Kamis, 26 Maret 2009

SeaWIFS/MODIS data download

SeaWIFS/MODIS data download

SeaWIFS Background

The purpose of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Project is to provide quantitative data on global ocean bio-optical properties to the Earth science community. Subtle changes in ocean color signify various types and quantities of marine phytoplankton (microscopic marine plants), the knowledge of which has both scientific and practical applications. The SeaWiFS Project will develop and operate a research data system that will process, calibrate, validate, archive and distribute data received from an Earth-orbiting ocean color sensor.
(http://oceancolor.gsfc.nasa.gov/SeaWiFS/BACKGROUND/SEAWIFS_BACKGROUND.html)
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Topic Announcements / Ocean Color Announcements / SeaWiFS Data Available for Download from (http://oceancolor.gsfc.nasa.gov/forum/oceancolor/topic_show.pl?tid=85)

By @gene Date 2004-05-04 20:20

1) seawifs data now available from the oceancolor web

although it has taken a little longer than we had initially thought, we are
happy to announce that it is now possible to download and/or order seawifs data
(up to data collected 14 days ago, the required embargo period) directly from
the oceancolor web browser along with the modis/aqua data that is currently
being provided. this service is provided in addition to the continuing access
and user services for seawifs data that are provided by the goddard daac.

2) you still need to be an authorized seawifs user

as with data access from the daac, you must be an authorized seawifs data
user and have a password. for those of you who already are authorized users,
just request a password directly from a link in the lower right portion
on the oceancolor web page ( http://oceancolor.gsfc.nasa.gov ) to use this
option. if you are not currently an authorized researcher, there is also a
link on that web page that you can use to request to become one.

upon authorization, new users will be provided with a password. if you
are not sure if you are on the authorized list or if you want to verify the
e-mail address at which you are listed at (information that we require),
you can check at:

http://daac.gsfc.nasa.gov/CAMPAIGN_DOCS/OCDST/SeaWiFS_auth.html

3) improved seawifs 1 kilometer data product available

we are currently producing an improved high resolution seawifs data product
(MLAC = Merged Local Area Coverage) derived from the 1 kilometer seawifs
hrpt and recorded lac data that reduces geographic overlap from multiple
receiving stations and maximizes data quality. both level-1 and level-2 data
are available for this new data set along with the same products derived
from the gac (4 kilometer) data. we are currently processing the entire
MLAC archive to create a complete set of level-1 and level-2 products and
the entire mission should be available by early next week. currently,
1997 is online with 1998 and the rest of the mission following close behind.

4) geographic subsetting for seawifs data

in addition to being able to order the full level-1 and level-2 files,
you can also now request a geographic extract from the full sized file to
only get the data for your specific region of interest. this option only
works through the order and ftp option (rather than the direct download from
the web browser which provides you with the entire file). once you've used
the browser to find all the potential files for the time frame and general
region of interest and hit the button, you'll be given the option
of extracting the data products into a smaller geographic box. it will be
these extracts (all fully supported in seadas) that will be staged for you
to download.

5) updated seawifs calibration model

the seawifs data that you can get from the oceancolor web is slightly
different from the data archived at the goddard daac in that we have
switched to a revised calibration table which better handles the temporal
degradation of the instrument in the very early and later parts of the mission.
a comprehensive description of this change in the level-1 calibration can be
found under the "validation" section of the oceancolor web. our analyses
show that the differences are relatively minor which is why we did not
believe it necessary to replace all the data that are currently archived
at the daac based on reprocessing #4 at this time. as was discussed at the
recent science team meeting, we anticipate an official reprocessing of the
entire seawifs mission either later this year or early next which will most
likely include a number of additional parameters based on the recommendations
of the ocean color community.

6) help available

for those of you who are not familiar with all the functions of the oceancolor
web browse and order tool, there is an extensive help function available.
we will be keeping our eyes on the oceancolor forum for feedback and questions
regarding this new feature.

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To download SeaWIFS/MODIS Data from OceanColor, you may click this link/url :
http://oceancolor.gsfc.nasa.gov/cgi/browse.pl?sen=am

best regards,
Aji Putra Perdana
http://ajiputrap.blogspot.com/
http://gisresetutor.blogspot.com/

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