esa capacity study final presentation estec, 2 nd june 2005 presentation by b. j. kerridge (ral, uk)...

ESA CAPACITY Study Final Presentation

ESTEC, 2nd June 2005

Presentation by B. J. Kerridge (RAL, UK)

on behalf of WP3200 team

Definition of Mission Concept for Polar Orbit

CAPACITY Final Presentation - 2nd June, ESTEC

Definition of Mission Concept for Polar Orbit

1. Consortium

2. Criteria for assessment of techniques

3. Value added to MetOp/NPOESS

4. Assessments

5. Recommendations


Consortium

RAL - J.Reburn (co-ordinator)

IMK/FZK - G.Stiller

U.Leicester - J.Remedios

CNRS/Noveltis - C.Camy-Peyret, C.Clerbaux, P.Prunet

SRON - R.Jongma, I.Aben, R.Hoogeveen

U.Bremen - C.Verdes, H.Bovensmann

LSCE - F-M.Breon

• Acknowledgements to all for co-operative, efficient and constructive contributions within limited resource.


Criteria for assessment of Measurement Techniques

1. Whether MetOp/NPOESS capability will exist at all and, if so, degree of non-compliance with requirements.

2. Extent to which major non-compliances could realistically be mitigated

3. Needs of operational (NRT) users assigned priority in CAPACITY.

4. For early Sentinel implementation: technical concept mature and demonstrated in space

→ only modest further technical development


Degree of MetOp/NPOESS non-compliance

Major – Key measurements not made by MetOp/NPOESS in required height range and/or time of day Significant – Key measurements by MetOp/NPOESS seriously non-compliant in vertical resolution, spatio-temporal sampling and/or precision


Value added by new instruments to MetOp/NPOESS

• The operational observing system could be augmented in three physical dimensions:

1. Geometrical2. Spectral3. Temporal

1. Geometrical

• Operational observing system devoid of:– Limb-emission sounders for global height-

resolved data in upper troposphere and stratosphere for operational users

– Solar occultation sensors to extend stratospheric profiling by this established technique for scientific assessments.


Odin SMR data on Antarctic Vortex 12-13th Sept’04 475K 30-90oS

T N2O O3

SZA HNO3ClO

← 30oS

SZA range: 85 – 95o Courtesy J.Urban, Chalmers


CO observed in UT (147hPa) by Aura MLS on 30th Aug’04

CO plume – polluted boundary layer air transported up by Asian monsoon circulation.White curves – tropopause (PV = +2.0 x 10-6 K m2 kg-1 s-1)

Courtesy M.Filipiak, Edinburgh


Preliminary HNO3 retrieval from MIPAS for 21/10/03 -12/11/03

Courtesy G.Stiller, IMK

HNO3 at ~9kmHNO3 Zonal-Mean ppbv

- HNO3 plume over Africa- HNO3 in mid-trop higher in tropics


CH4 and C2H6 daily zonal means from preliminary MIPAS retrievals

C2H6 - 16/11/02ppbv

CH4 - 17/10/02ppmv

Courtesy G.Stiller, IMK

- C2H6 in mid-trop higher in N.Hem- Structure in upper trop CH4


GOME-1 only and synergistic MIPAS + SCIA O3 orbit cross-sections 23/08/02

GOME-1 standard a priori ≥16km a priori = MIPAS L2

MIPAS + SCIA retrievalGOME-1 only retrieval

Sou

th Atlantic

anom

aly

Courtesy R.Siddans, RAL


GOME-1 only and synergistic MIPAS + SCIA lower troposphere O3 23/08/02

GOME-1 only

1012

mol

ec/c

m3

MIPAS+SCIA

MIPASCloud

Contaminatedat 12km

Increased “noise” in SAA but retrieval

still possible

SAA


Value added by new instruments to MetOp/NPOESS (contd)

1. Geometrical (contd)

• Deployment of nadir-viewing uv/vis spectrometer with ground pixel smaller than GOME-2 and OMPS

→ Increase density of cloud-free observations of boundary layer for pollution monitoring & air quality forecast applications.


