http://nopr.niscpr.res.in/handle/123456789/36341 2026-10-11T21:00:42Z 2026-10-11T21:00:42Z Chandrasekhar, T http://nopr.niscpr.res.in/handle/123456789/36466 2016-10-31T06:07:44Z 1988-12-01T00:00:00Z

Title: Comet Halley - India Observations Authors: Chandrasekhar, T Abstract: The recent apparition of Comet Halley in 1985-86 witnessed a well planned coordinated study by the space probes as well as by an extensive observational network on the ground which has resulted in a sea change in our understanding of the cometary environment. The Indian astronomers actively participated in the coordinated observational programme under the aegis of the International Halley Watch (IHW) and Indian Halley Observation Programme (IHOP) and have obtained several interesting results on the spatial distribution of coma emissions and on some transient events. The observations and some of the results are discussed. Page(s): 296-304

1988-12-01T00:00:00Z Narayanan, M S Joshi, P C Pal, P K http://nopr.niscpr.res.in/handle/123456789/36465 2016-10-31T06:06:32Z 1988-12-01T00:00:00Z

Title: Input of Space-based Data in Numerical Weather Prediction Authors: Narayanan, M S; Joshi, P C; Pal, P K Abstract: The lack of adequate observational data has been a major limiting factor in the numerical weather forecasting. The role of the meteorological satellites in filling the data gaps for medium range weather forecasting is discussed. A brief review of the methods of assessment and accuracy of operational forecast models is made. Impact and simulation results of the pre-FGGE era are summarized. The quality, coverage and accuracy of the FGGE (1979) observations, which provided the first truly global coverage, particularly from satellite platforms, are discussed. The results of various observing system experiments using different combinations of satellite and conventional data obtained during FGGE are mentioned in detail. The importance of satellite-derived winds for the tropics and satellite-derived temperatures for southern hemisphere is brought out from these studies. The studies also show the indifferent impact of surface winds from SEASAT on the forecasts over mid-latitudes of the northern hemisphere. Results from our own numerical experiments on impact of satellite cloud motion winds on monsoon forecasting indicate the desirability of additional level winds from satellites, while supporting the usefulness of the 850 and 200 mbar winds which are currently available. A brief mention of future global observing systems (and also for monsoon) and desired improvements in the model as brought out by the various studies is also made. Page(s): 283-295

1988-12-01T00:00:00Z Gupta, Rajendra Kumar http://nopr.niscpr.res.in/handle/123456789/36464 2016-10-31T06:05:18Z 1988-12-01T00:00:00Z

Title: Atmospheric Profiles Retrieval from NOAA Satellites Data Authors: Gupta, Rajendra Kumar Abstract: With a conceptual introduction to temperature and moisture profile estimation through remote measurements from satellite-based sensors, the radiative transfer equation of the measurement process together with the inherent problem in its analytical solution is discussed. With the description of current sensipg systems on-board NOAA satellites, the reasons for the synergistic use of 4.3, 15 micron and 5 mm absorption bands for temperature profile estimation are discussed. With the discussions on currently practised statistical, physical, simultaneous and 3I retrieval methods, and on the critical aspects of cloud effects, an account of intercomparisons for statistical, physical (iterative) and simultaneous retrieval methods, is presented. Current trends of using pattern recognition techniques for selecting initial guess profile, 1.1 km spatial resolution data in identifying partly cloudy measurement of 17.4 km resolution sounder observation, and forthcoming totally microwave sensors have been discussed. Page(s): 271-282

1988-12-01T00:00:00Z Sridharan, R http://nopr.niscpr.res.in/handle/123456789/36463 2016-10-31T06:03:36Z 1988-12-01T00:00:00Z

Title: Optical Studies of Thermospheric Structure & Dynamics-Recent Developments Authors: Sridharan, R Abstract: A brief outline of the thermospheric structure and dynamics and the possible interaction of the same with the F-region of the ionosphere is given. It points out to the need that these two regions should be treated as a closely coupled system. Some of the most recent developments in optical measurements of neutral temperature and winds in the thermosphere by photometry as well as by high resolution Fabry-Perot spectrometers are outlined. Page(s): 252-263

1988-12-01T00:00:00Z