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No Slide Title - Environmental Modeling Center - NOAA

VIEWS: 2 PAGES: 16

									        The North American Land Data Assimilation
        System (N-LDAS) Project:
        Validation of the Energy Budget Components

Eric F. Wood1, Lifeng Luo2, Jesse Meng3, Fenghua Wen1, Rachel
Pinker4, Dan Tarpley5, Alan Robock2, Justin Sheffield1, Kenneth
Mitchell3, Paul R. Houser6, John Schaake7, Dennis Lettenmaier8,
Brian Cosgrove6, Qingyun Duan7, Dag Lohmann3, Wayne Higgins9
1Department of Civil Engineering, Princeton University
2Department of Environmental Sciences, Rutgers University
3NOAA/NWS/NCEP/EMC
4Department of Meteorology, University of Maryland
5NOAA/NESDIS/ORA
6Hydrological Sciences Branch, NASA/GSFC
7NOAA/NWS/OHD
8Department of Civil and Environmental Engineering, University of Washington
9NOAA/NWS/NCEP/CPC



                   GCIP/GAPP Investigator Meeting
                      New Orleans, May 2002
      LDAS Goals and Energy Budget Validation

1) Improve LSM physics by sharing methodologies and data
    sources;
   Comparisons of energy states and fluxes with observations
2) Identify causes of the spread in magnitudes of surface fluxes
    and states typically seen in LSM intercomparisons;
   Try to distinguish between errors in forcings and differences in
   model predictions
3) Compare land states of the uncoupled LDAS with
    traditional coupled 4DDA
   Compare forcings from EDAS with observations
4) Provide land-state initial conditions land-memory
    predictability studies and real-time 4DDA forecasting.
   Estimate the errors in the LDAS predictions
          LDAS Energy Balance Validation Design

1. Model Energy Forcings.
   Incoming Solar Radiation
   (NESDIS 0.5-degree, hourly GOES solar insolation or EDAS is compared with
   stations from NOAA’s SURFRAD, Oklahoma Mesonet and ARM/CART)
   Downward Longwave Radiation
   (Eta model-estimated longwave is compared with measurements ARM/CART)

2. Model-predicted Energy States.
   Skin temperature
   (Compared with measurements NESDIS 0.5-degree, hourly GOES skin
   temperature for clear sky areas, comparisons with SURFRAD)
   Surface heat fluxes
   (Compared with ARM/CART EBBR measurements)
           Validation of Model Energy Forcing
Data Sources
1.LDAS (EDAS-model) insolation data
2.GOES-based 0.5 degree resolution insolation data
3.Insolation data from 6 sites in SURFRAD network
4.Data from 115 sites in OK Mesonet network
5.Data from ARM/CART sites
Time: 04/1999 – 09/1999




          SURFRAD Sites              Oklahoma Mesonet Sites
                Forcing Validation: SURFRAD
Monthly mean diurnal solar insolation intercomparison
           (GOES, EDAS vs. SURFRAD)


                                             May 1999
                                             Notice EDAS
                                             phasing
                                             problem
                Forcing Validation: SURFRAD
Monthly mean diurnal solar insolation intercomparison
           (GOES, EDAS vs. SURFRAD)


                                             May 2000
                                             Notice EDAS
                                             phasing
                                             problem
                                             resolved
                         Forcing Validation: ARM/CART

          Monthly Averaged Hourly               Monthly Averaged Hourly
           All-Sky SW [Wm-2]                    All-Sky SW [Wm-2]

          Summer (MJJA)                         Winter (NDJF)
UMD/SRB




                                      UMD/SRB
                        RMS BIAS n                            RMS BIAS n
                         40  27  46                            24  11  30


                   ARM/SGP                               ARM/SGP
              Downward Shortwave: OK Mesonet

                  hourly   Solar Insolation
                           ACME station
Comparisons                (Jan98-Sep99)
carried out for
all the
Oklahoma          daily     5-day
mesonet
stations
(Jan 98-Sep 99)
                  15-day    monthly
Downward Longwave: ARM/CART
Validation of Model Energy Components

            Data: 14 ARM/CART EBBR stations
            Time: 10/01/1997 - 09/30/1999
             Skin Temperature
           ( GOES-NOAH ) October 2001

Region 2        Region 5
                                                            Skin Temperature
                                                                ( GOES-VIC ) July 1999

                                                     Northern mountain region for 07/1999

Comparisons of surface
temperature between
VIC and GOES




                          GOES Surface Temperature
Data Sources:
GOES (NESDIS, 0.5o,
hourly, clear sky)


Six regions (14ox19.4o)
in continental USA.



                                                        GOES Surface Temperature
Soil Temperature
Surface Fluxes (VIC)
            Validation  Improvements (VIC)
Diagnostic analysis of the initial results lead to re-calibration with
more realistic vegetation parameters.
                                              Conclusions


1. Considerable validation efforts are required to quality
   control the operational data stream for the forcing data.
   More efforts (and problems) were encountered than
   originally expected.

2. The community must spend more efforts in validating soil
   and vegetation classifications, especially for croplands.

3. Validation programs can be used to identify where model
   parameters (and processes) can be improved.

								
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