04_turbulent_APS_example.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Created on Tue Oct  6 11:35:11 2020

@author: matthew

This example tests the ability to set the length scale in the atmosphere_turb function when the covariance method is used.  
When working correctly, it should show that the function can create noise correlated on the correct length scale, regardless
of the size of the pixels.  

"""

import numpy as np    
import matplotlib.pyplot as plt
import sys
sys.path.append('./lib/')

from syinterferopy_functions import atmosphere_turb

#%% Things to set

pixel_sizes_degs = [1/200, 1/1200, 1/3600]                              # ~ 0.5km, 90m, 30m
Lcs = [100, 500, 1000, 2000, 5000, 10000]                                      # these are in metres.  
    
#%% The covariance based method for generating atmospheres is slower (~x100!), but allows the length scale to be set, as this exampe shows.  

f, axes = plt.subplots(len(pixel_sizes_degs),len(Lcs))

for row_n, pixel_size_degs in enumerate(pixel_sizes_degs):
    lons = np.arange(14.0, 14.4, pixel_size_degs)                                                        # create a simple grid of lons and latitudes at the correct size
    lats = np.arange(55.0, 55.2, pixel_size_degs)
    lons_mg = np.repeat(lons[np.newaxis,:], len(lats), axis = 0)
    lats_mg = np.repeat(lats[::-1, np.newaxis], len(lons), axis = 1)

    for col_n, Lc in enumerate(Lcs):
        ph_turb = atmosphere_turb(1, lons_mg, lats_mg, verbose=True, mean_m = 0.02,
                                  method = 'cov', cov_Lc = Lc, cov_interpolate_threshold = 10000)
        
        im = axes[row_n, col_n].imshow(ph_turb[0,])
        
        if col_n == 0:
            axes[row_n, col_n].set_ylabel(f"Pixel size: {int(111e3 * pixel_size_degs)} m ")                             # take 1 deg of latitude as 111km (111000m)
        if row_n == 0:
            axes[row_n, col_n].set_title(f"Correlation length (m): {Lc}")