Summary

Description

The Climate Data Records (CDR) for Channel 7 contains Radio Occulation (RO) calibrated brightness temperatures from AMSU-A channel 7 measurements at 54.9 GHz from 2001 through present on a 2.5 degree grid. Data are partitioned into yearly files with monthly variables, where each file contains RO-calibrated channel 7 brightness temperatures from AMSU-A measurements from NOAA-15, 16, 17, 18, 19, NASA AQUA and Metop-A. The dataset uses version 2010.2640 of the RO mission data from the UCAR COSMIC Data Analysis and Archival Center (CDAAC), the NOAA archive of the Level 1b AMSU dataset, and the NASA DAAC archive of the Aqua Level 1B dataset. The RO satellites measure the bending angle of GPS signals as they pass through the atmosphere. Temperature profiles are derived from these GPS bending angles from the COSMIC and CHAMP data from 2001 through present. Calibration coefficients are calculated from coincident measurements of AMSU channel 7 brightness temperatures and corresponding values derived from an AMSU forward model applied to temperature profile measurements from RO identified radiosondes. The monthly calibration coefficients are applied to adjust the AMSU Temperature Troposphere Stratosphere (TTS) measurements for each polar orbiter to the temperature profiles from the RO identified Radiosonde Observations (RAOBs). The calibrated AMSU measurements are then combined into gridded monthly values. From these the climatology is calculated using 12 years of data. Anomaly values are then obtained by subtracting this climatology from the monthly values.