are a major emphasis of the land surfaceEOP, and will remain so for at least 2008 and 2009.A series of 13 flux stations were deployed from 7°Nto 17°N and are documented using two scintillometers(one in Niger, one in Bénin), providing a spatiallyintegrated measurement of the sensible heat flux overareas of a few squared kilometers. Another key EOPinstrument is the X-band Doppler and polarized XPORTweather radar installed at Ouémé for fine resolutionobservations of the rainfields at high time-samplingfrequency (typically one volume scanning every 10minutes) over the Donga catchment. The land surfaceLOP-EOP program provides a comprehensive set ofdata, for water cycle studies across scales and forhydrologic model parameterization. The three mesositesalso function as “field schools” for training a newgeneration of young African scientists to use newinstruments and methods in hydrometeorology. Duringthe 2006 rainy season, three hydrometeorological ra-dars were deployed along a West to East Saheliantransect. The French Ronsard C-band Doppler andpolarized radar was installed at Kopargo to comple-ment the smaller EOP XPORT radar. The figure atthe top of page 1 illustrates the space-time distribution

of rainfall over the region in 2006, characterized by avery late start of the rainy season over the wholesubcontinent and overall exceeding rainfall in the Northand an overall deficit in the South.

Oceanic campaigns. The respective role of theocean and of the continental surfaces in shaping theinterannual and decadal variabilities of the West Af-rican Monsoon is a key question to be addressed byAMMA, leading to a coordinated observation programfor the ocean and the continent. The 3-year oceanEOP consists of two annual cruises following thesame track lines, one during the establishment of thecold tongue and the monsoon onset (June), and onecorresponding to the retreat to the south of the inter-tropical convergence zone (September). ClassicalAcoustic Doppler Current Profiles, hydrological mea-surements, surface drifters and Argo/Coriolis profilersdeployment are performed during each cruise. TheSOP 2006 onset campaign saw the concomitant de-ployment of three research vessels (the French Atalante,the German Meteor, the U.S. Ronald H. Brown)centered on the month of June, simultaneously cover-ing the whole tropical Atlantic during the monsoononset. These vessels documented the air-sea exchanges,through both the ocean and the atmospheric boundarylayers. A notable achievement for AMMA was thereal time transmission of data to operational centers.In the same way, the radiosoundings from the threeships have been provided in real-time through Argofor assimilation in weather prediction models. Thefigure at the bottom of page 16 compares the seasurface salinity and temperature recorded in June2006 with those recorded in June 2005, showingthat in 2006 the upwellings were not yet ob-served at the period of normal onset of themonsoon, a fact that has probably some bearingon the very unusually late onset of the monsoonin 2006.

SOP0: the dry phase of the WAM. The SOP0period (January and February 2006) used the BritishBAe146 aircraft and a French lidar-equipped microlightaircraft, both operating from Niamey to make in situand remote sensing measurements on smoke frombiomass burning and mineral dust aerosols. High qual-ity measurements of the physical and optical propertiesof mixtures of these aerosols allowed their effect onthe radiation budget over the region to be quantified.Results from 15 aircraft flights suggest that, forNiamey, the monthly-mean surface solar radia-tion is reduced by more than 50 Wm-2 owing tothe presence of dust/biomass burning and thatdistinct, discrete layers of biomass burning aero-sol frequently overly layers of mineral dust.

Observations (solid lines and star symbols) and results fromtwo models (squares, triangles) showing the amount of solarenergy absorbed in the atmosphere before, during, and after theMarch 7–9, 2006 dust storm. During the dust storm, observa-tions show a significant increase in atmospheric absorptionwhile the models underestimate the amount of energy absorbed.Before and after the dust storm, the model predictions areconsistent with observations.

February 20076

Under the auspicies of the GEWEX Global Land-Atmosphere System Study (GLASS) and theInternational Geosphere-Biosphere Project (IGBP)-international Land Ecosystem-Atmospheric ProcessesStudy (iLEAPS), the LUCID Project was created toexplore, using methodologies that the major climatemodelling groups recognize, impacts of land-coverchange that are above the noise generated by modelvariability.

Over the last decade there has been a tremen-dous increase in the literature describing the impactof land-cover change on climate at the regional andglobal scale. As with most of the work on theimpact of Amazonian deforestation, modelling groupshave used different models, land parameterizations,land-cover maps, model configurations and experi-mental protocols. As a result, the actual impact oflarge scale land-cover change on the Earth’s cli-mate is believed to be one of the following: (a)significant and large; (b) only local to the perturba-tion; or (3) small enough to be ignored. Some groupsfind significant teleconnections that other groupsdismiss as model variability. Ultimately, much ofthe land-cover change community at the time of theThird Assessment of the Intergovernmental Panelon Climate Change (IPCC, 2001) believed the casefor including land-cover change in climate simula-tions was “proven.” Even if the community was notcertain about global-scale teleconnections, confidencethat land-cover change drove significant regionalimpacts was very high and it was assumed thatmodel simulations for the Fourth IPCC AssessmentReport (AR4, 2007) would take 20th century land-cover change into account and likely incorporatescenarios for 21st century change.

The AR4 is now basically complete and thecoupled climate model simulations did not take intoaccount land-cover change through the 20th Centuryor into the 21st Century. Clearly, the land coverchange community had failed to communicate itsbelief that land-cover change was a major forcingfactor effecting climate (regionally or globally). In

LAND-USE AND CLIMATEIDENTIFICATION OF ROBUST IMPACTS

(LUCID) PROJECT

Nathalie de Noblet1 and Andy Pitman2

1Laboratoire des Sciences du Climat et del’Environnement, CEA-CNRS-UVSQ, France,2Environment and Life Sciences, Macquarie

University, Sydney, Australia

SOP1 and SOP2: the onset phase and the peakmonsoon. SOP1 and SOP2 extended from 1 June to21 August with four different aircraft operating fromNiamey and two from Ouagadougou. An importantcomponent of SOP2 was the partnership betweenAMMA and Stratospheric-Climate Links with Empha-sis on the Upper Troposphere and Lower Stratosphere(SCOUT) Program in order to explore the tropicaltropopause layer. Ozone and backscatter sondes (witha variety of payloads devoted to water vapor, chem-istry, aerosols and cloud measurements) were launchedin this framework, helping to show the active trans-port of these chemicals through the tropopause inWest Africa.

