This dataset depends on the following independent variable (i.e, grid):
    grid: /P  (mb) ordered [ (1000) (925) (850) (700) (600) (500) (400) (300) (250) (200) (150) (100) (70) (50) (30) (20) (10)] :grid
so there will be 17 links below for the different files.
You may want to get a utility like wget which can download sets of files. For example (all one line)
wget -r -l2 -nd --no-parent -e robots=off -v --relative 'http://digilib.icpac.net/SOURCES/.NOAA/.NCEP-NCAR/.CDAS-1/.MONTHLY/.Intrinsic/.PressureLevel/.CBMZW/%5BT%5Daverage/%5BX+%5Ddetrend-bfl/%5BP+%5Ddetrend-bfl/downloadsarcinfo.html'
single quotes are necessary in unix to protect the url from expansion; probably necessary in other cases as well
| 1000 mb |  | 
|---|---|
| 925 mb |  | 
| 850 mb |  | 
| 700 mb |  | 
| 600 mb |  | 
| 500 mb |  | 
| 400 mb |  | 
| 300 mb |  | 
| 250 mb |  | 
| 200 mb |  | 
| 150 mb |  | 
| 100 mb |  | 
| 70 mb |  | 
| 50 mb |  | 
| 30 mb |  | 
| 20 mb |  | 
| 10 mb |  |