Climate Monitoring with Radio Occultation Data

The provision of accurate, long-term consistent data to sustain and expand the observational foundation for climate studies is one of the high priority areas for action formulated by the Intergovernmental Panel on Climate Change (IPCC) in its 2001 Report. Such data are vital to improve the ability to detect, attribute and understand climate variability and change. Until now it has not been possible to determine trends in atmospheric temperature from satellite data sets with convincing accuracy. Radio occultation (RO) data using Global Navigation Satellite System (GNSS) signals have the potential to overcome problems of traditional data sources due to their unique combination of the properties of high accuracy and vertical resolution, long-term stability due to intrinsic self calibration, global coverage, and all-weather capability. The potential of RO data for climate monitoring has been shown with simulation studies and through climatological analyses based on real data. The CLIMROCC project focuses on using RO data from the occultation sensors on CHAMP, SAC-C, MetOp (launch scheduled April 2006), and COSMIC (launch scheduled March 2006) satellites for deriving accurate and validated monthly, seasonal, and annual benchmark climatologies of temperature, geopotential height, humidity, and refractivity fields of the global upper troposphere and lower stratosphere (UTLS), with a horizontal resolution of about 500-1500 km. This work will build on existing initial single-satellite climatologies from CHAMP, the first opportunity to obtain such climatologies, currently prepared for temperature fields for the years 2002-2005 and scheduled to be finished by end 2005. By including additional climate variables and advancing from the single satellite CHAMP to multi-satellite climatologies, with expected higher data quality from the new COSMIC and MetOp RO sensors, CLIMROCC aims at initiating a new reference standard for global UTLS climatologies. The climatologies will be obtained in a model-independent manner by statistical binning and averaging techniques, together with carefully prepared observational as well as sampling error estimates, and validated against analysis fields from major weather prediction centers as well as inter-validated amongst different RO missions and RO sensors. Based on the climatologies, indicators of climate change are studied. The overall goal is to globally monitor the climate evolution of the UTLS region with unprecedented accuracy and consistency and thereby help to improve the ability to detect, attribute, and predict climate variability and change.

The provision of accurate, long-term consistent data to sustain and expand the observational foundation for climate studies is one of the high priority areas for action formulated by the Intergovernmental Panel on Climate Change (IPCC) in its 2001 Report. Such data are vital to improve the ability to detect, attribute and understand climate variability and change. Until now it has not been possible to determine trends in atmospheric temperature from satellite data sets with convincing accuracy. Radio occultation (RO) data using Global Navigation Satellite System (GNSS) signals have the potential to overcome problems of traditional data sources due to their unique combination of the properties of high accuracy and vertical resolution, long-term stability due to intrinsic self calibration, global coverage, and all-weather capability. The potential of RO data for climate monitoring has been shown with simulation studies and through climatological analyses based on real data. The CLIMROCC project focuses on using RO data from the occultation sensors on CHAMP, SAC-C, MetOp (launch scheduled April 2006), and COSMIC (launch scheduled March 2006) satellites for deriving accurate and validated monthly, seasonal, and annual benchmark climatologies of temperature, geopotential height, humidity, and refractivity fields of the global upper troposphere and lower stratosphere (UTLS), with a horizontal resolution of about 500-1500 km. This work will build on existing initial single-satellite climatologies from CHAMP, the first opportunity to obtain such climatologies, currently prepared for temperature fields for the years 2002-2005 and scheduled to be finished by end 2005. By including additional climate variables and advancing from the single satellite CHAMP to multi-satellite climatologies, with expected higher data quality from the new COSMIC and MetOp RO sensors, CLIMROCC aims at initiating a new reference standard for global UTLS climatologies. The climatologies will be obtained in a model-independent manner by statistical binning and averaging techniques, together with carefully prepared observational as well as sampling error estimates, and validated against analysis fields from major weather prediction centers as well as inter-validated amongst different RO missions and RO sensors. Based on the climatologies, indicators of climate change are studied. The overall goal is to globally monitor the climate evolution of the UTLS region with unprecedented accuracy and consistency and thereby help to improve the ability to detect, attribute, and predict climate variability and change.