Engineering topics

Rasool, S. I.

Publications and source records attributed to Rasool, S. I..

At least 19 records

NASA NTRS1991

Space Observations for Global Change

There is now compelling evidence that man's activities are changing both the composition of the atmospheric and the global landscape quite drastically. The consequences of these changes on the global climate of the 21st century is currently a hotly debated subject. Global models of a coupled Earth-ocean-atmosphere system are still very primitive and progress in this area appears largely data limited, specially over the global biosphere. A concerted effort on monitoring biospheric functions on scales from pixels to global and days to decades needs to be coordinated on an international scale in order to address the questions related to global change. An international program of space observations and ground research was described.

Rasool, S. I.↗

NASA NTRS1990

A review of satellite data algorithms for studies of the land surface

The major groups of algorithms used to convert satellite data into land-surface climatological parameters are reviewed. The International Satellite Land-Surface Climatology Project (ISLSCP) and the Satellite Data Algorithm Workshop are described. ISLSCP was initiated to address the research problems associated with interpretation and utilization of satellite data over the earth's land surface. The proceedings of a workshop sponsored by ISLSCP to investigate the state and potential of satellite sensor output into surface parameters is presented. The current status of algorithms used to determine land-surface parameters is assessed; the methodologies that ultilize these parameters and other data for estimates of the surface energy balance are reviewed; and a preliminary assessment of the effort required to construct an operational system for the routine processing of satellite data into land-surface parameters is made.

Sellers, P. J.↗

NASA NTRS1986

Predicting earth's dynamic changes

Given a suitable strategy for conducting measurements, satellite-based remote sensing of the earth can furnish valuable information on the dynamic changes of such planetary characteristics as ocean surface temperatures and atmospheric CO2. Observations must be global and synoptic, quantitatively validated, and consistent over the long term. A program spanning 20 years will study such critical variables as solar flux, stratospheric temperature, aerosols and ozone, cloud cover, tropospheric gases and aerosols, radiation balance, surface temperature, albedo, precipitation, vegetation cover, moisture, snow and ice, as well as oceanic color, topography, and wind stress.

Rasool, S. I.↗

NASA NTRS1984

Calibration of TM data from ground-based measurements

Methods of calibrating Thematic Mapper (TM) data by the use of ground based measurements are presented. Applications of the TM remote sensing data are discussed in addition to the ground truth measurement equipment and techniques.

Rasool, S. I.↗

NASA NTRS1984

ISLSCP - International Satellite Land-Surface Climatology Project

Three workshops have been conducted in order to define a research program which would in the course of five years lead to a concensus on methodologies for the conversion of satellite-measured irradiances into quantitative data concerning the earth's surface. Standardized data analysis algorithms would be the major product of this concensus. The three workshops have recommended the evaluation of retrospective satellite data, starting from the July, 1972 initial operation of Landsat-1, in order to demonstrate whether they can be used to detect climate-related or man-induced changes on the earth's surface quantitatively. Also suggested is the validation of current satellite data with ground truth campaigns in several different regions, and the preparation of an operational phase involving the testing of the selected data extraction algorithms for conversion of satellite-measured radiances into albedo, moisture, and vegetation data.

Rasool, S. I.↗

NASA NTRS1980

Working group 3: Space measurements

Solar variability regarding spectral irradiance, with significant variations in the extreme UV and at cm wavelengths and changes in total luminosity were discussed. The question of time scales of solar variations and the problem of establishing past variability were raised, since direct measurements of variability have begun. Enough data have been acquired to begin intercomparison of results, review of different techniques and interaction with theoreticians. The need to establish solar variability as a function of time scale and spectral domain and to relate this variability with such indices as sunspot number, radio flux (10.7 cm), solar diameter, photospheric temperature was addressed. The need for continued long term solar measurements, ozone measurements, stratospheric and mesospheric temperatures and stratospheric trace species was stressed.

