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MERRA-2 data set from GMAO now available at the GES DISC

New version of the Modern Era Retrospective-analysis for Research and Analysis (MERRA) data set

MERRA-2 data set from GMAO now available at the GES DISC

Image of MERRA-2 Monthly Total Aerosol Scattering (AOT) at 550 nm for the month of April, averaged over the period 1980-2014.

MERRA-2 data set from GMAO now available at the GES DISC
 
 
The MERRA-2 data set, produced by the Global Modeling and Assimilation Office (GMAO), is now available from the Goddard Earth Sciences Data and Information Services Center (GESDISC)!
 
 
 
  • GMAO and GES DISC would like to inform the science community that MERRA-2 data is available at the GES DISC:

http://disc.sci.gsfc.nasa.gov/uui/search/%22MERRA-2%22

  • There is also a new MERRA-2 subsetter that was developed to provide additional functionality, including regridding:

http://disc.sci.gsfc.nasa.gov/daac-bin/FTPSubset2.pl

  • The New MERRA-2 Web page at GMAO is available, but much of the content is still being developed:

http://gmao.gsfc.nasa.gov/reanalysis/MERRA-2/

  • A draft of the Initial Climate Evaluation is also now available:

http://gmao.gsfc.nasa.gov/reanalysis/MERRA-2/docs/

  • In using the data, you will want to refer to the  MERRA-2 File Specification Document:

http://gmao.gsfc.nasa.gov/pubs/docs/Bosilovich785.pdf

 

The MERRA-2 File Specification Document is important because while the nominal resolution of MERRA-2 is still ~0.5°, the grid is slightly different from MERRA.  

In addition to the grid, there are a few other changes to note. There  is a difference  between MERRA  and  MERRA-2 over  land  surfaces, where MERRA-2 uses  observation-based  precipitation  data  as  forcing  for  the  land  surface  parameterization.  This approach  is similar  to  the  gauge-based  precipitation  forcing  developed  for  MERRA-Land ( Reichle  et  al.,  2011Reichle,  2012Reichle  and  Liu,  2014 ).  The  precipitation  forcing  data derived  from  this  approach  is  archived  as  the  output  variable  called  PRECTOTCORR  in  the MERRA-2  FLX  and  LFO  collections  (see  Section  6 in the MERRA-2 File Specification Document).  Note  that  the  forcing  precipitation  is  not purely  gauge  observations,  as  it  tapers  back  to  MERRA-2  model  generated  precipitation poleward  of  42.5°  latitude,  and  is  completely  MERRA-2  precipitation  poleward  of  62.5°.  Also, over  continental  Africa,  the  observations  change  to  the  CMAP  gauge-satellite  product,  due  to limitations in the available gauge observations. Care must be taken in mass balance studies, as the difference between the observation-based and model-generated precipitation will affect the water budget when land and atmosphere budgets are combined.

Along with the enhanced use of satellite observations in MERRA-2, a secondary motivation was to include more aspects of the Earth System.  An important aspect of this is the assimilation of aerosol information,  based  on  the  off-line  “MERRAero”  dataset that  was integrated using meteorological fields from MERRA. MERRA-2 aerosol variables are included in additional file collections,  which use  the  tags  AER,  ADG  and  GAS  in  their  file  names,  similar  to  the MERRAero data file (Da Silva et al., 2015).

Reflecting  the  broader  scope  of  the  assimilation  system,  there  are  several  other  new  file collections. MERRA-2 includes a mass balance over glaciated land surfaces, which is written in the GLC collection. Several surface variables have additional daily statistics written in a separate collection called statD

Regarding the quality of the data, several documents and presentations are being finalized and will be added to the MERRA-2 Web pages over time — thank you for your patience.

Lastly, it is important to inform the community that the computing platform MERRA is produced on will no longer be supported. When it is gone, real-time MERRA data will no longer be produced. While this date is not presently fixed, we expect to stop the MERRA production on February 29, 2016. When we know the end date, it will be shared on this list and the GMAO and GESDISC Web pages. 

Two other examples of MERRA-2 data are shown in the images below.  Thank you for your interest and use of the MERRA data products! 

 

MERRA-2 Dust Column Mass Density, April 2001

Above: Time-averaged maps of MERRA-2 Dust Column Mass Density for the period April 4-14, 2001.  During this period, one of the largest dust storms ever observed originating in China transported dust over the North Pacific Ocean to North America. The dust from this storm affected air clarity across the United States, from California to Maryland.  Click on the image to view it full-size.

 MERRA-2 Eastward and Northward Wind Speed, August 28, 2012

Above:   Image of MERRA-2 eastward and northward wind speed at 2 meters above the Earth surface on August 28, 2012.  On this date, while Hurricane Isaac approached the northern Gulf Coast of the United States, Typhoon Bolaven was located in the Yellow Sea between China and the Korean Peninsula.  Typhoon Bolaven was the most powerful typhoon to strike the Korean Peninsula in a decade.   Click on the image to view a much larger version. 

 

 


Questions or comments? Email the NASA GES DISC Help Deskgsfc-help-disc@lists.nasa.gov

 

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Last updated: Feb 04, 2016 03:17 PM ET
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