Effects of vegetation canopy structure on remotely sensed canopy temperatures
(Previously announced in STAR as N79-33530)
Kimes, D. S.↗
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Remote sensing of temperature profiles in the atmosphere
Methods of regularized and generalized cross validation can be used to estimate the atmosphere's temperature, moisture, and wind structure from a finite number m noisy measurements by meteorological satellites on the intensity of upwelling radiation in selected channel frequencies. The inversion of the equation of radiative transfer is discussed for data obtained by TIROS N satellite.
Osullivan, F.↗
The use of remotely sensed surface temperature and a spectral vegetation index for evaluating heat fluxes over the Konza Prairie
The relationship between surface temperature T(s) and the normalized difference vegetation index (NDVI) is examined to determine whether it can be used to characterize latent heat fluxes (LEs). The regression of T(s) on NDVI is studied in the context of surface heat fluxes over the prairie with a limited data set for four flux-measurement sites. The 17 flux-measurement stations at the sites provided data that are consistently significant at the 99-percent confidence level for the regression of T(s) on NDVI. Variations in the regression slopes are found to correlate with variations in the ground heat flux but not with LE. Important components of the regression of T(s) on NDVI include fractional vegetation cover and surface-soil moisture conditions. The relationship is important for determining the relative contributions of the soil and vegetation components of an area's total evaporative flux.
Hope, A. S.↗
Estimation of sensible heat flux from remotely sensed canopy temperatures
Temperatures of tallgrass priarie vegetation were measured with infrared thermometers (IRT) at different view zenith and azimuth angles. The optimum IRT view zenith angle for estimating sensible heat fluxes (H) was determined by comparing H estimated with eddy correlation and/or Bowen ratio techniques to H calculated by a method suggested by Hatfield et al. (1984). For wind speeds of 5 m/s or greater, H estimated with surface temperatures measured at a 0 deg or 20 deg view zenith angle gave the best agreement, but for wind speeds of less than 4 m/s the best estimate of H was made with surface temperatures measured at a 40 deg or 60 deg view zenith angle.
Vining, R. C.↗
The remote sensing of stratospheric temperatures and some results from the Nimbus 2 satellite experiment
Remote sensing techniques for stratospheric temperatures and results of Nimbus 2 radiometer experiment
Warnecke, G.↗
Dynamical Core Damping of Thermal Tides in Martian Atmosphere
Atmospheric oscillations with daily periodicity are observed in in-situ near-surface pressure, temperature, and winds observations, and also in remotely sensed temperature and pressure observations of the Martian atmosphere. Such oscillations are interpreted as thermal tides driven by the diurnal cycle of solar radiation and occur at various frequencies, with the most prominent being the diurnal, semidiurnal, terdiurnal and quadiurnal tides. Mars global circulation models reproduce these tides with varying levels of success. Until recently, both the MarsWRF and newly developed MarsMPAS models were able to produce realistic diurnal and semidiurnal tide amplitudes but predicted higher-order mode amplitudes that were significantly weaker than observed. We use linear wave analysis to show that the divergence damping applied within both MarsWRF and MarsMPAS is responsible for suppressing the amplitude of thermal tides with frequency greater than 2 per sol, despite being designed to suppress only acoustic wave modes. Decreasing the strength of the divergence damping in MarsWRF and MarsMPAS allows for excellent prediction of the higher order tidal modes. This finding demonstrates that care must be taken when applying numerical dampers and filters that may eliminate some desired dynamical features in planetary atmospheres.
Yuan Lian↗
Optimal determination of geopotential base height for stratospheric temperature sounders
A technique is presented by which a geopotential base height between 100 and 10 mbar may be estimated to serve as a reference for the construction of stratospheric height fields from remotely sensed temperatures. The scheme employs conventional data obtained below 100 mbar coupled with remotely sensed observations above this level to derive an accurate estimate of the height field by the minimization of the error at the tie-on level, the pressure level of the base height. In a series of numerical realizations, it is demonstrated that the technique yields an unbiased and optimal estimate of the height at levels where conventional errors are typically large, particularly where the conventional height error grows rapidly in the vertical.
Salby, M. L.↗
Experimental remote sensing of subsurface temperature in natural ocean water
The first successful depth-resolved remote sensing measurements of subsurface ocean water temperature were obtained by spectral analysis of the 3400 per cm O-H stretching Raman band of liquid water. Raman spectral data were obtained from a research vessel at various depths from the surface to 10 meters below the surface in a tidal estuary. The temperature inferred from the spectra was consistent with ground truth temperature to within the shot noise limited accuracy of plus or minus 2 C. The performance of a future fully developed airborne laser Raman water temperature measurement system is estimated on the basis of these first tests.
Leonard, D. A.↗
Brillouin Asymmetric Spatial Heterodyne Oceanographic Lidar Receiver for Profiling Temperature, Salinity, and Sound Velocity
No sensor today is capable of remotely sensing temperature and salinity at depth in oceanic waters, yet the physics to do so exists. Blue-green light (450-550 nm) can penetrate 10’s of meters into the water and interacts with water by the Brillouin scatter process. Temperature and salinity can be determined by analyzing the spectrum of Brillouin scatter. A host of scientific and operational drivers exist for such a sensor, from improved hurricane and red tide forecasting to studies of ocean fronts, eddies, and freshwater lenses. A low flying airborne light detection and ranging (lidar) instrument concept that exploits this physics is presented, along with simulation tools that potential data users can use to model its measurement performance, determine suitability for their application, and assess its implications.
