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Bias characterization of CrIS shortwave temperature sounding channels using fast NLTE model and GFS forecast field
Author(s) -
Yin Mengtao
Publication year - 2016
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2015jd023876
Subject(s) - depth sounding , daytime , longwave , radiative transfer , atmospheric sciences , shortwave , environmental science , atmosphere (unit) , ionosphere , middle latitudes , atmospheric model , latitude , meteorology , physics , geology , geophysics , astronomy , oceanography , quantum mechanics
The strong nonlocal thermal equilibrium (NLTE) emission in the upper atmosphere impedes the usage of Cross‐track Infrared Sounder (CrIS) temperature channels near 4.3 µm in the operational data assimilation. This study explores the bias characteristics of those temperature channels near 4.3 µm with and without a fast NLTE model implemented in the Community Radiative Transfer Model (CRTM). It is shown that the biases of those temperature channels can reach up to 12 K and are dramatically reduced to below 4 K during daytime by the fast NLTE model with small differences from the nighttime biases. However, the biases after applying the NLTE correction remain large for CrIS upper atmospheric temperature channels during both daytime and nighttime. A further investigation suggests that the remaining biases in those temperature channels mainly originate from the cold biases in the stratospheric temperature profiles of National Center for Environmental Prediction Global Forecast System (GFS) forecasts as input to CRTM. The cold biases reach the maximum of about 8 K near the tropics at about 1 hPa, decreasing toward higher latitudes and lower altitudes.