SOP3: late monsoon and downstream evolu-tion. SOP3 extended from 15 August to 25 Septemberwith one aircraft (the NASA DC-8) operating fromCabo Verde and two from Dakar (the BAe146 andthe French Falcon). SOP3 was focused on the obser-vation of the transition of synoptic and convectiveweather systems as they move from the land out overthe Atlantic. Seven African Easterly Waves weresampled by the DC-8, four of which became namedstorms (Ernesto, Debby, Gordon, Helene), and eightdust aerosol flights were conducted.

Concluding remarks. It is not common for afield programme to embrace such a wide range ofspatial and temporal scales, nor to involve such arange of scientific disciplines. The fact that this pro-gram has been achieved in an environment that canbe very tough on personnel and equipment is a testa-ment to the efforts of many dedicated people, inAfrica and overseas.

Acknowledgements: Based on a French initiative,AMMA was built by an international scientific groupand is currently funded by a large number of agen-cies, especially from France, UK, U.S. and Africaand the European Community’s Sixth Framework Re-search Programme. For more information about AMMA,see: http://www.amma-international.org.

References

Redelsperger, et al., 2006. AMMA West African monsoonstudies are addressing GEWEX water cycle issues. GEWEXNews, 15(1).

Redelsperger, J.-L., C. Thorncroft, A. Diedhiou, T. Lebel, D.Parker, J. Polcher, 2007. African Monsoon, MultidisciplinaryAnalysis (AMMA): An International Research Project and FieldCampaign. Bull. Amer. Meteorol. Soc., in press.

Slingo, A., T. P. Ackerman, R. P. Allan, et al., 2006. Obser-vations of the impact of a major Saharan dust storm on theEarth’s radiation budget. Geophys. Res. Lett., 33, L24817.

7February 2007

discussions within GEWEX-GLASS and IGBP-iLEAPS, there was a sense that the land-coverchange community had proven to itself that land-cover change was important, but had not shown tothe major modelling groups just how important itwas. This led to the decision to launch LUCID, amajor experiment to evaluate the impact of land-use induced land-cover changes on climate.

The objective of LUCID is to identify and quantifythe impacts of land-use induced land-cover changeson the evolution of climate between the pre-indus-trial epoch and the present day. Multi-model andensemble simulations will be used to assess therobustness of the identified changes. Impacts ofland-cover change will be assessed by examiningthe mean climate, climate variability and climateextremes. The possible impact of land-cover changeon sea-surface temperatures (SSTs) and on oceancirculation will also be assessed. Among the finalobjectives is determining if a case can be made toensure land-cover changes are included in any fu-ture assessments by the IPCC.

The design includes fixed SSTs and a landcover perturbation reflecting both crops and pas-ture. To assess the robustness of the results ensemblesimulations will be conducted for each natural land-cover and current land-cover (at least six realiza-tions of each cover will be required to samplemodel variability well). The intent is to identifyrobust changes via fixed SST experiments, but thenmove rapidly to coupled model simulations sincethese are the tools now used for climate projection.Fixed SST experiments will be performed first andthese will be used as a baseline for subsequentmore extensive simulations. For more informationabout LUCID or if you are interested in conductingthe fixed SST experiment, contact Nathalie de Nobletat Nathalie.De-Noblet@cea.fr.

THE GLOBAL LAND-ATMOSPHERECOUPLING EXPERIMENT – PHASE 2

Randal KosterNASA Goddard Space Flight Center

The goal of Phase II of the Global Land Atmo-sphere Coupling Experiment (GLACE-2) is to quantify,across a broad range of forecast models, the subseasonalforecast skill associated with the initialization of land-surface variables. GLACE-1 addressed the followingquestion: to what extent are variations in meteorologi-cal variables such as precipitation and air temperatureguided by variations in land-surface prognostic states?Because meteorological variables themselves have astrong impact on land-surface state variations, thereverse direction of causality—the impact of land con-ditions on atmospheric variables—cannot be teasedout directly from standard atmospheric general circu-lation models diagnostics. GLACE-1 defined anexperiment that could isolate these land impacts.

The details of the experimental design and anoverview of the GLACE-1 results are provided byKoster et al. (2006). The study featured severalimportant findings: (i) within a given model, thelocations for which precipitation variations are con-trolled by variations in soil moisture state showstrong geographical variations; (ii) the coupling strengthbetween soil moisture and precipitation varies widelybetween models; and (iii) to a certain degree, themodels behavior in some regions is similar, fromwhich we can deduce multi-model estimates of land-atmosphere coupling “hotspots” (Koster et al., 2004a).These “hotspots,” for the most part, are found inthe transition zones between humid and dry areas(e.g., central North America and the Sahel)—zonesfor which evaporation is both large and responsiveto variations in soil moisture.

Note that for soil moisture initialization to affecta forecast, two things must happen: (i) the initial-ized soil moisture anomaly must be rememberedinto the forecast period, and (ii) the atmospheremust respond in a predictable way to the soil mois-ture anomaly. GLACE-1 is, in essence, a thoroughanalysis of the second element and filled a void,since a broad, multi-model analysis of this importantaspect of the climate system had never before beenperformed.

An analysis of the combination of the two ele-ments, however, is arguably far more important. Thefull initialization question—how would an accurate landsurface initialization affect a meteorological forecast?—motivates much of today’s research into land-atmosphere

Applications are invited for the position of Directorof the International GEWEX Project Office (IGPO).The Director of IGPO leads the development andimplementation of the GEWEX Project and its interna-tional coordination with all WCRP strategies. TheIGPO is the focal point for the planning and implemen-tation of all GEWEX projects and activities. For moreinformation about the position, see http://www.gewex.org/igpo-director-ad.pdf.

POSITION ANNOUNCEMENT:DIRECTOR OF IGPO

February 20078

interaction. Despite its importance, the question hasnever been comprehensively and systematically ad-dressed by the community. Indeed, relevant studieswith individual modelling systems, in addition to beinguncoordinated, are relatively rare. A community-widemulti-model analysis is needed to ascertain the valueof land initialization in today’s forecast systems.

