this overlay use for sst,drifter and codar.
It include progress about getting codar, drifter and sst,"overlay.py" is main program.
"hx.py" include functions
"getcodar_bydrifter_ctl.txt" and "getcodar_byrange_ctl.txt" are control files
"drift_udel_2012_.txt" is data file of drifter,you can change it to what you want
Others are subprograms.