Dynlib utils functions
Contents
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:
Type  Dim  Description  

dat  real  (nz,ny,nx)  Input data 
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, i1) (in metres) 
dy  real  (ny,nx)  dy(j,i) = y(j+1, i)  y(j1, i) (in metres) 
Typically, the results for each level or time are computed individually in 2D fashion, though they are returned as a 3D 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.
Type  Dim  Description  

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

res  real  (nz,2*ny2,nx)  output data 
dynlib.diag.sum_kix : sum along k for flagged kvalues
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).
Type  Dim  Description  

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

res  int*1  (nz,ny,nx) 
