4th JCSDA Science Workshop, 31 May – 1 June 2006

Broadband Satellite-Like (Infrared) Cloud Products from NCEP Models and Preliminary Cloud Verification

B. Ferrier1,2, H.-Y. Chuang1,2, E. Rogers1, B. Zhou1,2, J. McQueen1, and G. DiMego1

1NOAA/NWS/NCEP/EMC2SAIC/GSO

Thanks also to P. Manousos (NWS/NCEP/HPC),K. Campana1, M. Hart1,2, and J. Hanna (NESDIS)

4th JCSDA Science Workshop, 31 May – 1 June 2006

Background on Satellite Cloud Products Project motivation

Interest in forecast satellite look-a-like clouds by Hydrologic Prediction Center (HPC) and NWS Eastern Region

Such products already produced by CMC & U. Wisconsin

2 simple infrared (IR) algorithms in WRF Nonhydrostatic Mesoscale Model (WRF NMM – to replace Eta on June 13)

Brightness temperature (Tb) from TOA outgoing longwave fluxes (= *Tb

4, =1, =5.67·10-8 W m-2 K-1 ; Stefan-Boltzman Law) WRF NMM, NAM use GFDL LW radiation (’85, ’91), modified by

Global Branch (Hou et al.)

NCAR algorithm (Stoelinga) – starting from TOA find air temperature at cloud optical depth of = 1 (using cloud emissivities in model)

4th JCSDA Science Workshop, 31 May – 1 June 2006

Forecasts (left) & obs (right) @ 00Z 30 May 2006

24-h WRF NMM forecasts• TOA total IR (top, left):

colder Tb’s (atmos abs/emis)• NCAR algorithm (bot, left):

warmer Tb’s

0015 UTC

4th JCSDA Science Workshop, 31 May – 1 June 2006

Forecasts (left) & obs (right) @ 00Z 30 May 2006

12-h WRF NMM forecasts• TOA total IR (top, left):

colder Tb’s (atmos abs/emis)• NCAR algorithm (bot, left):

warmer Tb’s

0015 UTC

4th JCSDA Science Workshop, 31 May – 1 June 2006

Forecasts (left) & obs (right) @ 12Z 29 May 2006

24-h WRF NMM forecasts• TOA total IR (top, left):

colder Tb’s (atmos abs/emis)• NCAR algorithm (bot, left):

warmer Tb’s

1215 UTC

4th JCSDA Science Workshop, 31 May – 1 June 2006

Forecasts (left) & obs (right) @ 12Z 29 May 2006

12-h WRF NMM forecasts• TOA total IR (top, left):

colder Tb’s (atmos abs/emis)• NCAR algorithm (bot, left):

warmer Tb’s

1215 UTC

4th JCSDA Science Workshop, 31 May – 1 June 2006

Final Remarks on Cloud Products

TOA IR and NCAR IR cloud-top will be available in 32-km grid 221 files (next slide)

Can be viewed from our parallel WRF NMM runs (“NAMX”, “NAMY”) from the past week athttp://wwwt.emc.ncep.noaa.gov/mmb/mmbpll/nampll12_fullcyc_2mbtop/

Jump link “TOA Brightness Temperatures” (left frame) More improvements needed before use in operations

at HPC and WFOs More accurate narrowband calculations Use CRTM in our unified (regional, global) post

processing for multiple frequencies (e.g. water vapor) JCSDA funding would accelerate pace of effort

4th JCSDA Science Workshop, 31 May – 1 June 2006

32-km Grid 221 vs. full NAM domain (Eta-12)

4th JCSDA Science Workshop, 31 May – 1 June 2006

Preliminary Cloud Verification

Objective verification using NCEP’s Forecast Verification SSystem (FVS)

Typical verification uses values of model grid points at observation points (“grid-to-obs” verification)

Expanded to verify model grids using analysis grids (“grid-to-grid” verification) AFWA total cloud cover product Clouds from AVHRR (CLAVR) total cloud cover Validation over 12-km grid 218 (next slide)

Focus mostly on operational NAM (Eta), but also show preliminary results from WRF NMM

4th JCSDA Science Workshop, 31 May – 1 June 2006

12-km Grid 218 vs. full NAM domain (Eta-12)

Verification

4th JCSDA Science Workshop, 31 May – 1 June 2006

12Z NAM (Ops Eta) vs. AFWA, CLAVR1200 UTC 23 March – 1200 UTC 15 May 2006

RM

SE

(%

)

CLAVR

AFWA

0 6 12 18 24 30 36 42 48 54 60 66 72 78 84

12 18 00 06 12 18 00 06 12 18 00 06 12 18 00Time (UTC)

Forecast Hour

Bia

s (%

)

12 18 00 06 12 18 00 06 12 18 00 06 12 18 00Time (UTC)

Forecast Hour 0 6 12 18 24 30 36 42 48 54 60 66 72 78 84

• Smallest NAM biases at midday (18Z), largest in early morning• Closer agreement (smaller errors) with CLAVR

4th JCSDA Science Workshop, 31 May – 1 June 2006

Time Series of 48-h NAM and WRF NMM Cloud Forecasts

1200 UTC 23 March – 1200 UTC 15 May 2006

RM

SE

(%

)

Missing WRF NMM Runs

March April May

Bia

s (%

)

NAM - AFWA

NAM - CLAVR

WRF NMM - AFWA

WRF NMM - CLAVR

March April May

• Both models agree more closely with CLAVR• Both models have a high bias in total cloudiness• WRF NMM has a higher cloud bias than NAM (low clouds?)

4th JCSDA Science Workshop, 31 May – 1 June 2006

Model Biases as Functions of Cloud Fraction

Threshold Cloud Fraction (%)

Are

a B

ias

(Mod

el /

An

alys

is)

23 March - 15 May 2006

Forecast-Hit-Observation (FHO) stats(48-h forecasts valid at 12Z)

FC

ST

OB

SH

IT

• Almost 50% high bias in overcast conditions• Dominated by low clouds (esp over oceans; not shown)

NAM - AFWA

NAM - CLAVR

WRF NMM - AFWA

WRF NMM - CLAVR

4th JCSDA Science Workshop, 31 May – 1 June 2006

Final Remarks on Cloud Verification

Models tend to predict too much cloudiness compared to AFWA, CLAVR analyses Better agreement during midday, worse

agreement during early morning hours Models compare more favorably to CLAVR Slightly higher bias in WRF NMM cloudiness

compared to NAM-Eta (esp. for AFWA at 12Z, less so for CLAVR)

Largest over prediction in overcast conditions JCSDA funding would also accelerate pace and

scope of development to include more models and “verifying” analyses (next slide as an example)

4th JCSDA Science Workshop, 31 May – 1 June 2006

18-h FCST vs. GOES Retrieved (SW↓)sfc

• Useful for quick sanity checks of forecast incoming surface solar• Thanks to Istvan Laszlo (NESDIS) for providing 18Z images online, and to K. Mitchell, D. Tarpley

Op

s E

taW

RF

NM

M