Specifies the target grid which can be either a Gaussian or a Latitude/Longitude grid.
MARS requests specifying
grid=av will return the archived model grid. For Latitude/Longitude output, the format is in degrees, i.e. grid = 2.5/2.5, where the first number denotes the east-west resolution (longitude) and the second denotes the north-south resolution (latitude). The grid spacing needs to be an integer fraction of 90 degrees (latitude range from the Equator to the Pole), e.g. 0.225, 0.25, 0.28125, 0.3, 0.4, ...
Output on a Gaussian grid is specified by a letter denoting the type of Gaussian grid followed by an integer (the grid number) representing the number of lines between the Pole and Equator, e.g.
grid = F160- full (or regular) Gaussian grid with 160 latitude lines between the pole and equator
grid = N320- ECMWF original reduced Gaussian grid with 320 latitude lines between the pole and equator, see Reduced Gaussian Grids for grid numbers used at ECMWF
grid = O640- ECMWF octahedral (reduced) Gaussian grid with 640 latitude lines between the pole and equator
Not all grid names and grid number combinations are supported. Currently, the Gaussian grid names and numbers supported for MARS retrievals are:
|Octahedral reduced Gaussian (O grids)
|Original reduced Gaussian (N grids)
|Regular (Full) Gaussian (F grids)
MARS requests specifying an unsupported grid will fail. For example, a retrieval request with
grid=O123 will return an error. If the letter denoting the type of Gaussian grid is omitted, e.g.
grid=320, a full (or regular) Gaussian grid with 320 grid lines is returned.
For other keywords controlling the interpolation see the diagram below.
Dissemination lat/lon grids allowed are describe for each data set in the Catalogue pages