Progress in hydrological modeling over high latitudes
--under Arctic Climate System Study (ACSYS)
Dennis P. Lettenmaier and Fengge Su
Arctic Climate System Study (ACSYS) Mission
• What are the global consequences of
natural or human-induced change in the
Arctic climate system?
• Is the Arctic climate system as sensitive to
increased greenhouse gas concentrations
as climate models suggest?
ACSYS is a core project of the World Climate Research Programme (WCRP). It started from January 1994, and ended in December 2003.
Components of ACSYS
1. Arctic ocean circulation programme
2. Arctic sea-ice programme
3. Arctic atmosphere programme
4. Hydrological cycle in the Arctic region
5. ACSYS modelling programme
6. Data Management and Information
Objectives of ACSYS hydrological programme
• Developing mathematical models of the hydrological cycle under
specific Arctic climate conditions suitable for inclusion in
coupled climate models;
• Determining the elements of the fresh water cycle in the Arctic
region and their time and space variability;
• Quantifying the role of atmospheric, hydrological and land surface processes in the exchanges between different elements of the hydrological cycle;
• Providing an observational basin for the assessment of possible long-term trends of the components of the fresh water balance in the Arctic region under changing climate.
Major components of the ACSYS hydrological programme
• Development regional data bases for the
main components of the fresh water
balance of the Arctic region;
• Development of hydrological models of
selected Arctic river basins and their
validation using appropriate observational
data sets.
Projects contributing to ACSYS
1. The project for the Intercomparison of Land-Surface Parameterization Schemes Phase 2(e) – PILPS 2(e)
2. GEWEX Continental Scale Experiments (CSEs)
. MAGS . BALTEX . GAME-Siberia . GCIP/GAPP
Hydrological modelling activities in ACSYS were performed in close collaboration with WCRP Global Water and Energy Experiment (GWEX) project.
The Project for the Intercomparison of Land-Surface Parameterization Schemes (PILPS) 2(e)
A small working group was established
by ACSYS in August 1998 for the
purposes of planning an Arctic hydrology
model intercomparison project. The
resulting project, PILPS phase 2(e), was a
joint experiment of ACSYS and GEWEX,
and was designed to evaluate the
performance of land surface models in
high latitudes.
Special Issue on PILPS 2(e): Global and Planetary, 38(1-2), 2003
List of participating models of PILPS Phase 2(e)
Torne– Kalix River basin and the 218 computational ¼ ° latitude/longitude grid cells.
Bowling et al., 2003
Bal
tic S
ea
Mean monthly observed (dots) and simulated (lines) discharge for the Kalix and Torne river basins.
Nijssen et al., 2003
Observed (dots) and simulated (lines) snow water equivalent for five locations
Number of days with snow cover for models participating in PILPS 2(e). Lowest right panel shows a satellite derived estimate
Mean annual latent heat flux for the model reruns. The last panel shows annual latent heat flux estimated from basin water balance.
after Nijssen et al, 2003Bowling et al., 2003
MAGS
BALTEX
GAME-Siberia
Mackenzie GEWEX Study (MAGS)
Models• CLASS• WATFLOOD• WATCLASS• CRCM/CLASS
WATFLOOD representation of Mackenzie River drainage basin. Each linear segment represents a 50 kilometre river reach.
Snelgrove et al, 2005
Canadian Land Surface Scheme (CLASS)
Soulis et al., 2005
Framework for hydrological modelling
in MAGS
Snelgrove et al, 2005
WATFLOOD (Level 0) WATCLASS (Level 2)
Snelgrove et al, 2005
Baltic Sea Experiment (BALTEX)
Models:
HBV- conceptual hydrological model
SEWAB - land-surface scheme
49° N - 69 ° N
Baltic Sea Drainage Basin
Monthly averages of freshwater flow into the major subbasins of the Baltic Sea, calculated with the HBV mode
Raschke et al., 2001
Baltic Sea drainage area: 1.6 ×106 km2
Modeled seasonal river discharge to the Baltic Sea from HBV-Baltic for present-day conditions (shaded) and four climate
change scenarios.
Graham, 2004
Bal
tic
Sea
Hydrological components of the land surface scheme
SEWAB (Surface Energy and Water Balance)
• VIC approach (Warrach et al.,
1999)
• TOPMODEL approach
( Stieglitz et al., 1997)
• The concept of ponding at the
surface (Mengelkamp et al.,
2001)
• The processes of soil freezing
and thawing and the seasonal
snow cover (Warrach et al.,
2001)
Various optional versions of SEWAB
49° N
54° N
The Odra drainage basin (119,000 km2 ) with 18 km mesh size
Daily streamflow simulated with SEWAB and Lohmann et al. (1996) routing scheme
Mengelkamp et al., 2001
GEWEX Asian Monsoon Experiment GAME-Siberia
GAME-Siberia project
concentrates on observation
and modeling of land
surface processes, and
regional analysis of energy
and water cycle in
permafrost region of eastern
Siberia.
