particle tracking model, works with the ROMS output file(qck.nc, his.nc)

this is a 2-dimensional particle tracking model based on ROMS output files, including his.nc, qck.nc.

• 4th order RK method is applied to the particle movement progress.
• support time backward tracking.
• diffusion is implemented by random walk algorithm.

1. edit the parameter is para.py, the meaning are explained in the comment
2. cd to the path where "start_tracking.py" is in, run:

python ./start_tracking.py

if on linux platform:

python3 ./start_tracking.py