Deriving Atmospheric Temperature of the Tropopause Region–Upper Troposphere by Combining Information from GPS Radio Occultation Refractivity and High-Spectral-Resolution Infrared Radiance Measurements

Abstract

Global positioning system radio occultation (GPS/RO) measurements from the Challenging Minisatellite Payload (CHAMP) and Satelite de Aplicaciones Cientificas-C (SAC-C) satellites are used to improve tropospheric profile retrievals derived from the Aqua platform high-spectral-resolution Atmospheric Infrared Sounder (AIRS) and broadband Advanced Microwave Sounding Unit (AMSU) measurements under clear-sky conditions. This paper compares temperature retrievals from combined AIRS, AMSU, and CHAMP/SAC-C measurements using different techniques: 1) a principal component statistical regression using coefficients established between real (and in a few cases calculated) measurements and radiosonde atmospheric profiles; and 2) a Bayesian estimation method applied to AIRS plus AMSU temperature retrievals and GPS/RO temperature profiles. The Bayesian estimation method was also applied to GPS/RO data and the AIRS Science Team operational level-2 (version 4.0) temperature products for comparison. In this study, including GPS/RO data in the tropopause region produces the largest improvement in AIRS-AMSU temperature retrievals-about 0.5 K between 100 and 300 hPa. GPS/RO data are found to provide valuable upper-tropospheric information that improves the profile retrievals from AIRS and AMSU.

Assessing the performance of GPS radio occultation measurements in retrieving tropospheric humidity in cloudiness: A comparison study with radiosondes, ERA-Interim, and AIRS data sets

“…Ho et al [] obtained smaller specific humidity root‐mean‐square‐errors (RMSE) by combining GPSRO refractivities with temperatures derived from the Atmospheric Infrared Sounder (AIRS) on the NASA Aqua satellite, compared to each instrument individually. Borbas et al [] improved tropopause temperature retrieval errors by ~0.5 K compared to rawinsondes by assimilating GPSRO with AIRS temperatures.…”

Observations of Temperature in the Upper Troposphere and Lower Stratosphere of Tropical Weather Disturbances

“…Temperature data in this region have been obtained by a variety of remote sensing platforms in recent years. Radio occultation data have also been used to improve temperatures retrieved from the Atmospheric Infrared Sounder (AIRS) aboard the Aqua satellite (Borbas et al 2008). Such measurements are important for documenting climatological seasonal and intraseasonal conditions (Kim and Son 2012) and for sampling profiles through clouds (Biondi et al 2012).…”

Studying the Atmosphere Using Global Navigation Satellites

“…Several studies have shown that RO provides complementary data to hyperspectral infrared sounders such as AIRS [Borbas et al, 2008;Ho et al, 2007].…”