Near-surface O3 from GOME-1 1996-2002


Global mean cloud stats vs px size from ATSR-2 data for 1 day

OMPS

OMI 8 px

OMI 1 px

- As px size decreases, no. samples can increase as well as % cloud-free



2. Spectral

• Range 0.8 – 3.7 m (swir) not covered by MetOp/NPOESS

• Addition of channels near 2m to nadir-viewing uv/vis/nir would: (a) Provide sensitivity to boundary layer CH4 (b) resolve aerosol into several tropospheric layers

→add value to operational system for climate applications

• Deployment of FTIR with spec res higher than IASI and CrIS

→tropospheric CO data of higher quality & detection of NMHCs

• Deployment of a limb-uv/vis/nir sounder with: (a) higher spectral resolution than OMPS in BrO and NO2 bands (b) channels added in 1 – 2m (swir) range

→improve compliance of operational system for ozone/uv and climate scientific assessments.


Optical Depths in SWIR

CH4

CO2

H2O


CH4 from nadir-SWIR (2.35m) channel

Courtesy I.Aben, SRON

- CH4 emissions from rice paddies in S.E.Asia


Aerosol from 2m

Scattering coefficient error / km-1x/xt

Alt

itud

e / k

m

• Simulated retrieval for spectral band 1.8 – 2.0 m • Spectral resolution: 0.4nm (1cm-1)• Average over cloud-free pixels across-track



3. Temporal• Afternoon observations of trace gas pollutants in

boundary layer -> unique for polar orbit: – Attribution of pollution episodes in afternoon– Closer than GOME-2 (9:30am) & OMPS (1:30pm)

to the early morning AQ forecast time


Local time at which SZA = 90o

SZA < 90o

so sunlit

- At 3:30pm can see to ~55oN all year round

SZA > 90o

so dark


Quantitative Comparisons

• Instrument specs & performance estimates for new designs made available to CAPACITY:– Limb-FTIR and limb-mm (Explorer studies) – Multi-angle polarimeter– Nadir-viewing grating spectrometers

• uv/vis (OMI-derived)• swir (SCIA- & OMI-derived)• uv/vis + swir (OMI-derived)

• Comparisons with requirements conducted to supplement those for planned missions.



Major = Measurement not made by MetOp/NPOESS or other mission planned 2010-20Significant = Improved height-resolution, sensitivity or timeliness (for NRT) Some = Increase in number of samples per day


Complementary attributes of limb-mm/submm & limb-FTIR

Attribute Limb-mm Limb-FTIR

Tropospheric penetration for gases measured in common(eg H2O, O3, HNO3)

Less sensitive to cirrus:→high probability of observing upper trop

For cloud-free scenes:→ visibility into mid trop in IR windows

Aerosol and PSCs Insensitive:→ highly desirable for trace gas retrievals

Sensitive:→ aerosol & PSC can be measured

Temperature Less sensitive to T errors → highly desirable for trace gas retrievals

T needed too→ high sensitivity advantageous

Additional trace gases required for NRT

operational applications

Eg mm: UT COSubmm: strat ClO & HCl

Eg CH4, SF6 & NO2


Predicted annual mean probability of limb transmittance > 3%

• Estimate from ECMWF T, q, liq & ice cloud sampled globally 1 day in 10 over 1 yr • Dashed white line is climatological tropopause.• 3% limb transmittance => threshold determined from retrieval simulations

~1mm


Assessments:Solar occultation & lidar/DIAL

ir & uv/vis solar occultation

• Offers stratospheric profiles of high quality for scientific assessments of climate and ozone/uv, though non-compliant on horizontal sampling.

• No operational NRT users• US, Canada and Japan have strong technical heritages, so well-

placed to lead occultation mission for stratospheric monitoring.

Lidar & DIAL

• Lidars on ADM-Aeolus and EarthCARE can profile tropospheric aerosol to mitigate this deficiency of MetOp/NPOESS

• Aerosol lidar therefore not priority for Sentinel mission (possibility for post-EPS, following evaluation of ADM-Aeolus?)

• DIAL technology not sufficiently mature for Sentinel mission


Assessments (contd):Nadir-uv/vis/nir grating spectrometer

Nadir-uv/vis spectrometer with small ground pixel in complementary orbit to GOME-2 & OMPS for pollution monitoring and AQ forecasting:

Unambiguous, large increase in BL sampling per day factor >2 cf OMPS+GOME-2 (MetOp data rate limits to 24 px)

Late afternoon observations closer to early am AQ forecast European heritage internationally competitive Mature concepts exist for uv/vis/nir from OMI and GOME-2 swir channels near 2m would add value for climate applications:

Near-surface CH4 Aerosol resolved into several tropospheric layers

Technical development for swir channels would benefit from: new HgCdTe detector arrays experience gained from SCIA (data analysis; swir design, pre-

flight characterisation and in-flight calibration).

