#!/usr/bin/env python
# Wenchang Yang (wenchang@princeton.edu)
# Sun Apr  7 23:06:56 EDT 2024
# calculate vapor pressure (vp) from q and ps: https://www.pnas.org/doi/10.1073/pnas.2302480120
if __name__ == '__main__':
    import sys,os
    from misc.timer import Timer
    tt = Timer(f'[{os.getcwd()}] start ' + ' '.join(sys.argv))
import sys, os.path, os, glob, datetime
import xarray as xr, numpy as np, pandas as pd, matplotlib.pyplot as plt
#more imports
wython = '/tigress/wenchang/wython'
if wython not in sys.path: sys.path.append(wython); print('added to python path:', wython)
#from misc import get_kws_from_argv
#
if __name__ == '__main__':
    tt.check('end import')
#
#start from here
ofile = 'era5.2m_vapor_pressure.1980-2020.westUS.nc'
if os.path.exists(ofile):
    print('[exists]:', ofile)
    sys.exit()
#q
ifile = 'era5.2m_specific_humidity.1980-2020.westUS.nc'
q = xr.open_dataarray(ifile)
#ps
ifile = 'era5.surface_pressure.1980-2020.westUS.nc'
ps = xr.open_dataarray(ifile) #units Pa
#vp
vp = (q*ps)/(0.622+0.378*q)/100 #units = hPa
vp = vp.assign_attrs(units='hPa', long_name='vapor pressure')
#save
vp.to_dataset(name='vp').to_netcdf(ofile)
print('[saved]:', ofile)
 
if __name__ == '__main__':
    #from wyconfig import * #my plot settings
    
    #savefig
    if 'savefig' in sys.argv or 's' in sys.argv:
        figname = __file__.replace('.py', f'.png')
        if 'overwritefig' in sys.argv or 'o' in sys.argv:
            wysavefig(figname, overwritefig=True)
        else:
            wysavefig(figname)
 
    tt.check(f'**Done**')
    print()
    if 'notshowfig' in sys.argv or 'n' in sys.argv:
        pass
    else:
        if 'plt' in globals(): plt.show()