The community is now poised to embark onGLACE-2, an international model intercomparisonexperiment that will provide a multi-model, compre-hensive view of the impact of land state initializationon forecast skill. Participants in GLACE-2 will learnthe quantitative benefits that can stem from the incor-poration of a realistic land-surface state initializationinto their forecast algorithms. They will be asked toperform two series of forecasts. Each series consistsof 100 2-month forecast ensembles (ten members perensemble) covering ten boreal spring and summerstart-dates in each of the years 1986–1995. The totalsimulation period for the two series together amountsto 333 simulation years.

Series 1 will utilize realistic land-surface stateinitialization and optimally, these will be establishedthrough participation in the Global Soil Wetness Project–Phase 2 (GSWP-2; see Dirmeyer, 2006), an ongoingresearch activity of the Global Land-Atmosphere Sys-tem Study (GLASS) of GEWEX. Through GSWP-2,modellers produce global fields of land-surface statevariables—and thus initial conditions for forecasts—bydriving their models offline with global arrays of ob-servations-based meteorological forcing.

Series 2 is identical to Series 1 except for thefact that it will not benefit from realistic land stateinitialization. Through the comparison of Series 1and 2, we will isolate the impact of land initializa-tion on the forecasts. A prototype version of thisexperiment was successfully performed by Kosteret al. (2004b; hereafter K04b). The proposed analyseswill start with (but will not be limited to) thoseoutlined in that work. GLACE-2 will first deter-mine the degree to which each model can “predictitself”—the extent to which simulated atmosphericchaos in the model can foil a forecast. The analysiswill reveal the geographical and temporal variationof this “potential predictability” at subseasonaltimescales as produced by both the ocean boundaryand the land initialization.

Next, GLACE-2 will evaluate forecast skill. Theobserved precipitation or air temperature in a forecastperiod will be regressed against the forecasted value,and the resulting r2 value will be taken as the skilllevel. An example of the type of results that will

come out of GLACE-2 is shown in the figure at thetop of page 16 which shows the generally positiveimpact of realistic land initialization on the predic-tion skill realized for 1-month temperature forecasts,as established by K04b for a specific modellingsystem. The GLACE-2 analyses will consider sepa-rately the four 15-day periods within a forecast, sothat the fall-off of skill with lead time can bequantified. Comparing the r2 values obtained fromthe Series 1 and Series 2 forecasts will isolate thecontribution of land initialization to forecast skill.

K04b suggests that the contribution of land ini-tialization to skill in regions of high potentialpredictability, although statistically significant, maybe modest. Teasing out the skill levels in the pres-ence of large natural chaotic variability may turnout to be a challenge. Thus, GLACE-2 participantsare encouraged (but not required) to perform addi-tional forecast simulations that span a much longerperiod of time. Forcing data will be provided toallow the forecast simulations to cover multipledecades. GLACE-2 participants are also encour-aged to repeat the experiments for austral summer.

GLACE-2 will provide the first-ever com-prehensive survey of forecast skill levelsassociated with land state initialization in today’sstate-of-the-art atmospheric GCMs. In additionto contributing to this survey, participants will achievethe added, and perhaps invaluable, benefit of docu-menting the value of land initialization withintheir own modelling systems. Any modelling groupwilling to perform the baseline experiments iswelcome and encouraged to participate. Inter-ested groups should contact Randal Koster(randal.d.koster@ nasa.gov) for further informa-tion. GLACE-2, like GLACE-1 is jointly sponsoredby the GLASS panel of the GEWEX and the Work-ing Group on Seasonal-to-Interannual Prediction ofthe Climate Variability Experiment (CLIVAR).

References

Dirmeyer, P. A., X. Gao, M. Zhao, Z. Guo, T. Oki, and N.Hanasaki, 2006. GSWP-2, multimodel analysis and implicationsfor our perception of the land surface. Bull. Amer. Soc., 84,1013–1023.

Koster, R. D., P. A. Dirmeyer, Z.-C. Guo, et al., 2004a. Regionsof strong coupling between soil moisture and precipitation. Sci-ence, 305, 1138–1140.

Koster, R. D., M. J. Suarez, P. Liu, U. Jambor, A. Berg, M.Kistler, R. Reichle, M. Rodell, and J. Famiglietti, 2004b. Realisticinitialization of land surface states: Impacts on subseasonal fore-cast skill. J. Hydrometeorology, 5, 1049–1063.

Koster, R. D., Z.-C. Guo, P. A. Dirmeyer, et al., 2006. GLACE,the Global Land-Atmosphere Coupling Experiment, 1, Overview.J. Hydrometeorology, 7, 590–610.

9February 2007

THE DIURNAL CYCLE – GABLSSECOND INTERCOMPARISON PROJECT

Gunilla Svensson1 and Bert Holtslag2

1Department of Meteorology, StockholmUniversity, Sweden, 2Department of

Meteorology and Air Quality, WageningenUniversity, The Netherlands

The goal of the GEWEX Atmospheric Bound-ary Layer Study (GABLS) is to improve therepresentation of the atmospheric boundary layer inweather and climate models, which should also benefitair quality, wind engineering and earth system stud-ies. The first GABLS study was on a weak stablystratified idealized case with a constant surface-cooling rate. The outcome is reported in a specialissue in Boundary Layer Meteorology (Holtslag,2006). After this initial exercise, it was decided thatthe next step was to study the full diurnal cycle ofthe boundary layer over land. While the first ex-periment was an idealized study involvingsingle-column models (SCMs) (Cuxart et al., 2006)and Large Eddy Simulation (LES) (Beare et al.,2006), the set up for the second one is based onobservations of the Cooperative Atmosphere-Sur-face Exchange Study–1999 (CASES-99) (Poulos etal., 2002). The main purpose of the second study isto examine the extent to which the diurnal cycleover land is represented by the boundary layerschemes included in today’s numerical weather pre-diction and climate models.

