Kenneth R. Knapp, Steve Ansari, Caroline L. Bain, Mark A. Bourassa, Michael J. Dickinson, Chris Funk, Chip N. Helms, Christopher C. Hennon, Christopher D. Holmes, George J. Huffman, James P. Kossin, Hai-Tien Lee, Alexander Loew, Gudrun Magnusdottir
With the recent passing of the fiftieth anniversary of the first U.S. weather satellite, questions on how to best use historical satellite data come to the forefront of the discussion on climate observation. There are now over 30 years of globally sampled geostationary and polar satellite data, and while the visible and infrared (IR) imaging instruments on the satellites were not specifically designed for climate purposes, the record has great potential to be used for observational climate studies. With this in mind, the National Oceanic and Atmospheric Administration (NOAA) recently embarked on an effort to derive climate data records (CDRs) from environmental satellite data (National Research Council 2004), including geostationary satellites. At present, most CDRs derived from historical satellites are based on polar-orbiting instruments, such as sea surface temperature data (Reynolds et al. 2002). Climatic use of geostationary data has been limited largely to teams of satellite experts—for example, the international community activities of the Global Energy and Water Experiment (GEWEX) such as the International Satellite Cloud Climatology Project (ISCCP) and the Global Precipitation Climatology Project (GPCP).
Numerous issues hinder use of the complete global geostationary data record by the climate research community. First, each country archives its own geostationary data. Thus, to obtain global data, one could access data from the United States [for the Geostationary Operational Environmental Satellites (GOES)], Europe [for the Meteorological Satellites (Meteosat)], Japan [for the Geostationary Meteorological Satellites (GMS) and Multi-functional Transport Satellite (MTSAT)], and China [for the Feng Yun (FY) geostationary satellite]. Additionally, users might access geostationary data from other nations for climate studies, such as India, South Korea, and Russia. Second, the volume of full-resolution data can be unwieldy for any study at climate time scales. Third, the data format from each agency will be heterogeneous; furthermore, the data from any one agency may have multiple file formats. Assuming that users can overcome these hurdles, they must also calibrate (i.e., calculate radiances and brightness temperatures from the data) and navigate (i.e., determine the latitude and longitude for each image pixel) the data from each satellite.
As mentioned, the ISCCP and GPCP projects are two of the few climate uses of geostationary data prior to 2000. This is due in part to the international collaboration that overcame the hindrances described above. In doing so, the ISCCP stored a subset of satellite data at NCDC called ISCCP B1 that included data from each international meteorological satellite. However, necessary information about the data such as file format, navigation algorithms, and so on were not archived. This caused the ISCCP B1 archive to be mostly unusable until a rescue effort rectified these issues (Knapp et al. 2007) and provided access to the data for 1983–present. In addition, further efforts (Knapp 2008b) have expanded the period of record back to 1980.