Abstract
Abstract. This paper mainly focuses on the validation of temperature estimates derived with the newly launched Constellation Observing System for Meteorology Ionosphere and Climate (COSMIC)/Formosa Satellite 3 (FORMOSAT-3) system. The analysis is based on the radio occultation (RO) data samples collected during the first year observation from April 2006 to April 2007. For the validation, we have used the operational stratospheric analyses including the National Centers for Environmental Prediction - Reanalysis (NCEP), the Japanese 25-year Reanalysis (JRA-25), and the United Kingdom Met Office (MetO) data sets. Comparisons done in different formats reveal good agreement between the COSMIC and reanalysis outputs. Spatially, the largest deviations are noted in the polar latitudes, and height-wise, the tropical tropopause region noted the maximum differences (2–4 K). We found that among the three reanalysis data sets the NCEP data sets have the best resemblance with the COSMIC measurements.
Highlights
Temperatures are important in many aspects of atmospheric research and many studies have investigated the accuracy of derived temperature profiles (e.g. Hertzog et al, 2003; Pommerau et al, 2002; Knudsen et al, 2002)
We focus on comparison of COSMIC temperature profiles with the National Centers for Environmental Prediction - Reanalysis (NCEP), Met Office (MetO), and JRA-25 reanalysis data sets
In order to note the global coverage of COSMIC Radio occultation (RO), an example of the global occultations for the Northern Hemisphere (NH) summer season is shown in Fig. 2, where the total number of occultations is 49 302
Summary
The GPS-RO technique has been very useful in collecting the global high-resolution data sets of atmospheric refractivity, temperature, pressure, and water vapour profiles. Wang et al (2004) compared more than 100 temperature profiles collected using the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) and the CHAMP during 14 days in September/October 2002 They found good agreement in the upper troposphere and lower stratosphere. The US/Taiwanese Constellation Observing System for Meteorology Ionosphere and Climate (COSMIC/FORMOSAT-3) satellite was successfully launched on 15 April 2006 This mission is expected to bring the innovative use of GPS RO data for atmospheric and ionospheric research, for improving global weather forecasts and climate change related studies. A distinctive feature of the COSMIC mission, compared to previous RO missions, is tracking both setting and rising neutral atmospheric occultations in the lower troposphere in an open-loop (OL) mode (Schreiner et al, 2007) This is very important for detecting the moisture variation in the lower troposphere, which is very useful for weather prediction and climate analysis. Results obtained from the present analysis in terms of comparison between COSMIC satellite and reanalysis are described
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