A period from the CASES-99 observations wasselected because of the relatively flat location, drysurroundings and clear sky conditions. The casewell represents a textbook case of a radiation forceddiurnal cycle. In this study, we focus on theintercomparison of various boundary layer schemesand as such we simplify the forcing conditions tofacilitate a better intercomparison between models.

The CASES-99 data set was collected duringOctober 1999 in Kansas, United States (37.6N,96.7W). Here, we focus on two diurnal cycles duringthe period 23–24 October. When designing the modelexperiment, our ambition was to keep the set-up ofthe simulation as simple as possible to make itpossible for many groups to participate and to en-sure that model specific implementation of morecomplicated processes would not obscure the re-sults. Thus, all the participating SCMs are drivenby a prescribed surface temperature, constant geo-strophic wind and a small subsidence rate startingin the afternoon of 23 October 1999.

To find a situation in atmospheric observationaldata that is horizontal, homogeneous and quasi-sta-tionary on the synoptic scale is extremely difficult.As mentioned above, a constant geostrophic ofabout 9.5 ms-1 wind was used to force the SCMs.To examine the large-scale flow, we diagnosedthe geostrophic wind from the pressure field of athree-dimensional simulation using the Coupled Ocean-Atmosphere Prediction System (COAMPS®). Thegeostrophic wind was approximately constant forthe first 12 hours followed by an almost lineardecrease for the next 24 hours. By the morning ofOctober 24 the quasi-stationary conditions requiredfor the comparison with observations had ended.As a result the comparison with observations isfrom 20LT October 22–07LT October 24, (i.e., twofull nights and the intermediate day).

More than 20 groups, including numerical weatherprediction centers and global climate modellers havesubmitted model results, some for more than onemodel configuration adding up to more than 30 simu-lations. Both models with prognostic turbulent kineticenergy, as well as first orders models are repre-sented. The model results are grouped together bytheir closure (first order or Turbulent Kinetic En-ergy schemes) and the height to the first verticalcomputational level, thus constructing four groupsof model results.

Even though the surface temperature is given inthe case set up, the SCMs give quite different 2-mtemperatures. The intermodel spread, during bothday and night, is approximately 2 degrees. Thedifferences manifest themselves in the sensible heatfluxes (see the left panel of the figure at the bot-tom of page 1), and in very different boundary-layerheights. As in the first GABLS experiment, manymodels have a too strong surface wind speed dur-ing the night (Cuxart et al., 2006). This occursdespite the too weak background forcing during thefirst night. However, almost all models have a de-crease in the wind speed during the morning hourswhile the observations show a very sudden increasein the wind at the time when the boundary layerbecomes convective. The models capture the tran-sition from night time stably stratified conditions todaytime convective boundary layer well, but not thesudden increase in wind speeds and they underes-timate day time wind speeds. The right panel of thefigure at the bottom of page 1 presents the diurnalamplitude for 10 m winds for all models (i.e., eachmodel's mean wind is subtracted) and observationsfor October 23 as well as the observed monthlymean. As seen in the figure, October 23 is a rep-

February 200710

19TH MEETING OF THE GEWEXSCIENTIFIC STEERING GROUP

Rick Lawford and Dawn ErlichInternational GEWEX Project Office

The Nineteenth Session of the GEWEX Scien-tific Steering Group (SSG) was held at the East-WestCenter at the University of Hawaii in Honolulu, 22–26 January 2007. The meeting was hosted by Dr.Julian P. McCreary, Jr. of the International PacificResearch Center with excellent support from hisassistant, Ms. Jeanie Ho. Approximately 45 expertsfrom 10 countries attended the meeting. The meet-ing focused on GEWEX activities and on howGEWEX could organize itself to most effectivelymeet the requirements of the GEWEX Phase IIRoadmap, the World Climate Research Programme(WCRP) strategic plan and, more generally, thegoals of climate research. As a result of this ap-proach the discussions focused on GEWEX projectsand their links with some central projects includingthe Climate Variability and Predictability (CLIVAR)Project, the Global Water System Project (GWSP),THe Observing System Research and PredictabilityExperiment (THORPEX), and Global Climate Ob-serving System (GCOS).

In addition a number of scientific talks weregiven, including:

• Dr. Robert Houze on the Tropical RainfallMeasuring Mission (TRMM) data and latentheating estimates.

• Dr. William Rossow on Cloudsat and itsimplications for global data sets.

• Dr. Bin Wang on monsoon research needs.

• Dr. Martin Werscheck on EUMETSAT’sSatellite Applications Facility

Other presentations were given by Drs RikoOki, Jared Entin, and Eileen Shea. The followingparagraphs summarize some of the main conclu-sions and actions arising from the programmaticdiscussions at the meeting.

The most significant and far reaching decisionat this meeting was the SSG’s approval of a pro-posal to merge the Coordinated Enhanced ObservingPeriod (CEOP) and the GEWEX HydrometeorologyPanel (GHP) into a single entity known as theCoordinated Energy and Water Cycle ObservationsProject (CEOP). A background paper describingthe rationale for this decision is given at http://www.gewex.org. In addition it was agreed that theGEWEX Continental-Scale Experiments (CSEs) will

resentative day for CASES-99. The model meanwinds vary between 3.6 and 5.8 ms-1 while themean observed wind for this period is 4.1 ms-1.Note that all models underestimate the diurnal cycle,and most models forecast a too high mean windspeed (not shown).

The first conclusion from the second GABLSexperiment is that the models produce verydifferent results in all parameters and that theyall differ substantially from the observations.When comparing the models and the observations,the most significant difference is the underestimateddiurnal cycle in the 10-m wind speed. The modelledwind speeds are generally too high during the stablystratified night and too low during the unstably strati-fied daytime conditions. The difference is most strikingduring the morning hours when most models give adecrease in the wind speed while the observationshave a distinct increase in the low-level wind speedas soon as the change to convective conditions occur.

These preliminary results from the intercomparisonof column models have inspired other studies usingLES and mesoscale model intercomparisons. Theseand other recent results will be further discussed ata forthcoming workshop to be held at StockholmUniversity, 19–21 June 2007. If you are interestedin participating, please contact the authors as soonas possible or visit: http://www.misu.su.se/~gunilla/gabls/workshop.

