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Land-Sea Mask Datasets

Similar to ETOPO 2022, NASA also provides global land-sea masks at the same resolution as the IMERG and TRMM datasets. NASAPrecipitation.jl - in a manner similar to GeoRegions.jl for ETOPO 2022 data - is able to retrieve the land-sea mask datasets provided by NASA that allows for us to easily distinguish between precipitation data points over land and over the ocean.

This land-sea mask is then saved into a LandSea data type, which is defined to be a subType of the LandSeaFlat abstract type in GeoRegions.jl.

Units for the Land-Sea Mask

For standardization purposes, NASAPrecipitation.jl converts the land-sea mask provided by NASA to the same units as the LandSea Dataset provided by GeoRegions.jl

0 represents fully ocean, while 1 represents fully land.

See the figure below:

landseamaskunits

NASAPrecipitation.LandSea — Type
NASAPrecipitation.LandSea <: GeoRegions.LandSeaFlat

Object containing information on the Land Sea mask for IMERG or TRMM, a subType extension of the GeoRegions.LandSeaFlat superType

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GeoRegions.AbstractLandSea — Type
AbstractLandSea

Abstract supertype for LandSea Datasets, with the following subtypes:

LandSeaTopo <: AbstractLandSea
LandSeaFlat <: AbstractLandSea

Both LandSeaTopo and LandSeaFlat types contain the following fields:

  • lon - Vector containing the longitude points for the Land-Sea Dataset
  • lat - Vector containing the latitude points for the Land-Sea Dataset
  • lsm - Array containing data regarding the Land-Sea Mask. 1 is Land, 0 is Ocean, NaN is outside the bounds of the GeoRegion
  • mask - Mask determining if point is within the GeoRegion or not. 1 is true, 0 is false.

A LandSeaTopo type will also contain the following field:

  • z - Array containing data regarding the Orographic Height in meters. NaN is outside the bounds of the GeoRegion
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