intercomparisons working groupe activities

IGST XIII – Washington 2/06/2008

Intercomparisons Working Groupe activities

• Status of the intercomparison exercice

• Some exemples of diagnostics based on Class 1/2

Prepared by F. Hernandez

K. Lisaeter, L. Bertino, F. Davidson, M. Kamachi, G. Brassington, P. Oke, A. Schiller, C. Maes, J. Cummings, E. Chassignet, H. Hulburt, P. Hacker, J. Siddorn, M. Martin, S. Dobricic, C. Regnier, L. Crosnier, N. Verbrugge, M. Drévillon, J-M Lellouche


Status of the intercomparison exercice

• Methodology decided:

– Compare operational/dedicated hindcast from Feb-March-April period.

– Consistency and quality assessment (not performance)

– Intercomparison based on Class 1 and Class 2 metrics, and reference data

– Files shared on OpenDap/FTP, assessment performed by different teams on dedicated ocean basins

• Preliminary work performed:

– Intercomparison plan endorsed

– Technical implementation documents (metrics definition) written and distributed


Status of the intercomparison exercice: definition of metrics

• New description of Class 1, Class 2 and Class 3 metrics:

– Regional areas revisited to fit recommendations'

– Complete description of mooring, sections etc…

– Up-grade NetCDF files definition to be consistent with COARDS CF1.2 conventions

– Include sea-ice variables in the definitions

– Saving half storage capacity by use of “compressed” NetCDF files (data written “short” instead of “floats”, using “scale_factors”)

– Proposition of a set of reference data (availability, access)



• Class 1 definition (provided with fortran programs):

0 30 50 100 200 400 700 1000 1500 2000 2500 3000




– 2D fields:

• The zonal and meridional wind stress (Pa) on top of the ocean,

• The total net heat flux (including relaxation term) (W/m2) into the sea water,

• The surface solar heat (W/m2) into the sea water,

• The freshwater flux (including relaxation term) (kg/m2/s) into the ocean,

• The Mixed Layer Depth (henceforth MLD) (m). Two kinds of MLD diagnostics are provided, to be compliant with [de Boyer Montégut et al., 2004] and [D'Ortenzio et al., 2005]. A temperature criteria MLD(θ) with temperature difference with the ocean surface of T=0.2°C. And a surface potential density criteria MLD(ρ) with a 0.03 kg/m3 surface potential density criteria.

• The Sea Surface Height (SSH) (m).

– 3D fields:

• The potential temperature (K) and salinity (psu).

• The zonal and meridional velocity fields (m/s).

• The vertical eddy diffusivity (kz, in m2/s): if compressed, first in LOG10!




– 2D fields (for ARC, ACC, NAT, NPA and GLO):

• Sea-Ice thickness (m)

• Sea-Ice concentration (fraction)

• Sea-Ice x and y velocities (m/s)

• Surface snow thickness over sea ice (m)

• Sea ice downward x and y stress (Pa)

• Tendency of sea ice thickness due to thermodynamics (m/s)

• Surface downward heat flux in air (W/m2)

– Ancillary data:

• The Mean Dynamic Topography (henceforth MDT) (m) used as a reference sea level during the assimilation procedure. MDT is also called Mean Sea Surface Height (MSSH).

• Climatologies of Sea Surface Temperature (SST) (K), of surface current (m/s), of MLD (m).

• Climatology of potential temperature (K) and salinity (psu) fields from (T,S) used as a reference.



• Class 2 mooring/sections– potential temperature (K) and salinity (psu).

– zonal and meridional velocity fields (m/s).

– Sea Surface Height (SSH) (m).



78 vertical levels (WOA and GDEM3.0 standard levels

straight sections (yellow); XBT sections (brown); gliders sections (purple); tide gauges (blue), and other moorings (red).



• Class 3 definition (transport):

In black, sections without specific class of computation on the vertical. Transport computed with classes: temperature (red), salinity (yellow), density (blue) and depth (green).


Status of the intercomparison exercice: assessment through Class 1-2-3 metrics

• Consistency: Monthly averaged fields compared to:

– WOA’2005, Hydrobase, CARS, MEDATLAS, Janssen, climatologies

– De Boyet Montégut MLD climatology

– SST climatology

• Quality: Daily fields compared to

– In situ data (Coriolis data server)

– Dynamic topography, or SLA (AVISO products)

– SST (depending on groups)

– SSM/I Sea-Ice concentration and drift products

– Surface currents (DBCP data, OSCAR, SURCOUF products)


Status of the intercomparison exercice: Where are we ?

• Partners involved / status:Status of 3 months hindcast

productsOpenDAP or FTP

addressesPartner’s main regions of

interest

MER Produced TBC NAT, TAT, SPA, TPA, IND, ARC

UKM TBC TBC tbc

TOP TBC TBC tbc

BLK Produced BlueLink OpenDAP : TBC IND, SPA, tbc

MFS TBC TBC tbc

MRI Produced at MRI, provided to University of Hawaii

Univ of Hawaii OpenDAP : TBC

NPA

HYC TBC TBC tbc

CNF Produced, need to transition to new NetCDF

format

FTP server of CNOOFS North West Atlantic



• Agenda:

– Shift (one month now) for availability of products

– Not clear view of “intercomparison strength of work” in the different areas (ie how many groups plan a dedicated work looking at more than their own hindcast? )

– Target: define a deadline to be prepared for the SymposiumValidation and intercomparison of analysis and forecast productsF. Hernandez (Mercator-Ocean), G. Brassington (BoM), J. Cummings (NRL), L. Crosnier (Mercator-Ocean), F. Davidson

(DFO), S. Dobricic (ICMCC), P. Hacker (Univ. of Hawaii), M. Kamachi (JMA), K. A. Lisæter (NERSC), M. Martin (UK Met Office)

• Availability of products (end of July ?????)• Availability of intercomparison results (mid October ????)

– Managing the outcomes:

• How do we take profit from feedbacks ? • Initiative to keep on this activity?


Assessment diagnostics

SST SST-WOA05

NOAA RTG SST SST - RTG



Surface currents comparison to drifters

Salinity-WOA05Salinity



• Agenda:

– Shift (one month now) for availability of products

– Not clear view of “intercomparison strength of work” in the different areas (ie how many groups plan a dedicated work looking at more than their own hindcast? )

– Target: define a deadline to be prepared for the SymposiumValidation and intercomparison of analysis and forecast productsF. Hernandez (Mercator-Ocean), G. Brassington (BoM), J. Cummings (NRL), L. Crosnier (Mercator-Ocean), F. Davidson

(DFO), S. Dobricic (ICMCC), P. Hacker (Univ. of Hawaii), M. Kamachi (JMA), K. A. Lisæter (NERSC), M. Martin (UK Met Office)

• Availability of products (end of July ?????)• Availability of intercomparison results (mid October ????)

– Managing the outcomes:

• How do we take profit from feedbacks ? • Initiative to keep on this activity?

intercomparisons working groupe activities

Documents