Amazon River Basin Precipitation Data Set Document

Data Set Identification:

Amazon River Basin precipitation data

Data Set Introduction:

The Amazon River Basin precipitation data were derived from data which was collected daily by the gauging network operated by the Divisao Nacional de Aguas e Energia Eletrica (DNAEE, SGAN 603 Modulo J, Anexo DNC, CEP 70.830-030 Brasilia DF, Brazil). The DNAEE provided the EOS Regional Amazon Model (EOSRAM) project with this data for cooperative analysis. The monthly total precipitation is in a 126 by 151 element array. The data is based on monthly rain datasets from Peru and Bolivia and daily rain datasets from Brazil. The extent of the gridded data ranges from latitudes of 20.0S to 5.2N and longitudes from 79.6W to 49.4W.

Objective/Purpose:

The purpose of this research project is to understand biogeochemistry, hydrology, and sedimentation of the Amazon River and its drainage basin. The Amazon was chosen as the first target in the study of Earth's continental scale river systems, which represent some of the largest and most dynamic environmental units on the planet. The researchers involved in this project, while located at various institutes, share a common focus, the Patterns and Processes of Change in the Amazon River Basin.

Summary of Parameters:

The precipitation data is 0.2 degree gridded monthly precipitation in millimeters per month. The precipitation data are based on monthly rain data sets from Peru and Bolivia and daily rain data sets from Brazil. The data were derived from a linear interpolation of all stations within one degree from a minimum of four stations.

Discussion:

The extent of the gridded data ranges from latitudes of 20.0 degrees South to 5.2 degrees North and longitudes of 79.6 degrees West and 49.4 degrees West. The data were extropolated to the edge of the Amazon River Basin and are much less reliable outside Brazil and Bolivia.

Related Data Sets:

Another data set from the EOSRAM project which is related to the Amazon River Basin precipitation data is the Carbon in the Amazon River Experiment (CAMREX) data set. The CAMREX study is establishing a baseline needed for assessing any future anthropogenic perturbations, with the main goal being to gain a broad mechanistic understanding of the river system that also can be applied to other large rivers.

Investigator(s) Name and Title:

Dr. Thomas Dunne
Project Management, United States Team Leader

Title of Investigation:

Earth Observing System Regional Amazon Model Project

Contact Information:

Please direct all queries to the ORNL DAAC User Services Office:

ORNL Distibuted Active Archive Center User Services Office
Bldg. 1507, M.S. 6407
P.O. Box 2008
Oak Ridge, Tennessee 37831-6407
USA Voice: (423) 241-3952
Fax: (423) 574-4665
Email: ornldaac@ornl.gov

Sensor/Instrument Description:

Collection Environment:

The precipitation measurements were derived from data which was collected daily by gauging network throughout the Amazon River Basin region.

Source/Platform:

The source for this data set is a ground station.

Source/Platform Mission Objectives:

The source mission objective was to provide quality precipitation observations to support the study of the Amazon River and its drainage basin.

Key Variables:

The key variable is precipitation.

Principles of Operation:

This information is not available at this time.

Sensor/Instrument Measurement Geometry:

This information is not available at this time.

Manufacturer of Sensor/Instrument:

This information is not available at this time.

Calibration:

Specifications:

This information is not available at this time.

Tolerance:

This information is not available at this time.

Frequency of Calibration:

This information is not available at this time.

Other Calibration Information:

This information is not available at this time.

This information is not available at this time.

Data Notes:

This data set depends highly on the procedures used to collect the rain gauge data.

Field Notes:

No field notes are available at this time.

Spatial Characteristics:

Spatial Coverage:

The precipitation grid extends from 20.2 degrees South to 5.6 degrees North and 79.8 degrees West to 45.6 degrees West. This area covers the Amazon River Basin region.

Spatial Coverage Map:

The 0.2 degree gridded data directly maps to the area in which the measurements were taken.

Spatial Resolution:

The spatial resolution of the precipitation data is 0.2 degrees.

Projection:

No projection was used to process the data since the data are directly related to geographic areas.

Grid Description:

Rain is derived from monthly data sets for Peru and Bolivia, and daily data sets for Brazil. It is inter/extrapolated, taking a linear interpolation of all stations within one degree, but using at least four stations. Topographic and other information is not used in the interpolation. Data are extrapolated to edges of the basin, but should not be trusted in the Andes.

Temporal Characteristics:

Temporal Coverage:

The data spans the period from January, 1972 to December, 1992.

Temporal Coverage Map:

The data set spans the period from January, 1972 to December, 1992 with data for each month during that time period. During each month, the number of stations within the gauging network that were used to compute the monthly precipitation data can vary. The following table is an example of the number of stations used to compute the data for each month for the year of 1986.