→ Concept recommended for early Phase A study: uv/vis/nir spectrometer with option to add swir channels.


Assessments (contd):Nadir-FTIR

• IASI and CrIS to fly in parallel in (at least) two different orbits Will sample (at least) four times of day IASI-type FTIR could increase IASI + CrIS sampling by <50% →Value added by stand-alone FTIR less than uv/vis/nir/swir

• Synergy with uv/vis for tropospheric O3 profiling and co-location requirements to be demonstrated by IASI & GOME-2 on MetOp

• Instrument spec and retrieval simulations for advanced design not available for CAPACITY, but FTIR with higher spec res could offer:– CO data of higher quality than IASI/CrIS – Detection of NMHCs and other trace gases for climate

assessment

→ Europe well-placed with IASI heritage to evolve FTIR design for trace gas monitoring post-EPS.


Assessments (contd) Multi-angle polarimeter & limb-uv/vis/nir

Multi-angle polarimeter

• Instrument flying in parallel to APS on NPOESS → Aerosol properties additional to AOT and size

• Strong US heritage from MISR and now APS development

→ Parallel development in Europe not the most effective use of Sentinel

Limb-uv/vis/nir/swir spectrometer

• Higher spectral resolution than OMPS → stratospheric BrO and NO2 profiles of potentially higher quality for

climate scientific assessment and ozone/uv applications• Additional channels >1m

→ scattering by aerosol and cirrus to below tropopause.• Use by operational centre not yet demonstrated • Strong heritage from SOLSE/LORE and OMPS in US and from OSIRIS

in Canada

→ Parallel development in Europe not the most effective use of Sentinel


Assessments (contd):Limb-ir & -mm/sub-mm

No limb-emission sensor on MetOp/NPOESS

Those on Odin, Envisat and Aura unlikely to function beyond 2010.

Height-resolved observations of UTLS from limb-emisson would: Remedy major non-compliances for climate and ozone/uv

operational NRT applications and others Directly, and indirectly through limb-nadir synergy, mitigate

MetOp/NPOESS non-compliances on tropospheric data

Positive impact demonstrated by ECMWF in Envisat MIPAS assimilaton Anticipated that Aura MLS range should extend to below tropopause.

European heritage competitive with US for both FTIR and mm/sub-mm and no current US plans for limb-emission sounding.

→ Recommend preparation in 2005/6 for limb-sounder Phase A study:

(a)Evaluate impact of Envisat & Aura limb-sounder data in: assimilation by ECMWF & other operational centres. extensive demonstration of limb-nadir synergy

(b)Refine limb-mm/submm and -ir instrument specs through retrieval simulations to meet operational user requirements for monitoring


Recommendations

• Planned operational observing system comprising ground networks, MetOp, NPOESS & MSG should be exploited fully and augmented efficiently to monitor atmospheric composition during 2010-20, in line with GMES approach.

• Polar system should evolve from MetOp /NPOESS towards post-EPS system which better serves user needs for monitoring atmospheric composition.

• Seek to achieve this through co-operation, eg: US via reciprocal agreements on data access Eumetsat on post-EPS definition. Possible provision of occultation mission by US,

Canada or Japan, who each have strong heritage


Recommendations (contd)

• Phase A study leading to early implementation of Sentinel comprising nadir-viewing instrumentation in complementary orbit to MetOp/NPOESS 9:30am/1:30pm eq crossing times.

→Better serve needs of operational users in Europe and worldwide for pollution monitoring and AQ forecasting, together with AQ assessment, climate and O3/surface uv applications.

• Prepare in 2005/6 for Phase A study of limb-sounder component:(a)Evaluate impact of Envisat and Aura limb-sounder

data in assimilation by operational centres(b)Refine limb-mm/submm and -ir instrument specs

to meet user requirements for monitoring through retrieval simulations


Recommendations (contd)

• Definition of additional components would benefit from evaluations of:

(a) nadir-FTIR: IASI & synergy with GOME-2

(b) limb-uv/vis/nir: OMPS on NPP

(c) multi-angle polarimeter: APS on NPP/NPOESS

(d) lidar: CALIPSO and ADM-Aeolus


Supplementary Slides


Statistics of simulated CO retrievals from IASI, CrIS and AIRS for one day

IASI has most skill in lower troposphere

Background Variability

RMS BIAS

Courtesy C.Clerbaux, CNRS


Aerosol from 2m

Res

olut

ion

/ cm

-1

Error source

x/xt

Scattering coefficient error / km-1

1cm-1 (0.4nm) ACOR 2-d array instrument, averaging all cloud free pixels across swath Errors at 4km altitude

* mapped radiometic offset approx = cloud-free radiance (outside lines). Needs to be ~factor 100 lower to avoid dominating ESD.

