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Estimation of instantaneous air temperature above vegetation and soil surfaces from Landsat 7 ETM+ datain northern Germany
Autor: Wloczyk, C.; Borg, E.; Richter, R. & K. Miegel
In:
International Journal of Remote Sensing
Bandangabe: 32 (24)
Ergaenzung: Publisher: Taylor ¬ Francis
ISBN: ISSN 0143-1161
Seite: 9119 - 9136
Jahr: 2011
Einordung:
Institut: Professur Hydrologie und Angewandte Meteorologie
Abstract:
The temperature–vegetation index method (TVX method, also called contextual
method) for the area-wide mapping of instantaneous air temperature is adopted for
use with Landsat 7 Enhanced Thematic Mapper Plus (ETM+) data. The method
requires multispectral data consisting of bands in the red, near-infrared and ther-
mal spectral regions, and no additional data. The approach is complemented with
an iterative filtering routine for eliminating outliers and an interpolation algorithm
for filling data gaps. The adopted method is applied to a multi-temporal dataset
of nine ETM+ scenes, covering large parts of north-eastern Germany including
the Durable Environmental Multidisciplinary Monitoring Information Network
(DEMMIN) test site. Thus, for the first time the TVX method is applied to fine
spatial resolution data and a central European region. The satellite-derived air
temperatures (60 m spatial resolution) are compared with in situ measurements,
showing an average error of about 3 K (root mean square, RMS), whereas the mean
error in land surface temperature (LST) estimation is about 2 K. The results com-
pare well with the in situ values throughout all seasons. The accuracy of about 3 K
is in line with previously reported results for the TVX method (employing medium
spatial resolution data) as well as for physically based approaches (ecosystem- or
energy-balance models). Only remote sensing models incorporating in situ air tem-
perature (as training data for neural networks or in multiple regression analysis) are
reported to perform better in terms of RMS deviations. In the past, overestimation
of air temperature by the TVX method was repeatedly observed. It is shown that
the remote sensing approach tends to under- or overestimate the in situ air tem-
peratures, depending on the in situ measurement heights. In conjunction with the
attempt to assign the satellite-derived air temperature to a certain height above
ground, the possibility of a simple correction for reference height is investigated.
Over- and underestimations larger than 2 K seem to reflect existing differences
in temperature rather than calculation errors. Furthermore, the dependence of
the derived air temperature spatial pattern on different moving window sizes is
shown. Possible sources of errors and limitations of the approach are discussed
in detail.
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Letzte Änderung des Eintrages:
28.01.2014
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