SnowSTAR 2002 TransectSnowSTAR 2002 Transect Reconstruction Using Reconstruction Using SNTHERM ModelSNTHERM Model
July 19, 2006
Xiaogang Shi and Dennis P. Lettenmaier
ContentsContents
SnowSTAR2002
Objective
Data Sets and ModelData Sets and Model
Results and Problems
Future Work
SnowSTAR2002SnowSTAR2002
U. S. Army Corps of EngineersCold Regions Research and Engineering Lab (CRREL)
Matthew Sturm
ALASKANome
BarrowThe traverse: From The traverse: From Nome, Alaska on the Nome, Alaska on the Seward Peninsula to the Seward Peninsula to the most northern point in most northern point in U.S., Barrow in Alaska.U.S., Barrow in Alaska.
Route Length: about 700 Route Length: about 700 milesmiles
Period: March 30 - April Period: March 30 - April 26 , 200226 , 2002
SnowSTAR2002 Transect Domain
Measurement sites: 83 Snow Pits: 415 Snow Water Equivalent:830
SnowSTAR2002
Objective
The objective of this project is to apply the one-The objective of this project is to apply the one-dimensional energy balance snow model SNTHERM dimensional energy balance snow model SNTHERM (Jordan, 1991) to simulate snow properties along (Jordan, 1991) to simulate snow properties along SnowSTAR2002 route throughout the winter/spring of SnowSTAR2002 route throughout the winter/spring of 2002. 2002.
Especially, the main purpose is to simulate the Especially, the main purpose is to simulate the vertical distribution and temporal change of snow vertical distribution and temporal change of snow properties in the point mode, and further investigate properties in the point mode, and further investigate the regional trends in the snow properties in Alaska . the regional trends in the snow properties in Alaska .
Data Sets and ModelData Sets and Model
ALASKANome
BarrowMeteorological stations: 293
Data length: 1950 -2005
Resolution: 1/16 degree
Time Step: Daily
1/16-degree Gridded Meteorological Data SetData Set 1
11 Download the raw data of Alaska (P,Tmax,Tmin) from the Download the raw data of Alaska (P,Tmax,Tmin) from the NCDC web site and use the Control package (Alan NCDC web site and use the Control package (Alan Hamlet,2004) to reformat the data.Hamlet,2004) to reformat the data.
22 Scale the precipitation data with PRISM monthly mean in Scale the precipitation data with PRISM monthly mean in Alaska from 1961 through 1990. PRISM was developed by Dr. Alaska from 1961 through 1990. PRISM was developed by Dr. Daly of Oregon State University. It is a statistical-geographic Daly of Oregon State University. It is a statistical-geographic approach to mapping climate. PRISM uses point precipitation approach to mapping climate. PRISM uses point precipitation measurements and DEM, to generate estimates of monthly measurements and DEM, to generate estimates of monthly mean precipitation in Alaska.mean precipitation in Alaska.
33 Get the 1/16 degree VIC input format data using regridding Get the 1/16 degree VIC input format data using regridding package which is based on the interpolation routine called package which is based on the interpolation routine called SYMAP (Shepard, D.S., 1984). [GRID_2000, UW Hydro ]SYMAP (Shepard, D.S., 1984). [GRID_2000, UW Hydro ]
4. Combine the 10-meter daily wind data, which was obtained 4. Combine the 10-meter daily wind data, which was obtained from the NCEP Reanalysis, and gridded linearly interpolated to from the NCEP Reanalysis, and gridded linearly interpolated to 1/16 degree. 1/16 degree.
1/16-degree Gridded Meteorological Data Set in Alaska
Data Set 1
1. ERA-40 dataset from European Centre for Medium-Range Weather Forecasts (ECMWF) (Reanalysis )
2. Period: 1979-2002.
3. Time step: daily
4. Resolution:0.5 degree (Downscaled from 2.5 degree by Nathalie)
5. VIC input format data
ERA-40 DATAData Set 2
Using VIC model to get the hourly data
Purpose:
1. Get Radiation data and Relative Humidity (by modifying the write_data.c )
2. Disaggregate the daily Meteorological and Radiation data to hourly data
Using VIC model to get the hourly data
PrecipitationPrecipitationMaximum TemperatureMaximum TemperatureMinimum TemperatureMinimum TemperatureWind SpeedWind Speed
Precipitation Precipitation
Air TemperatureAir Temperature
Wind speedWind speed
Incoming solar radiationIncoming solar radiation
Reflected solar radiationReflected solar radiation
Incoming longwave radiationIncoming longwave radiation
Relative humidityRelative humidity
Input (Daily)
Output (hourly)
Schematic diagram of SNTHERM
model (CRREL,2004)
Developed by Dr. Rachel Jordan from Cold Regions Research and Engineering Lab (CRREL).
Physically-based 1-D snow model
Solves energy and mass balance equations
Accounts for densification, metamorphosis, freeze/melt, liquid water percolation
SNTHERM Model
SSnow depthnow depthSnow densitySnow densitySnow temperatureSnow temperatureSnow grain sizeSnow grain sizeSnow water equivalentSnow water equivalent
Precipitation Precipitation
Air TemperatureAir Temperature
Wind speedWind speed
Incoming solar radiationIncoming solar radiation
Reflected solar radiationReflected solar radiation
Incoming longwave radiationIncoming longwave radiation
Relative humidityRelative humidity
Input (hourly)
Output (hourly)
SNTHERM Model
Initial conditions of snow and soilThe initial condition
starts from no snow.
Model Validation
Station: IvotukStation: Ivotuk
Location: 68.49 Location: 68.49 N,155.74 W N,155.74 W
Slope: FlatSlope: Flat
Vegetation type: tundraVegetation type: tundraALASKA
Barrow
Nome
Ivotuk
Model Validation
Observed Data:Observed Data:
snow depth datasnow depth data
Net RadiationNet Radiation
Soil Temperature and MoistureSoil Temperature and Moisture
Relative HumidityRelative Humidity
Meteorological data ( winter Meteorological data ( winter precipitation is not measured)precipitation is not measured)
Validation Experimental Design
Meteorological inputs from:
1. 1/16 Degree Data Set Pseudo Station (68.46875 N,155.78125W)
2. ERA-40 0.5 Degree Data Set Pseudo Station (68.75 N, 155.75 W)
VICVIC
SNTHERMSNTHERM Snow depth data validation
with observed site ivotuk-Met1 (68.49 N,155.74 W)
Results Results and Problemsand Problems
Snow depth comparison between 1/16 Degree Snow depth comparison between 1/16 Degree and and ERA-40 0.5 Degree data setsERA-40 0.5 Degree data sets
Snow DepthSnow Depth PrecipitationPrecipitation
Comparison between 1/16 Degree Comparison between 1/16 Degree and ERA-40 0.5 and ERA-40 0.5 Degree data setsDegree data sets
Snowpack TSnowpack T Air TAir T
ALASKA
Nome
Barrow
Comparison between 1/16 Degree Comparison between 1/16 Degree and ERA-40 0.5 and ERA-40 0.5 Degree data setsDegree data sets
SWESWE Snow Grain SizeSnow Grain Size
Future WorkFuture Work
Run SNTHERM at 83 sites along the SnowSTAR2002 using the two data sets.
Get SnowSTAR2002 snow properties measured data from Matthew Sturm of Cold Regions Research and Engineering Lab (CRREL).
Compare SNTHERM outputs with the field measurements and further investigate the regional trends in the snow properties for Alaska.
Thank YouThank You
Question?Question?