TRMM_3B42RT_Daily_7

TRMM (TMPA-RT) Near Real-Time Precipitation L3 1 day 0.25 degree x 0.25 degree V7 (TRMM_3B42RT_Daily) at GES DISC

Version 7 eng
  • Abstract
    This daily accumulated precipitation product is generated from the Near Real-Time 3-hourly TRMM Multi-Satellite Precipitation Analysis TMPA (3B42RT). It is produced at the NASA GES DISC, as a value added product. Simple summation of valid retrievals in a grid cell is applied for the data day. The result is given in (mm). Although the grid is from 60S to 60N, the high latitudes (beyond 50S/N) near real-time retrievals are considered very unreliable and thus are screened out from the daily accumulations. The beginning and ending time for every daily granule are listed in the file global attributes, and are taken correspondingly from the first and the last 3-hourly granules participating in the aggregation. Thus the time period covered by one daily granule amounts to 24 hours, which can be inspected in the file global attributes. Counts of valid retrievals for the day are provided for every variable, making it possible to compute conditional and unconditional mean precipitation for grid cells where less than 8 retrievals for the day are available. Efforts have been made to make the format of this derived product as similar as possible to the new Global Precipitation Measurement CF-compliant file format. The latency of this derived daily product is about 7 hours after the UTC day is closed. Users should be mindful that the price for the short latency of these data is the reduced quality as compared to the research quality product. The information provided here on the TRMM mission, and on the original 3-hr 3B42 product, remain relevant for this derived product. Note, however, this product is in netCDF-4 format. The following describes the derivation in more details. The daily accumulation is derived by summing *valid* retrievals in a grid cell for the data day. Since the 3-hourly source data are in mm/hr, a factor of 3 is applied to the sum. Thus, for every grid cell we have Pdaily = 3 * SUM{Pi * 1[Pi valid]}, i=[1,Nf] Pdaily_cnt = SUM{1[Pi valid]} where: Pdaily - Daily accumulation (mm) Pi - 3-hourly input, in (mm/hr) Nf - Number of 3-hourly files per day, Nf=8 1[.] - Indicator function; 1 when Pi is valid, 0 otherwise Pdaily_cnt - Number of valid retrievals in a grid cell per day. Grid cells for which Pdaily_cnt=0, are set to fill value in the Daily files. Note that Pi=0 is a valid value. On occasion, the 3-hourly source data have fill values for Pi in a very few grid cells. The total accumulation for such grid cells is still issued, inspite of the likelihood that thus resulting accumulation has a larger uncertainty in representing the "true" daily total. These events are easily detectable using "counts" variables that contain Pdaily_cnt, whereby users can screen out any grid cells for which Pdaily_cnt less than Nf. There are various ways the accumulated daily error could be estimated from the source 3-hourly error. In this release, the daily error provided in the data files is calculated as follows. First, squared 3-hourly errors are summed, and then square root of the sum is taken. Similarly to the precipitation, a factor of 3 is finally applied: Perr_daily = 3 * { SUM[ (Perr_i * 1[Perr_i valid])^2 ] }^0.5 , i=[1,Nf] Ncnt_err = SUM( 1[Perr_i valid] ) where: Perr_daily - Magnitude of the daily accumulated error power, (mm) Ncnt_err - The counts for the error variable Thus computed Perr_daily represents the worst case scenario that assumes the error in the 3-hourly source data, which is given in mm/hr, is accumulating within the 3-hourly period of the source data and then during the day. These values, however, can easily be conveted to root mean square error estimate of the rainfall rate: rms_err = { (Perr_daily/3) ^2 / Ncnt_err }^0.5 (mm/hr) This estimate assumes that the error given in the 3-hourly files is representative of the error of the rainfall rate (mm/hr) within the 3-hour window of the files, and it is random throughout the day. Note, this should be interpreted as the error of the rainfall rate (mm/hr) for the day, not the daily accumulation.

