HR: 0800h
AN: A31B-0313    [Abstracts]
TI: An investigation of the capability of CLARREO to calibrate operational sounders with a focus on both spatial and temporal sampling uncertainties
AU: * Holz, R E
EM: reholz@ssec.wisc.edu
AF: SSEC-Space Science and Engineering Center, University of Madison-Wisconsin, 1225 W. Dayton, Madison, WI 53706, United States
AU: Nagle, F
EM: fred.nagle@ssec.wisc.edu
AF: SSEC-Space Science and Engineering Center, University of Madison-Wisconsin, 1225 W. Dayton, Madison, WI 53706, United States
AU: Tobin, D C
EM: dave.tobin@ssec.wisc.edu
AF: SSEC-Space Science and Engineering Center, University of Madison-Wisconsin, 1225 W. Dayton, Madison, WI 53706, United States
AU: Knuteson, R O
EM: bob.knuteson@ssec.wisc.edu
AF: SSEC-Space Science and Engineering Center, University of Madison-Wisconsin, 1225 W. Dayton, Madison, WI 53706, United States
AU: Dutcher, S
EM: steved@ssec.wisc.edu
AF: SSEC-Space Science and Engineering Center, University of Madison-Wisconsin, 1225 W. Dayton, Madison, WI 53706, United States
AU: Revercomb, H E
EM: hank.revercomb@ssec.wisc.edu
AF: SSEC-Space Science and Engineering Center, University of Madison-Wisconsin, 1225 W. Dayton, Madison, WI 53706, United States
AB: In addition to the primary goals of CLARREO of producing climate products and providing rigorous tests of climate forecasts, a secondary goal is to provide an in-orbit standard for the inter-calibration of other infrared space-borne sensors. The goal is to use CLARREO to improve the absolute calibration and consistency of other infrared observations from space. This study considers the case where three CLARREO satellites in 90-degree polar orbits with 120-degree orbital separation are used to transfer the absolute calibration from the CLARREO instruments to an operational advanced IR sounder in a sun-synchronous orbit, e.g. IASI on MetOp or CrIS on NPOESS. This particular inter-calibration goal addresses the needs of the operational weather community for improved absolute accuracy while opening the possibility of using the weather observations to contribute to the long-term climate record. To quantify the radiometric calibration of operational sounders using CLARREO requires that the uncertainties resulting from the inter-calibration process be well characterized and smaller than the required accuracy of the calibration. It is the goal of this study to investigate the accuracy to which CLARREO can be used to inter-calibrate operational sounders (IASI and CrIS) for climate studies and in the process determine the necessary noise characteristics of CLARREO to meet the inter-calibration requirements. The primary sources of uncertainty in the inter-calibration process are from instrument noise and the spatial and temporal sampling differences of the instruments. The impact of random sensor noise is relatively straightforward to assess. The uncertainties resulting from the spatial and temporal sampling differences, which are dynamic, and function of the natural scene variability are more difficult to characterize and the focus of this work. Spatial and temporal collocation errors are analyzed using one year of Aqua MODIS data, along with knowledge of the spatial and temporal sampling characteristics of the sounders (IASI and CrIS) and CLARREO. We find that the inter-calibration between CLARREO and the operational sounders can be performed with an accuracy of less than 0.1 K 3-sigma for MODIS band 32 (11 microns). This assumes monthly averages, nadir CLARREO sampling with 100 km diameter FOVs, and CLARREO single FOV random noise of less than 0.6 K NEDT
DE: 3305 Climate change and variability (1616, 1635, 3309, 4215, 4513)
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting