Engineering topics

Luvall, J. C.

Publications and source records attributed to Luvall, J. C..

22 records · Page 2

NASA NTRS1990

Application of remote sensing in tropical forests

Cloud cover in tropical humid forests can pose serious operational constraints on Landsat TM and SPOT HRV instrumentation, given their respective orbital frequencies of 16 and 26 days. SAR data intrinsically precludes such problems; the increase of data acquisition frequency to daily rates, as with the NOAA AVHRR instrument, also bears consideration. It is deemed essential that SAR data-related research be expedited, in order to ascertain inherent SAR information for tropical forests in a timely and cost-effective manner.

Joyce, Armond T.↗

NASA NTRS1989

Measurements of short-term thermal responses of coniferous forest canopies using thermal scanner data

Thermal Infrared Multispectral Scanner (TIMS) data were collected over a coniferous forest in western Oregon. Concurrent radiosonde measurements of atmospheric profiles of air temperature and moisture provided inputs to LOWTRAN6 for atmospheric radiance corrections of the TIMS data. Surface temperature differences measured by the TIMS over time between flight lines were combined with surface radiative energy balance estimates to develop thermal response numbers (TRN). These numbers characterized the thermal response of the diffent surface types. Barren surfaces had the lowest TRN, whereas the forested surfaces had the highest.

Luvall, J. C.↗

NASA NTRS1989

Modeling surface temperature distributions in forest landscapes

A model of the frequency distributions of the spatial variability in surface temperature is presented. Surface temperature data are obtained from two daytime and two nighttime flights of the Thermal IR Multispectral Scanner (TIMS) over forest land in western Oregon in August, 1985. The temperature values are corrected for atmospheric attenuation and thermal radiation emission with the LOWTRAN-6 algorithm. The temperature distributions were modeled with a two-parameter beta probability density distribution and the fit of the model was evaluated by comparison with the TIMS data set. Use of the model's parameters to identify and classify surface types shows good discrimination among various surfaces for the daytime images, with less distinct discrimination for the nighttime images.

Holbo, H. R.↗

NASA NTRS1987

Using the thermal infrared multispectral scanner (TIMS) to estimate surface thermal responses

A series of measurements was conducted over the H.J. Andrews, Oregon, experimental coniferous forest, using airborne thermal infrared multispectral scanner (TIMS). Flight lines overlapped, with a 28-min time difference between flight lines. Concurrent radiosonde measurements of atmospheric profiles of air temperature and moisture were used for atmospheric radiance corrections of the TIMS data. Surface temperature differences over time between flight lines were used to develop thermal response numbers (TRNs) which characterized the thermal response (in KJ/sq m/C, where K is the measured incoming solar radiation) of the different surface types. The surface types included a mature forest (canopy dominated by dense crowns of Pseudosuga menziesii, with a secondary canopy of dense Tsuga heterophylla, and also a tall shrub layer of Acer circinatum) and a two-year-old clear-cut. The temperature distribution, within TIMS thermal images was found to reflect the surface type examined. The clear-cut surface had the lowest TRN, while mature Douglas fir the highest.

Luvall, J. C.↗