Data

SRTM Grid Cell Area (3" resolution) derived from 3" SRTM DEM-S

Commonwealth Scientific and Industrial Research Organisation
Gallant, John ; Austin, Jenet
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ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rfr_id=info%3Asid%2FANDS&rft_id=info:doi10.4225/08/50AC89675E6DD&rft.title=SRTM Grid Cell Area (3 resolution) derived from 3 SRTM DEM-S&rft.identifier=https://doi.org/10.4225/08/50AC89675E6DD&rft.publisher=Commonwealth Scientific and Industrial Research Organisation&rft.description=The SRTM grid cell area dataset has values of cell area in square metres.The grid cell area product was derived from the Smoothed Digital Elevation Model (DEM-S; ANZCW0703014016), which was derived from the 1 second resolution SRTM data acquired by NASA in February 2000. The calculation of grid cell area from the DEM-S accounted for the varying spacing between grid points in the geographic projection. Lineage: Source data1.\t3 second SRTM-derived Smoothed Digital Elevation Model (DEM-S; ANZCW0703014016)Area calculationThe 3 second resolution data has a cell size of 0.0008333333333 decimal degrees and the 1 degree extent input tiles have 1200 rows and 1200 columns. Cell width changes with latitude (decreases as latitude increases); width is recalculated for each row in the grid based on the centre of the cell.Radius for calculating distance around a parallel (constant latitude, in radians): N = a / sqrt ( 1 - e^2 sin^2(lat) ) e^2 is the square of the eccentricity, calculated from flattening (f)Radius for calculating distance along a meridian (constant longitude): M = a ( 1 - e^2 ) / ( 1 - e^2 sin^2(lat) ) ^ (3/2) The 1 - e^2 sin^2(lat) term is used in both M and N, so it is calculated as p a = 6 378 137 m (in WGS84) f = 1/298.257223563 (in WGS84) e2 = f * (2 - f) p = 1 - e2 * sqr(sin(lat)) N = a / sqrt(p) M = a * (1 - e2) / (p * sqrt(p))The length of 1 degree in longitude and latitude are: long_len = N * cos(lat) * PI / 180.0 lat_len = M * PI / 180.0The area of a 3 second grid cell is: lat_len * long_len / 1200^2&rft.creator=Gallant, John &rft.creator=Austin, Jenet &rft.date=2012&rft.edition=v1&rft.coverage=westlimit=113.0; southlimit=-44.0; eastlimit=154.0; northlimit=-10.0; projection=WGS84&rft_rights=Creative Commons Attribution 3.0 Unported Licence https://creativecommons.org/licenses/by/3.0/&rft_rights=Data is accessible online and may be reused in accordance with licence conditions&rft_rights=All Rights Reserved (including copyright) CSIRO Australia 2012.&rft_subject=Grid Cell Area&rft_subject=LAND Topography Models&rft_subject=ECOLOGY Landscape&rft_subject=TERN_Soils&rft_subject=Land Surface&rft_subject=Australia&rft_subject=Landscape ecology&rft_subject=Ecological applications&rft_subject=ENVIRONMENTAL SCIENCES&rft_subject=Environmental management&rft_subject=Environmental management&rft_subject=Natural resource management&rft_subject=Land capability and soil productivity&rft_subject=Soil sciences&rft_subject=Soil sciences not elsewhere classified&rft.type=dataset&rft.language=English Access the data
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Data is accessible online and may be reused in accordance with licence conditions

All Rights Reserved (including copyright) CSIRO Australia 2012.

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The SRTM grid cell area dataset has values of cell area in square metres.

The grid cell area product was derived from the Smoothed Digital Elevation Model (DEM-S; ANZCW0703014016), which was derived from the 1 second resolution SRTM data acquired by NASA in February 2000.

The calculation of grid cell area from the DEM-S accounted for the varying spacing between grid points in the geographic projection.
Lineage: Source data
1.\t3 second SRTM-derived Smoothed Digital Elevation Model (DEM-S; ANZCW0703014016)

Area calculation
The 3 second resolution data has a cell size of 0.0008333333333 decimal degrees and the 1 degree extent input tiles have 1200 rows and 1200 columns. Cell width changes with latitude (decreases as latitude increases); width is recalculated for each row in the grid based on the centre of the cell.

Radius for calculating distance around a parallel (constant latitude, in radians):
N = a / sqrt ( 1 - e^2 sin^2(lat) )
e^2 is the square of the eccentricity, calculated from flattening (f)

Radius for calculating distance along a meridian (constant longitude):
M = a ( 1 - e^2 ) / ( 1 - e^2 sin^2(lat) ) ^ (3/2)
The 1 - e^2 sin^2(lat) term is used in both M and N, so it is calculated as p

a = 6 378 137 m (in WGS84)
f = 1/298.257223563 (in WGS84)
e2 = f * (2 - f)
p = 1 - e2 * sqr(sin(lat))

N = a / sqrt(p)
M = a * (1 - e2) / (p * sqrt(p))

The length of 1 degree in longitude and latitude are:
long_len = N * cos(lat) * PI / 180.0
lat_len = M * PI / 180.0

The area of a 3 second grid cell is:
lat_len * long_len / 1200^2

Available: 2012-11-21

Data time period: 2000-02-11 to 2000-02-22

This dataset is part of a larger collection

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Subjects
Australia | ECOLOGY Landscape | Environmental Sciences | Ecological Applications | Environmental Management | Environmental Management | Grid Cell Area | LAND Topography Models | Land Surface | Land Capability and Soil Productivity | Landscape Ecology | Natural Resource Management | Soil Sciences | Soil Sciences Not Elsewhere Classified | TERN_Soils |

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Identifiers
ACN 633 798 857