Engineering topics

Mcmillin, L.

Publications and source records attributed to Mcmillin, L..

4 records

NASA NTRS1989

Simulation studies of improved sounding systems

Two instrument designs for indirect satellite sounding of the atmosphere in the infrared are represented by the High Resolution Infra-Red Sounder, Model 2 (HIRS-2) and by the Advanced Meteorological Temperature Sounder (AMTS). The relative capabilities of the two instruments were tested by simulating satellite measurements from a group of temperature soundings, allowing the two participants to retrieve the temperature profiles from the simulated data, and comparing the results with the original temperature profiles. Four data sets were produced from radiosondes data extrapolated to a suitable altitude, representing continents and oceans, between 30S and 30N. From the information available, temperature profiles were retrieved by two different methods, statistical regression and inversion of the radiative transfer equation. Results show the consequence of greater spectral purity, concomitant increase in the number of spectral intervals, and the better spatial resolution in partly clouded areas. At the same time, the limitation of the HIRS-2 without its companion instrument leads to some results which should be ignored in comparing the two instruments. A clear superiority of AMTS results is shown.

Yates, H.↗

NASA NTRS1988

Results of a joint NOAA/NASA sounder simulation study

This paper presents the results of a joint NOAA and NASA sounder simulation study in which the accuracies of atmospheric temperature profiles and surface skin temperature measuremnents retrieved from two sounders were compared: (1) the currently used IR temperature sounder HIRS2 (High-resolution Infrared Radiation Sounder 2); and (2) the recently proposed high-spectral-resolution IR sounder AMTS (Advanced Moisture and Temperature Sounder). Simulations were conducted for both clear and partial cloud conditions. Data were analyzed at NASA using a physical inversion technique and at NOAA using a statistical technique. Results show significant improvement of AMTS compared to HIRS2 for both clear and cloudy conditions. The improvements are indicated by both methods of data analysis, but the physical retrievals outperform the statistical retrievals.

Phillips, N.↗

NASA NTRS1980

Improvements to satellite retrieval systems. The operational perspective

Operational weather satellites are built as a series of nearly identical instruments which are flown for 5 to 7 years. Minor improvements are made during the life of the series. However, major improvements and changes in design are made with the initiation of a new series of instruments. Similarly, procedures used to process the data are characterized by frequent changes early in the life of a satellite series as user experience is gained with the new instrument. Later the changes become less frequent, both because the processing system becomes well tuned to that particular set of instruments and because, at the end of a series, resources are devoted to generating the processing system for the next set of instruments. Past and present systems are considered with emphasis on the vertical temperature profile radiometer and a procedure for deriving clear radiances in partly cloudy areas.

Mcmillin, L.↗

NASA NTRS1977

Capabilities of operational infrared sounding systems from satellite altitude

Initial attempts at using satellite radiances resulted in the production of temperature profiles similar to those produced by radiosondes. While increases in accuracy were made and additional increases are expected to result from increased instrument capabilities, it was recognized that the production of level temperatures is not consistent with the average temperature that is represented by the radiances.

Mcmillin, L.↗