15 May 2009 ACSPO v1.10 GAC 1

ACSPO upgrade to v1.10Effective Date: 04 March 2009

Sasha Ignatov, XingMing Liang, Yury Kihai, Boris Petrenko, John Stroup

NOAA/NESDIS/STAR

John Sapper and Denise Frey

NOAA/NESDIS/OSDPD

15 May 2009 ACSPO v1.10 GAC 2

Major upgrades in ACSPO v1.10

daily (AVHRR-based) 0.25º Reynolds SST (instead of weekly 1º)

new Community Radiative Transfer Model v1.1 (instead of r577)

CRTM built-in Wu-Smith emissivity model (instead of flat-surface Fresnel)

Plank-weighted (PW) CRTM coefficients for NOAA-17, -18, -19, and MetOp-A (for NOAA-16, ORD coefficients are still used)

Improved cloud detection- Using dynamic biases for brightness temperatures and SST filters

estimated in real-time. (Before, biases were assumed to be constant)

- Introducing ambient cloud filter

Day-night switch for cloud mask and SST algorithm occurs at 90° Solar Zenith Angle (instead of 85° in v1.00)

15 May 2009 ACSPO v1.10 GAC 3

Number of Observations

15 May 2009 ACSPO v1.10 GAC 4

During nighttime, number of OBS reduced due to- Change in day-night threshold from 85° to 90° SZA- Using ambient cloud filter

Number of Observations: NIGHTTIME

v1.00

v1.10

15 May 2009 ACSPO v1.10 GAC 5

During daytime, number of OBS increased due to- Change in day-night threshold from 85° to 90° SZA

(despite adding ambient cloudiness filter)

Number of Observations: DAYTIME

v1.00

v1.10

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Cloud Mask

15 May 2009 ACSPO v1.10 GAC 7

“Sat-Reynolds” SST anomalies in ACSPO v1.00 (3 March 2009)- Note multiple areas with negative anomalies (likely due to cloud leakage)- Cold biases at swath edges

Cloud Mask Quality: ACSPO v1.00

Night Day

15 May 2009 ACSPO v1.10 GAC 8

“Sat-Reynolds” SST anomalies in ACSPO v1.10 (4 March 2009)- Areas with negative anomalies reduced- Cold biases at swath edges reduced

Cloud Mask Quality: ACSPO v1.10

Night Day

15 May 2009 ACSPO v1.10 GAC 9

SST

15 May 2009 ACSPO v1.10 GAC 10

- Standard Deviation of “SAT-Reynolds” SST reduced- Weekly cycle significantly reduced or removed

Nighttime RMS “Sat-Reynolds” SST improved

v1.00

v1.10

15 May 2009 ACSPO v1.10 GAC 11

Daytime RMS “Sat-Reynolds” SST improved

v1.00

v1.10

- Standard Deviation of “SAT-Reynolds” SST reduced- Weekly cycle significantly reduced or removed

15 May 2009 ACSPO v1.10 GAC 12

Channel 4

Clear-Sky Brightness Temperatures

15 May 2009 ACSPO v1.10 GAC 13

Nighttime RMS “CRTM-AVHRR”

v1.00

v1.10

- Standard Deviation of “CRTM-AVHRR” BT reduced- Weekly cycle significantly reduced or removed

15 May 2009 ACSPO v1.10 GAC 14

v1.00

v1.10

Daytime RMS “CRTM-AVHRR”

- Standard Deviation of “CRTM-AVHRR” BT reduced- Weekly cycle significantly reduced or removed

15 May 2009 ACSPO v1.10 GAC 15

Number of nighttime observations slightly reduced

Number of daytime obs slightly increased

Cloud mask improved during both day and night

AVHRR SST in v1.10 agrees better with Reynolds SST

Brightness Temperatures agree better with CRTM

For more information see

http://ams.confex.com/ams/pdfpapers/143875.pdf

Summary of PerformanceACSPO v1.10 vs1.00

15 May 2009 ACSPO v1.10 GAC 16

View Zenith Angle biases in retrieved SSTs have been reduced in v1.10 but we still do not recommend using SSTs beyond VZA>55º, at least for quantitative analyses. (Note that the clear-sky brightness temperatures are less subject to the angular biases.)

Residual cloud problem has been reduced in v1.10 but nighttime SSTs are still subject to residual cloud in the areas with persistent cloudiness (such as the roaring forties in the North and in the South and ITCZ). Caution should be used with the current nighttime product in those areas.

The aerosol optical depth parameters for channels 1, 2, and 3a have not been fully evaluated yet so please use caution if using these parameters

Known Limitations in ACSPO v1.10

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ACSPO v1.20- Land-sea mask (1km instead of 8km) + land proximity distance- Day-night twilight zone indication - Code modularization, stability, & error handling- Resolve remaining FRAC/GAC inconsistencies

ACSPO v1.30- Graceful degradation (Reynolds SST & GFS)- Cloud mask improvements

ACSPO v1.40- L1b converter as front end- Further code modularization & clean-up

Level 2P, 3 and 4 development- Currently, ACSPO products are only available in L2 (swath granules)- Development of L2P (GHRSST compliant), L3 (field analysis) and L4

(weekly and monthly composites) products is currently underway

Ongoing ACSPO improvements