The elevation is different from the GPS

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cici.li
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The elevation is different from the GPS

by cici.li » Thu Oct 29, 2020 10:46 pm America/New_York

When I use the POWER Data Access Viewer, input the longitude and latitude, output the file in CSV formats, an elevation will showed automatically. However, this elevation data is different from what I read in the map. Why this condition may happen? And which one should I believe?
by ASDC - pstackhouse » Fri Oct 30, 2020 9:00 am America/New_York
The data sets provided through POWER are "gridded" in the sense that the value of the parameter you request is effective for the entire area of the grid box. For meteorological parameters like temperature and relative humidity this value is representative of the 1/2 x 1/2 degree area; for solar the irradiance is determined using cloud statistics from a 1x1 degree area. The surface elevation provided is that of the 1/2 x 1/2 degree area grid box. So, if your surface site has a surface elevation within about 100 m of the grid box average, then you should be able to use the provided values for the estimated parameter. However, if there is a large difference between the actual surface site elevation and the grid box average elevation, then one might review as to whether an altitude correction is needed. Regardless, the value is given is for the grid box average and that is why it doesn't correspond exactly to elevation of a particular location. Does that answer your question. Please see our documentation pages for more information on the data source.
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ASDC - pstackhouse
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Re: The elevation is different from the GPS

by ASDC - pstackhouse » Fri Oct 30, 2020 9:00 am America/New_York

The data sets provided through POWER are "gridded" in the sense that the value of the parameter you request is effective for the entire area of the grid box. For meteorological parameters like temperature and relative humidity this value is representative of the 1/2 x 1/2 degree area; for solar the irradiance is determined using cloud statistics from a 1x1 degree area. The surface elevation provided is that of the 1/2 x 1/2 degree area grid box. So, if your surface site has a surface elevation within about 100 m of the grid box average, then you should be able to use the provided values for the estimated parameter. However, if there is a large difference between the actual surface site elevation and the grid box average elevation, then one might review as to whether an altitude correction is needed. Regardless, the value is given is for the grid box average and that is why it doesn't correspond exactly to elevation of a particular location. Does that answer your question. Please see our documentation pages for more information on the data source.
Dr. Paul Stackhouse
NASA Langley Research Center
Hampton, VA, USA

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