U.S. operational space program for climate observations

Satellites provide two important characteristics to earth climate studies not available from other, conventional sources: (1) full global coverage, and (2) consistency within the data set. This latter arises from the fact that the satellite data are usually derived from one instrument (or at least from a small number) whereas other sources involve large numbers of separate instruments and hence exhibit a substantial standard deviation. Satellite data, of course, are more subject to bias and must therefore be carefully validated, usually via ground truth.The ISCCP and ISLSCP are examples of the increasing reliance on satellite data for climate studies. In addition to the multispectral images, quantitative products of importance are: (1) atmospheric temperature structure, (2) snow cover, (3) precipitation, (4) vegetation index, (5) maximum/minimum temperature, (6) insolation, and (7) earth radiation balance. The U.S. civil space program is presently committed to its current geostationary (GOES) and polar (NOAA) programs through this decade and to continue both programs into the next decade with spacecraft carrying improved and augmented instrumentation. GOES VISSR Atmospheric Sounder (VAS) data, presently in research status and available only for special observation periods, will become available operationally in 1987 from the current spacecraft series. GOES-Next will provide additional spectral channels, simultaneous imaging, atmospheric soundings, and possibly increased resolution starting in 1990. The NOAA follow-on spacecraft, in the same time frame, is expected to provide additional spectral channels, improved passive microwave radiometry, and possibly increased spatial resolution. The Landsat program is expected to be continued by a commercial operator following the useful life of Landsat-5. All three follow-on programs are presently at various stages of definition and procurement. Final definition may not be completed until late in 1984. However, their status as of the time of this presentation will be reviewed in detail.     

Meteorological satellites and cooperative programs

Satellite data are available to meteorological centers around the world in two forms: (1) real-time reception directly from the spacecraft to the users; (2) processed data via the Global Telecommunications System (GTS). Real-time data is broadcast by satellites operated by both the U.S. and the U.S.S.R. From the NOAA series, Automatic Picture Transmission (APT) has been in wide use for 19 years. High Resolution Picture Transmission (HRPT) has been available to users with more sophisticated receiving equipment for the past 10 years. The Meteor satellites have been broadcasting for over 10 years. From the geostationary satellites (GOES), specialized products are broadcast via weather facsimile (WEFAX), and for users with very sophisticated ground systems, real-time geostationary images are available. Derived data, i.e., vertical temperature soundings of the atmosphere, etc., are routinely available on the GTS. The characteristics, utility, current utilization and future developments of these services will be reviewed and discussed.     

Circular polarisation in star-forming regions: possible implications for homochirality.

Our discovery of high degrees of circular polarisation in some star-forming regions provides an attractive mechanism for the origin of homochirality. The largest degrees of circular polarisation, so far observed at near-infrared wavelengths, are thought to arise from the scattering of stellar radiation from aligned dust grains and are calculated to extend down to UV wavelengths. The extent of the region where circularly polarised light (CPL) of a single handedness originates is very large, and it is likely that the whole of a planetary system would see a single handedness of CPL also. We present the observational data, models of the scattering that leads to the production of CPL, and a model for the origin of homochirality. We also discuss briefly future laboratory and space-based experiments.     

The United States operational polar-orbiting satellite series,TIROS-N

The U.S. launched the first of its new series of polar-orbiting, operational satellites, named TIROS-N, on 13 October 1978. The second, named NOAA-A, was launched on 27 June 1979. Together they comprise the operational system since from an average altitude of 840 km two satellites are required to provide global coverage in the equatorial zone. Operational products for FGGE (atmospheric temperature profiles, sea surface temperature analysis, and other data) are discussed and compared with prior performance. New uses in support of oceanology (Service ARGOS) are described.