Instructions for plotting transient heat fluxes from NCEP/NCAR reanalysis
1. Download the data file for monthly mean transient heat flux:
vt.mon.mean.3_10.nc or
vt.mon.mean.3_10.mat
2. Download this Matlab driver script that will read in the netcdf file,
manipulate the data, and plot figures: transheatflux.m
The first two options in the script will plot the transient heat flux for individual layers and averaged in the vertical (see figure). These two utility files will plot coastlines when needed: world.m, coasts.mat. You do not need to modify these utility files.
You will need to modify the driver script to calculate and plot zonally averaged transient heat fluxes and vertically and zonally averaged transient heat fluxes. Use your plots to estimate the net northward transport of sensible heat at a chosen latitude of 45°N:
where a is the Earth radius, φ is the latitude and we have
used hydrostatic balance to express the rhs as an integral in pressure. Compare
your estimate with the requirement (from the Earth radiation budget) that the
net (atmosphere and ocean) heat transport must be about 5 PW (1015
W).
The ocean (thin) and atmosphere (dotted) contributions to the total northward heat flux based on NCEP Reanalysis - due to Trenberth and Caron (2001). The units of heat transport are in PW (1015 W).