MeteoInfoLab脚本示例：计算温度平流

需要温度和风场U/V分量格点数据，计算中主要用到cdiff函数，结果用GrADS验证一致。

脚本程序：

print 'Open data files...'
f_air = addfile('D:/Temp/nc/air.2011.nc')
f_uwnd = addfile('D:/Temp/nc/uwnd.2011.nc')
f_vwnd = addfile('D:/Temp/nc/vwnd.2011.nc')

print 'Read data array...'
tidx = 173    # Jun 23, 2011
t = f_air.gettime(tidx)
lidx = 0    # 1000 hPa
air = f_air['air'][tidx,lidx,::-1,:]
uwnd = f_uwnd['uwnd'][tidx,lidx,::-1,:]
vwnd = f_vwnd['vwnd'][tidx,lidx,::-1,:]
lon = f_air['lon'][:]
lat = f_air['lat'][::-1]
lon, lat = meshgrid(lon, lat)

# Calculate
print 'Calculate...'
dtx = cdiff(air, 'x')
dty = cdiff(air, 'y')
dx = cdiff(lon, 'x') * pi / 180
dy = cdiff(lat, 'y') * pi / 180
tadv = -1*((uwnd*dtx)/(cos(lat*pi/180)*dx)+vwnd*dty/dy)/6.37e6

#Plot
print 'Plot...'
axesm()
mlayer = shaperead('D:/Temp/map/country1.shp')
geoshow(mlayer, edgecolor='black')
layer = contourfm(tadv, cmap='grads_rainbow')
title('Temporature advection (' + t.strftime('%Y-%m-%d') + ')')
colorbar(layer)
xlim(0, 360)
ylim(-90, 90)