Hydrological Simulations for the pan- Arctic Drainage System

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Hydrological Simulations for the pan- Arctic
Drainage System Fengge Su1, Jennifer C. Adam1,
Laura C. Bowling 2, and Dennis P.
Lettenmaier1 1Department of Civil and
Environmental Engineering, Box 352700, University
of Washington, Seattle, WA 98195 2Department of
Agronomy, Purdue University, West Lafayette, IN
47907
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Streamflow Simulations
Outline

• 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.

Long-term mean monthly temp- eratures over the
four watersheds
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).
a) Aldan at Verhoyanski Perevoz (Drainage Area
696,000 km2)

• 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.

b) Lena at Kusur (Drainage Area 2,430,000 km2)
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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.

Dates of Lake Freeze-up and Break-up
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• 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.

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.
Meteorological forcings (1979-1999)
Observation-based precipitation, maximum
temperature, minimum temperature, wind speed
(precipitation adjusted for catch
deficienciesusing method of Adam et al (in
review, J Clim.) Land surface characteristics
soil texture and land cover characterizations Obs
erved data Discharge data R-ActicNet 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
a) Podkamennaya Tunguska at Kuz'movka (Area
218,000 km2)

• 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.

Model Calibration
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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.
• 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.

Surface Water Fluxes in ERA-40
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Lena Basin
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Snow Cover Extent
Summary
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• Eleven Regions were calibrated separately (not
  including Greenland)
• Calibration was focused on matching the shape of
  the monthly hydrograph and annual runoff.
• Parameter transfer to un-gauged basins was based
  on the hydro-climatology of the region.

• 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

Implied E as a residual of observed P and E-P
calculated from the ERA-40 atmospheric water
budget.
Remotely sensed (left) and model simulated
(right) annual mean number of days with snow
cover (1980-1999)