J. F. Bartholic

Significance of vegetation in interpreting thermal radiation from a terrestrial surface

Abstract The regions between crop rows are modeled as infinitely long diffuse cavities. Geometrical view factors are calculated, accounting for reflected radiation emanating internal to the cavity and from the background sky. A “cavity” emissivity dependent on local geometry is defined to allow for correcting apparent temperatures to true temperatures. The total emissivity appropriate for correcting aircraft thermal data is then calculated by averaging all emissivity components to account for soil, crop and background. It is shown that even for the lowest crop and vegetation emissivities if the crop height-to-spacing ratio is greater than 1, the composite emissivity is greatly increased giving rise to a decreased error in remotely sensed temperature data.

Comparison of winter-nocturnal geostationary satellite infrared-surface temperature with shelter—height temperature in Florida☆

Abstract Geostationary satellite surface temperatures derived from a Visible and Infrared Spin Scan Radiometer ( vissr ) sensor (10.5 to 12.6 microns) were compared with 1.5-m air temperatures collected by a thermocouple on a traversing vehicle along rural highway transects in Florida, and with two fixed thermographs located in rural and agricultural areas. Statistical comparisons between satellite and 1.5-m observations yielded a mean correlation coefficient of 0.87 and an average sample standard deviation from regression of 1.57°C during clear nights for four winters (1978–1981). The satellite-temperature image of Lake Okeechobee was compared with its geographic outline for areal image registration. Manual overlays of temporal images were repeatable to within one pixel. Satellite-sensed water temperature of Lake Okeechobee was used as an indicator of satellite radiometer repeatability and stability.

Satellite-Sensed Winter Nocturnal Temperature Patterns of the Everglades Agricultural Area

Abstract Surface temperature patterns of drained organic soil farmland in the Everglades Agricultural Area south of Lake Okeechobee, Florida, were studied using GOES-1 satellite infrared digital data for the winters of 1976–77 and 1977–78. Local thermal features were explained in terms of soil types, soil depths and climate modification caused by organic soil drainage. A cold-prone area was delineated in the Everglades Agricultural Area with satellite data. The winter nighttime surface temperatures of this area were more characteristic of north central Florida, approximately 370 km further north, than of surrounding areas of mineral soil or undrained organic soil.

Emissivity correction for interpreting thermal radiation from a terrestrial surface

Abstract A general method of accounting for emissivity in making temperature determinations of greybody surfaces from radiometric data is presented. The method differs from previous treatments in that a simple blackbody calibration and graphical approach is used rather than numerical integrations which require detailed knowledge of an instruments spectral characteristics. Also, errors caused by approximating instrumental response with the Stephan-Boltzman law rather than with an appropriately weighted Planck integral are examined. In the 8–14 μm wavelength interval, it is shown that errors are at most on the order of 3°C for the extremes of the earths temperature and emissivity. For more practical limits, however, errors are less than 0.5°C.

Delineation of Cold-Prone Areas Using Nighttime SMS/GOES Thermal Data: Effects of Soils and Water

Abstract Infrared digital data from geostationary satellites were used to demonstrate the usefulness of remotely sensed surface temperature data to delineate microscale and mesoscale climates. Nocturnal winter data (December-February) from 1976–77 to 1978–79 over Florida revealed noticeable contrasts in surface temperature patterns. Colder areas were associated with low soil moisture content in the upper layers of excessively-drained and well-drained sandy soils, whereas warmer areas were associated with bodies of water, wetlands, or poorly drained soils. An unexpected surface temperature pattern for one night where the north-central Florida climatic zone was colder than the north Florida climatic zone was found to be caused by differences in antecedent frontal rainfall. Differences in surface radiant energy fluxes over these two areas at 0200 EST 20 December 1977, based on average satellite-sensed surface temperatures, were compared with differences in soil heat fluxes that were computed from 1.5 m clima...

Observations of the convective plume of a lake under cold-air advective conditions

Moderating effects of Lake Apopka, Florida on downwind surface temperatures were evaluated under cold-air advective conditions. Point temperature measurements north and south of the lake and data obtained from a thermal scanner flown at 1.6 km indicate that surface temperatures directly downwind may be higher than surrounding surface temperatures by as much as 5 °C under conditions of moderate winds (~4 m s−1). No substantial temperature effects were observed with surface wind speed less than 1 m s−1. Fluxes of sensible and latent heat from Lake Apopka were calculated from measurements of lake temperature, net radiation, relative humidity and air temperature above the lake. Bulk transfer coefficients and the Bowen ratio were calculated and found to be in agreement with reported data for non-advective conditions.

Grid Computing for Real Time Distributed Collaborative Geoprocessing

Grid computing has emerged as an important new field in the distributed computing arena. It focuses on intensive resource sharing, innovative applications, and, in some cases, high-performance orientation. In this paper we describe Grid computing concepts and technologies and establish compelling reasons for why they may prove useful for important geospatial research and application issues. Then we review high performance parallel geoprocessing in general. Finally, we propose an example GIS application scenario that will employ underlying Grid computing technology intensively. We report results on a prototype employing a universal soil loss equation implemented on an array of supercomputer processors.

Simulating the moderating effect of a lake on downwind temperatures

A steady-state, two-dimensional numerical model is used to simulate air temperatures and humidity downwind of a lake at night. Thermal effects of the lake were modelled for the case of moderate and low surface winds under the cold-air advective conditions that occur following the passage of a cold front. Surface temperatures were found to be in good agreement with observations. A comparison of model results with thermal imagery indicated the model successfully predicts the downwind distance for which thermal effects due to the lake are significant.

A real-time satellite data acquisition, analysis and display system - A practical application of the GOES network

Abstract A real-time satellite data acquisition, analysis and display system is described which uses analog data transmitted by telephone line over the GOES network. Results are displayed on the system color video monitor as “thermal” images which originated from infrared surface radiation sensed by the Geostationary Operational Environmental Satellite (GOES).

Assessment of modified surface temperatures and solar reflectance using meteorological satellite and aircraft data

Abstract Changes in surface temperature resulting from the activities of man are evaluated using meteorological satellite (NOAA and HCMM) and aircraft data. Study sites were located in Florida and Michigan. Thermal data showed that day surface temperatures over large areas could be increased by 10–15°C by modifications resulting from agricultural practices. Changes in reflected solar radiation as a function of agricultural practices were detectable using HCMM data.