Web-based Reanalysis Intercomparison Tools (WRIT)

Created by Cathy.Smith@noaa.gov on - Updated on 10/28/2021 12:14

Web-based Reanalysis Intercomparison Tools  (WRIT) BAMS article: 


A set of web-based reanalysis intercomparison tools (WRIT) is available from the NOAA Physical Sciences Laboratory and University of Colorado CIRES.


WRIT Maps WRIT Time-series WRIT Correlations WRIT Trajectories WRIT Distributions

The "WRIT" Maps tool allows users to examine 20CR, ERA-Interim, ERA-20C, JRA-55, MERRA, MERRA-2, NCEP R1, NCEP R2, and NCEP CFSR reanalyses datasets. Pressure level data are available for most reanalyses, as well as 5 single level variables including sea level pressure, 2 m air temperature, 10 m winds, precipitation. Maps and pressure-level by longitude and pressure-level by latitude can be generated for monthly means, anomalies, and climatologies. Observational datasets have been made available that can be compared to 2m air temperature and precipitation. These quantities can be differenced between datasets.

Future enhancements include different time scales.

is also available from WRIT. It allows users to examine 20CR, ERA-Interim, ERA-20C, JRA-55, MERRAMERRA-2, NCEP R1,  NCEP R2, and NCEP-CFSR as well as some observational dataset. Users can compare timeseries from different datasets, regions, variables and levels. Distributions, scatter plots, and auto-correlation are also available. Statistics for each timeseries including means, standaed deviations, slope and correlations are provided.

The "WRIT" Trajectory Tool is a new tool available from WRIT. It allows users to plot forward and backward trajectories from different reanalyses (currently NCEP R1, NCEP R2, and 20CR with more planned). Users can plot  the trajectories of one or more levels on a single plot. The output is plotted and is available as netCDF and as KMZ files suitable for Google Earth.

Other analysis products are planned.

Feedback and suggestions are welcome. Please give comments/issues/suggestions in the Post a comment or question below.



The Twentieth Century Reanalysis Project (20CR) used resources of the National Energy Research Scientific Computing Center managed by Lawrence Berkeley National Laboratory and of the Oak Ridge Leadership Computing Facility at Oak Ridge National Laboratory, which are supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 and Contract No. DE-AC05-00OR22725, respectively. Support is provided by the U.S. Department of Energy, Office of Science Innovative and Novel Computational Impact on Theory and Experiment (DOE INCITE) program, and Office of Biological and Environmental Research (BER), and by the National Oceanic and Atmospheric Administration Climate Program Office. Data are freely available from NOAA, NCAR, the IRI, KNMI, and DOE NERSC.

NASA's Modern Era Retrospective analysis for Research and Applications (MERRA) was developed by the Global Modeling and Assimilation Office (GMAO) and produced through NASA's Modeling, Analysis and Prediction (MAP) program, and is freely available from the Goddard Earth Sciences (GES) Data Information Services center (DISC).

NCEP's Climate Forecast System Reanalysis (CFSR) was developed by the Environmental Modeling Center (EMC) and was partially funded through the NOAA Climate Program Office. It is available free to the public from both NCDC and NCAR.

The ERA-Interim reanalysis is being produced by the European Centre for Medium-Range Weather Forecasts (ECMWF) in Reading, UK. ERA-Interim data with near-real time updates are freely available from the ECMWF data server and from the CISL Data Archive at NCAR. 

WRIT contributes to the Atmospheric Circulation Reconstructions over the Earth (ACRE) Initiative.

WRIT is supported in part by NOAA and by the US Department of Energy Office of Science (BER).

Yaren Duygu Atalay (not verified)

Wed, 01/24/2024 - 12:40

Hello, For my master's thesis, I need the wind speed, solar radiation and sunshine hours of the city of Stuttgart in 10-minute periods for the last 5 years. Coould you direct me to access this data please?



Is there any source for multiyear WRIT reanalysis for water equivalence of snow depth for the Mediterranean region. I have tried your interface for ERA5, JRA55, MERRA databses and the option appears to be frozen and not allowed. I am testing a statistical ANN and Cluster analysis model that I utilized to identify possible approximate seasons for snowfall and severe weather events, it worked well for flood risk and severe weather , however i wish to trry it for snowfall/depth using multiyear analogous months or seasons . Any suggestions/solutions for analogous re-analysis for snowfall risk and depth?


Thank you B y all results and outcomes. 

Warmest Regards

Mohammed Alkhateeb

Anonymous (not verified)

Thu, 03/20/2014 - 16:24

Why only 2 time series maximum? Do you plan to increase that number? Since this tool is for INTER-comparison (not just comparison), I would expect this function to be useful. It would be particularly good to allow users to choose a group of the reanalyses to plot.Whereas this is more difficult to do for 2d plots, time series should allow such intercomparison to be performed easily.

While comparing more than one timeseries would be ideal, in the current implementation of the tool, it would not be possible as the entire timeseries at all gridpoints is read in and that is very large. We would need to process the data one timestep at a time instead to have it work on the server. It is still possible this is too resource intensive for a web tool but but if we are able to get more programming resources, it would be a very nice feature and a higher priority than other new features for time series plots.--Cathy


Mon, 05/06/2013 - 14:06

When a user selects MERRA pressure level data for time series as one or both of the variables, we now print "Note: MERRA does not interpolate pressure level variables below the surface. Your MERRA timeseries may average "missing" grids. Please check the MERRA maps of the variable to see where this may occur." MERRA maps points to the mapping WRIT page. Is this sufficient? How should we handle pressure level data below the surface? A user could pick a box that has some values below the surface and some not. We could alternatively not allow any comparisons below the surface. We may be able to report average percent of grids in each month available or something like that. Any other ideas?

MERRA 3D atmospheric data were produced without extrapolation to pressure surfaces where the pressure level would be greater than the surface pressure (in other words, under ground). The impact that this has on averaging is discussed here:


A third party routine is available to extrapolate continuous pressure levels.


This would be best applied to 3 or 6 hourly fields.

Gintautas (not verified)

Fri, 11/30/2012 - 12:50

It is a "cool" tool for my students analysing anomalies and compositions, drawing timeseries and trajectories. And all is available without any knowledge in programming, data format or additional data visualisation software. Thanks. Gintas

Anonymous (not verified)

Thu, 08/16/2012 - 15:12

What we could add or change to page: Ability to composite on a set of dates. Allow users to use own dates More variables (what?) Standardized anomalies. We can consider these though they may require too much time to compute. What we hope to improve. Speed! We know where some of the slowness is and hope to find ways around it. Labeling... Please list other suggestions.


I am just starting to work with WRIT. It's proving excellent for all sorts of analyses we're doing but one aspect that I'm struggling to undertake is to extract data for specific seasons or a selected run of months. The option to chose a range of months is there on the page but I'm not having any luck getting it to work. Profuse apologies if I'm missing something obvious.


Thanks for providing such great software!


Best wishes, Chris 

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