* 2-boxes per error / resolution correspond to 2 view / solar angles (21 & 71o)

Alt

itud

e / k

mA

ltit

ude

/ km


H2O & T retrieval from limb-sounders in frame of operational assimilation


Tropical limb-opacity contributions from H2O vapour, liq & ice clouds

No cloud+ Liquid cloud+ Liq & ice cloud

mid-ir window(solid)

mm-wave(dashed)

Tropopause

Mm-wave:- Penetration controlled by H2O vapour- High probability of sounding UT

IR: - Penetration controlled by ice cloud- Can see into mid-troposphere


CH4 from nadir-SWIR (2.35m) channel


SCIA CH4: Aug-Nov’03 1.65m (ratio to 1.57 CO2)


Satellite Instruments Sensitive to Carbon Molecules in the Atmosphere

Launch

date

Platform/

Instrument

Bands

(microns)

Trace Gases

Measured

FOV

(km)

Dec. 18

1999

Terra/

MOPITT

4.7 CO 22

nadir

Mar. 1

2002

Envisat/

MIPAS

2.2, 7.7 O3,

CO,CO2,CH4

3x30

limb

Mar. 1

2002

Envisat/

SCIAMACHY

2.2 O3,

CO,CO2,CH4

0.6x25

limb

May 4

2002

Aqua/

AIRS

3.7-15 O3,

CO,CO2,CH4

45

nadir

July 15

2004

Aura/

TES

3.3-15 O3,

CO,CO2,CH4

Nadir: 2.3x23

Limb: 0.5x8.3

4Q 2005

2010, 2015

METOP-1/

IASI

3.7-15 O3,

CO,CO2,CH4

45

nadir

2Q 2006

2010, 2011

NPP/

CrIS

3.7-15 O3,

CO,CO2,CH4

45

nadir

2Q

2007

ESSP/

OCO

1.58/0.74

(solar occul.)

CO2 1

nadir


Spectral Resolution in Trace Gas Bands for AIRS, IASI, CrIS

gas Wave

number

AIRS

ν/1200

IASI

L=2 cm

CrIS

L=.8,.4,.2

CO 2142 cm-1 1.79 0.5 4.50

CH4 1306 cm-1 1.09 0.5 2.25

CO2 735 cm-1 0.61 0.5 1.13

CO2 791 cm-1 0.66 0.5 1.13

CO2 2385 cm-1 1.99 0.5 4.50

O3 1045 cm-1 0.88 0.5 1.13


Carbon Monoxide S/N for a 10% (10 ppb) perturbation

Polar

Mid-Latitude

Tropical


Wavelength Dependence of Cirrus Extinction


COAverage March-April-May (2004)

MOPITTSCIAMACHY

Cloud-free, day time


• ECMWF 3-D fields of T, q, liq & ice cloud sampled as per 14 (ERS-2) orbits for 1-day in 10 for one year

• Limb opacity calculated in windows at 1m,12m & 1mm

– Clear-air first

– Liq and ice cloud then added

• Tangent heights from 0-20 km at 1km intervals

• Sampling 60km along-track; 16km x 4km across

• Seasonal & annual zonal-means generated by:

– binning limb opacities into 10o latitude intervals

– calculating probability of: transmittance > threshold

Tropospheric Limb Transmittance Climatology


1) Clear-air optical depth: H2O & dry air continua from CKD (mid/near-ir) and

Liebe’89 (mm-wave) formulations Vibration-rotation lines (nb H2O/O3/CO2) ignored

→ Calculation at 12m is lower limit for IR2) Cloud optical depth:

Liq droplets: ECMWF RTM Ice crystals:

IWC:Reff correlation (F.Evans) vis/ir: “aggregates” (A.Baran) mm-wave: “T-matrix” (U.Bremen)

• Adding cloud has negligible impact if clear-air opacity high

• Validation against SAGE-II 1m climatology

Tropospheric Limb Transmittance Climatology (contd)


MIPAS CTH occurrence9/02-11/03 21+/-1.5km

Courtesy M.Milz, IMK


MIPAS CTH occurrence9/02-11/03 9.0+/-1.5km



Courtesy M.Milz, IMK Karlsruhe


MIPAS (v4.61) vs GOME O3 Zonal Mean 19/09/02-21/09/02

– [MIPAS-GOME] SD < MIPAS SD – MIPAS SD high in 16-24km >60S (PSCs) and also <20km in tropics (cirrus)


3.Tomographic Limb-Sounding of UTLS

• UTLS region is characterised by vertical and horizontal structure in O3,H2O and other species

• Conventional limb-sounding provides high vertical resolution but comparatively low horizontal resolution.

