Assessment of COSMIC radio occultation and AIRS hyperspectral IR sounder temperature products in the stratosphere using observed radiances

Abstract

Upper air temperature is defined as an essential climate variable by the World Meteorological Organization. Two remote sensing technologies being promoted for monitoring stratospheric temperatures are GPS radio occultation (RO) and spectrally resolved IR radiances. This study assesses RO and hyperspectral IR sounder derived temperature products within the stratosphere by comparing IR spectra calculated from GPS RO and IR sounder products to coincident IR observed radiances, which are used as a reference standard. RO dry temperatures from the University Corporation for Atmospheric Research (UCAR) Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) mission are compared to NASA Atmospheric Infrared Sounder (AIRS) retrievals using a previously developed profile‐to‐profile collocation method and vertical temperature averaging kernels. Brightness temperatures (BTs) are calculated for both COSMIC and AIRS temperature products and are then compared to coincident AIRS measurements. The COSMIC calculated minus AIRS measured BTs exceed the estimated 0.5 K measurement uncertainty for the winter time extratropics around 35 hPa. These differences are attributed to seasonal UCAR COSMIC biases. Unphysical vertical oscillations are seen in the AIRS L2 temperature product in austral winter Antarctic regions, and results imply a small AIRS tropical warm bias around ~35 hPa in the middle stratosphere.

Observation of Very Short Period Atmospheric Gravity Waves in the Lower Ionosphere Using Very Low Frequency Waves

“…The temperature profile uses COSMIC occultation data which is obtained by the bending angle of electromagnetic waves generated by the GPS constellation satellites that are detected by the low earth orbiting satellites. For more details on this, please see paper by Feltz et al (). The data may be obtained from the following link (https://cdaac-www.cosmic.ucar.edu/).…”

Quantifying the Tropical Upper Tropospheric Warming Amplification Using Radio Occultation Measurements

“…RO is on average colder than MERRA-2 by 0.52 K and warmer than AIRS v6 by 0.50 K with these differences being statistically significant. Feltz et al (2017) 1b). Both RO and the two reanalyzes indicate warmer air than NorCPM1 and EC-Earth3, whereas IPSL-CM6A-LR simulated the warmest tropical UT of all of the data sets examined here, being 0.6 K warmer than RO.…”

“…Feltz et al. (2017) also reported AIRS 0.5 K cold bias relative to University Corporation for Atmospheric Research (UCAR) RO measurements in the tropical UT and Hearty et al. (2014) reported AIRS 0.8 K cold bias relative to MERRA at the tropical 300 hPa level.…”

Atmospheric Sciences Perspectives on Integrated, Coordinated, Open, Networked (ICON) Science

“…At the larger spatial scales, remote sensing data from satellites provide valuable information from the surface up to the upper atmosphere. Many missions such as TIMED (Christensen et al., 2003; Niciejewski et al., 2006) (data website: http://www.timed.jhuapl.edu/WWW/scripts/mdc_rules.pl), COSMIC (Feltz et al., 2017) (data website: https://cdaac-www.cosmic.ucar.edu/) and CHAMP (Park et al., 2020; Reigber et al., 2002) (website: https://isdc.gfz-potsdam.de/champ-isdc/) are openly available to scientists all over the world for research purpose, but more efforts are needed to fully integrate and coordinate these data sources while allowing greater participation in mission development for the benefits of the network of all scientists.…”