Rasool, S. I.↗

NASA NTRS1977

What the exploration of Mars tells us about earth

Data obtained from the Viking missions to Mars have lead to comparisons between characteristics of that planet and certain aspects of earth. Topics discussed include: thermal and compositional evolution of the planets' interiors, the origin of their atmospheres, the history of their fluid environments, the evolution of organic material, and climatic changes. Examples of convective and magmatic activity on the crusts of the two planets are contrasted; outgassing evidenced in the crustal zones is related to the evolution of atmosphere. Analysis of experimental degassing of meteorites provides further insight into the origin and composition of planetary atmospheres. Attributes of the Martian surface, which is apparently an oxidizing rather than reducing medium, are reviewed, and explanations proposed to account for its lack of an organic richness comparable to that found on earth. Data on long-range climatic changes on earth, related to precession, obliquity, and eccentricity of the planet, may contribute to understanding of the Martian polar caps, and vice versa.

Rasool, S. I.↗

NASA NTRS1977

Implications of the Viking results for volatile outgassing from earth and Mars

Recent measurements of rare gas abundances on Mars by Viking are used in testing an inhomogeneous accretion model for Mars. It is found that not only the relative abundance of H, C, N, Ne-20, A-36, Kr, and Xe, but their total amounts can be best explained if the outer layers of earth and Mars were made of a material similar to ordinary chondrites.

Rasool, S. I.↗

NASA NTRS1976

The Venusian surface

Numerous questions generated by past Soviet and U.S. Venus missions regarding the climate and history of Venus have stimulated the initiation of a new U.S. program of Venus probes and orbiters. Among the issues that these missions are intended to resolve are the intensity of sunlight reaching the surface of the planet, the extent and composition of the cloud layer, and the mechanisms responsible for the extremely high surface temperatures measured by earlier probes. Also of interest are the reasons for the sharply differing terrains revealed by the Soviet probes Venera 9 and 10. Clarification of such questions may be expected to improve understanding of the origin of life on earth.

Rasool, S. I.↗

NASA NTRS1975

The atmosphere of Io from Pioneer 10 radio occultation measurements

The occultation of the Pioneer 10 spacecraft by Io (JI) provided an opportunity to obtain two S-band radio occultation measurements of its atmosphere. The day-side entry measurements revealed an ionosphere having a peak density of about 60,000 el/cu cm at an altitude of about 100 km. The topside scale height indicates a plasma temperature of about 406 K if it is composed of Na(+) and 495 K if N2(+) is principal ion. A thinner and less dense ionosphere was observed on the exit (night side), having a peak density of 9,000 el/cu cm at an altitude of 50 km. The topside plasma temperature is 160 K for N2(-) and 131 K for Na(+). If the ionosphere is produced by photoionization in a manner analogous to the ionospheres of the terrestrial planets, the density of neutral particles at the surface of Io is less than 10 to 1 trillion per cu cm, corresponding to a surface pressure of less than 10 to 1 nanobars.

Kliore, A. J.↗

NASA NTRS1974

Exploring Jupiter and its satellites with an orbiter

Review of the initial studies that define a challenging Mariner Jupiter Orbiter mission. Elegant and precise astrodynamics are shown to make possible a bravura examination of the entire Jovian system with two Mariner-class spacecraft to be launched in 1981. This mission is expected to advance considerably our understanding of the origin and evolution of the solar system.

Beckman, J. C.↗

NASA NTRS1974

Summary of highlights of the symposium

Organized studies to isolate the mechanism which might link solar activity to meteorological phenomena are outlined. The importance of relating meteorological and purely solar parameters is stressed, and the need for further satellite studies on the relation of solar sectors to interplanetary properties of the solar wind and magnetic field lines is emphasized.