• Horizontal structure can be captured with higher fidelity by tomographic limb-sounding in the satellite orbit plane.


Principles of Tomographic Limb-Sounding

• 2-D RTM instead of spherically-symmetric atmosphere

• State-vector: 2-D grid instead of 1-D profile• Measurement-vector: set of limb-scans which

are inverted simultaneously• Limb-scan spacing along-track fine enough to

oversample retrieval grid• Given air volume viewed from many different

directions -> tomography


Tomographic Limb Sounding

100km.


MIPAS Limb-Geometry for Standard Mode and UTLS Special Mode S6

Spectral resolution reduced to 0.1cm-1

(cf 0.025cm-1 for standard mode)


Practical Considerations

Iterative solution to Optimal Estimation equation:

– Sa is a priori covariance matrix of x – K is weighting function matrix w.r.t. x– Sy is measurement error covariance matrix

• Memory limitations preclude storage of matrices which have dimension Ny

• Provided Sy is diagonal, matrices such as KTSy-1K can

be accumulated sequentially on limb-view by limb-view basis

• Since Nx is also large, further matrix manipulation required to make the problem computationally viable.


Tomography: status

• MIPAS:– L1 data from one day in UTLS Special Mode (S6)

available soon from ESA– 2-D schemes to be applied by several groups

• Aura MLS:– Implemented for standard operational processing

(inverting ~14 limb-scans @ ~120km spacing, cluster of 512 processors)

• Future ESA mission:– Simulations to specify instrument requirements– Include first attempts at sophisticated (ie realistic)

treatment of cloud


O3 2-D Retrieval Simulations in absence of cloud

A priori and First Guess True


• Fully-spherical 3-d scattering too CPU intensive for retrievals

• Solution to

– Use fast plane parallel model (derived from GOMETRAN) to calculate scattering source function Js in 1-d

– Integrate source function in full 2-d (spherical) geometry

• Weighting functions determined analytically

MM-wave retrievals in the presence of cloudRadiative transfer model development


First simulations of H2O 2-D retrievals in presence of realistic cloud

Solid lines - mm-wave cloud ext. coeff

AMIPAS – cloud contaminated limb-views screened out with Envisat MIPAS algorithmMASTER – penetration controlled by H2O opacity (dashed lines - retrieved: a priori error = 0.1 & 0.9)

• Measurements synthesised with RTM coupling cloud multiple-scattering into limb-geometry

• Cloud params added to state-vectors


2. Limb-Nadir Synergy

• Limb: higher vertical resolution higher sensitivity in stratosphere less frequent sampling of mid troposphere cannot see lower troposphere.


Limb-Nadir Synergy (contd)

• Nadir:• denser horizontal sampling• views in between clouds• sensitivity in lower troposphere

Optimal approach for tropospheric O3: –Combine limb emission (MIPAS) with nadir uv (GOME-1 /

SCIAMACHY)


O3 Profiling with Synergistic Scheme MIPAS + GOME-1/SCIA

Recap:• GOME-1 optimal estimation scheme includes:

1. Hartley band (260-306nm) step : O3 weighting-function peaks span the stratosphere

2. Huggins band (325-335nm) step: T-dependent differential structure adds information at low altitudes

• In stratosphere, MIPAS L2 & GOME-1 O3 consistent within +/-10%• In upper troposphere, MIPAS contaminated by cloud• SCIA radiometric calibration in Hartley band not yet adequate

Aim of synergistic scheme:– Replace Hartley band step with limb-retrievals→ Represent vertical structure in stratosphere more accurately

Comparison of two Huggins band retrievals:1. Hartley band retrieval as a priori in standard GOME-1 2. MIPAS L2 as a priori <100hPa in SCIA (corresponding orbit)


Limb-Nadir Synergy: Status

• Mechanics of synergistic limb-nadir retrieval demonstrated for O3. Allows retrievals in SAA (important for tropospheric O3) By-passes SCIA radiometric calibration issues <310nm Mitigates sensitivity of MIPAS to cloud in upper troposphere

→ Advance on simple differencing of O3 total - strat columns

• Next steps: Apply to MIPAS + GOME-1/SCIA O3 data on larger scale Evaluate extensively against ozonesondes

→ Quantify benefit for trop O3 cf nadir-uv only scheme

• Possible future applications:

–Other trace gases measured in common (eg NO2, SO2, H2CO)

–Aura:

• Upper troposphere sampled more frequently by MLS

• Additional trace gases detectable in IR by TES-nadir


3. Summary

• Trace gases in the troposphere and lower stratosphere are central to global climate change and related issues.