Acknowledgements: We are indebted to theparticipating modelling groups for the time they havedevoted to making the simulations and to theexperimentalists providing the CASES-99 data.Thorsten Mauritsen, Gert-Jan Steeneveld and MichaelTjernström are also acknowledged for their valu-able input.

References

Beare, R. J., M. K. MacVean, A. A. M. Holtslag, et al., 2006.An intercomparison of Large-Eddy Simulations of the stableboundary layer. Bound.-Layer Meteor., 118, 247–272.

Cuxart, J., A. A. M. Holtslag, R. J. Beare, E. Bazile, A. Beljaars,A. Cheng, et al., 2006. Single-column model intercomparisonfor a stably stratified atmospheric boundary layer. Bound.-Layer Meteor., 118, 273–303.

Holtslag, A. A. M., 2006. GEWEX Atmospheric Boundary-Layer Study (GABLS) on stable boundary layers, Bound.-LayerMeteor., 118, 243–246.

Poulos, G. S. and Coauthors, 2002. CASES-99: A comprehen-sive investigation of the stable nocturnal boundary layer. Bull.Amer. Meteor. Soc., 83, 555–581.

11February 2007

Participants at theGEWEX SSG-19 Meeting.

be known as GEWEX Regional Hydro-climateProjects (RHPs) within this new structure. TheGEWEX SSG believes that the new panel will pro-vide a global framework for the RHP activities andthat the CEOP data services will benefit the fullrange of science being undertaken in the RHPs.The technical and scientific criteria used as termsof reference for CSEs will be updated for theRHPs to better reflect current WCRP and GEWEXobjectives. The restructured CEOP will be meetingin Washington, DC in March to address some ofthe issues related to the merger and to discussways to clarify and strengthen CEOP’s contribu-tions to the GEWEX Roadmap.

Assessments of global data products have beencarried out under the leadership of GEWEX Radia-tion Panel (GRP). All four principal sets of dataproducts [International Satellite Cloud ClimatologyProject (ISCCP), Global Aerosol Climatology Project(GACP), Global Precipitation Climatology Project(GPCP), and the Surface Radiation Budget (SRB)Project] now cover periods longer than 20 yearsand are increasingly being used in climate studies.The projects continue working towards a coordi-nated reprocessing activity so that these productscan have even broader application. GRP is propos-ing to make ISCCP an operational product. Theprecipitation assessment is complete and the reportis in review. Other assessment reports are alsonearing completion. GPCP is now collaborating withthe International Precipitation Working Group con-cerning improved measurements of snowfall andwith a consortium for quantitative precipitation es-timation under the WCRP/THORPEX activity.

The GEWEX Modelling and Prediction Panel(GMPP) outlined its new approach to model evalu-ation and parameterization development. The SSG

welcomed this structured approach and supports theambitious GMPP agenda. GMPP will lead the GEWEXcoordination of the Aerosol Cloud Precipitation Cli-mate Initiative with the international LandEcosystem-Atmospheric Processes Study (iLEAPS)and with the international Global Atmospheric Chem-istry Program. GMPP will also investigate collaborationwith the Task Force on Seasonal Prediction throughthe Global Land Atmospheric Coupling Experiment-2(GLACE-2) and how the effects of snow and veg-etation initialization on predictive skill at intraseasonalto seasonal time scales can be assessed. The GEWEXSSG encouraged GMPP to advance a proposal fora joint GEWEX Cloud System Study (GCSS)/WCRPWorking Group on a Coupled Modelling collabora-tion on the Cloud Feedback Model IntercomparisonProject (CFMIP) to assess climate change cloudfeedbacks and to potentially use the Data Integra-tion for the Model Evaluation (DIME) web site tohost model and observational data to facilitate thisenterprise. CFMIP will encourage the systematiccomparisons of cloud feedbacks among GCMs andcomparisons of model clouds with observations.

The SSG approved the Northern Eurasia EarthScience Partnership Initiative (NEESPI) as a Re-gional Hydroclimate Project. NEESPI seeks tounderstand how the land ecosystems and continen-tal water dynamics in northern Eurasia interact withand alter the climatic system, biosphere, atmosphere,and hydrosphere of the Earth. In addition, the draftstrategic plan of the Hydrology Applications Project(HAP) was reviewed. This project, which succeedsthe Water Resources Application Project (WRAP),will be the primary GEWEX link with the GlobalWater System Project (GWSP). After some modi-fications to the plan and some broadening of thelevel of participation GEWEX should be ready tolaunch this new initiative in the summer of 2007.

February 200712

FIRST GEWEX AEROSOL PRODUCTSASSESSMENT WORKSHOP

14–15 September 2006College Park, Maryland, USA

Zhanqing LiUniversity of Maryland

The GEWEX Aerosol Product Assessment (GAPA)Working Group was established to assess the qualityand compatibility of global aerosol products with afocus on the Global Aerosol Climatology Project (GACP)product. GAPA is led by Drs. Z. Li and X. Zhao,University of Maryland, with members representing allmajor teams producing global aerosol products.

Aerosols are a major atmospheric variable influ-encing both the transfer of radiative energy, and theconversion of water vapor into cloud droplets andraindrops. Most Global Circulation Models (GCMs)now incorporate aerosol parameters and physical pro-cesses linking aerosols with the energy and watercycles so that aerosol direct and indirect effects onclimate can be computed. Over the years, many glo-bal aerosol products have been generated from historical[e.g., Advanced Very High Resolution Radiometer(AVHRR), POLarization and Directionality of the Earth'sReflectances (POLDER)] and current satellite sensors[e.g., Moderate Resolution Imaging Spectroradiometer(MODIS), Multi-Angle Imaging Spectroradiometer(MISR)], and new products are expected from futuresensors [e.g., Visible Infrared Imager/Radiometer Suite(VIRS)]. As the number of aerosol products increases,discrepancies among the products also increase. Datausers are confronted with an ever-increasing chal-lenge of deciding which product is the best to use andhow much uncertainty exists in the different products.

