1. M. Goldberg NOAA/NESDIS Z. Cheng (QSS)
Ensuring consistency between AMSU-A climate temperature retrieval products from NOAA-15 and NOAA-16
M. Goldberg
NOAA/NESDIS
Z. Cheng (QSS)

2. Topics Review Strategy for using N16 and N15
Comparisons between N16 and N15 observations.
Retrieval Results

3. Datasets Daily, Pentad and Monthly 1x1 grids - ascending/descending
- July 1998 to present
Products
- Limb adjusted brightness temperatures
- Temperature profile from 0.1 mb to 1000 mb
- Total Precipitable Water – ocean only
- Cloud Liquid Water - ocean only
Accuracy ~ 1.5 K over 3 km layers

4. Ecmwf forecast - AMSU-A retrieval @ 3mb
Bias = , Sdv = September 18, 2001
(HALOE K, 2.2 K)

5. ch13
-2.6, 1.35
-.08, 0.26

6. Climate Quality Algorithm is constant. Coefficients are not updated.
As a result:
- trends/changes are due to changes in the atmosphere and not due to changes in algorithm or coefficients.

7. NOAA 15 AMSU-A Retrieval Methodology
Limb adjust brightness temperatures
Linear regression to solve for atmospheric temperature
Coefficients:
- July limb adjustment coefficients
- July 1998 – Dec collocated radiosondes to derive regression coefficients
- Synthetic regression used above 10 mb.

8. Strategy for consistent climate quality NOAA-15 & NOAA-16 AMSU-A temperature product
Goal: To ensure that differences between N15 and N16 AMSU-A temperature retrievals are due only to atmospheric differences.
Requirements:
- Retrieval coefficients are the same (synthetic).
- All empirical coefficients are from the same time period.
- Compute offsets between N15 and N16

9. NOAA-15 and NOAA-16 AMSU-A comparisons
Reconfirmed that asymmetry in AMSU-A exists.
It is different in NOAA-15 and NOAA-16
Differences between NOAA-16 and NOAA-15 are generally small --- especially near nadir.
Differences increase if antenna corrections are applied .

14. FOV #

15. FOV #

16. Offsets between N15 and N16
Generated annual mean limb adjusted brightness temperature field for both N15 and N16 (Nov 00. – Oct. 01)
Offsets should be independent of satellite observing time
Averaged ascending/descending for N mean time of 1:30 pm and compared with ascending N16 data.
Averaged ascending/descending for N mean time of 7:30 am and compared with descending N15 data.

17. OFFSETS
channel n15all – n16asc n15desc – n16all

18. NOAA NOAA 16 no offsets

19. NOAA Adjusted NOAA-16

23. Summary NOAA-16 and NOAA-15 retrievals
Algorithm is very robust and retrievals are accurate.
Model independent retrievals are very important for validating model dependent analyses and climate prediction models.
Microwave observations are very important for monitoring temperature.
New microwave sounders are on the horizon (SSMIS, ATMS, CMIS).