forked from knaughten/roms_tools
-
Notifications
You must be signed in to change notification settings - Fork 0
/
iceberg_melt.py
131 lines (109 loc) · 4.84 KB
/
iceberg_melt.py
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
from netCDF4 import Dataset
from numpy import *
from scipy.interpolate import griddata
# Read Martin and Adcroft's monthly climatology of freshwater fluxes
# from iceberg melt, interpolate to the ROMS grid, and save as a
# forcing file.
# Input:
# out_file = path to desired output file
def iceberg_melt (out_file):
# Naming conventions for iceberg files
iceberg_head = '/short/m68/kaa561/metroms_iceshelf/data/originals/MartinAdcroft2010_iceberg_meltfluxes/icebergs.1861-1960.'
iceberg_tail = '.melt.nc'
# Iceberg grid file
iceberg_grid = '/short/m68/kaa561/metroms_iceshelf/data/originals/MartinAdcroft2010_iceberg_meltfluxes/icebergs.static.nc'
# ROMS grid file
roms_grid ='/short/m68/kaa561/metroms_iceshelf/apps/common/grid/circ30S_quarterdegree.nc'
# Read ROMS grid
id = Dataset(roms_grid, 'r')
lon_roms = id.variables['lon_rho'][:,:]
lat_roms = id.variables['lat_rho'][:,:]
id.close()
num_lon = size(lon_roms, 1)
num_lat = size(lon_roms, 0)
# Read the iceberg grid
id = Dataset(iceberg_grid, 'r')
lon_iceberg = id.variables['lon'][:,:]
lat_iceberg = id.variables['lat'][:,:]
id.close()
# Make sure longitudes are between 0 and 360
index = lon_iceberg < 0
lon_iceberg[index] = lon_iceberg[index] + 360
# Set up output file
out_id = Dataset(out_file, 'w')
# Define dimensions
out_id.createDimension('xi_rho', num_lon)
out_id.createDimension('eta_rho', num_lat)
out_id.createDimension('time', None)
# Define variables
out_id.createVariable('lon_rho', 'f8', ('eta_rho', 'xi_rho'))
out_id.variables['lon_rho'].long_name = 'longitude of rho-points'
out_id.variables['lon_rho'].units = 'degree_east'
out_id.variables['lon_rho'][:,:] = lon_roms
out_id.createVariable('lat_rho', 'f8', ('eta_rho', 'xi_rho'))
out_id.variables['lat_rho'].long_name = 'latitude of rho-points'
out_id.variables['lat_rho'].units = 'degree_north'
out_id.variables['lat_rho'][:,:] = lat_roms
out_id.createVariable('time', 'f8', ('time'))
out_id.variables['time'].units = 'days since 1992-01-01 00:00:0.0'
out_id.variables['time'].cycle_length = 365.25
out_id.createVariable('icebergs', 'f8', ('time', 'eta_rho', 'xi_rho'))
out_id.variables['icebergs'].long_name = 'freshwater flux from iceberg melt'
out_id.variables['icebergs'].units = 'kg/m^2/s'
# Loop over months
for month in range(12):
print 'Processing month ' + str(month+1)
# Reconstruct the filename of this month's iceberg data
if month+1 < 10:
month_str = '0' + str(month+1)
else:
month_str = str(month+1)
iceberg_file = iceberg_head + month_str + iceberg_tail
# Read iceberg freshwater flux in kg/m^2/s
id = Dataset(iceberg_file, 'r')
melt_iceberg = id.variables['melt'][0,:,:]
id.close()
# Interpolate to ROMS grid
melt_roms = interp_iceberg2roms(melt_iceberg, lon_iceberg, lat_iceberg, lon_roms, lat_roms)
# Calculate time values centered in the middle of each month
out_id.variables['time'][month] = 365.25/12*(month+0.5)
# Save data
out_id.variables['icebergs'][month,:,:] = melt_roms
out_id.close()
# Given a field A on the iceberg grid, linearly interpolate to the ROMS grid.
# Input:
# A = 2D array (m x n) containing data on the iceberg grid
# lon_iceberg = 2D array (m x n) contaning longitude values on the
# iceberg grid, from 0 to 360
# lat_iceberg = 2D array (m x n) containing latitude values on the
# iceberg grid
# lon_roms = 2D array (p x q) containing longitude values on the ROMS grid,
# from 0 to 360
# lat_roms = 2D array (p x q) containing latitude values on the ROMS grid
# Output:
# A_interp = 2D array (p x q) containing A interpolated to the ROMS grid
def interp_iceberg2roms (A, lon_iceberg, lat_iceberg, lon_roms, lat_roms):
# Set up an nx2 array containing the coordinates of each point in the
# iceberg grid
points = empty([size(lon_iceberg), 2])
points[:,0] = ravel(lon_iceberg)
points[:,1] = ravel(lat_iceberg)
# Also flatten the data
values = ravel(A)
# Now set up an mx2 array containing the coordinates of each point
# we want to interpolate to, in the ROMS grid
xi = empty([size(lon_roms), 2])
xi[:,0] = ravel(lon_roms)
xi[:,1] = ravel(lat_roms)
# Now call griddata; fill out-of-bounds values (such as under ice shelves)
# with zeros
result = griddata(points, values, xi, method='linear', fill_value=0.0)
# Un-flatten the result
A_interp = reshape(result, shape(lon_roms))
# Enforce periodic boundary
A_interp[:,0] = A_interp[:,-2]
A_interp[:,-1] = A_interp[:,1]
return A_interp
if __name__ == "__main__":
file = raw_input('Path to desired output file: ')
iceberg_melt(file)