Transcript 1st CliC poster, April 2005 Beijing ()

Hydrological Simulations for the pan-Arctic Drainage System
Fengge Su1, Jennifer C. Adam1, Laura C. Bowling 2, and Dennis P. Lettenmaier1
1Department
•
2
Streamflow Simulations
Yenisei Basin
Observed versus simulated hydrographs at two locations within the Lena
river basin: (a) Aldan at Verkhoyanskiy Perevoz, (b) Lena at Kusur (mouth
of the Lena river).
Observed
Simulated
Precipitation
•
a) Aldan at Verhoyanski Perevoz (Drainage Area: 696,000 km2)
•
b) Lena at Kusur (Drainage Area: 2,430,000 km2)
Model Description and Data Sets
Model features:
•
multiple vegetation classes in each cell
•
energy and water budget closure at each
time step
•
subgrid infiltration and runoff variability
•
non-linear baseflow generation
•
critical elements relevant to high latitude
implementations: a snow model, a frozen
soil algorithm, a lake/wetland model, and a
blowing snow model.
Meteorological forcings (1979-1999):
Observation-based precipitation, maximum temperature, minimum temperature, wind
speed (precipitation adjusted for catch deficiencies using method of Adam et al (in
review, J Clim.)
Land surface characteristics:
soil texture and land cover characterizations
Observed data:
Discharge data: R-ArcticNet V 3.0 [Lammers et al, 2001]
Snow cover extent: NOAA Northern Hemisphere EASE-Grid Weekly Snow Cover and
Sea Ice Extent Version 2
The ECMWF 40-yr reanalysis: ERA-40
Mean monthly basin
snow cover fraction over
the Lena, Yenisei,
Mackenzie, Ob, and
Nelson River basins
(1980-1999).
The spatial variation in
temperature and
precipitation is the main
reason for the variability
in snow accumulation
and ablation processes in
different Arctic basins.
Observed
Simulated
Reconstructed
Dates of Lake Freeze-up and Break-up
6
Observed versus simulated hydrographs at two locations within the Yenisei
river basin: (a) Podkamennaya Tunguska at Kuz'movka, (b) Yenisey at Igarka
(mouth of the Yenisei river). Reservoir impacts were reduced in the
reconstructed data [Ye et al., 2003; Yang et al., 2004].
a) Podkamennaya Tunguska at Kuz'movka (Area: 218,000 km2)
240
370
y = 0.9992x
R = 0.7037
360
•
Mackenzie
Lena
Nelson
Yenisei
Ob
R2 = 0.9122
220
200
•
350
340
180
•
•
•
Eleven regions were calibrated
separately (not including
Greenland).
Calibration was focused on
matching the shape of the monthly
hydrograph and annual runoff.
The years of 1979-1988 for
calibration and 1989-1999 for
validation.
Parameter transfer to un-gauged
basins was based on the hydroclimatology of the region.
ERA-40
Implied E
The ERA-40 P shows surprising similarities in the interannual
variations compared with the observed P.
E has similar seasonal patterns among the estimates from the VIC,
ERA-40 reanalysis, and Implied E.
Snowmelt floods in ERA-40 occur one month earlier in April, and
there are two runoff peaks unlike observations and VIC simulations.
160
330
140
320
120
100
310
310
320
330
340
350
360
100
370
120
140
7
A routing scheme [Lohmann et al., 1996;
1998] was run offline using daily VIC
surface and subsurface runoff as inputs to
obtain simulated streamflows at the
outlets of selected study basins.
160
180
200
220
240
•
Observed
The VIC simulated dates of lake freeze-up and break-up were compared to the
records derived from the Global Lake and River Ice Phenologh Database
[Benson et al., 2000].
b) Yenisey at Igarka (Drainage Area: 2,440,000 km2)
Digital river networks for the pan-Arctic
drainage basins at the 100 km resolution,
showing the watershed boundaries of the
Lena, Yenisei, Ob, and Mackenzie.
•
Surface Water Fluxes in ERA-40
Lena Basin
Precipitation
Observed
5
•
•
y = 0.9837x
2
Model Calibration
•
Runoff
•
Observed
3
Evaporation
VIC/OBS
Simulated
•
A set of simulations with the macroscale hydrologic model VIC (Variable Infiltration
Capacity) implemented at 100 km EASE-Grid across the pan-Arctic domain was
conducted to evaluate the model's ability to represent high latitude hydrologic
processes, and to provide a consistent baseline hydroclimatology for the Arctic land
region. .
The VIC model simulations for the period of 1979 to 1999 were evaluated with
available observations of streamflow, snow cover extent, and dates of lake freeze-up
and break-up.
Reanalysis products, like the VIC simulations, are consistent and continuous in space
and time, and therefore represent an additional data source for estimating high latitude
water budgets. Therefore, we evaluated pan-Arctic land surface water fluxes from the
off-line VIC simulations in comparison with ERA-40 reanalysis.
4
Simulated
1•
Outline
of Civil and Environmental Engineering, Box 352700, University of Washington, Seattle, WA 98195
2Department of Agronomy, Purdue University, West Lafayette, IN 47907
Simulated
Reconstructed
Snow Cover Extent
Evaporation
8
Summary
•
Runoff
•
•
VIC/OBS
Remotely sensed (left) and model simulated (right) annual mean number of
days with snow cover (1980-1999)
The areas with high
winter implied E are
generally those with
high observed P.
In general, E from the
VIC and ERA-40
model, and atmospheric
budget show similar
seasonal and spatial
variations for most of
the Arctic land areas,
although large
difference exists in
absolute values.
ERA-40
Implied E
Implied E as a residual of observed P and E-P calculated from the ERA40 atmospheric water budget.
A set of VIC model simulations of crucial hydrologic processes in
the Arctic suggested that the VIC model was able to reproduce
these processes reasonably well.
The large-scale budgets from the VIC and ERA-40 reanalysis
provide some insight into how the hydrologic cycle operates over
the pan-Arctic land region.
This evaluation also helps identify surface processes that are
poorly represented in VIC and ERA-40 and thus leads to
improvements in surface parameterizations.
The authors would like to thank Dave Stepaniak and Lesley Smith at NCAR for their calculation of
E-P from ERA-40