Linking Water Vapor Channels of GOES-11 and GOES-12 Imagers Using IASI Hyperspectral Observations Likun Wang 1 & Changyong Cao 2 1. Perot System Government Service 2. NOAA/NESDIS/STAR. Motivation. Global Water Vapor Composite Image from CIMSS.
Linking Water Vapor Channels of GOES-11 and GOES-12 Imagers Using IASI Hyperspectral ObservationsLikun Wang1 & Changyong Cao21. Perot System Government Service2. NOAA/NESDIS/STAR
Global Water Vapor Composite Image from CIMSS
MOTRAN simulation for
Tropical Atmosphere profile
Limb correction does not help!
Difference is still ~2-5 K!
From liu et al. 2008
GOES-11 imager CH3
GOES-12 imager CH3
From CIMSS website
If we can link GOES-11 and GOES-12, the same method can be used to resolve the spectral differences for other geostationary imager water vapor channels.
If it works for GEO instruments, the same method can be extended to LEO instruments to resolve their spectral response difference.
From CIMSS website
IASI versus SHIS, NASTI
AIRS versus IASI
Water vapor absorption region
Courtesy of D. Tobin and D.Blumstein
Courtesy of David Tobin
IASI pixel (12 km)
Four IASI pixels are averaged to compare with GOES pixels
(~200) falling into the corresponding IASI FOR
Metop-A orbit passes the GOES satellite sub-point several times each month
R is the IASI radiance
S is the GOES imager spectral response function
L is the IASI-convolved GOES imager radiance
i is the channel number
ν is the wavenumber
How does the BT difference vary with the scene uniformity?
How does the BT difference vary with the observational time difference?
IASI-GOES : -0.271±0.170 K
Seasonal variation of BT difference between IASI and GOES.
GOES-12 decontamination on 07/02/07
A GOES-12 imager “decontamination procedure” was performed on 02 July 2007, where certain internal optical components were heated in an attempt to drive off contaminants that had been accumulating for several years.
<= 0.3K at the BT range of 240-260 K with a standard deviation of ~0.2 K
Stdev (residual)=0.6 K
GOES11 BT (K)BT relationship between GOES-11 and GOES-12 water vapor channels
0.6 K (~0.3%) uncertainty when one predicts the GOES-12 BT using the GOES-11 BT in the temperature range of 200-265K.
Note that 15-minites observational difference