Data Identification Fields:

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    Data Dates
    Creation
    Last Revision
    Processing Level

    3

    Quality
    Since the quality of the source 3B42RT product is worse than the research product (3B42), so is the quality of this derived Daily (TRMM_3B42RT_Daily) worse than (TRMM_3B42_Daily) as well. It is highly sensitive to the availability and quality of the input data, e.g. TMI (product 2A12), as well as other input datasets listed in the provider's documentation. Although the grid is from 60S to 60N, the high latitude (beyond 50S/N) near real-time retrievals are considered very unreliable and thus are screened out from the daily accumulations. Check the most recent assessment, TMPA-to-IMERG_transition.pdf, issued after the decommissioning of the TRMM satellite, in the Realated URL section here.
    Collection Progress

    In Work

    Use Constraints
    None
    Access Constraints

    None

    Publication References
    • Publication reference title not provided
        Not provided
Related URLs
    Science Keywords
    • EARTH SCIENCE
    • ATMOSPHERE
    • PRECIPITATION
    • PRECIPITATION RATE
Other Descriptive Keywords
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Ancillary Keywords
  • EOSDIS
ISO Topic Categories
  • CLIMATOLOGY/METEOROLOGY/ATMOSPHERE
Additional Attributes
  • Data Granularity
    STRING
    The time coverage of individual data granules.
    Resolution Range Begin Range End Unit of Measure Accuracy

  • metadata.uuid
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    Not provided
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  • metadata.extraction_date
    STRING
    Not provided
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  • metadata.keyword_version
    FLOAT
    Not provided
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  • DIF9.0-to-DIF10-Converter
    STRING
    Not provided
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  • Discipline
    STRING
    Not provided
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  • IDN_Node.Short_Name
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    STRING
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  • Original.xsi:schemaLocation
    STRING
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Acquisition Information Fields:

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Platforms
  • Models/Analyses
    TMPA
    Instruments
    • NOT APPLICABLE
Projects
Project Short Name Campaigns Project Dates
TRMM No campaigns listed. No dates provided.

Temporal Information Fields:

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Spatial Information Fields:

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    Coverage Type Zone Identifier Geometry Granule Representation
    HORIZONTAL CARTESIAN CARTESIAN
Location Keywords
    • GEOGRAPHIC REGION
    • GLOBAL

Data Centers

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  • NASA/GSFC/SED/ESD/GCDC/GESDISC
    ARCHIVER
    Goddard Earth Sciences Data and Information Services Center (formerly Goddard DAAC), Global Change Data Center, Earth Sciences Division, Science and Exploration Directorate, Goddard Space Flight Center, NASA

    This data center does not have any addresses listed.

    This data center does not have any contact mechanisms listed.

Data Contacts

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  • GEORGE
    Investigator
    GEORGE HUFFMAN

    NASA Goddard Space Flight Center
    Mailstop 612
    Greenbelt, MD 20771

    • Email
    • 301-614-6308
    • 301-614-5492
  • ANDREY
    Metadata Author
    ANDREY SAVTCHENKO

    Distributed Active Archive Center Global Change Data Center
    Code 610.2
    NASA Goddard Space Flight Center
    Greenbelt, MD 20771

  • GES DISC HELP DESK SUPPORT GROUP
    Technical Contact
    GES DISC HELP DESK SUPPORT GROUP

    Goddard Earth Sciences Data and Information Services Center
    Code 610.2
    NASA Goddard Space Flight Center
    Greenbelt, MD 20771

    • Email
    • 301-614-5224
    • 301-614-5268
  • GES DISC HELP DESK SUPPORT GROUP
    Data Center Contact
    GES DISC HELP DESK SUPPORT GROUP

    NASA/GSFC/SED/ESD/GCDC/GESDISC

    Goddard Earth Sciences Data and Information Services Center
    Code 610.2
    NASA Goddard Space Flight Center
    Greenbelt, MD 20771

    • Email
    • 301-614-5224
    • 301-614-5268

Collection Citations Fields:

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    Collection Citations
    • TRMM (TMPA-RT) Near Real-Time Precipitation L3 1 day 0.25 degree x 0.25 degree V7
      7

      Created by:

      Editor: Andrey Savtchenko

      Published by: Goddard Earth Sciences Data and Information Services Center (GES DISC)

      Released: