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passing time of the GRACE satellite

PostPosted: Tue Aug 20, 2019 1:36 am
by jyolsna
How can i know the passing time of the GRACE satellite over a location? Particularly in the following coordinates, latitudes 13.5,14.5,15.5 and longitudes 76.5,77.5,78.5

Re: passing time of the GRACE satellite

PostPosted: Mon Aug 26, 2019 9:29 am
by podaac
Thank you for your inquiry.

Please see the following response from the GRACE science team:

Neither GRACE nor GRACE-FO have a repeat orbit, so there is no such thing as a specific time at which the satellites pass over a specific location during the month. The orbital states/position of the satellites can be found in the GNV1B and GNI1B Level-1 data products (see the “GRACE-FO Level-1 Data Product User Handbook” for descriptions of these products, and Section 3.2.3 “Coordinate Systems” for a definition of the coordinates systems used for these states). You would need your own way of mapping these satellite states to Earth latitude and longitude coordinates. With that, it is possible to search for if the satellites pass over a specific lat/lon location, or within a specified proximity. However, note that gravity fields and mass change grids are solved for monthly over the entire globe, and a local ‘along-track’ type measurement of these quantities does not exist.