Construction of Temperature Climate Data Records from June 2006 to December 2015 using COSMIC, Metop-A and Metop-B RO Missions and Potential Climate Applications from COSMIC-2

Monitoring and detecting the vertical structure of atmospheric temperature trends are key elements in the climate change problem. In addition, identifying the long-term change of temperature and tropopause structure (i.e., tropopause height) in the upper troposphere and lower stratosphere (UTLS) is necessary to advance reliable predictions of trends in climate or global change. Current long-term variations of atmospheric vertical thermal distributions are mainly constructed from passive satellite microwave and infrared sounders. However, due to lack of on board stable calibration references, the inter-satellite biases are still large when they are overlapped. The IPCC AR5 identified that “there is only medium to low confidence in the rate of change of tropospheric warming and its vertical structure, and there is low confidence in the rate and vertical structure of the stratospheric cooling”. 

Recently, the UCAR Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) Data Analysis and Archive Center (CDAAC) has developed an improved reprocessing package, which is used to consistently process RO data from multiple years of multiple RO missions including COSMIC (launched in April 2006),  Meteorological Operational Polar Satellite–A (Metop-A)/GRAS (GNSS Receiver for Atmospheric Sounding (launched in October 2006), and Metop-B/GRAS (launched in September 2012). These consistently processed GPS RO data extending over a period of close to 10 years provide unique long-term and stable climate measurements, which will be useful for validating and calibrating other satellite and in situ observations, offering insights on the uncertainty of climate models and the modes of atmospheric variability. In this study, we focused on construction of temperature climate data records from 2006 to 2015 using COSMIC, Metop-A/GRAS and Metop-B/GRAS. This is to generate long-term climate quality temperature monthly mean climatologies (MMCs) using dry temperature profiles from these multiple RO missions in the UTLS (mainly from 8km to 30 km altitude with a vertical grid every 200 meters). In addition, we also developed a robust method to estimate sampling errors for each mission. The method for quantifying and removing the sampling errors and results for the new MMCs are presented.

COSMIC’s success has also prompted U.S. agencies to move forward with a follow-on COSMIC-2 RO mission with Taiwan that will launch six satellites into low-inclination orbits in mid-2017 and another six satellites into high-inclination orbits in 2019. It is expected to yield up to 12,000 RO profiles per day after the two constellations are fully deployed. With an improved design in the RO receiver and antenna, the RO data from COSMIC-2 will also be of much higher quality than COSMIC. Potential climate applications of COSMIC-2 are also presented.