Lena River Basin
Ma et al., 2000
Six hydrological stations within the Lena River Basin.
Simulated runoff at the six hydrological stations from October 1986to September 1987, using a combined model which is composed of a SVAT model, runoff model, and river routing model .
Annual effective rainfall (P-E), Oct 1986- Sep 1987
Simulated evapotranspiration (E), Oct 1986-Sep 1987
Precipitation, Oct 1986- Sep 1987
Ma et al., 2000
A number of changes have
been made to improve the VIC
model's representation of cold
season processes, in
conjunction with the GEWEX
Continental-scale International
Project (GCIP) activities in the
upper Mississippi River basin,
and the PILPS Phase 2(e)
experiment in the Torne-Kalix
River basin.
The VIC model
Cold
land
processes in
VIC
A two-layer energy balance snow model (Storck et al, 1999; Cherkauer et al, 2003, JGR)
A frozen soil/permafrost algorithm (Cherkauer et al, 1999; 2003, JGR)
A lake and wetlands model (Bowling et al, 2003,WRR)
A blowing snow model (Bowling et al, 2004, J. Hydromet)
Cold land processesCold land processes
The VIC model was applied to
the Mackenzie and Ob River
basins at 2° spatial resolution
and daily temporal resolution to
examine the space-time
structure of the predicted
hydrologic variables (i.e., runoff,
evaporation, soil moisture, and
snow water equivalent)
Bowling et al., 2000Routing networks for the Mackenzie (A) and the Ob (B)
A
B
Ob Mackenzie
Bowling et al., 2000
The goal of ACSYS hydrological
programme is to determine the space-
time variability of the Arctic hydrological
cycle and the fluxes of freshwater to the
Arctic Ocean.
Arctic river network over 100km grid system
Estimates of Annual Continental Freshwater into the Arctic Ocean
Basin Definition
Contribution Area (×1000 km2)
Volume (km3/yr)
Periods
“Arctic Ocean River Basin” in Prowse et al.[2000]a 11045/15504 2338/3299 1975-1984
“All Arctic Regions” in Shiklomanov et al.[2000] 18875 4300 1921-1996
“Arctic Ocean Basin” in Shiklomanov er al.[2000] 23732 5250 1921-1996
“Arctic Climate System” in Grabs et al.[2000]a 12868/18147 2603/3671
AORB - Northern Greenland + Arctic Archipelago in [Lammers et al.2001]
16192 3302 1960-1989
The largest Arctic Rivers in Dai et al.[2002] 16850 3658
AORB - Northern Greenland, VIC1 15017 3354 1979-1999
AORB - Northern Greenland + Arctic Archipelago, VIC2
16397 3596 1979-1999
Basin area-annual flow volume relationship for different estimations
y = 217.81x
R2 = 0.9756
2000
3000
4000
5000
6000
10 12 14 16 18 20 22 24 26
Contribution Area (106km3)
Flo
w V
olu
m (
km3 /y
r)
VIC1VIC2VIC1 VIC2
Simulated mean monthly streamflow discharge into the Arctic Ocean (1979-1999)
Monthly mean discharge to the Arctic Ocean(1979-1999)
0
200
400
600
800
1000
1200
1 2 3 4 5 6 7 8 9 10 11 12
Month
Dis
cha
rge
(km
3 /yr)
Total = 3354km3/yr
Area = 1.5×106km2Total =3354km3/yrArea = 1.5×106km2
What did the ACSYS achieve? 1. Several land surface models had been improved in representing snow accumulation
and ablation, soil freeze/thaw and permafrost, and runoff generation motivated by the
PILPS 2(e) experiment in Torne-Kalix River basin and other projects related to ACSYS.
2. Intensive field measurement under MAGS and GAME-Siberia promoted the
development of process algorithms of snow accumulation, redistribution, and ablation,
and water infiltration into frozen soil, and the development of one-dimensional land
surface models for cold region.
3. The VIC model and the macroscale hydrological models developed under the MAGS,
BELTEX, and GAME-Siberia have been used to simulate the surface water and energy
balance of high-latitude river basins.
4. The Arctic river runoff in both gauged and ungauged basins and the freshwater river
inflow to the Arctic Ocean were estimated and analyzed by using a macroscale
hydrological model.
5. The water balance terms of the land surface water in the Arctic region and their time
and space variability were determined and evaluated by using a land surface model and
the ERA-40 reanalysis.
What remains to be done ?
• The roles of frozen soil moisture and blowing snow
parameterizations in the large-scale simulation of runoff,
temperature, and evaporation are not completely clear.
• Existing wetlands and lake models in land surface models need to
be further improved and validated.
• Many results from process investigations of snow and frost-related
hydrological processes remain to be incorporated into large-scale
hydrological models.
• Continued development of hydrological models and linkages
between atmospheric and hydrological models are needed in
scientific studies of the interactions between climate, snow and
frost hydrology.
• Most of the key issues have also been addressed in the Science
Plan of Climate and Cryosphere (CliC), which is the successor of
ACSYS.
Thank You!