The objectives of GAPA are: (1) Use currentdata sets to assess and improve the confidence levelin the 30-year satellite aerosol climatology of aerosoloptical depth (AOD) and Ångström exponent fromAVHRR/Total Ozone Mapping Spectrometer (TOMS);(2) Understand and resolve discrepancies among allmajor global aerosol products and to document uncer-tainties; and (3) Produce improved, consistent, unifiedglobal aerosol products that link both historical, cur-rent, and future satellite observations for long-termtrend studies and climate studies.

The workshop objectives were: (1) Review majorglobal aerosol products; (2) Evaluate all key issues in

Given the WCRP crosscuts and the responsi-bility that GEWEX has for leading the monsooncrosscut, the research priorities for this topic re-ceived significant attention at the meeting. A keyoverarching issue for monsoon prediction is the fun-damental need for improved representation of tropicalconvection. The SSG endorsed the concept for theTHORPEX/WCRP Year of Tropical Convection(YOTC), a coordinated observing, modelling andforecasting tropical convection activity. YOTC willexploit the vast amounts of existing and emergingobservational and computational resources now avail-able in conjunction with the development of newhigh resolution modelling frameworks to advancethe characterization, diagnosis, modelling and pre-diction of multiscale convective/dynamic interactionsand processes, including the two-way interactionbetween tropical and extra-tropical weather/climate.

The Asian Monsoon Year (AMY) also gainedGEWEX support as a joint GEWEX/CLIVAR [plusthe Climate and Cryosphere (CliC) Project andStratospheric Processes And their Role in Climate(SPARC)] activity designed to provide improvedobservations, analyses, and modelling in the Asianmonsoon regions. AMY would focus on the 2008time period and cover the full annual cycle of bo-real summer monsoon thus contributing to the YOTCinitiative. AMY would bring together the GEWEXand CLIVAR monsoon efforts in the Asian-Austra-lian region, and in particular, the Monsoon AsianHydro-Atmosphere Scientific Research and predic-tion Initiative (MAHASRI). The idea of extendingthis effort to the global perspective for an Interna-tional Monsoon Year was discussed.

Concern was expressed about the status of theEuropean GEWEX Coordinator function beyond 2007.The SSG recognized the valuable contribution ofthe European GEWEX Coordinator (Dr. Peter vanOevelen) in supporting GEWEX activities over thepast 2½ years and asked the SSG Chair to requestthat the European Space Agency (ESA) continue tosupport this function.

On behalf of GEWEX, the International GEWEXProject Office expresses its appreciation to those agen-cies (ESA, EUMETSAT, Japan Aerospace ExplorationAgency, National Aeronautics and Space Administra-tion, National Oceanic and Atmospheric Administration)that sent representatives to the meeting. Althoughthere were no formal presentations on agency activi-ties these representatives enriched the discussion aboutGEWEX goals and brought new perspectives to beconsidered in GEWEX strategies.

WORKSHOP/MEETING SUMMARIES

13February 2007

aerosol retrievals such as sensor calibration, cloudscreening, algorithm, surface effects, and synergy;(3) Develop a strategy for identifying major sourcesof discrepancies among the aerosol products; (4)Estimate the range of uncertainties on various timeand space scales; and (5) Develop a roadmap forreconciling the differences and for generating uni-fied consistent products.

Aerosol product development teams provided up-dates on products from satellites [AVHRR-GACP,AVHRR Pathfinder-Atmosphere (PATMOS), AVHRR-National Institute of Environmental Studies, TOMS,Sea-viewing Wide Field-of-view Sensor (SeaWiFS),MODIS, MODIS-Deep Blue, MISR, and Cloud-Aero-sol Lidar Infrared Pathfinder Satellite Observation(CALIPSO)] and detailed descriptions of the retrievalprocedures. Several comparative studies/analyses werepresented that provided some insight into the impactof different assumptions made in the retrieval algo-rithms (e.g., aerosol size distribution, refractive index,surface spectral albedo ratio) on the differences inthe retrieved aerosol quantities. It was noted that theMODIS aerosol product is upgraded in its latest re-lease (Version 5) to correct some errors in the AODretrieval over land.

Advances in aerosol remote sensing technologywere introduced, such as the CALIPSO mission. Anupcoming newer version (Version 2) of the widelyused ground-based AErosol RObotic NETwork(AERONET) product is expected to produce morerealistic aerosol size distributions and single scatteringalbedos. Issues associated with spatial and temporalmatching between satellite and ground aerosol retriev-als were reviewed. A new computationally more efficientretrieval approach based on machine-learning tech-niques appears to offer some guidance for thedevelopment of an algorithm that can incorporate allavailable satellite data. In parallel with satellite remotesensing of aerosols, model simulations of global aero-sol distributions have made remarkable progress. Overland, the quality of AODs simulated by some modelsis as accurate as that of remotely sensed AODs,while the latter is superior over oceans. This indicatesthat the synergy between model simulations and re-mote sensing should be exploited. Joint experimentalstudies are planned to quantify and eventually removediscrepancies between the various aerosol products,which will lead to a coherent aerosol product derivedfrom all available sensors that is compatible with thelong-term historical product of the GACP.

For more information about GAPA activities, see:http://www.atmos.umd.edu/~zli/GAPA/gapa_main.htm.

GEWEX RADIATION PANEL MEETING

16–20 October 2006Frascati, Italy

William B. RossowCity College of New York

As a part of the Pan-GEWEX Meeting to com-plete the GEWEX Phase II Roadmap, the GEWEXRadiation Panel (GRP) met and reviewed its fouractive global satellite data projects [the Interna-tional Satellite Cloud Climatology Project (ISCCP),Global Aerosol Climatology Project (GACP), GlobalPrecipitation Climatology Project (GPCP) and theSurface Radiation Budget (SRB) Project, the lattertwo supported by surface data projects, Global Pre-cipitation Climatology Centre (GPCC) and BaselineSurface Radiation Network (BSRN), respectively)]and the four associated data product assessmentactivities. All four data products now cover periodslonger than 20 years and the projects continue towork towards a coordinated reprocessing to beginwithin the next year or two, after completion of theproduct assessments.

