Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA2)¶
NASAs Global Modeling and Assimilation Office (GMAO) produces the Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA2) which is a 30+ year global climate reanalysis dataset.This dataset complements existing MERRA2 Earth Engine assets: https://developers.google.com/earth-engine/datasets/tags/merra. You can find additional information on this dataset here and read more about the dataset in the climate org data page
Dataset Description¶
Spatial Information
| Parameter | Value |
|---|---|
| Spatial extent | Global |
| Spatial resolution | ~50-km (0.5-deg x 0.625-deg) |
| Temporal resolution | Daily |
| Time span | 1980-04-02 to present |
| Update frequency | Updated every 1-2 months |
Variables
| Variable | Details |
|---|---|
| Minimum temperature, 2m ('T2MMIN') | - Units: Degrees Kelvin |
| - Scale factor: 1.0 | |
| Maximum temperature, 2m ('T2MMAX') | - Units: Degrees Kelvin |
| - Scale factor: 1.0 | |
| Precipitation ('PRECTOTCORR') | - Units: Millimeters |
| - Scale factor: 1.0 | |
| Wind speed, 10m ('WIND2M') | - Units: Meters/second |
| - Scale factor: 1.0 | |
| - NOTE: Windspeed outputs are based on the | |
| standard 10m measurement height, despite | |
| the erroneous ‘2M’ suffix. | |
| ASCE Grass Reference Evapotranspiration | - Units: Millimeters |
| ('ETo_ASCE') | - Scale factor: 1.0 |
| ASCE Alfalfa Reference Evapotranspiration | - Units: Millimeters |
| ('ETr_ASCE') | - Scale factor: 1.0 |
| Specific humidity, 2m ('QV2M') | - Units: kg kg-1 |
| - Scale factor: 1.0 | |
| Surface pressure ('PS') | - Units: Pa |
| - Scale factor: 1.0 | |
| Surface incoming shortwave flux ('SWGDN') | - Units: W m-2 |
| - Scale factor: 1.0 | |
| Surface incoming shortwave flux assuming | - Units: W m-2 |
| clear sky ('SWGDNCLR') | - Scale factor: 1.0 |
Citation¶
MERRA-2 Overview: The Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2), Ronald Gelaro, et al., 2017, J. Clim.,
doi: 10.1175/JCLI-D-16-0758.1
Earth Engine Snippet¶
// Read in Image Collection and get first image
var merra2_ic = ee.ImageCollection('projects/earthengine-legacy/assets/projects/climate-engine/merra2/daily')
var merra2_i = merra2_ic.first()
// Print first image to see bands
print(merra2_i)
// Visualize select bands from first image — additional bands are present in the Image Collection
var prec_palette = ["#ffffcc", "#c7e9b4", "#7fcdbb", "#41b6c4", "#1d91c0", "#225ea8", "#0c2c84"]
var temp_palette = ["#b2182b", "#ef8a62", "#fddbc7", "#f7f7f7", "#d1e5f0", "#67a9cf", "#2166ac"].reverse()
var eto_palette = ["#ffffb2", "#fed976", "#feb24c", "#fd8d3c", "#fc4e2a", "#e31a1c", "#b10026"]
Map.addLayer(merra2_i.select('PRECTOTCORR'), {min: 0, max: 10, palette: prec_palette}, 'PRECTOTCORR')
Map.addLayer(merra2_i.select('T2MMAX').subtract(273.15), {min: -10, max: 30, palette: temp_palette}, 'T2MMAX')
Map.addLayer(merra2_i.select('T2MMIN').subtract(273.15), {min: -10, max: 30, palette: temp_palette}, 'T2MMIN')
Map.addLayer(merra2_i.select('ETo_ASCE'), {min: 0, max: 10, palette: eto_palette}, 'ETo_ASCE')
Map.addLayer(merra2_i.select('ETr_ASCE'), {min: 0, max: 10, palette: eto_palette}, 'ETr_ASCE')
Sample code: https://code.earthengine.google.com/?scriptPath=users/sat-io/awesome-gee-catalog-examples:/weather-climate/MERRA-2
License¶
NASA promotes the full and open sharing of all data with research and applications communities, private industry, academia, and the general public.
Keywords: MERRA2, NASA, global, climate, reanalysis, temperature, precipitation, evapotranspiration, evaporative demand, wind
Datasets provided by: NASA
Dataset curated in GEE by: Climate Engine Org