This script adds `Time` variable to all netCDF files in the CWD and then concatenates them all into a single netCDF file.

nc_combiner.py

#! /usr/bin/env python
# Copyright 2014 by S. Brewster Malevich <malevich@email.arizona.edu>

# This script adds `Time` variable to all netCDF files in the current working 
# directory (CWD) and then concatenates them all into a single netCDF file 
# `all.nc` in the CWD. This this uses Bash's `ncks` and `ncecat`.

import os
from shutil import rmtree

TEMP_DIR = "/tmp/nc_combiner/"

target_files = [f for f in os.listdir(".")
                if os.path.isfile(f) and f.endswith(".nc")]
target_files.sort()
os.mkdir(TEMP_DIR)
for f in target_files:
    os.system("ncks --mk_rec_dmn Time " + f + " " + TEMP_DIR + f)
os.system("ncecat -u Time " + TEMP_DIR + "*.nc ./all.nc")
rmtree(TEMP_DIR)