segunda-feira, 7 de maio de 2012

Como baixar imagens TRMM de precipitação mensal

The Tropical Rainfall Measuring Mission (TRMM) is a joint U.S.-Japan satellite mission to monitor tropical and subtropical precipitation and to estimate its associated latent heating. TRMM was successfully launched on November 27, at 4:27 PM (EST) from the Tanegashima Space Center in Japan.

The rainfall measuring instruments on the TRMM satellite include the Precipitation Radar (PR), an electronically scanning radar operating at 13.8 GHz; TRMM Microwave Image (TMI), a nine-channel passive microwave radiometer; and Visible and Infrared Scanner (VIRS), a five-channel visible/infrared radiometer.
The purpose of 3B43 algorithm is to produce the best-estimate precipitation rate (mm/hr) and root-mean-square (RMS) precipitation-error estimates from TRMM and other data sources. The algorithm combines four independent precipitation fields: (1) the monthly average unclipped TRMM Microwave Imager (TMI) estimate (intermediate product from Algorithm 3B42), (2) the monthly average Special Sensor Microwave/Imager (SSM/I) estimate (TRMM product 3A46), (3) the pentad-average adjusted merged-infrared (IR) estimate (TRMM product 3B42), and (4) the monthly accumulated Climate Assessment and Monitoring System (CAMS) or Global Precipitation Climatology Centre (GPCC) rain gauge analysis (TRMM product 3A45). All input data have a calendar month temporal resolution except the adjusted merged-IR data, which have a daily resolution. To obtain the requisite calendar month average of adjusted merged-IR data, the 3B43 algorithm averages the adjusted merged-IR daily data that span the calendar month of interest. Also, the monthly average unclipped TMI data, prior to their combination with the SSM/I, adjusted merged-IR, and rain gauge data, are converted (calibrated) to TRMM Combined Instrument (TCI) data, using the TMI/TCI calibration parameters (from TRMM product 3B31). After the preprocessing is complete, the four independent precipitation fields are merged together to form the best-estimate precipitation rate and RMS precipitation-error estimates. These gridded estimates have a calendar month temporal resolution and a 0.25-degree by 0.25-degree spatial resolution. Spatial coverage extends from 50 degrees south to 50 degrees north latitude.

The data are stored in the Hierarchical Data Format (HDF), which includes both core and product specific metadata. The file size is about 0.28 MB (compressed).

O produto TRMM 3B43

Data set
Dataset Creator: Tropical Rainfall Measuring Mission Project (TRMM)
Dataset Title: TRMM and Other Sources Rainfall Product (TRMM Product 3B43)
Version: 6

Temporal Coverage
Start Date: 1998-01-01

Data Resolution
Latitude Resolution: 0.25 degree
Longitude Resolution: 0.25 degree
Horizontal Resolution Range: 10 km - < 50 km or approximately .09 degree - < .5 degree Vertical Resolution: Surface Temporal Resolution: Monthly Temporal Resolution Range: Monthly - < Annual

Link para download
3B43: Monthly 0.25 x 0.25 degree merged TRMM and other sources estimates

Na imagem observa-se a precipitação media sobre a Bacia Amazonica entre o periodo 2000-Jan e 2006-Jun obtida a partir do produto TRMM 3B43.

2 comentários:

  1. Falta um tutorial sobre como processar esses dados, pois estes não apresentam cabeçalho e em determinadas situações os dados vem rotacionados. Como faço para utilizar os dados TRMM em um SIG?

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  2. Bem, estou baixando os dados de 3 em 3 horas. Também acho que seria super legal se explicasse como processar esses dados. Mesmo com o programa em Fortran ainda não descobri como extrair o que preciso...

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