MACA Data Products

We currently are producing three kinds of MACA data products:MACAv1-METDATA,MACAv2-METDATA and MACAv2-LIVNEH where the differences in these products lie in utilizing:

  • two slightly different downscaling methods (MACAv1 and MACAv2)
  • two different training datasets (METDATA and LIVNEH).

Comparison of MACA Data Products

The following describes some properties of the MACA data products:

Status Available Available Available
Training Dataset Abatzoglou et. al, 2012
(Years 1979-2010)
Livneh et. al, 2013
(Years 1950-2011)
Abatzoglou et. al, 2012
(Years 1979-2012)
Resolution 4-km (1/24-deg) ~6-km (1/16-deg) 4-km (1/24-deg)
Spatial Extent WUSA
(31.02-49.1N, -124.77 to -103.02E)
Contiguous USA (CONUS) and Columbia Basin into Canada Contiguous USA (CONUS)
Spatial Projection WGS 1984 datum WGS 1984 datum WGS 1984 datum
Temporal Resolution daily(on METDATA grid)
monthly aggregations (adjusted to 4-km PRISM grid)
daily daily
Temporal Extent 1950-2100 1950-2099 1950-2099
Downscaled Variables tasmax,tasmin,rhsmax,
Leap Days No leap days Yes, even if model excludes leap days Yes, even if model excludes leap days
Size of individual netcdf files 3GB-daily, 100MB-monthly 2-4GB compressed-daily,0.1GB compressed-monthly 2.5GB-daily
Size of total dataset 13.7TB-daily, 0.3TB-monthly 5TB-daily,0.5TB-monthly 20TB-daily

The MACAv1-METDATA monthly data is a little different than you might expect. The monthly data was aggregated from the daily downscaled data for MACAv1-METDATA but this data was further adjusted from the 4-km METDATA grid to a 4-km PRISM grid (calculated from a 25-cell average of the 800-m PRISM data) so that the historical MACAv1-METDATA monthly data for 1950-2005 will have the same statistics as a 4-km PRISM for 1979-2010. All data represents daily extrema,sums or means over a given calendar day. One other difference in the MACA products is in the units of precipitation. MACAv2 has precipitation in units of inches/day or inches/month. But MACAv1 has precipitation as a 'precipitation flux' in units of kg/m^2/s. The metadata clarifies the units of the precipitation. Here we show how to convert precipitation flux to a precipitation amount.

Precipitation flux is the weight of precipitation over a square meter area per sec. To convert this to a depth of daily precipitation(in millimeters), we assume the density of the precipitation is 1000.0 kg/m3:

daily precipitation (mm) =

(day precipitation flux kg/m2 s)* ( m3/ 1000.0 kg)*(3600 sec/hr) *(24 hr/day)* (1000 mm/m)

Here are some quick guides depending on the time scale you want for your precipitation:
  • daily precipitations(mm) = (daily precipitation flux) * 24*3600
  • monthly precipitations(mm) = (monthly precipitation flux) * 24*3600*daysInMonths, where
    daysInMonths = number of days in that month
    daysInMonths = [31 28 31 30 31 30 31 31 30 31 30 31] for the 12 months for all non-HadGEM2 models
    daysInMonths = 30 for each month for the HadGEM2 models
  • annual precipitations(mm): add up all 12 monthly precipitations(mm)
  • MACA Downscaled Variables

    The variables downscaled with MACA are:

    • tasmax - Maximum daily temperature near surface
    • tasmin - Minimum daily temperature near surface
    • rhsmax - Maximum daily relative humidity near surface
    • rhsmin - Minimum daily relative humdity near surface
    • huss - Average daily specific humidity near surface
    • pr - Average daily precipitation amount at surface
    • rsds- Average daily downward shortwave radiation at surface
    • was - Average daily wind speed near surface
    • uas - Average daily eastward component of wind near surface
    • vas - Average daily northward component of wind near surface