Comparison of GERB and Met Office UM broadband fluxes: SINERGEE project results
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Comparison of GERB and Met Office UM broadband fluxes: SINERGEE project results Richard Allan, Tony Slingo ESSC, Reading University
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Comparison of GERB and Met Office UM broadband fluxes: SINERGEE project results. Richard Allan, Tony Slingo ESSC, Reading University. INTRODUCTION. - SINERGEE aims Comparison of GERB L2 broadband fluxes with Met Office forecast model (analysis times 00,06,12,18 GMT) - PowerPoint PPT Presentation
Transcript of Comparison of GERB and Met Office UM broadband fluxes: SINERGEE project results
Comparison of GERB and Met Office UM broadband fluxes:
SINERGEE project results
Richard Allan, Tony Slingo
ESSC, Reading University
INTRODUCTION
- SINERGEE aims
- Comparison of GERB L2 broadband fluxes with Met Office forecast model (analysis times 00,06,12,18 GMT)
- July Means, Clear-sky sampling
- Data issues (geolocation, resolution, bad data, ADMs)
- Model Issues (Sahara, convection, cloud properties)
Recent Comparison (OLR)
Recent Comparison (Albedo)
Example Comparion (OLR)
Example Comparion (Albedo)Stratocumulus Convection
Geolocation
July Mean OLRUM GERB
GERB-UM OLR
Difference
July Mean
Limb effects??
Consistently sampled clear-sky “Type-I”
OLR
July
GERB
UM
Clear-sky OLR bias with TsGERB minus UM OLR (Wm-2)
280 300 320 340
SURFACE TEMPERATURE (K)
30
20
10
0
-10
-20
-30
-40
-50
-60
Desert Dust? Aerosol?
July Mean Albedo (GERB)
06z
July Mean Albedo (UM)
06z
Geolocation
Mean clear-sky albedo
July
GERB
UM
23rd July
Geo-location
(2): Albedo
11th August
Time series (diurnal cycle removed)
Reduced spatial coverage amplifies 06z Albedo bias
May June July Aug
Light stripe (~25N or 25 S): 06z late May and 11-14th June, 12z 24-29th May
Dark Band, 12z: 1-3rd, 5th June; 18z 12th June; 12z 31st July, 1st and 5th Aug
Vertical dark stripe: 06z 20th May; 12z 4th June; 00z&18z 10th June; 00z 26th, 27th & 30th June; 18z 30th June/1st July; 00z 2nd/3rd July
Bad Pixel.
OTHER ISSUES
22nd June & 10th Aug also dodgy
10th August 12z: GERB
couldn’t cope with record UK
temperature of 38oC!
August OLR Animation
Conclusions (1)
• DATA problems– Geolocation (spatial comparison, processing)
– Resolution
– Albedo diurnal cycle (problems at 06z)
– Limb darkening in East? (Lower OLR and Higher albedo)
– Meteosat data replacement = Bad
• Model problems– Too much stratocumulus
– 12z Convection (too early, lack of organisation)
– Dark Sahara / Hot Sahara
– ITCZ positioning
Conclusions (2)
• Quality of BARG improved recently (August)• ARG - reasonable quality (res/geo probs)• ADMs? – bright at 06z, dark at 18z• Bad data (manual correction?):
– Geolocation– light stripes, dark bands (E/W)– Dark bands (N/S)
• Future comparison of SEVIRI with UM simulations• http://www.nerc-essc.ac.uk/~rpa/GERB/gerb.html