                 Month (in 1986)         Number of Stations

                 Jan                     387     
                 Feb                     382
                 Mar                     380
                 Apr                     378
                 May                     383
                 Jun                     383     
                 Jul                     384
                 Aug                     385
                 Sep                     384
                 Oct                     382
                 Nov                     377
                 Dec                     378

Temporal Resolution:

The temporal resolution is monthly.

Data Characteristics:

Parameter/Variable:

The key parameter is precipitation.

Variable Description/Definition:

Precipitation - Any or all forms of liquid or solid water particles that fall from the atmosphere and reach the surface of the Earth. It includes drizzle, rain, snow, snow pellets, snow grains, ice crystals, ice pellets, and hail. Precipitation is also defined as a measurement of the quantity, expressed in centimeters or milliliters of liquid water depth, of the water substance that has fallen at a given location in a specified amount of time.

Unit of Measurement:

The monthly precipitation data are in millimeters per month.

Data Source:

The source of the data was a ground station that collected the precipitation measurements gathered by the rain gauging network

Data Range:

The data ranges from 0 millimeters per month to approximately 800 millmeters per month. Some monthly values may exceed 800 mm/month.

Sample Data Record:

     Item                 HDF Ref Number          HDF Object Type
      Numeric Data Group              0               Jan86--based_on_387_stations
      Numeric Data Group              1               Feb86--based_on_382_stations
      Numeric Data Group              2               Mar86--based_on_380_stations
      Numeric Data Group              3               Apr86--based_on_378_stations
      Numeric Data Group              4               May86--based_on_383_stations
      Numeric Data Group              5               Jun86--based_on_383_stations
      Numeric Data Group              6               Jul86--based_on_384_stations
      Numeric Data Group              7               Aug86--based_on_385_stations
      Numeric Data Group              8               Sep86--based_on_384_stations
      Numeric Data Group              9               Oct86--based_on_382_stations
      Numeric Data Group              10              Nov86--based_on_377_stations
      Numeric Data Group              11              Dec86--based_on_378_stations
      Version Descriptor              1               (No label)
      File Identifier                 2               (No label)
      File Descriptor                 3               (No label)
      Scientific Data                 4               (No label)
      Number Type                     4               (No label)
      SciData dimension record        4               (No label)
      SciData labels                  4               (No label)
      SciData units                   4               (No label)
      SciData formats                 4               (No label)
      SciData coordsys                4               (No label)
      Scientific Data                 5               (No label)
      Number Type                     5               (No label)
      SciData dimension record        5               (No label)
      SciData labels                  5               (No label)
      SciData units                   5               (No label)
      SciData formats                 5               (No label)
      SciData coordsys                5               (No label)
      Scientific Data                 6               (No label)
      Number Type                     6               (No label)
      SciData dimension record        6               (No label)
      SciData labels                  6               (No label)
      SciData units                   6               (No label)
      SciData formats                 6               (No label)
      SciData coordsys                6               (No label)
      Scientific Data                 7               (No label)
      Number Type                     7               (No label)
      SciData dimension record        7               (No label)
      SciData labels                  7               (No label)
      SciData units                   7               (No label)
      SciData formats                 7               (No label)
      SciData coordsys                7               (No label)
      Scientific Data                 8               (No label)
      Number Type                     8               (No label)
      SciData dimension record        8               (No label)
      SciData labels                  8               (No label)
      SciData units                   8               (No label)
      SciData formats                 8               (No label)
      SciData coordsys                8               (No label)
      Scientific Data                 9               (No label)
      Number Type                     9               (No label)
      SciData dimension record        9               (No label)
      SciData labels                  9               (No label)
      SciData units                   9               (No label)
      SciData formats                 9               (No label)
      SciData coordsys                9               (No label)
      Scientific Data                 10              (No label)
      Number Type                     10              (No label)
      SciData dimension record        10              (No label)
      SciData labels                  10              (No label)
      SciData units                   10              (No label)
      SciData formats                 10              (No label)
      SciData coordsys                10              (No label)
      Scientific Data                 11              (No label)
      Number Type                     11              (No label)
      SciData dimension record        11              (No label)
      SciData labels                  11              (No label)
      SciData units                   11              (No label)
      SciData formats                 11              (No label)
      SciData coordsys                11              (No label)
      Scientific Data                 12              (No label)
      Number Type                     12              (No label)
      SciData dimension record        12              (No label)
      SciData labels                  12              (No label)
      SciData units                   12              (No label)
      SciData formats                 12              (No label)
      SciData coordsys                12              (No label)
      Scientific Data                 13              (No label)
      Number Type                     13              (No label)
      SciData dimension record        13              (No label)
      SciData labels                  13              (No label)
      SciData units                   13              (No label)
      SciData formats                 13              (No label)
      SciData coordsys                13              (No label)
      Scientific Data                 14              (No label)
      Number Type                     14              (No label)
      SciData dimension record        14              (No label)
      SciData labels                  14              (No label)
      SciData units                   14              (No label)
      SciData formats                 14              (No label)
      SciData coordsys                14              (No label)
      Scientific Data                 15              (No label)
      Number Type                     15              (No label)
      SciData dimension record        15              (No label)
      SciData labels                  15              (No label)
      SciData units                   15              (No label)
      SciData formats                 15              (No label)
      SciData coordsys                15              (No label)
        

Data Granularity:

A general description of data granularity as it applies to the IMS appears in the EOSDIS Glossary.

