# Presentation: 378982

- 12km North American Land Data Assimilation System (NLDAS-E) Research at the NASA Goddard Space Flight Center
**Brian A. Cosgrove, Paul R. Houser, and Charles J. Alonge; NASA GSFC Hydrological Sciences Branch**
**Collaborators: Kenneth E. Mitchell, Dag Lohmann, Michael Ek, Mark Iredell, and Eric Rogers; NOAA/NCEP/EMC**

- Recent Results

- Sample Workstation Eta Output

- Acknowledgements and References

- Accurate LSM land surface states are central to the success of the NLDAS-E project.  These states will be used to initialize the Eta model, and it is the quality of these initial conditions that will determine the quality of the weather forecasts that the Eta model produces.  Such land surface states are greatly impacted by the forcing data used to drive the LSMs.  As such, the NLDAS-E project has assembled a high quality, flexible set of forcing data.  The backbone of this forcing data set consists of model output from NCEP’s operational 12km Eta Data Assimilation System (EDAS).  Observation-based CMORPH, merged CPC Gauge / Stage II, and CMAP precipitation data is included when available, as is AGRMET and GOES SW radiation data, GOES PAR and skin temperature data, and IMS snow cover data.  Examples of this 12km forcing data are shown below.

- This research is supported by GAPP funding through the NASA Terrestrial Hydrology Program.  Additional information on the NLDAS project can be found at http://ldas.gsfc.nasa.gov and in the following papers:

- Cosgrove, B. A., D. Lohmann, K. E. Mitchell, P. R. Houser, E. F. Wood, J. C. Schaake, A. Robock, C. Marshall, J. Sheffield, Q. Duan, L. Luo, R. W. Higgins, R. T. Pinker, J. D. Tarpley, and J. Meng (2003), Real-time and retrospective forcing in the North American Land Data Assimilation System (NLDAS) Project, J. Geophys. Res., 108(D22), 8842, doi:10.1029/2002JD003118.
- Cosgrove, B. A., K. E. Mitchell, P. R. Houser, E. F. Wood, J. C. Schaake, A. Robock, D. Lohmann, J. Sheffield, Q. Duan, L. Luo, R. W. Higgins, R. T. Pinker, J. D. Tarpley (2003), Land surface model spin-up behavior in the North American Land Data Assimilation System (NLDAS), *J. Geophys. Res.*, 108(D22), 8845, doi:10.1029/2002JD00331603.
- Mitchell, K. E., D. Lohmann, P. R. Houser, E. F. Wood, A. Robock, J. Schaake, B. A. Cosgrove, J. Sheffield, L. Luo, Q. Duan, D. Lettenmaier, R. T. Pinker, J. D. Tarpley, R. W. Higgins, J. Meng, C. Marshall, A. Bailey,  F. Wen, and J. K. Entin (2004), The multi-institution North American Land Data Assimilation System (NLDAS): Utilizing multiple GCIP products and partners in a continental distributed hydrological modeling system, *J. Geophys. Res.*, 109, D07S90, doi:10.1029/2003JD003823.

- New 12km Arakawa E Grid LDAS System (NLDAS-E)

- Project Overview

- Land Surface Modeling Component

- Data Sources

- Land surface conditions from uncoupled LSMs forced by observations are free from many of the biases which affect closed, coupled systems, and are well-suited for NWP model initialization.  The NLDAS-E project seeks to assess the impact of such initialization on NCEP’s 12km coupled workstation Eta model.  Featuring multiple LSMs and assimilating multiple land surface quantities, this system will serve to supply the Eta model with accurate, unbiased and uncoupled initial land surface conditions on its native Arakawa E grid.  Project components include:  1) Generation of land surface states over the North and Central American domain, with and without application of land data assimilation techniques, 2) Initialization of the NCEP workstation Eta model with uncoupled NLDAS-E states and internally cycled Eta land surface states, 3) Execution of ensemble model runs using NLDAS-E and Eta modeling system.

- NLDAS-E research is based at NASA GSFC with support from NOAA NCEP
- Noah, Mosaic, and CLM LSMs will be used
- Hourly uncoupled LSM output will be generated on the 12km Arakawa E grid (Figure 1) used by the operational Eta model for the period from 2000-2004

- Experiments will assess the impact that NLDAS-E initialization of Eta model has on short- to medium-range forecasts (Figure 2)

- Initialization experiments and subsequent validation efforts will occur over the full domain, as well as several regional windows (Figure 1)

- Table 1. Data sources available for use in the NLDAS-E project for modeling and validation efforts.

- Figure 1. Domain of NCEP 12km Eta model, NLDAS-E land surface modeling system, and Workstation Eta initialization experiments (black box).  Validation will occur over full domain and over regional windows (colored boxes).

- Figure 2. NLDAS-E initialization strategy.  Forced by observation and model-based data, and constrained by data assimiiliation, NLDAS-E will generate several years of land surface output which will be used to initialize the Eta model’s land surface states.

- Figure 3. NLDAS-E vegetation and soils data.  Standard Eta (left), high-resolution (right).

- NLDAS-E experiments will make use of both standard Eta and high-resolution data sets in order to assess the impact that the inclusion of such data sets has on forecast accuracy (Figure 3)

- Eta Model Initialization

-  S      LS     SL   SIL   SI       L        SCL SICL CL     SC   SIC          C        OM   W    BR   Other

- 12km NLDAS-E Forcing Files

- A recent NLDAS-E project development is the execution of workstation Eta simulations over the full domain used by NCEP’s operational 12km Eta model.  Examples of 12km output are shown below.

- IMS Snow Cover

- AGRMET SW Radiation (W/m2)

- Stage II / Gauge Merged Precip (mm/hr)

- Figures 4a-h. Sample NLDAS-E forcing data at 15Z on December 4th 2002.  Precipitation data sets used in NLDAS-E are featured in the top row, while the SW radiation data sets (and IMS snow cover used in the SW radiation data set merging process) are featured in the bottom row.

- Figures 5a-d. Sample 6 hour forecast output at 18Z on February 5th, 2003 from a full-domain workstation Eta model simulation.

- Eta 0-10cm Volumetric Soil Moisture

- Eta 10-meter V Wind Component (m/s)

- Eta 2-meter Temperature (K)

- Eta Snow Depth (mm)