Using Reanalysis Data to Estimate the Sampling Biases of the Atmospheric Infrared Sounder (AIRS) Obs4MIPs V2 Dataset for Climate Model Intercomparisons

The ``Observations for Model Intercomparison Projects'' (Obs4MIPs) collects, organizes, and publishes various well-established satellite datasets for the Coupled Model Intercomparison Project (CMIP) model evaluation. The Atmospheric Infrared Sounder (AIRS) Obs4MIPs Version 2 (V2) dataset includes the monthly mean tropospheric air temperature, specific humidity, and relative humidity profiles from September 2002 to September 2016. Due to the limitations of the Aqua satellite orbit and the AIRS retrieval algorithm, the sampling biases of the AIRS Obs4MIPs V2 data can be as large as the measurement uncertainties for certain cases and must be considered when the AIRS Obs4MIPs V2 data are used in CMIP model evaluations. We examine estimates of the sampling biases of the AIRS Obs4MIPs V2 dataset based on European Centre for Medium-Range Weather Forecasts Version 5 (ERA5) and Modern Era Retrospective-Analysis for Research Applications Version 2 (MERRA-2) reanalysis data and identify regions where the sampling biases should be considered. These sampling bias estimates and the sampling bias corrected AIRS Obs4MIPs V2.1 data will be published on the ESGF to assist the climate modeling community to better use the AIRS data for CMIP6 model evaluation.