The data for the entire period of record is contained in a single file. This file is in UNIX tar and compress format. When the file is uncompressed and untarred, 21 HDF files are generated. Each HDF file corresponds to a single year in the period of record and contains 12 images, one for each month. The precipitation total for each month is stored in a 126 by 151 element array.

Data Format:

The data are stored using the Hierarchical Data Format (HDF), developed at the National Center for Supercomputing Applications (NCSA) at the University of Illinois, Urbana-Champaign.

Formulae:

Derivation Techniques and Algorithms:

The precipitation data are based upon monthly rainfall data from Peru and daily rainfall data from Brazil. The gridded precipitation data are derived from a linear interpolation of all stations within a one degree grid box, with data from a minimum of four stations.

Data Processing Sequence:

Processing Steps:

This information is not available at this time.

Processing Changes:

This information is not available at this time.

Calculations:

Special Corrections/Adjustments:

No special corrections were made to this data set.

Calculated Variables:

The monthly gridded precipitation values are computed from the daily observations.

Graphs and Plots:

This information is not applicable to this data set.

Sources of Error:

There are sources of error for the collection of precipitation measurements from a gauging network. These errors could include: human error in reading the measurement on the gauges, the location and orientation of each gauge in the network, and changes in the time at which measurements are collected from each gauge.

Quality Assessment:

Data Validation by Source:

This information is not available at this time.

Confidence Level/Accuracy Judgement:

This information is not available at this time.

Measurement Error for Parameters:

This information is not available at this time.

Additional Quality Assessments:

This information is not available at this time.

Data Verification by Data Center:

The verification of this data set was performed by the Marshall Space Flight Center Distributed Active Archive User Services Team. This verification included access of the information using standard HDF viewers and visual inspection of the images to determine if the spatial coverage was approriate and if the data was within the expected range of values. Contact the ORNL DAAC User Services Office for additional verification information.

Limitations of the Data:

The data set is limited to the Amazon River Basin region. The data are extrapolated to the edge of the region but are much less reliable outside Brazil and Bolivia. Cells outside the Amazon River Basin are coded zero.

Known Problems with the Data:

There are no known problems with the data at this time.

Usage Guidance:

This information is not available at this time.

Any Other Relevant Information about the Study:

This data set was collected as part of the EOS Amazon Project at the University of Washington. The Amazon region was the first target area of the study of the Earth's continental scale river systems. Other programs within the project include biogeochemistry and land cover change.

There are no future modifications or plans at this time.

Software Description:

The data set is stored in HDF format. The HDF library and software tools can be used to access the data.

Software Access:

The HDF library and tools are available from the National Center for Supercomputing Applications at the University of Illinois in Urbana-Champaign. The HDF library may be accessed via anonymous ftp at the site of ftp.ncsa.uiuc.edu. Information on the HDF may be accessed through the HDF Information Server.

Contact Information:

ORNL Distibuted Active Archive Center User Services Office
Bldg. 1507, M.S. 6407
P.O. Box 2008
Oak Ridge, Tennessee 37831-6407
USA Voice: (423) 241-3952
Fax: (423) 574-4665
Email: ornldaac@ornl.gov
This data is available online via the ORNL DAAC's WWW search and order system.

Data Center Identification:

ORNL Distributed Active Archive Center

Procedures for Obtaining Data:

This data is available online via the ORNL DAAC's WWW search and order system. The data is also available via the EOSDIS V0 IMS or by contacting the ORNL DAAC User Services Office.

Data Center Status/Plans:

The ORNL Distributed Active Archive Center will include any updates to the data set that are generated by the EOSRAM project.

These products are available on 8 mm (Exabyte) and 4mm DAT tapes.

A site located on the surface of the earth that collects various meteorological parameters from a variety of instruments.

Rain gauge

An instrument that measures the amount of precipitation in the location of the instrument since the last collection was made from the rain gauge.

A List of Acronyms for biogeochemical dynamics data is available, as is the list of EOSDIS acronyms

Document Revision Date:

March 26, 1996

Document Review Date:

March 26, 1996

Document ID:

ORNL-AMZ-001

Citation:

Not available at this time.

Document Curator:

DAAC Staff

Document URL:

http://www.daac.ornl.gov/LBA/guides/amazon_precip_guide.html