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The Influence of the Time Equation on Remote Sensing Data Interpretation

Fichtelmann, Bernd and Borg, Erik and Schwarz, Egbert (2015) The Influence of the Time Equation on Remote Sensing Data Interpretation. In: The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XL-7/W3, 2015, pp. 195-201. 36th International Symposium on Remote Sensing of Environment (ISRSE), 11.–15. Mai 2015, Berlin, Deutschland. DOI: 10.5194/isprsarchives-XL-7-W3-195-2015

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Official URL: http://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XL-7-W3/195/2015/isprsarchives-XL-7-W3-195-2015.pdf

Abstract

The interpretation of optical Earth observation data (remote sensing data from satellites) requires knowledge of the exact geographic position of each pixel as well as the exact local acquisition time. But these parameters are not available in each case. If a satellite has a sun-synchronous orbit, equator crossing time (ECT) can be used to determine the local crossing time (LCT) and its corresponding solar zenith distance. Relation between local equator crossing time (LECT) and LCT is given by orbit geometry. The calculation is based on ECT of satellite. The method of actual ECT determination for different satellites on basis of the two-line-elements (TLE), available for their full lifetime period and with help of orbit prediction package is well known. For land surface temperature (LST) studies mean solar conditions are commonly used in the relation between ECT given in Coordinated Universal Time (UTC) and LECT given in hours, thus neglecting the difference between mean and real Sun time (MST, RST). Its difference is described by the equation of time (ET). Of particular importance is the variation of LECT during the year within about ±15 minutes. This is in each case the variation of LECT of a satellite, including satellites with stable orbit as LANDSAT (L8 around 10:05 a.m.) or ENVISAT (around 10:00 a.m.). In case of NOAA satellites the variation of LECT is overlaid by a long-term orbital drift. Ignatov et al. (2004) developed a method to describe the drift-based variation of LECT that can be viewed as a formal mathematical approximation of a periodic function with one or two Fourier terms. But, nevertheless, ET is not included in actual studies of LST. Our paper aims to demonstrate the possible influence of equation of time on simple examples of data interpretation, e.g. NDVI.

Item URL in elib:https://elib.dlr.de/97325/
Document Type:Conference or Workshop Item (Speech)
Title:The Influence of the Time Equation on Remote Sensing Data Interpretation
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Fichtelmann, Berndbernd.fichtelmann (at) dlr.deUNSPECIFIED
Borg, Erikerik.borg (at) dlr.deUNSPECIFIED
Schwarz, EgbertEgbert.Schwarz (at) dlr.deUNSPECIFIED
Date:May 2015
Journal or Publication Title:The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XL-7/W3, 2015
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
DOI :10.5194/isprsarchives-XL-7-W3-195-2015
Page Range:pp. 195-201
Status:Published
Keywords:Equator crossing time, Equation of time, Land surface temperature, Trend analysis, Validation
Event Title:36th International Symposium on Remote Sensing of Environment (ISRSE)
Event Location:Berlin, Deutschland
Event Type:international Conference
Event Dates:11.–15. Mai 2015
Organizer:International Society for Photogrammetry and Remote Sensing, DLR
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Erdbeobachtung
DLR - Research theme (Project):R - Vorhaben Fernerkundung der Landoberfläche (old)
Location: Neustrelitz
Institutes and Institutions:German Remote Sensing Data Center > National Ground Segment
Deposited By: Fichtelmann, Dr.rer.nat. Bernd
Deposited On:04 Aug 2015 11:17
Last Modified:31 Jul 2019 19:54

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