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NRT AMSR-E/Aqua Daily L3 Global Snow Water Equivalent EASE-Grids

Entry ID: AE_dysno_nrt

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Summary

Abstract: The Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) instrument on the NASA EOS Aqua satellite provides global passive microwave measurements of terrestrial, oceanic, and atmospheric variables for the investigation of global water and energy cycles.

These near real-time (NRT) products are generated within 3 hours of the last observations in the file, by the Land ...

Related URL

Link: VIEW RELATED INFORMATION

Description: Land Atmosphere Near real-time Capability for EOS (LANCE) web site

Geographic Coverage

(Click for Interactive Map)

Spatial coordinates

N: 90.0

S: -90.0

E: 180.0

W: -180.0

Data Set Citation

Dataset Originator/Creator: A. Chang

Dataset Title: AMSR-E/Aqua Daily L3 Global Snow Water Equivalent EASE-Grids

Dataset Release Date: 2004-01-01

Temporal Coverage

Start Date: 2013-05-12

Stop Date: 2013-05-19

Location Keywords

GEOGRAPHIC REGION > GLOBAL

Data Resolution

Latitude Resolution: 25 km
Longitude Resolution: 25 km
Horizontal Resolution Range: 10 km - < 50 km or approximately .09 degree - < .5 degree
Temporal Resolution: daily
Temporal Resolution Range: Daily - < Weekly

Science Keywords

CRYOSPHERE > SNOW/ICE > SNOW WATER EQUIVALENT

TERRESTRIAL HYDROSPHERE > SNOW/ICE > SNOW WATER EQUIVALENT

ISO Topic Category

CLIMATOLOGY/METEOROLOGY/ATMOSPHERE

Platform

AQUA > Earth Observing System, AQUA

Instrument

AMSR-E > Advanced Microwave Scanning Radiometer-EOS

Project

EOS > Earth Observing System

EOSDIS > Earth Observing System Data Information System

ESIP > Earth Science Information Partners Program

LANCE > Land Atmosphere Near Real-time Capability for EOS

Quality Differences between the LANCE NRT and standard products are currently under investigation. Known, but not yet quantified, differences include
• the ephemeris files (LANCE uses predicted ephemeris and standard products use definitive ephemeris) and
• standard product generation includes more sophisticated, dynamic cross calibration and ... geolocation processes.

Each HDF-EOS file contains core metadata with Quality Assessment (QA) metadata flags that are set by the Science Investigator-led Processing System (SIPS) at the Global Hydrology and Climate Center (GHCC) prior to delivery to NSIDC. A separate metadata file in XML format is also delivered to NSIDC with the HDF-EOS file; it contains the same information as the core metadata. Three levels of QA are conducted with the AMSR-E Level-2 and Level-3 products: automatic, operational, and science QA. If a product does not fail QA, it is ready to be used for higher-level processing, browse generation, active science QA, archive, and distribution. If a granule fails QA, SIPS does not send the granule to NSIDC until it is reprocessed. Level-3 products that fail QA are never delivered to NSIDC (Conway 2002).

Chang visually examined random samples of SWE products to ensure they were consistent with an understanding of climate and that no gross errors were present. Future validation will involve comparing retrieved SWE values with estimates from airborne gamma observations over the U.S. (Carroll 1997) and with snow gauge data (Carroll et al. 1995), as well as comparing snow extent with MODIS snow maps (Chang and Rango 2000).

AMSR-E Level-2A data arriving at GHCC are subject to operational QA prior to processing higher-level products. Operational QA varies by product, but it typically checks the following criteria for a given file (Conway 2002):
* File is correctly named and sized
* File contains all expected elements
* File is in the expected format
* Required EOS fields of time, latitude, and longitude are present and populated
* Structural metadata is correct and complete
* The file is not a duplicate
* The HDF-EOS version number is provided in the global attributes
* The correct number of input files were available and processed Science QA

AMSR-E Level-2A data arriving at the GHCC are also subject to science QA prior to processing higher-level products. If less than 50 percent of a granule's data is good, the science QA flag is marked 'suspect' when the granule is delivered to NSIDC. In the SIPS environment, the science QA includes checking the maximum and minimum variable values, and percent of missing data and out-of-bounds data per variable value. At the Science Computing Facility (SCF), also at GHCC, science QA involves reviewing the operational QA files, generating browse images, and performing the following additional automated QA procedures (Conway 2002):
* Historical data comparisons
* Detection of errors in geolocation
* Verification of calibration data
* Trends in calibration data
* Detection of large scatter among data points that should be consistent

Geolocation errors are corrected during Level-2A processing to prevent processing anomalies such as extended execution times and large percentages of out-of-bounds data in the products derived from Level-2A data. The Team Lead SIPS (TLSIPS) developed tools for use at SIPS and SCF for inspecting the data granules. These tools generate a QA browse image in Portable Network Graphics (PNG) format and a QA summary report in text format for each data granule. Each browse file shows Level-2A and Level-2B data. These are forwarded from Remote Sensing Systems (RSS) to the GHCC along with associated granule information, where they are converted to HDF raster images prior to delivery to NSIDC. SWE is estimated for SD retrievals greater than 1 mm. Based on the 2002-2003 winter AMSR-E data and 38 coincident ground observations in the World Meteorological Organization (WMO) Global Telecommunications System (GTS) network, the standard error is 24.2 cm. Further validation is planned using multiple local, regional, and global data sets. See NSIDC's AMSR-E Validation Data for information about data used to check the accuracy and precision of AMSR-E observations.

Access Constraints You must register using the EOSDIS User Registration System in order to access LANCE NRT AMSR-E data. You can register at https://users.eosdis.nasa.gov/.

Ancillary Keywords

AE_DySno_NRT

AE_DySno

Data Set Progress

IN WORK

Data Center

Advanced Microwave Scanning Radiometer - Earth Observing System Science Investigator-led Processing System

Data Center URL: http://wwwghcc.msfc.nasa.gov/AMSR/
Dataset ID: AE_DySno_NRT

Data Center Personnel
Name: GHRC USER SERVICES OFFICE Phone: 256-961-7932 Fax: 256-961-7859 Email: ghrcdaac at itsc.uah.edu Contact Address: GHRC User Services Office Global Hydrology Resource Center (GHRC) 320 Sparkman Drive City: Huntsville Province or State: AL Postal Code: 35805 Country: USA

Distribution

Distribution Media: FTP

Distribution Size: Each daily granule is 2.1 MB

Distribution Format: HDF-EOS

Personnel

SHERRY HARRISON

Role: DIF AUTHOR

Phone: 256-961-7973

Email: ghrcdaac at itsc.uah.edu

Contact Address:

320 Sparkman Dr.

City: Huntsville

Province or State: AL

Postal Code: 35805

Country: USA

Publications/References

Basist, A., N. C. Grody, T. C. Peterson, and C. N. Williams. 1998. Using the Special Sensor Microwave Imager to Monitor Land Surface Temperatures, Wetness and Snow Cover. Journal of Applied Meteorology 37(9): 888-911.

Brodzik, M. J. 1997. EASE-Grid: A Versatile Set of Equal-Area Projections and Grids. Boulder, CO, USA: National Snow and Ice Data Center.

Brown, R. D. and ...

Creation and Review Dates

DIF Creation Date: 2010-08-17

Last DIF Revision Date: 2011-08-10

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