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These data are part of the NERC Clouds, Water Vapour and Climate (CWVC) programme. With a diameter of 25 metres the 3 GHz CAMRa at Chilbolton Observatory (UK) is the largest steerable meteorological radar in the world. Polarisation and Doppler data are stored in netCDF format for 30 March 1999, 9 June 2000, 20 October 2000, 21 November 2000, and 28 February 2001. Quicklook images are also available.
The SMMR and SSM/I Pathfinder brightness temperatures provide scientists with more than 20 years of consistently processed, passive microwave data for use in climatological and earth science research. Each file represents gridded data for a single sensor channel and polarization, derived from either ascending or descending orbits for one day, thereby allowing discrimination of diurnal changes in earth surface processes. Each data sets consists of three series: the Northern and Southern Hemispheres and a global projection. Grids represent spatially interpolated data. The interpolation techniques maximize the radiometric integrity of original brightness temperature values, maintain high spatial and temporal precision, and involve no averaging of original swath data. SMMR coverage began October 1978 and continued through July 1987. Grid resolution is 25 km for all channels. SSM/I coverage began August 1987 and continues through the present. Processing is ongoing with current data available within three to six months of sensor data acquisition. Resolution is 25 km for all channels and 12.5 km for the 85 GHz channels. A sample data set comprising selected SSM/I EASE-Grid brightness temperature data and time files for all three projections from September 8 (day 251), 1997 is included on this CD-ROM.
Derived from the global TIROS Operational Vertical Sounder (TOVS) data set, the TOVS Polar Pathfinder provides users with gridded daily and monthly arctic atmospheric soundings. Since 1979, TOVS has been a vital tool for weather forecasting, supplying users with information on the vertical distribution of temperature and moisture in the global atmosphere. TOVS has been particularly useful in providing atmospheric soundings over regions where in situ measurements are sparse. TOVS Polar Pathfinder data were obtained using a modified version of the Improved Initialization Inversion Algorithm to identify geophysical parameters in snow- and ice-covered areas. The data set has been designed to address the particular needs of the polar research community, and includes quantities used to compute surface turbulent fluxes and drive ocean models. Variables retrieved from satellite observed radiances for this product include atmospheric temperature profiles, water vapor, surface (skin) temperature, total effective cloud fraction, cloud top pressure, cloud top temperature, turning angle between geostrophic wind and surface stress over ice, emissivity, boundary layer stratification and geostrophic drag coefficient. TOVS data coverage spans July 7, 1979 through December 31, 1996 at a resolution of 100 km. Sample products for four selected dates in 1988 are included on this CD-ROM.
The P-Cube data set is a 100 km resolution subset of many important variables from three Polar Pathfinder Projects in common projection (Lambert azimuthal equal-area) and common grid (EASE-Grid). For the first time, data sets from multiple sensors measuring the Arctic region are being distributed in a manner that facilitates study of polar processes and interactions between them. A "data cube" of the Polar Pathfinder Products, hence the name "P-Cube," allows users to access variables derived from three satellite sensors and use them together. The common spatial resolution for P-Cube is dictated by the lowest resolution product (TOVS data). The P-Cube allows browsing of the multi-sensor data and exploring the relationships among the variables. For AVHRR and SSM/I data, the user may turn to the full resolution, single instrument Polar Pathfinder data sets for greater details. A wide range of polar climate research applications is possible using this multi-dimensional suite of variables from AVHRR, TOVS and passive microwave instruments. The prototype version of the P-Cube included on this CD-ROM has a temporal coverage of January 1, 1988 to December 31, 1989, and a spatial coverage poleward of 60 degrees N latitude. Future versions of the P-Cube will have expanded temporal and spatial coverage, as well as additional variables. The current prototype version of the P-Cube includes the following: atmospheric temperature (10 levels), precipitable water (5 layers), boundary layer stratification parameter, geostrophic drag coefficient, turning angle, and microwave surface emissivity (from TOVS); surface albedo, surface (skin) temperature, solar zenith angle, cloud fraction, standard deviation of surface albedo, and standard deviation of surface temperature (from AVHRR); and total ice concentration, surface type and ice velocity (from AVHRR and SSM/I). From the National Centers for Environmental Prediction (NCEP) surface pressure is provided. Please note that the P-Cube data set is a prototype for a potential long term data set consisting of integrated Polar Pathfinder Products. At the time of the production of the Polar Pathfinder Sampler CD-ROM, the algorithms for a number of variables are still undergoing development and validation.