Dynlib utils functions

Dynlib diagnostic functions

The functions generally operate on real arrays with dimension (nz,ny,nx) where nz is number of times or levels, and ny and nx are the number of latitudes and longitudes, respectively. The function descriptions below contain detailed descriptions of arguments and returns where there is any deviation from this pattern; otherwise they may be assumed to be of the form:

Arguments:

	Type	Dim	Description
dat	real	(nz,ny,nx)	Input data

Returns:

	Type	Dim	Description
res	real	(nz,ny,nx)	output data

The ubiquitous inputs dx and dy are all of the form

	Type	Dim	Description
dx	real	(ny,nx)	dx(j,i) = x(j, i+1) - x(j, i-1) (in metres)
dy	real	(ny,nx)	dy(j,i) = y(j+1, i) - y(j-1, i) (in metres)

Typically, the results for each level or time are computed individually in 2-D fashion, though they are returned as a 3-D array of the same size as the input.

dynlib.diag.mirror_y_domain : make data periodic in y for FFT

res = mirror_y_domain(dat,dx,dy)

Returns the data extended along complementary meridians (to facilitate FFT). For each lon, the reflected (lon+180) is attached below so that data is periodic in x and y. NOTE: Input data must be lats -90 to 90, and nx must be even.

Arguments:

	Type	Dim	Description
dat	real	(nz,ny,nx)	input data

Returns:

	Type	Dim	Description
res	real	(nz,2*ny-2,nx)	output data

dynlib.diag.sum_kix : sum along k for flagged k-values

This function is currently not available in dynlib. Use python dat[kix].sum() instead.

(res,nres) = sum_kix(dat,kix,dx,dy)

Calculates sum along k dimension for k values which are flagged to 1 in kix vector (length nz).

Arguments:

	Type	Dim	Description
dat	real	(nz,ny,nx)	input data
kix	int	(nz)	index flag for summation

Returns:

	Type	Dim	Description
res	real	(ny,nx)	(summed) output data
nres	int	0	Number of data summed = sum(kix)

dynlib.diag.sum_kix is typically used for calculating seasonal means. To do this, kix is set to 1 for times in the relevant season and 0 elsewhere. After (further) summing res and nres over all years, res/nres gives the mean for the season for all years.

dynlib.diag.high_enough : flags points which are sufficiently above ground

This function is currently not available in dynlib. Use python res = zdata[zdata > ztest+zthres] instead.

res = high_enough(zdata,ztest,zthres,dx,dy)

Arguments:

	Type	Dim	Description
zdata	real	(nz,ny,nx)	geopotential of gridpoints
ztest	real	(1,ny,nx)	geopotential of topography
zthres	real	0	threshold geopotential height difference

Returns:

	Type	Dim	Description
res	int*1	(nz,ny,nx)	Flag array set to: 1 if zdata(t,y,x) > (ztest(1,y,x) + zthres) 0 otherwise