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I am calculating volume of bathymetric data in the form of a clipped raster in GRASS with a Custom Lambert projection centered around 70degrees North, using the module r.volume in GRASS.

Side note: I have concluded that my original raster appears have both depth of the ocean (in negative figures) and height above see level (in positive figures). However I have now clipped it to represent only information covering the water in the NE Atlantic. Please see at the bottom a copy of all the info in the metadata tab for this bathymetric file and do not hesitate to correct me if you notice something strange as this information has changed a lot since I imported it into GRASS. If you require the metadata of my original bathymetric file I can provide it.

My question is:

How do I know that the r.volume module in GRASS has accurately calculated the volume of the ocean for this area? Please see screen shots below of my data and of the r.volume results generated.

Additionally can someone please confirm that this output is in units m3 seeing as the LAMBERT projection is in meters? Is this correct?

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Driver GRASS raster provider GISDBASE: /Users/aninahenggeler/Documents/Humboldt/Thesis /High seas proposal/GIS & Google Earth/GRASSDATA LOCATION: allnewicesareasgeotiffLAMBERTLocation MAPSET: allnewicesareasLAMBERTclippedgeotiffraster MAP: LAMBERTCLIPPEDwithnewICESdensifiedareasGRASS MAX_VALUE : 1.74800000000000000e+03 TYPE : 0 MIN_VALUE : -6.37400000000000000e+03 No Data Value -2.14748e+09 Data Type Int32 - Thirty two bit signed integer Pyramid overviews Layer Spatial Reference System +proj=laea +lat_0=70 +lon_0=0 +x_0=0 +y_0=0 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs Layer Extent (layer original source projection) -3685610.5270899999886751,-3707057.7249250002205372 : 2075705.6314520000014454,2218572.3506209999322891 Band Band 1 Band No 1 No Stats No stats collected yet

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