Proceedings of the Symposium on Global and Environmental Monitoring: Proceedings of the Symposium on Global and Environmental Monitoring

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Persistent identifier:: 856665355

Title:: Proceedings of the Symposium on Global and Environmental Monitoring

Sub title:: techniques and impacts ; September 17 - 21, 1990, Victoria Conference Centre, Victoria, British Columbia, Canada

Year of publication:: 1990

Place of publication:: Victoria, BC

Publisher of the original:: [Verlag nicht ermittelbar]

Identifier (digital):: 856665355

Language:: English

Document type:: Multivolume work

Volume

Persistent identifier:: 856669164

Title:: Proceedings of the Symposium on Global and Environmental Monitoring

Sub title:: techniques and impacts; September 17 - 21, 1990, Victoria Conference Centre, Victoria, British Columbia, Canada

Scope:: XIV, 912 Seiten

Year of publication:: 1990

Place of publication:: Victoria, BC

Publisher of the original:: [Verlag nicht ermittelbar]

Identifier (digital):: 856669164

Illustration:: Illustrationen, Diagramme, Karten

Signature of the source:: ZS 312(28,7,1)

Language:: English

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Editor:: International Society for Photogrammetry and Remote Sensing, Commission of Photographic and Remote Sensing Data

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Volume

Collection:: Earth sciences

Chapter

Title:: [TP-2 SPECTRAL SIGNATURES]

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: ON THE POSSIBLE USE OF SPATIAL VARIABILITY IN AVHRR DATA TO ESTIMATE LOW LEVEL MOISTURE AND TEMPERATURE. John C. Price

Document type:: Multivolume work

Structure type:: Chapter

Figure 4. Estimated values for surface moisture £p are in the range 15-35 millibars, where lower values are darker, higher values are brighter Although derived values for optical depth generally agree with radiative transfer calculations (Price, 1984), notably poor values exist in some locations. These problem areas are mostly far off nadir. ERROR SOURCES Many approximations have been used in the above analysis. We simply list the error sources, without attempting to quantify them in this short paper: 1. Clouds produce variability in the thermal infrared data that is not associated with surface phenomena. This effect is relatively severe, as shown in areas of black/white in images 1-3. More sophisticated cloud filtering is required. 2. Surface emissivity variations have been neglected. There are two effects: a) simultaneous variability of emissivity of features sensed in channels 4 and 5 increases the range of deduced temperatures in both channels. This is a second order effect, b) variability in the response of one spectral channel, independent of the other, has the same effect as a change in atmospheric transmittance r. This effect should be included in the treatment of St. 3. The linear analysis of atmospheric effects is approximate, and produces increasing errors as the optical depth increases. In fact the Kneizys et al. expression for k^ leads to the value 1.45 for R, while actual computation for the 5T for this data set leads to an effective value of R of 1.35 (Price, 1984). This illustrates the more exact treatment required for values of r which are not much smaller than 1. 4. The crude expressions assumed for e(p) and T(p) do not compare closely with actual sounding data. In particular moisture does not generally fall to zero above some relatively low level of the atmosphere. However, these or equivalent expressions are needed in order to derive useful information from the derived values of t and T , . Figure 2. The area in Fig. 1 has been processed in 40x40 blocks to produce values of optical depth that range from .25 (darker tones) to .45 (lighter tones). Figure 3. The area illustrated in fig. 1 has been processed in 40x40 blocks to produce this image of 6p/p, with the majority of the image in the range of values .2-.4, i.e. moisture falls to zero in the range 800-600 mb in areas with surface pressure of 1000 mb. Higher values of 5p/p are brighter.

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