average_ew

average_ew(fs, area, increment)

Computes the zonal average for each field in fs for a set of latitude belts.

Parameters

  • fs (Fieldset) – input fieldset

  • area (list) – area as [N,W,S,E] to perform the averaging

  • increment (number) – increment in degrees defining the size of the latitude belts

Return type

1d-ndarray or 2d-ndarray

If fs only contains one field a 1d-ndarray is returned otherwise the result is a 2d-ndarray.

The averaging is performed for each field individually within the latitude belts defined by area and increment. Each grid point value is weighted by the cosine of its latitude. Missing values are ignored. If a latitude belt contains no grid point values Nan is returned for that belt.

Example
ave = mv.average_ew(fs, [60,-180,-60,180], 2.5)

Here we compute the averages over full latitude circles starting from 60N, stepping by 2.5 degrees until 60S. If fs contains only one field the output will be a 1d-ndarray of 49 E-W average values, from North to South. If fs contains n fields then the output will be an array of n 1d-arrays each containing 49 values. Each value in the result represents the average at latitude Lat based on those grid points whose latitude coordinate is between Lat-1.25 and Lat+1.25 (1.25 is 2.5/2), i.e. within a latitude belt with width of 2.5 degrees, centered around Lat.

Note

See also average_ns().