# Presentation: 321607

- simulations in the land surface models of the
- Land Data Assimilation (LDAS) Project   (J1.4)

- January, 14th  2002

- AMS 16th Conference on Hydrology, Orlando

**D. Lohmann, K. Mitchell, P. Houser, E. Wood. J. Schaake, A. Robock, D. Lettenmaier, B. Cosgrove, J. Sheffield, Q. Duan, L. Luo, W. Higgins, R. Pinker , D. Tarpley, J. Ming**

## N-LDAS Collaborators

**      ****NOAA                 NASA               Universities**
**                              ***http://ldas.gsfc.nasa.gov*

##     Major Initiative:  LDAS

**Goal**:  provide soil moisture / temperature initial conditions superior to current coupled Eta-based EDAS in realtime
**Method**:  drive land-surface model “off-line” with gage/radar precipitation and satellite-derived solar radiation
**Main Contribution:** improve coupled-model forecast skill (temperature, precipitation) via improved initial land states
**Other Contributions:** land states and land surface energy and water fluxes for water cycle research and applications such as agriculture
**Future Additions**:  assimilate satellite-derived skin temperature, soil moisture, snowpack, and vegetation state

## LDAS Implementation

- Models: Mosaic (GSFC), VIC (Princeton, Washington),
- NOAH (NCEP/EMC), Sacramento (NWS-OH)
- 1/8 degree resolution
- Runoff routing: calibration, validation
- Parameters:
- Vegetation: EROS IGBP, UMD, NESDIS greenness, EOS products
- Soils: IGBP, STATSGO; Topography: Digital Elevation Models

**Soil type on LDAS grid**

**LDAS predominant vegetation from 1km EROS data**

## LDAS Implementation cont.

- Forcing:
- Precipitation: 24 hour gauges, NCEP Stage IV gage/radar precipitation
- Radiation: NESDIS 0.5 degrees hourly GOES solar insolation
- Meteorology: NOAA/NCEP EDAS analysis (wind, temperature,
-                       pressure, humidity, longwave downward, and backup)

**GOES shortwave radiation [W/m^2] 20011101 18Z**

**Gauge / Stage IV precip [mm] 20011101 18Z**

## LDAS model output example

- LDAS Soil Wetness Comparison

- PILPS
-   2(c)

##  LDAS Validation Across Scales

- RN – G – H – E             =                0                        t  =   minutes - hours
- P – E – dS/dt                  =                R                       x  =  1–100m (flux tower)
- RN                                   =         G – H – E               t   =  hours - days
- P – R                              =         dS/dt +  E                 x  =  10km (catchment)
- RN(Tskin)                          =    (G – H – E)(Tskin)      t   =  days – months
- P – R                               =          dS/dt + E                x  =  1000km (continent)
- dW/dt + *_Q_ + P             =                  E                                        (atmosphere)
- instantaneous: GOES  daily: Streamflow,Snow Water Equiv,Mesonet&Surfrad
-                                                                                                  ARM/CART
- ---------------------------------------------------------------------------------------------------
-                       Coupled Terrestrial – Atmospheric Water Budget
-                                 dS/dt  +  R         =    - dW/dt – *_Q_

-  LDAS Validation Across Scales

## LDAS Forcing Validation 2001 08-11

**Monthly mean shortwave radiation intercomparison**
**AGROMET**
**GOES**
**EDAS**
**SURFRAD**

## LDAS-NOAH Skin Temperature

- NOAH model (x-axis)
- GOES-East (y-axis)
- 18Z, all grid points in area 2 and 5

-  Validation with GOES October 2001

## LDAS-NOAH Skin Temperature 

- LDAS-NOAH Skin Temperature
- October 2001 Validation cont.

- Region 2

- Region 5

- 15 Z

- 21 Z

- NOHRSC snow water equivalent,
- cover: NW USA, 0.075 degrees, unit [2cm], 5days per week
- NOHRSC cloud and snow cover, cover: USA, 0.067 degrees, flag

- Snow depth from USAF, cover: global 1/8 bedient, unit [in], daily
- Snow cover product from NESDIS daily, cover: 1/16 bedient N.Hemisphere grid, flag

- Snowpack Simulation Comparison

-  = estimated

-  = future

## Snowpack Simulation Comparison cont.

## Snowpack Simulation Comparison cont.

## Snow Information

- NOAH LDAS Soil Wetness
- With / Without Snow Update

- Control run starting 1999
- 04 15 12Z, no update on
- any state variable, soil
- wetness on 2000 04 09
- NOAH model snow water
- equivalent was updated
- daily with blended
- NESDIS / USAF snow
- cover and snow depth

## LDAS Streamflow Validation

- 188 Basins

- Size between 1000km^3 and 10000km^3, realtime and retrospective data are available

## LDAS Models Total Runoff  

- LDAS Models Total Runoff
- Nov. 2000 – July 2001

## LDAS Models

-  Surface Runoff / Total Runoff

- Dominant Surface Runoff

- Dominant Sub-Surface Runoff

## LDAS Models Streamflow [m^3/s]

- 07052500 = James River, MO, 996 sq.miles
- 05592500 = Kaskaskia River, IL, 1940 sq. miles
- 02478500 = Chickasawhay River, MS, 2690 sq. miles

## LDAS Models Streamflow cont.

- 02192000 = Broad River, GA, 1430 sq. miles
- 01631000 = Shenandoah River, VA, 1642 sq. miles
- 01503000 = Susquehanna River, NY, 2232 sq. miles

## Conclusions & Outlook

- Showed LDAS results (forcing validation, skin temperature validation, snow cover comparison and runoff / streamflow comparison) from realtime runs (started April 15th 1999).
- Monthly mean hourly GOES shortwave radiation is very similar to measurements from 6 SURFRAD sites.
- Skin temperature validation is a useful tool, but needs to be explored more for data assimilation.
- Snow cover seems to be overestimated by the models (possible reason: EDAS cold bias), NOAH melts snow faster than VIC/MOSAIC (see PILPS 2e and Rhone Experiment).
- Streamflow comparison shows large differences between models, mainly due to different runoff production processes.
- More detailed analysis with upcoming 3 year retrospective runs