Rasool, S. I.↗

NASA NTRS1974

Preliminary results on the atmospheres of Io and Jupiter from the Pioneer 10 S-band occultation experiment

The preliminary analysis of data from the Pioneer 10 S-band radio occultation experiment has revealed the presence of an ionosphere on the Jovian satellite Io having an electron density peak of about 60,000 electrons per cubic centimeter at an altitude of approximately 60 to 140 kilometers. This suggests the presence of an atmosphere having a surface number density of about 10 billion to one trillion per cubic centimeter, corresponding to an atmospheric surface pressure of between .1 and 10 nanobar, at or below the detection threshold of the Beta Scorpii stellar occultation. A measurement of the atmosphere of Jupiter was obtained down to the level of about 80 millibars, indicating a large temperature increase at about the 20 millibar level, which cannot be explained by the absorption of solar radiation by methane alone and can possibly be due to absorption by particulate matter.

Kliore, A.↗

NASA NTRS1973

Exploring Jupiter, Saturn and their satellites.

By exploring the outer solar system, it is possible to go back in time and sample the conditions and the energetics of primitive solar nebula from which the sun and the planets are believed to have condensed. With the aid of particle detectors and magnetometers on a spacecraft going to the outer planets, it will be possible to study the gradients of the solar plasma, cosmic rays, and the interplanetary magnetic field. A number of questions regarding the outer solar system are examined, giving attention to problems of the origin of excess energy in the case of Jupiter, Jupiter radio emissions, problems of planetary meteorology, the rings of Saturn, and the planetary satellites. Critical in situ measurements are discussed together with exploratory missions, spacecraft characteristics, and aspects of preliminary mission design.

Rasool, S. I.↗

NASA NTRS1973

S-band occultation experiment: A summary

The objectives and requirements of the experiment are described. The Martian atmosphere and ionosphere, and the radius and shape of Mars are discussed.

Kliore, A. J.↗

NASA NTRS1973

Chemistry of the lower atmosphere

The presence of particulate matter in the lower atmosphere is considered, giving attention to the sources of particles in the troposphere, the composition of particles collected from the atmosphere, aspects of particle concentrations and size distributions, mechanisms of removal, residence times, and conditions in the lower stratosphere. The role of natural and anthropogenic pollutants in cloud and precipitation formation is discussed together with removal processes of gaseous and particulate pollutants, and the global sulfur cycle. Other topics examined include the chemical basis for climatic change and the carbon dioxide cycle. Individual items are announced in this issue.

Rasool, S. I.↗

NASA NTRS1972

The atmosphere of Mars from Mariner 9 radio occultation measurements.

Mariner-9 S-band radio occultation measurements conducted during November and December 1971 are described in terms of new information that was obtained about the shape and atmosphere of Mars. The arrival of the spacecraft coincided with a severely obscuring global dust storm, and the effect of the dust in the atmosphere was reflected in the reduced temperature gradients that were measured in the daytime near-equatorial atmosphere, indicating (1) heating of the atmosphere by solar radiation absorbed by dust and (2) simultaneous cooling of the surface. In general, surface atmospheric pressures measured in the equatorial regions are in very good agreement with previous radio-occultation and earth-based measurements. A global disparity in pressures strongly suggests that the physical shape of Mars is more oblate than the shape of its gravitational equipotential surface.

Kliore, A. J.↗

NASA NTRS1972

Radio occultation measurements of the Mars atmosphere with Mariners 6 and 7.

An analysis of the Mariner 6 and 7 occultation data has been completed. Final profiles of temperature, pressure, and electron density have been obtained for the Mariner 6 and 7 entry and exit cases, and results are presented for both the lower atmosphere and the ionosphere. At all four occultation points, the lapse rate of temperature was subadiabatic up to altitudes in excess of 20 km. A pronounced temperature inversion was present above the surface at the Mariner 6 exit point. All four profiles exhibit a sharp, superadiabatic drop in temperature at high altitudes, with temperatures falling below the frost point of carbon dioxide. These results give a strong indication of frozen carbon dioxide in the middle atmosphere of Mars.

Hogan, J. S.↗