• The challenge for satellite remote-sensing (nb Aura) is to measure the global distributions of key species which vary spatially and temporally.

• Different wavelength regions and viewing geometries have complementary attributes:– measurable species– penetration into the troposphere– vertical and horizontal resolution

• Nadir-viewing required to sound the lower troposphere, for which special attention must be paid to prior assumptions.


Summary continued

• Limb-viewing required to sound lower stratosphere and complement nadir-viewing in the upper troposphere

• Aura extends the opportunity provided by Envisat to pioneer two new techniques:– Tomographic limb-sounding– Limb/nadir synergy

and compare implementations via retrieval & assimilation• Realistic error characterisation vital in both cases.• A future mission to sound atmospheric composition

should exploit these new techniques and include advanced sensors, eg finer spatial sampling.


Supplementary Slides


% P

roba

bilit

y tr

ansm

issi

on >

3% Alt

itud

e /k

m0

5

10

15

20

Alt

itud

e /k

m

0

5

1

0 1

5

20A

ltit

ude

/km

0

5

10

15

20

Contributions to limb opacity

• Nominal: Continua + liquid + ice cloud

• Continua only mm-wave & strong

mid-ir bands limited by continua in mid-trop.

• Continua + liquid only


Alt

itud

e /k

m0

5

10

15

20

Alt

itud

e /k

m

0

5

1

0 1

5

20A

ltit

ude

/km

0

5

10

15

20

Contributions to limb opacity

• Nominal: Continua + liquid + ice cloud

• P(Continua only) - P(nominal)

• P(Continua+liquid) - P(nominal)

Only ice cloud impacts mm-wave

mid-ir sees liquid cloud


Alt

itud

e /k

m0

5

10

15

20

Alt

itud

e /k

m

0

5

1

0 1

5 2

0A

ltit

ude

/km

0

5

10

15

2 0

Sensitivity to transmission threshold

• Nominal: 3%

• P(10%)-(3%)

– Negligible change in mid-ir window

– 10-20% change in P or 2km shift in altitude in mm

• P(50%)-P(3%)-

– changes more significant in mm-wave.


Seasonal Dependence

• Nominal: Annual

• P(December-February) -P(annual)

• P(March-May) -P(annual)

• P(June-August) -P(annual)

• P(September-November) - P(annual)

Worst case in summer (more convection)

Larger variability in N.Hemisphere


Sensitivity to transmission threshold

• Results also presented averaged over latitude bands, as line plots for 12m and 318 GHz (MASTER Band C)

• mid-ir insensitive to transmission threshold

– Low fraction of cloud is thin so mid-ir stats ~ cloud frequency

• mm-wave not too sensitive to chosen transmission threshold below 10%

• mm-wave always opaque in mid-trop due to continuum

– mm-wave generally better sampling in UT (esp tropics)

– mid-ir can see cloud-free mid troposphere.

Probability / % Probability / % Probability / %


Local solar time dependence

• Dependence on local solar time weak

– negligible in mm-wave

– Biggest impact +/-5% in tropics between 16:30 & 04:30

– Day / night difference very small 10:30/22:30

– Not enough to explain lower altitude of peak occurrence of SAGE tropical opaque cloud.

• Results may be limited by method

– temporal resolution 6 hours (finer structures not resolved.)

– reliability of ECMWF model

Probability / % Probability / % Probability / %



Major = Measurement not made by MetOp/NPOESS or other mission planned 2010-20Significant = Improved height-resolution, sensitivity or timeliness (for NRT) Some = Increase in number of samples per day

esa capacity study final presentation estec, 2 nd june 2005 presentation by b. j. kerridge (ral, uk)...

Documents

ralcapacity final presentation

metopnpoess contd

courtesy r

hno3 plume

midtrop higher

upper troposphere

stiller u

technical concept mature