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 Live Access Server Documentation : User Help :
Accessing LAS products from the command line (batch access) |
It is possible to access LAS products from the command line using the LAS access
scripts that are part of an LAS download. The two scripts of interest are ls.pl
for inspecting the datasets, variables and grids available on an LAS and lasget.pl
for requesting products from an LAS. These two scripts are found in the $LASROOT/bin/
directory of an LAS installation. To use them you will have to point them at a
functioning LAS. Our NVODS LAS has lots of data. The normal LAS user interface
is here:
This is what we call the URL for the User Interface Server. Interacting with this sends requests to the (hidden) Product Server which actually lives here:
To wok with the batch access scripts you will need to point them at the product server. What follows is a sample session of ls.pl to get information and then lasget.pl to get data. 1) Running the ls.pl script with no arguments coaches you on how to use it. prompt> ls.pl Usage: ls.pl [-l] [-s separator] url [dataset] [variable] -l displays descriptive name for a dataset or variable and the type, units, and bounds of an axis. -s separator delimit fields with separator Example: ls.pl http://ferret.pmel.noaa.gov/las-bin/LASserver.pl 2) To see what datasets are available on the NVODS server do this: prompt> ls.pl -l http://ferret.pmel.noaa.gov/NVODS-bin/LASserver.pl DODS_IRI_ustopo America topography at 1/120 degree AOMIP_clouds_nc AOMIP Cloudiness surface_marine_sst_clm_nc Atlas of Surface Marine Data 1994 JPL_atlas_ssmi Atlas SSMI 5-day ocean winds ssta_bmrc_jul1993_dec1999_nc Australian Bureau of Met. SST CAC_sst CAC monthly observed SST, anomalies and climatology ldeo_cayan Cayan Analysis of COADS ... 3) What's in that JPL_atlas_ssmi dataset? prompt> ls.pl -l http://ferret.pmel.noaa.gov/NVODS-bin/LASserver.pl JPL_atlas_ssmi u10m_jpl u-wind at 10 meters ucnt_jpl u-wind bin count v10m_jpl v-wind at 10 meters vcnt_jpl v-wind bin count 4) Tell me everything about the v10m_jpl variable prompt> ls.pl -l http://ferret.pmel.noaa.gov/NVODS-bin/LASserver.pl JPL_atlas_ssmi v10m_jpl JPL_atlas_ssmi_lon x degrees_east -180 180 JPL_atlas_ssmi_lat y degrees_north -90 90 JPL_atlas_ssmi_time t day 04-Jan-1989 23-Dec-1996
6) Use the lasget.pl script to request an image (an odd thing to do from the command line but we're partial to visualizations.) prompt> lasget.pl -x -10:10 -y -30:-20 -t"15-jan-1993" -f gif http://ferret.pmel.noaa.gov/NVODS-bin/LASserver.pl JPL_atlas_ssmi v10m_jpl
<html>
<!-- LAS SERVER OK -->
<head>
<script language="JavaScript">
function openOptions(url) {
window.opener.root.openOptions(url);
}
</script>
</head>
<body bgcolor="white">
<table> <tr> <td>
<img border="0" src="http://ferret.pmel.noaa.gov:80/NVODS-output/bbc7f2232555070fc9551e55a594a5fc.gif">
</td> </tr>
</table>
</body>
</html>
You can paste the URL into a browser to see what the plot looks like. Or if you really want the data you can 7) Request ASCII data (or NetCDF files with '-f nc') prompt> lasget.pl -x -10:10 -y -30:-20 -t"15-jan-1993" -f txt http://ferret.pmel.noaa.gov/NVODS-bin/LASserver.pl JPL_atlas_ssmi v10m_jpl VARIABLE : v-wind at 10 meters (m/s) FILENAME : JPL_atlas_ssmi.des FILEPATH : des/ SUBSET : 8 by 6 points (LONGITUDE-LATITUDE) TIME : 13-JAN-1993 00:00 8.8W 6.2W 3.8W 1.2W 1.2E 3.8E 6.2E 8.8E 69 70 71 72 73 74 75 76 20S / 36: 2.183 2.400 2.223 2.091 1.487 1.961 3.316 4.986 22S / 35: 2.826 2.617 2.299 2.089 1.211 1.641 2.830 4.972 24S / 34: 3.158 2.929 2.286 1.587 0.874 1.112 2.297 4.469 26S / 33: 2.781 2.986 2.792 1.798 0.569 0.533 1.509 3.837 28S / 32: 1.672 1.887 2.207 2.516 0.321 0.320 1.104 3.198 30S / 31: -0.297 0.173 0.209 1.147 0.050 -0.154 0.591 2.164 Note: This should work fine with any of the gridded fields available
through LAS. As of LAS 6.4.1 the scripts cannot yet ask for "in-situ"
data. We hope to introduce scripts with more complete functionality in an upcoming
release. Jonathan.S.Callahan@noaa.gov | |
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Phone: (206) 526-6239 |