Transcript Climate Change Impacts on Future Design Standards of

SnowSTAR 2002 Transect Reconstruction Using
SNTHERM Model
Xiaogang Shi and Dennis P. Lettenmaier
July 19, 2006
Contents
 SnowSTAR2002
 Objective
 Data Sets and Model
 Results and Problems
 Future Work
SnowSTAR2002
Matthew Sturm
U. S. Army Corps of Engineers
Cold Regions Research and Engineering Lab (CRREL)
SnowSTAR2002 Transect Domain
Barrow
Nome
The traverse: From
Nome, Alaska on the
Seward Peninsula to the
most northern point in
U.S., Barrow in Alaska.
ALASKA
Route Length: about 700
miles
Period: March 30 - April
26 , 2002
SnowSTAR2002
Measurement sites: 83
Snow Pits: 415
Snow Water Equivalent:830
Objective

The objective of this project is to apply the onedimensional energy balance snow model SNTHERM
(Jordan, 1991) to simulate snow properties along
SnowSTAR2002 route throughout the winter/spring of
2002.

Especially, the main purpose is to simulate the
vertical distribution and temporal change of snow
properties in the point mode, and further investigate
the regional trends in the snow properties in Alaska .
Data Sets and Model
Data Set 1
1/16-degree Gridded Meteorological Data Set
Barrow
Meteorological stations: 293
Data length: 1950 -2005
ALASKA
Nome
Resolution: 1/16 degree
Time Step: Daily
Data Set 1
1/16-degree Gridded Meteorological Data Set in Alaska
1
Download the raw data of Alaska (P,Tmax,Tmin) from the
NCDC web site and use the Control package (Alan
Hamlet,2004) to reformat the data.
2
Scale the precipitation data with PRISM monthly mean in
Alaska from 1961 through 1990. PRISM was developed by Dr.
Daly of Oregon State University. It is a statistical-geographic
approach to mapping climate. PRISM uses point precipitation
measurements and DEM, to generate estimates of monthly
mean precipitation in Alaska.
3
Get the 1/16 degree VIC input format data using regridding
package which is based on the interpolation routine called
SYMAP (Shepard, D.S., 1984). [GRID_2000, UW Hydro ]
4.
Combine the 10-meter daily wind data, which was obtained
from the NCEP Reanalysis, and gridded linearly interpolated to
1/16 degree.
Data Set 2
ERA-40 DATA
1. ERA-40 dataset from European Centre for MediumRange 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
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
Input (Daily)
Precipitation
Air Temperature
Precipitation
Maximum Temperature
Minimum Temperature
Wind Speed
Wind speed
Incoming solar radiation
Reflected solar radiation
Incoming longwave radiation
Relative humidity
Output (hourly)
SNTHERM Model
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
Schematic diagram of SNTHERM
model (CRREL,2004)
SNTHERM Model
Precipitation
Input (hourly)
Air Temperature
Wind speed
Incoming solar radiation
Reflected solar radiation
Snow
Snow
Snow
Snow
Snow
depth
density
temperature
grain size
water equivalent
Incoming longwave radiation
Relative humidity
Initial conditions of snow and soil
Output (hourly)
The initial condition
starts from no snow.
Model Validation

Barrow

Ivotuk
Nome
ALASKA
Station: Ivotuk
Location: 68.49
N,155.74 W

Slope: Flat

Vegetation type: tundra
Model Validation

Observed Data:
snow depth data
Net Radiation
Soil Temperature and Moisture
Relative Humidity
Meteorological data ( winter
precipitation is not measured)
Validation Experimental Design
Meteorological inputs from:
1. 1/16 Degree Data Set Pseudo
Station (68.46875 N,155.78125W)
VIC
2. ERA-40 0.5 Degree Data Set
Pseudo Station (68.75 N, 155.75 W)
Snow depth data validation
with observed site ivotukMet1 (68.49 N,155.74 W)
SNTHERM
Results and Problems
Snow depth comparison between 1/16 Degree and
ERA-40 0.5 Degree data sets
Snow Depth
Precipitation
Comparison between 1/16 Degree and ERA-40 0.5
Degree data sets
Snowpack T
Air T
Barrow
ALASKA
Nome
Comparison between 1/16 Degree and ERA-40 0.5
Degree data sets
SWE
Snow Grain Size
Future 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 You
Question?