1. GSICS Telecon July 2012
AVHRR, MODIS, VIIRS Radiance Monitoring in MICROS and GSICS help to SST
Sasha Ignatov
Xingming Liang
NOAA/NESDIS/STAR
Specific for nesdis
July 2012
GSICS help to SST

2. M-O Biases and Double Differences (“DD”)
Model minus Observation (“M-O”) Biases
M (Model) = Community Radiative Transfer Model (CRTM) simulated TOA Brightness Temperatures (w/ Reynolds SST, GFS profiles as input)
O (Observation) = Clear-Sky sensor (AVHRR, MODIS, VIIRS) BTs
Double Differences (“DD”) for Cross-Platform Consistency
“M” used as a “Transfer Standard”
DDs cancel out/minimize effect of systematic errors & instabilities in BTs arising from e.g.
Errors/Instabilities in Reynolds SST & GFS
Missing aerosol
Possible systemic biases in CRTM
Updates to ACSPO algorithm
July 2012
GSICS help to SST

3. Nighttime DD’s @3.7 µm (Ref=Metop-A GAC)
N17 was most consistent with Metop-A (N17 scan motor stalled on 10 Feb 2010). Their equator crossing times (EXT) are very close – 10:00-10:30pm
N19 (launch Feb 2009; EXT~1:30am) largely consistent with Metop-A and N17
N18 (launch May 2005; EXT~1:30am): Less consistent
N16 (launch Sep 2000; EXT~5am): Most inconsistent
July 2012
GSICS help to SST

4. Nighttime DD’s @11 µm (Ref=Metop-A GAC)
N17 was most consistent with Metop-A (N17 scan motor stalled on 10 Feb 2010). Their equator crossing times (EXT) are very close – 10:00-10:30pm
N19 (launch Feb 2009; EXT~1:30am) largely consistent with Metop-A and N17
N18 (launch May 2005; EXT~1:30am): Less consistent
N16 (launch Sep 2000; EXT~5am): Most inconsistent
July 2012
GSICS help to SST

5. Nighttime DD’s @12 µm (Ref=Metop-A GAC)
N17 was most consistent with Metop-A (N17 scan motor stalled on 10 Feb 2010). Their equator crossing times (EXT) are very close – 10:00-10:30pm
N19 (launch Feb 2009; EXT~1:30am) largely consistent with Metop-A and N17
N18 (launch May 2005; EXT~1:30am): Less consistent
N16 (launch Sep 2000; EXT~5am): Most inconsistent
July 2012
GSICS help to SST

6. Nighttime DD’s SST (Ref=Metop-A GAC)
N17 was most consistent with Metop-A (N17 scan motor stalled on 10 Feb 2010). Their equator crossing times (EXT) are very close – 10:00-10:30pm
N19 (launch Feb 2009; EXT~1:30am) largely consistent with Metop-A and N17
N18 (launch May 2005; EXT~1:30am): Less consistent
N16 (launch Sep 2000; EXT~5am): Most inconsistent
July 2012
GSICS help to SST

7. Summary Observations from MICROS – for BTs and SSTs
AVHRRs on Metop-A, N17, N19 form the tightest “family”
N18 shows unexplained deviations from the “family”
N16 shows largest unexplained “out-of-family” behavior
Question 1: Are these MICROS observations consistent with
AVHRR trending against spectrometers (AIRS, IASI)?
VHRR trending using Simultaneous Nadir Overpasses?
Question 2: If they are, then we need GSICS help with
Reconciliation of BTs form various AVHRR sensors
Doing this from “first principles” (better understanding of sensors, improved cal procedures) rather than “empirical bias corrections”
MODIS and VIIRS are also trended in MICROS
We do see smaller anomalies for MODIS – need GSICS help, too
Specific for nesdis
July 2012
GSICS help to SST

8. Email from Sasha Ignatov 12/06/2012
we do see inconsistencies across various AVHRRs in MICROS
we wanted to know if these anomalies are also seen in AVHRR comparisons against multispectral radiances
if they are, we need GSICS help with resolving and reconciling radiances
we need this reconciliation based on "first principles" rather than any sort of empirical "bias corrections"
we do monitor both MODIS instruments, and VIIRS in MICROS, and see some (relatively smaller) inconsistencies for MODIS. we might need help here too …
our major message Xingming and I would like to send to the GSICS community: it's time to actually start "walking the walk" towards more stable and cross-platform consistent radiances from various platforms, sensors & bands employed for SST. we expect that the GSICS will respond to this "user's request" and help us improve and reconcile SSTs.
July 2012
GSICS help to SST