Optimal configuration of a far‐infrared radiometer to the study the Arctic winter atmosphere

Several FIR satellite missions are planned for the next decade, with a special interest for the Arctic region. A theoretical study is performed to help about the design of a FIR radiometer, whose configuration in terms of channels number and frequencies is optimized based on information content analysis. The problem is cast in a context of vertical column experiments (1D) to determine the optimal configuration of a FIR radiometer to study the Arctic polar night. If only observations of the FIR radiometer were assimilated, the results show that for humidity, 90 % of the total information content is obtained with 4 bands whereas for temperature 10 bands are needed. When the FIR measurements are assimilated on top of those from the Advanced Infrared Sounder (AIRS), the former bring in additional information between the surface and 850 hPa and from 550 hPa to 250 hPa for humidity. Moreover, between 400 hPa and 200 hPa, the FIR radiometer is better than AIRS at reducing the analysis error variance for humidity. This indicates the potential of FIR observations for improving water vapor analysis in the Arctic.