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NLDAS Phase 2 VIC Model Data Sets Released by NASA GES DISC

New data release complements previously released Mosaic and NOAH hydrological model data

NLDAS Phase 2 VIC Model Data Sets Released by NASA GES DISC

NLDAS-2 VIC hourly 0-100 cm soil moisture content of 00Z January 1, 2014. Note the low soil moisture in the Southwest, Pacific Northwest, and California, consistent with reported drought conditions.

NLDAS Phase 2 VIC Model Data Sets Released by NASA GES DISC

 The NASA GSFC Hydrological Sciences Laboratory (HSL) and Goddard Earth Sciences Data and Information Services Center (GES DISC) are pleased to announce the release of the North American Land Data Assimilation System Phase 2 (NLDAS-2) Variable Infiltration Capacity (VIC) land surface model (LSM) data and their availability from the GES DISC Hydrology Portal. This release includes three sets of NLDAS-2 VIC model data: hourly, monthly, and a monthly climatology. Details about the NLDAS-2 configuration of the VIC LSM can be found in Xia et al. (2012). The version of the VIC model for this new data set is VIC-4.0.3, which is the same version as that used in Sheffield et al. (2003).

 

The NLDAS-2 VIC model data contain a series of land surface parameters simulated from the VIC LSM, which was developed by the University of Washington and Princeton University as a macroscale, semi-distributed, grid-based, hydrologic model (Liang et al., 1994; Wood et al., 1997). The full water and energy balance modes of VIC were used for NLDAS-2. The VIC LSM uses three soil layers, with thicknesses that vary spatially. The root zone depends on the vegetation type and its root distribution and can span all three soil layers. The VIC model includes a two-layer energy balance snow model (Cherkauer et al., 2003). The VIC LSM is forced by the hourly NLDAS-2 forcing “File A” files and contains 43 fields (see NLDAS-2 README Table 4a). The vertical layers and time averages are described in NLDAS-2 README Tables 4b and 4c, respectively. More information about the VIC LSM can be found at http://ldas.gsfc.nasa.gov/nldas/NLDAS2model.php.

 

Because the thicknesses of VIC soil layers vary spatially, the VIC hourly 0-100 cm soil moisture content is generated by a specific interpolation, to relate the thicknesses of VIC soil layers to 0-100 cm. The VIC 0-100 cm soil moisture content is one of only two soil moisture variables that can be "fairly" compared with the corresponding variables from the Mosaic and Noah models (Figs. 1, 2, and 3). The VIC 0-100 cm moisture availability variable can also be compared with the corresponding Noah variable (not shown).

-2 VIC hourly 0-100 cm soil moisture content of 00Z January 1, 2014

Figure 1. NLDAS-2 VIC hourly 0-100 cm soil moisture content of 00Z January 1, 2014, generated via theGiovanni NLDAS Hourly Portal. (Click the image to view it full-size.)

NLDAS-2 Mosaic hourly 0-100 cm soil moisture content of 00Z January 1, 2014

Figure 2. NLDAS-2 Mosaic hourly 0-100 cm soil moisture content of 00Z January 1, 2014,  generated via theGiovanni NLDAS Hourly Portal. (Click the image to view it full-size.)

NLDAS-2 Noah hourly 0-100 cm soil moisture content of 00Z January 1, 2014

Figure 3. NLDAS-2 Noah hourly 0-100 cm soil moisture content of 00Z January 1, 2014, generated via the Giovanni NLDAS Hourly Portal. (Click the image to view it full-size.)
 
 

The NLDAS-2 monthly VIC model data are generated from the NLDAS-2 hourly VIC model data, as monthly accumulation for rainfall, snowfall, subsurface runoff, surface runoff, total evapotranspiration, and snow melt; and as monthly average for the other variables. The NLDAS-2 monthly climatology VIC model data are generated from the NLDAS-2 monthly VIC model data, as 30-year (1980 – 2009) monthly averages. More information about the NLDAS-2 VIC monthly and monthly climatology data sets can be found in the NLDAS-2 README. As an example of the VIC monthly and monthly climatology data, Figure 4 shows the time series of the anomaly of the monthly NLDAS-2 VIC model top 0-100 cm soil moisture content, from Jan. 1979 to Feb. 2014 (with the 1980 – 2009 climatological annual cycle removed), for a central area of Texas.

Time series of the anomaly of the monthly NLDAS-2 VIC model top 1-meter soil moisture content  from Jan. 1979 to Feb. 2014 

Figure 4. Time series of the anomaly of the monthly NLDAS-2 VIC model top 1-meter soil moisture content  from Jan. 1979 to Feb. 2014 (with the 1980 – 2009 climatological annual cycle removed), averaged over a central area of Texas (102-98W; 30-32N), generatedvia theGiovanni NLDAS Monthly Portal.Simple linear regression (red line) shows a slightly downward trend.  Note the drought periods in this region in 2000 and 2011. This time series can be “fairly” compared with a similar time series from NLDAS-2 Noah model. (See Fig. 8 of http://disc.sci.gsfc.nasa.gov/datareleases/nldas_monthly_climatology_data_release.)   

 

NLDAS-2 VIC model data, along with NLDAS forcing, Mosaic, and Noah; and other hydrology data sets, can be accessed from Hydrology Data Holdings via the following access methods: 

 

NLDAS is a collaborative project involving several groups: NOAA/NCEP's Environmental Modeling Center (EMC), NASA's Goddard Space Flight Center (GSFC), Princeton University, the University of Washington, the NOAA/NWS Office of Hydrological Development (OHD), and the NOAA/NCEP Climate Prediction Center (CPC). NLDAS is a core project with support from the NOAA Climate Program Office Modeling, Analysis, Prediction, and Projections (MAPP) program.

References

Cherkauer, K. A., L. C. Bowling, and D. P. Lettenmaier, (2003) Variable Infiltration Capacity (VIC) cold land process model updates, Global Planet. Change, 38, 151–159, doi:10.1016/S0921-8181(03)00025-0.

Liang, X., D. P. Lettenmaier, E. F. Wood, and S. J. Burges, (1994) A simple hydrologically based model of land surface water and energy fluxes for GCMs, J. Geophys. Res., 99, 14415–14428, doi:10.1029/94JD00483.
 
Sheffield, J., M. Pan, E. F. Wood, K. E. Mitchell, P. R. Houser, J. C. Schaake, A. Robock, D. Lohmann, B. Cosgrove, Q. Duan, L. Luo, R. W. Higgins, R. T. Pinker, J. Dan Tarpley, and B. H. Ramsay, (2003) Snow process modeling in the North American Land Data Assimilation System (NLDAS): 1. Evaluation of model-simulated snow cover extent. J. Geophys. Res., 108(D22), 8849, doi:10.1029/2002JD003274.

Wood, E. F., D. P. Lettenmaier, X. Liang, B. Nijssen, and S. W. Wetzel, (1997) Hydrological modeling of continental-scale basins, Annual Rev. Earth Planet. Sci., 25, 279–300, doi:10.1146/annurev.earth.25.1.279.
 

Xia, Y., K. Mitchell, M. Ek, J. Sheffield, B. Cosgrove, E. Wood, L. Luo, C. Alonge, H. Wei, J. Meng, B. Livneh, D. Lettenmaier, V. Koren, Q. Duan, K. Mo, Y. Fan, and D. Mocko, (2012) Continental-scale water and energy flux analysis and validation for the North American Land Data Assimilation System project phase 2 (NLDAS-2): 1. Intercomparison and application of model products, J. Geophys. Res., 117, D03109, doi:10.1029/2011JD016048. 

 


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