Data Distribution Center Research Articles

Köppen Climate Types in Observed and Simulated Climates

The Koppen climate classification was applied to the observed gridded climatological sets and the outputs of four general circulation models (GCMs) over the continents of the Earth. All data had been acquired via the Data Distribution Centre established by the Intergovernmental Panel on Climate Change. The ability of the GCMs to simulate the Koppen climate zones identified in the real data was explored and possible future (global warming) changes in the climate types' distribution for each GCM were assessed. Differences in the area distributions derived from the GCMs' recent climate simulations give evidence about uncertainties generally involved in climate models. As to the global warming simulations, all GCM projections of warming climate (horizon 2050) show that the zones representing tropical rain climates and dry climates become larger, and the zones identified with boreal forest and snow climates together with the polar climates are smaller.

Comparison of Arctic Climate Simulations by Uncoupled and Coupled Global Models

Abstract Simulations of present-day Arctic climate are assessed from suites of 1) 13 global atmosphere-only models from the Atmospheric Model Intercomparison Project (AMIP-II) and 2) 8 coupled atmosphere–ocean–ice models from the Data Distribution Center of the Intergovernmental Panel on Climate Change (IPCC). The assessment highlights the impact of coupling on the simulated Arctic climate, and also the improvement of the uncoupled models relative to a previous (early 1990s) phase of the AMIP project. The across-model variance of the simulated air temperature is larger in the coupled models than in the uncoupled models, and the spatial pattern of the variance indicates that differences in the coupled models' simulated sea ice contribute to the larger variance of temperature. The coupled models are also several degrees colder than the uncoupled models during the winter half of the year. As was the case with the earlier AMIP models, the simulated precipitation still exceeds the observational estimates, part...

Climate changes in Central Europe projected by general circulation models

The paper is based on recent climate simulations provided by the leading world climate centres and available through the Data Distribution Centre of the Intergovernmental Panel on Climate Change. Seven models have been considered. Three experiments: control, and two integrations for different greenhouse gases emission scenarios have been analysed. Assessments have been made for the European window defined as 5–40° E, 40–60° N. The paper presents some selected results for the air surface temperature and precipitation. This is not a study on evaluation of models, detailed intercomparisons between models can be found in other works (e.g., Barnett, 1999; Boer and Lambert, 2000; Lambert and Boer, 2001), as well as on Internet (e.g., a web-site of the Program for Climate Model Diagnosis and Intercomparison1). The intention of the authors was to show examples of analyses made specifically for the Central European region. For the reason of technical limitations of the paper only some results can be presented.

Experimental Communication Payload Project of the ROCSAT-1 Satellite

In this paper, an experimental communication payload (ECP) project of the Republic of China's ROCSAT-1 satellite program is introduced. The objective of the project is to study implementation techniques of the low earth orbit Ka-band satellite communication systems and to conduct Ka-band satellite communication experiments to study the performance of the video/voice/data/fax transmission and Ka-band propagation effect. The ECP consists of three subsystems, termed the ECP space segment (ECPSS), ECP ground segment (ECPGS), and ECP Science Data Distribution Center (ESDDC). The ECPSS provides a Ka-band bent-pipe transponder and a downlink beacon. The ECPGS is comprised of a fixed ground station with both transmitting and receiving capabilities and a transportable receive-only ground station. The ESDDC is responsible for scheduling the execution of various experiments, setup of configuration parameters of ECP, and dissemination of the pre-/post-experiment data.

The Scientific Project for ROCSAT-1/OCI

Taiwan's first scientific experimental satellite, ROCSAT-1, is scheduled to be launch in January 1999. It will carry three scientific payloads. One of them is an instrument named Ocean Color Imager (OCI) to monitor ocean colors. There are two major working groups for the scientific purpose of OCI, the Science Team (ST) and the Science Data Distribution Center (SDDC). The OCI-ST was formed for sensor calibration, atmospheric correction, algorithm development, and data validation. The OCI algorithms developed were tested by Sea-viewing Wide Field-of-view Sensor (SeaWiFS) data. The results show that the relative error of water-leaving radiance from OCI atmospheric correction algorithms is higher than that derived from SeaWiFS algorithms. However, the relative error of chlorophyll a concentration derived from OCI bio-optical algorithm using the water-leaving radiance derived from OCI atmospheric correction algorithms is smaller than that for SeaWiFS products. Data from OCI will be processed and then distributed by the OCI-SDDC. The OCI-SDDC is also a day-to-day operations center. Anyone who is interested in OCI products can request them via the OCI-SDDC web site at http://www.oci.ntou.edu.tw/.

Electric propulsion activities outside of the United States.

A has been made of electric propulsion activities in countries outside of the United States. The review was confined to electric thruster studies excluding studies of mission analysis, power supplies, or related diagnostic instrumentation. Since much work on plasma acceleration has been, and still is being carried out in connection with thermonuclear fusion studies and MHD power generation, only those papers were examined wherein specific reference was made to electric propulsion. It is recognized that these latter constraints preclude from this survey many basic studies in ion and plasma physics whose results could possibly be of interest to someone engaged in electric thruster studies. The information upon which this survey is based was obtained from a machine literature search (for qualified users) of unclassified material contained on microfilm in the Data Distribution Center, Alexandria, Va., and NASA files and information that was obtained directly from foreign authors. In most cases, foreign reports that have been translated into English are several years old. This time lapse occurs because of the time delay between publication of the original work and the subsequent translation and republication. Recent material, therefore, can only be had by contacting individuals engaged in research or by attending conferences at which recent research results are presented.