The four product assessment groups are at dif-ferent stages. The precipitation assessment, incollaboration with International Precipitation Work-ing Group (IPWG) is complete and the report isbeing reviewed by GRP members. The clouds andradiation assessment groups have completed twoworkshops and are now drafting reports. The radia-tion assessment group is planning a third workshopin 2007. The aerosol assessment group held its firstworkshop in September 2006 (see report on page12). Of particular note is that GPCP is now col-laborating with the IPWG concerning improvedmeasurements of snowfall with a consortium forquantitative precipitation estimation under the WCRP/THe Observing System Research and PredictabilityExperiment (THORPEX) activity. The SeaFlux Projectis moving towards completion of improved analysismethods and global product evaluations and may beready to produce a new global product (ocean sur-face turbulent fluxes) by early 2008. The similarLandFlux activity, in collaboration with GEWEXGlobal Land-Atmosphere System Study/Global SoilWetness Project, is being organized, starting withan international workshop to be held in Spring 2007,to evaluate the status of available land surfaceproperty data products and analysis methods. Insummary, the global data projects and associatedstudy activities are about on schedule to produceimproved, more homogeneous and more consistent

February 200714

cloud interactions in global models noting that thesophistication of these model representations has faroutrun the available observations needed for verifica-tion. F. Zhao described Chinese studies of aerosolsusing a combination of surface and satellite measure-ments, finding that the more absorbing aerosols overChina are concentrated at smaller sizes and loweroptical depths.

The other GRP study groups are also makinggood progress. The Continuous Intercomparison ofRadiation Codes Working Group is developing awebsite that contains synthetic and observation-basedtest cases for radiation codes, together with state-of-the-art calculations for the former, and measuredfluxes for the latter. The 3-D Radiative TransferWorking Group has now combined forces with otherworking groups to focus attention on the complexproblem of 3-D radiation in cloudy atmosphericboundary layers overlying complex vegetation cano-pies (and other heterogeneous surfaces) to examinehow important the non-linear 3-D effects are to ex-changes of radiation between the surface andatmosphere. Two other groups continue to work toorganize world efforts to produce systematic productsfrom surface lidar-cloud radar sites and from precipi-tation networks. The purpose of these efforts is, inpart, to provide complementary measurements to Cloud-Aerosol Lidar Infrared Pathfinder Satellite Observation(CALIPSO) satellite, CloudSat, and the Tropical Rain-fall Measuring Mission. These study efforts providecritical examinations of key problems related to thegeneral goals of the GRP—to complete a quantitativedescription of the weather-scale variations of the glo-bal energy and water cycle over more than one decade.To foster research using such a data collection, GRPwill organize a special symposium at the Fall 2007American Geophysical Union meeting on this topic.

Overall, progress on measuring radiation and cloudscontinues in a satisfactory way, but completing acomprehensive description of precipitation still requiressignificant effort. GRP is well along in establishingaccurate quantitative descriptions of radiation and clouds,as well as providing a test standard for representa-tions of radiative transfer in global models. In partnershipwith IPWG, GRP is planning important new initiativesto study key precipitation problems. Progress on im-proving determinations of surface fluxes is alsosatisfactory over oceans, but land and ice surfacefluxes need substantial new activities, as noted a newinitiative on land surface fluxes will begin in 2007.

The next GRP meeting will be held in Brazil inOctober 2007.

data products within the next few years. Monthlymean maps (common grid) for all of these dataproducts (and some others related to the energyand water cycle) have been posted to the GRPwebsite (http://grp.giss.nasa.gov/gewexdatasets.html).

Invited presentations were made by J. Russell onthe Geostationary Earth Radiation Budget mission, N.Loeb (on behalf of B. Wielicki) on Clouds and theEarth's Radiant Energy System, R. Cahalan on theSolar Radiation and Climate Experiment, and Y. Kerron the Soil Moisture Observing System. Y. Govaertsdescribed a European Organization for the Exploita-tion of Meteorological Satellites (EUMETSAT) activityto recalibrate the radiances from all first generationMeteosats. J. Bates provided an update on the statusof the National Polar-Orbiting Operational Environ-mental Satellite System; the GRP members indicatedthat the top priorities for restoration of instrumentswere the Total Solar Irradiance Sensor and EarthRadiation Budget Sensor. S. Buehler described thepotential for remote sensing of cirrus and upper tro-pospheric humidity using high (>100 GHz) frequencymicrowave measurements. D. Randall summarized thecurrent state of representing cloud processes in globalmodels and M. Bosilovich described the new globalmodel and assimilation system at the National Aero-nautics and Space Administration Goddard Space FlightCenter (called the Modern Era Retrospective-analysisfor Research and Applications). B. Nelson presentedan overview of the NEXRAD precipitation radar net-work and the potential that such networks have forstudying precipitation processes at high space-timeresolution. R. Bennartz summarized the results of aninternational workshop on remote sensing of snowfalland recommended a joint IPWG-GRP working groupto develop such techniques further. J. Schulz pro-vided an update on the status of EUMETSAT plansto produce new global water vapor products. J. Batesreviewed the development of principles to guide pro-duction of Climate Data Records.

New GRP members presented science talks.J. Schulz expanded on his report on water vaporproducts to focus on new satellite-based techniquesfor measuring water vapor profiles using new instru-ments, especially using the Spinning Enhanced Visibleand Infra-Red Imager and the Advanced MicrowaveScanning Radiometer. C. Kummerow reviewed thestate-of-art of retrieval of rainfall from satellites, es-pecially newer methods exploiting combined passiveand active microwave measurements. A key issue isthat the available in situ measurements are not ad-equate to evaluate the details of these new approaches.U. Lohmann presented an overview of modelling aerosol-

15February 2007

GEWEX/WCRP MEETINGS CALENDARFor a complete listing of meetings, see the

GEWEX web site: http://www.gewex.org1–2 March 2007—THE SCIENCE OF CLIMATE CHANGE:A ROYAL SOCIETY SHOWCASE OF THE IPCC 4TH AS-SESSMENT WG 1 REPORT, London, United Kingdom.

6–9 March 2007—SOLAS OPEN SCIENCE CONFERENCE,Xiamen, China.

12–17 March 2007—JOINT CEOP/IGWCO PLANNINGMEETINGS, Washington, DC, USA.

