1/16 Degree Gridded Meteorological Forcing Data Set and Derived Hydrological Fluxes and States: 1915-2011

1. Data Description

The meteorological data represent approximately 20,000 NCDC stations across CONUS, (plus a smaller number of Enviro-Can stations for the Canadian portion of the Columbia river) gridded to 211687 points at a 1/16 degree spatial resolution, running from 1 Jan 1915 - 31 Dec 2011.

Meteorological variables include:

daily precipitation (mm)

daily maximum temperature (C)

daily minimum temperature (C)

daily mean wind speed (m/s)

Hydrological variables were derived using the Variable Infiltration Capacity (VIC) model v.1.2.c, both daily and sub-daily outputs. Note: Hydrological variables are currently being regenerated and will be posted to the ftp site (listed below) when ready

Daily outputs include the following VIC variables:

ASCII file prefix: flux_snow, number of data columns: 12

OUT_EVAP (mm/s) Total ET rate-- includes Canopy, Sub-canopy Evaporation, Transpiration, and Snow Sublimation

OUT_RUNOFF (mm/s) Surface Runoff

OUT_BASEFLOW (mm/s) Baseflow

OUT_SOIL_MOIST (mm) Three layer values of Soil Moisture, i.e. three columns starting with upper layer

OUT_SWE (mm) Snow Water Equivalent

OUT_WDEW (mm) Canopy Water

OUT_SENSIBLE (W/m^2) Net Upward Sensible Heat Flux

OUT_LATENT (W/m^2) Net Upward Sensible Heat Flux

OUT_GRND_FLUX (W/m^2) Net Heat Flux into Ground

OUT_R_NET (W/m^2) Net Downward Radiation Flux

OUT_RAD_TEMP (K) Average Radiative Surface Temperature

OUT_PREC (mm/s) Incoming Precipitation Rate

Sub-daily (3-hrly) outputs include:

ASCII file prefix: full_data, number of data columns: 8

OUT_PREC (mm/s) Incoming Precipitation Rate

OUT_AIR_TEMP (K) Surface (2m) Air Temperature

OUT_WIND (m/s) Surface Wind Speed

OUT_REL_HUMID (fraction) Relative Humidity

OUT_SHORTWAVE (W/m^2) Downward Shortwave Radiation

OUT_NET_SHORT (W/m^2) Net Shortwave Radiation

OUT_LONGWAVE (W/m^2) Downward Longwave Radiation

OUT_NET_LONG (W/m^2) Net Longwave Radiation

OUT_RAD_TEMP (K) Average Radiative Surface Temperature

2. References to Cite

We request that users of this data set cite Livneh et al., 2013 in any reports or publications using it.

Livneh, B., E. A. Rosenberg, C. Lin, B. Nijssen, V. Mishra, K. M. Andreadis, E. P. Maurer, and D. P. Lettenmaier, 2013: A Long-Term Hydrologically Based Dataset of Land Surface Fluxes and States for the Conterminous United States: Update and Extensions. J . Climate, 26.

3. Data Set

This meteorological data set is available in both netCDF (not directly readable by VIC) and ASCII at the following ftp location with supplementary documentation. The data are compressed in bzip2 format, requiring unzipping using the bunzip2 utility:

ftp.hydro.washington.edu/pub/blivneh/CONUS/

ASCII data directory: asc.v.1.2.1915.2011.bz2

netCDF data directory: c.v.1.2.1915.2011.bz2

When the regeneration of VIC outputs is completed, they will be posted at the same ftp location.

4. Version History**

1.2: March, 2014

Resolved issues:

1. Repeated station entries in CA and TX were removed, which impacted the grid weighting in previous versions;

2. Stations with valid Tmax *or* Tmin but with 'nodata' for the other quanitity e.g. Tmax valid, Tmin nodata, were subsequently set to nodata to prevent erroneous diurnal temperature ranges.

3. Tmax, Tmin for USHCN stations were erroneously bound >= 0F (~-18C) in v.1.1;

4. A precipitation panel [-75 > lat > -80; lon > 37] was discovered in v.1.1 that suffered from precipitation issues present in v.1.0

Known issues:

1. Tmax, Tmin for a station in northeast Alabama contain large temporal discontinuities.

2. Number of wet-days for northern British Columbia portion of domain, as well as northwest New York state appear very high.

1.1: January, 2014

Resolved issues:

1. Precipitation data prior to 1950 were erroneously large due to days of zero precipitation being set to nodata as part of the DSI-3206 data set. This caused an overabundance of precipitaiton since the gridding code only considers valid days. These were corrected to zero using USHCN data, furthermore months with more than 50% missing data for precipitation were set to zero;

2. Both Tmax and Tmin were set to nodata for station days reporting Tmax<=Tmin

3. Forcings over Canada, there was a bug in how the coordinate system, i.e. latitude and longitude, was being read by the gridding code over Canada, which has been resolved. This bug fix will improve both temperature and precipitation, with the former having larger improvements due to the lack of PRISM scaling.

4. Finally, those stations that were coincedent with USHCN stations were replaced with the QC'd values from HCN, which were identical in most cases, this represents ~1200 total stations. (http://cdiac.ornl.gov/epubs/ndp/ushcn/ushcn.html)

1.0: September, 2013

Resolved issues:

1. The reanalysis wind data were re-gridded by Dr. Bart Nijssen (UW), after we found a shift of approximately 1.8 degrees north and west in the previous data set. Bart's netCDF-based regridding has fixed this.

Notes: Official release, corresponds to publication (citation below).

0.9: April, 2013

Notes: pre-release, contains erroneous 1/8 degree pattern in precipitation.

*0.8: February, 2013

* Note: versions 0.8 and 1.0 are equivalent

** Users are recommended to use only the most up-to-date data