John Anthony Smith↗
Remote sensing of chlorophyll and temperature in marine and fresh waters
Remote sensing of chlorophyll and temperature in marine and fresh waters by spectroradiometer and differential and IR filter radiometers onboard airplane
Arvesen, J. C.↗
A simple method to incorporate water vapor absorption in the 15 microns remote temperature sounding
The water vapor absorption in the 15 micron CO2 band, which can affect the remotely sensed temperatures near the surface, are estimated with the help of an empirical method. This method is based on the differential absorption properties of the water vapor in the 11-13 micron window region and does not require a detailed knowledge of the water vapor profile. With this approach Nimbus 4 IRIS radiance measurements are inverted to obtain temperature profiles. These calculated profiles agree with radiosonde data within about 2 C.
Dallu, G.↗
A power law fit to oxygen absorption at 60 GHz and its application to remote sensing of atmospheric temperature
The paper presents an empirical study of the oxygen spectrum near 60 GHz with reference to its applicability to the remote sensing of the tropospheric and lower stratospheric temperature. It is demonstrated that the absorption coefficient of oxygen at 60 GHz can be fitted to the power law form with a relative rms error of about 8%. The power law form, when used in conjunction with the weighting function, permits the definition of some basic quantities in the passive remote sensing of the atmospheric temperature. It is shown how the power law form has been utilized in processing data from the Nimbus 5 microwave spectrometer experiment. The algorithm presented can be applied to spectrometer experiments at infrared frequencies.
Poon, R. K. L.↗
Estimation of Regional Evapotranspiration Using Remotely Sensed Land Surface Temperature. Part 1: Measurement of Evapotranspiration at the Environmental Research Center and Determination of Priestley-taylor Parameter
In order to study the distribution of evapotranspiration in the humid region using remote sensing technology, the parameter (alpha) in the Priestley-Taylor model was determined. The daily means of the parameter alpha = 1.14 can be available from summer to autumn and alpha = to approximately 2.0 in winter. The results of the satellite and the airborne sensing done on 21st and 22nd January, 1983, are described. Using the vegetation distribution in the Tsukuba Academic New Town, as well as the radiation temperature obtained by remote sensing and the radiation data observed at the ground surface, the evapotranspiration was calculated for each vegetation type by the Priestley-Taylor method. The daily mean evapotranspiration on 22nd January, 1983, was approximately 0.4 mm/day. The differences in evapotranspiration between the vegetation types were not detectable, because the magnitude of evapotranspiration is very little in winter.
Kotada, K.↗
Geographic variation in the relationships of temperature, salinity or sigma sub t versus plant nutrient concentrations in the world ocean
A NODC data set representing all regions of the world ocean was analyzed for temperature and sigma-t relationships with nitrate, phosphate or silicic acid. Six cubic regressions were for each ten degree square of latitude and longitude containing adequate data. World maps display the locations that allow the prediction of plant nutrient concentrations from temperature or sigma-t. Geographic coverage improves along the sequence: nitrate, phosphate, and silicic acid and is better for sigma-t than for temperature. Contour maps of the approximate temperature of sigma-t at which these nitrients are no longer measurable in a parcel of water are generated, based on a percentile analysis of the temperature or sigma-t at which less than a selected amount of plant nutrient occurs. Results are stored on magnetic tape in tabular form. The global potential to predict plant nutrient concentrations from remotely sensed temperature of sigma-t and to emphasize the latitudinally and longitudinally changing phytoplankton growth environment in present and past oceans is demonstrated.
Kamykowski, D.↗
An overview of the results of the FIFE-87 and FIFE-89 campaigns
Results of a major land surface-atmosphere exchange study, the First ISLSCP Field Experiment (FIFE) are summarized. Findings result from nearly 80 days of field measurements over a 15 kilometer square area involving 30 science teams, seven remote sensing aircraft, and 5 satellites which acquired over 1200 low resolution and 35 high spatial resolution satellite images, maps of remotely sensed temperature, vegetation index and soil moisture, surface flux measurements from more than 20 ground stations and airborne sensors, and transects of vegetation, soil moisture and soil chemistry. Relationships between in situ, airborne, and spaceborne remote measurements and the problem of scaling will be discussed. Energy balance comparisons among sites were made. Diurnal measurements of latent heat fluxes indicated a strong correlation between the evaporative fraction at midday and the daytime average value.
Murphy, R. E.↗
Significance of vegetation in interpreting thermal radiation from a terrestrial surface
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 unity, the composite emissivity is greatly increased, giving rise to a decreased error in remotely sensed temperature data.
Sutherland, R. A.↗
Infrared scanner concept verification test report
The test results from a concept verification test conducted to assess the use of an infrared scanner as a remote temperature sensing device for the space shuttle program are presented. The temperature and geometric resolution limits, atmospheric attenuation effects including conditions with fog and rain, and the problem of surface emissivity variations are included. It is concluded that the basic concept of using an infrared scanner to determine near freezing surface temperatures is feasible. The major problem identified is concerned with infrared reflections which result in significant errors if not controlled. Action taken to manage these errors result in design and operational constraints to control the viewing angle and surface emissivity.
Bachtel, F. D.↗
Geologic application of thermal inertia imaging using HCMM data
The feasibility of using thermal inertia, inferred from remotely sensed temperature data, to complement LANDSAT reflectivity data for reconnaissance geologic mapping and mineral exploration is under investigation. The bulk of HCMM data tapes was received and processed, and a thermal inertia image of one data set was made. Additional areas of interest were identified on the HCMM photographic products and data tapes were ordered for these areas. During analysis of selected subareas, various sedimentary rock units were distinguished in the Death Valley, California test site and areas of altered rock were identified in the Cuprite/Goldifield, Nevada test site.
Paley, H. N.↗