12 March – 4 April 2007—WORKSHOP ON INTERDISCI-PLINARY SCIENCE OF CLIMATE CHANGES: BASICELEMENTS, Buenos Aires, Argentina.

13–15 March 2007—4TH INTERNATIONAL CLIVAR CLI-MATE OF THE 20TH CENTURY WORKSHOP, Exeter, UK.

20–23 March 2007—5TH CLIMATE PREDICTION APPLI-CATIONS SCIENCE WORKSHOP, Seattle, Washington, USA.

26–30 March 2007—28TH SESSION OF THE WCRP JOINTSCIENTIFIC COMMITTEE, Zanzibar, Tanzania.

15–20 April 2007—EGU GENERAL ASSEMBLY 2007, Vienna,Austria.

21–26 April 2007—13TH BRAZILIAN SYMPOSIUM ONREMOTE SENSING, Florianpolis, Brazil.

23–27 April 2007—ENVISAT SYMPOSIUM 2007, Montreaux,Switzerland.

30 April – 3 May 2007—7TH WORKSHOP ON DECADALCLIMATE VARIABILITY, Waikoloa Village, Hawaii.

3-4 May 2007—NEESPI SUMMIT, Helsinki, Finland.

7–9 May 2007—EARTHCARE WORKSHOP, Noordwijk, TheNetherlands.

20–21 May 2007—GLOBAL DIMMING, BRIGHTENING ANDRELATED ISSUES IN CLIMATE CHANGE, Nanjing, China.

22–25 May 2007—AGU JOINT ASSEMBLY, Acapulco, Mexico.

4–8 June 2007—WCRP WORKSHOP ON SEASONAL PRE-DICTION, Barcelona, Spain.

4–8 June 2007—5TH STUDY CONFERENCE FOR BALTEX,Island of Saaremaa, Estonia.

19–21 June 2007—GABLS WORKSHOP, Stockholm, Sweden.

25–29 June 2007—22ND CONFERENCE ON WEATHERANALYSIS AND FORECASTING/18TH CONFERENCE ONNUMERICAL WEATHER PREDICTION, Park City, Utah.

27–29 June 2007—3RD HEPEX WORKSHOP, Stresa, Italy.

2–13 July 2007—XXIV IUGG ASSEMBLY, EARTH, OURCHANGING PLANET, Perugia, Italy.

23–27 July 2007—IGARSS 2007, Barcelona, Spain.

31 July – 3 August 2007—7TH ASIAN LIDAR CONFER-ENCE, Bangkok, Thailand.

20–24 August 2007—10TH INTERNATIONAL MEETINGON STATISTICAL CLIMATOLOGY, Beijing, China.

GEWEX NEWS

Published by the International GEWEX Project Office

Richard G. Lawford, DirectorDawn P. Erlich, Editor

Mail: International GEWEX Project Office1010 Wayne Avenue, Suite 450Silver Spring, MD 20910, USA

Tel: (301) 565-8345Fax: (301) 565-8279

E-mail: gewex@gewex.orgWeb Site: http://www.gewex.org

26–30 August 2007—EARTH OBSERVING SYSTEMS XII(OP400), San Diego, California.

27–31 August 2007—2ND INTERNATIONAL CONFERENCEON EARTH SYSTEM MODELLING, Hamburg, Germany.

27–31 August 2007—3RD ALEXANDER VON HUMBOLTINTERNATIONAL CONFERENCE ON THE EAST ASIANSUMMER MONSOON, PAST, PRESENT AND FUTURE,Beijing, China.

27 August – 1 September 2007—3RD INTERNATIONALSYMPOSIUM ON RIVERINE LANDSCAPES, Brisbane,Australia.

1–4 September 2007—XIII WORLD WATER CONGRESS,Montpellier, France.

5–7 September 2007—GRP WGDMA MEETING, New York,NY.

9–14 September 2007—EUROPEAN AEROSOL CONFER-ENCE, Salzburg, Austria.

24–28 September 2007—CHAPMAN CONFERENCE: THEROLE OF THE STRATOSPHERE IN CLIMATE AND CLI-MATE CHANGE, Santorini, Greece.

24–28 September 2007—4TH SEAFLUX WORKSHOP,Amsterdam, Netherlands.

9–12 Oct 2007—GEWEX RADIATION PANEL MEETING,Buzios, Brazil.

22–25 October 2007—A-TRAIN-LILLE SYMPOSIUM, LilleGrand Palais, France.

22–26 October 2007—23RD SESSION OF WGNE, Shanghai,China.

22 October – 3 November 2007—2007 SOLAS INTERNA-TIONAL SUMMER SCHOOL, Corsica, France.

12–15 November 2007—INTERNATIONAL CONFERENCEON ADAPTIVE AND INTEGRATED WATER MANAGE-MENT (CAIWA 2006), Basel, Switzerland.

26–30 November 2007—2ND INTERNATIONAL AMMACONFERENCE, Karlsruhe-Leopoldshafen, Germany.

10–14 December 2007—FALL AMERICAN GEOSPHYSICALUNION MEETING, San Francisco, California.

February 200716

QUANTIFYING MONTHLY FORECAST SKILLASSOCIATED WITH REALISTIC LAND SURFACE INITIALIZATION

Sea-surface salinity and sea-surface temperature along the tracks of the AMMA-EGEE1 (June 2005) and AMMA-EGEE3(June 2006) oceanic campaigns. The Gulf of Guinea was much warmer in June 2006 than in June 2005, which isprobably one factor explaining the very late onset of the monsoon over the continent in 2006. See article by T. Lebel,et al. on page 4.

WARMER TEMPERATURES IN GULF OF GUINEA EXPLAIN THELATE ONSET OF WEST AFRICAN MONSOON

Increased skill for monthly air temperature forecasts (measured as the r2 between observed and forecasted values)resulting from a realistic land moisture initialization. For clarity, results are shown only where both the potentialpredictability and the rain gauge density over the forecast suite period is adequate. “Area 1” and “Area 2” refer topotential predictability levels above 0.1 and 0.3, respectively. See article by R. Koster on page 7.