I am using the 3-hourly 3B42-V6 rainfall rates from TRMM. How can I convert these 3-hourly rainfall rate (mm/hour) to total daily rainfall (mm/day)?
The 3B42-V6 rain rate is a 3-hourly average centered at the middle of each 3-hour period (i.e., 0Z, 3Z, 6Z, 9Z, 12Z, 15Z, 18Z, and 21Z). To convert these rainfall rates to total daily rainfall, first multiply each 3-hourly rainfall rate by 3 hours, to get the total rainfall for each 3-hour period. Then, for your desired 24-hour-day begin and end times, sum all the 3-hourly total rainfalls in your defined 24-hour period, to get the total daily rainfall.
What are the values for latitude and longitude in TRMM 3B42 and 3B43 HDF data files?
The data in the HDF file are written in the following order, (-49.875, -179.875), (-49.625, -179.875), (-49.375, -179.875), (-49.125, -179.875)......(49.875, -179.875), (-49.875, -179.625), (-49.625, -179.625)...... The dimension for longitude is 1440 and the dimension for latitude is 400. The value used to indicate missing data is "-9999.9".
Where can I find more information on the TRMM Data Set?
More information on the TRMM instruments and science can be found at the GES DISC/DAAC TRMM Data Web site: http://disc.sci.gsfc.nasa.gov/precipitation/
How current are the TRMM data?
The GES DISC/DAAC receives, under normal circumstances, processed standard orbital/swath data products about 2-3 days after satellite data acquisition, depending on the level of processing required. In addition to this ongoing collection of data, archives of older data are maintained.
What is the GES DISC/DAAC Search and Order Web Interface?
The GES DISC/DAAC data search and order interface is a simple point-and-click web interface that is based on a hierarchical organization of data, displayed as tables. At different levels of the hierarchy, the tables contain some or all of the following: a particular data product grouping such as data product name, year, or month in the first column on the left; followed by columns of short description, begin date, end date, number of items available in the archives, average item size, a preview feature (if a data product has browse images), and documentation ("readme"). The last column on the right allows one to "Select" an item. At certain levels of the hierarchy, you can also use orbital and parameter search features to customize your search.
Specific help is provided at the top of each page of this system.
URL: http://disc.sci.gsfc.nasa.gov/data/datapool/TRMM/index.html
Where can I find some documentation describing TRMM and TRMM data?
Information about TRMM and TRMM data can be found in:
Where can I find some information describing the TRMM algorithms?
Information about algorithms used for the TRMM products can be found in the Algorithm Status Page, where the links to the products take you to brief descriptions of the status of the products and, for some products, key references.
I would like to receive all new files generated for a data product, over a given time period, at a specified time interval (e.g., weekly). Can I set up a procedure by which specified data will be sent to me automatically?
Yes, just contact help@disc.gsfc.nasa.gov (or 301-614-5224, voice; or 301-614-5268, fax) and request a "subscription." Information that would be needed from you are data product(s) desired, begin date, and end date. You will receive an email notification whenever data are ready for FTP pickup.
How are the daily products computed from 3B42RT and Version 6 3B42 in TOVAS?
These daily products are computed by averaging all the estimates available in the eight observation times of a given UTC day, namely 00, 03, ..., 21 UTC. Formally, this "day" covers the period from 2230 UTC of the previous day through 2230 UTC of the given day. Other "day" products can be computed interactively for 3B42RT and Version 6 3B42 by specifying similar 8-period runs of data. For example, a day that starts at 09 UTC can be approximated by taking data from 09 UTC of one day through 06 UTC of the next. At present, there is no capability in TOVAS for a more exact approximation of a "day" for these data sets.
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