Variation of Surface Soil Moisture and its Implications Under Changing Climate Conditions 1.
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Transcript of Variation of Surface Soil Moisture and its Implications Under Changing Climate Conditions 1.
Variation of Surface Soil Moisture Variation of Surface Soil Moisture and its Implications Under and its Implications Under
Changing Climate ConditionsChanging Climate Conditions
Variation of Surface Soil Moisture Variation of Surface Soil Moisture and its Implications Under and its Implications Under
Changing Climate ConditionsChanging Climate Conditions
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Outline:Outline: Motivation
Importance
Study Region
Methodology
Results
Conclusions
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MotivationMotivationProblem
Statement:
Surface soil Moisture is highly variable in space and time and often difficult to predict using LSMs
Linkage:
Global climate models need accurate initial and boundary conditions for better prediction and forecasting
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Motions and disturbances of atmospheric fluid are influenced by differential heating and friction at the surface
Differential heating, radiative cooling, turbulent flux and thermal radiation all the processes strongly controlled by availability of soil moisture
Control evapotranspiration and partitioning of latent and sensible heat fluxes
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Study Region: (Illinois & Study Region: (Illinois & Indiana)Indiana)
19 sites in Illinois
Soil Moisture data at 10 cm depth ( Global soil Moisture Data Bank (Robock et al, 2000)
Climate Variables : Precip, Air temp., Soil Temp., Solar Radiation, Potential ET ( Illinois Climate Network (ICN)
Soil Type: Silt Loam, silt clay loam
11 sites in Indiana Soil temperature data
Monthly Stream Flow
Data from USGS for 5 gauging stations
Latent Heat Flux Data
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AmeriFlux Sites
Objectives:Objectives:Objectives:Objectives:
To improve surface soil moisture simulation with Variable Infiltration Capacity (VIC) model using multi-variable evaluation with observed data
To study the impact of projected future climate on soil moisture and its interaction with land surface variables
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Annual anomalies and soil Annual anomalies and soil moisturemoisture
Annual anomalies show good relationship with soil moisture anomaly
_____ Soil Moisture______ Precipitation.______ Air Temperature______ Potential Evapotranspiration
Observed Data
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Monthly Stream flow Monthly Stream flow SimulationSimulation
Calibration Period (1980 -1990)
Validation Period (1991 -2005) Total Period (1980-2005) ------- Observed ------- SimulatedNash-Sutcliffe Eff. (0.6-
0.7)
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Solar Radiation SimulationsSolar Radiation Simulations
VIC model predicts solar radiation in a good agreement with observation
The over prediction for spring season
It may influence spring season soil moisture dynamics
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-------- Obs.-------- Sim.
Soil Temperature Simulation (10 Soil Temperature Simulation (10 cm)cm) Soil Temperature
effects long wave radiation, sensible and ground heat flux
There is a good agreement between simulated and observed soil temperature, however model under predicts summer soil temperature
-------- Obs.-------- Sim
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Soil Temperature Simulations in Indiana Soil Temperature Simulations in Indiana (10 cm)(10 cm)
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-------- Obs.-------- Sim The under
prediction is more in summer than winter
It will influence summer ET, soil temperature and therefore soil moisture
Latent Heat Flux Latent Heat Flux SimulationsSimulations
Observed data from Ameriflux network
3 Sites in Illinois and Indiana
Might be land use effect
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Model captures less temporal variability than observed soil moisture
Over prediction in summer might be due to under prediction of solar radiation and soil temperature
Site no -11: outwash plains
Site no – 12 : poorly drained soil on knoll
Site no -34: Gravely loamy sand
Soil Moisture Simulation (0-10 cm)Soil Moisture Simulation (0-10 cm)
------ Obs.------- Sim.
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Simulated monthly anomaly of soil moisture shows less persistence
Soil Moisture Persistence (Obs. Vs Soil Moisture Persistence (Obs. Vs Sim.)Sim.)
------ Obs.------ Sim.
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Overall Model Performance for 16 Overall Model Performance for 16 sitessites((Monthly Time ScaleMonthly Time Scale))
Coefficient of variation for simulated soil moisture is under predicted
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Soil Moisture Interaction Soil Moisture Interaction (Avg. of 16 sites)(Avg. of 16 sites)Annual soil
moisture anomalies have strong correlation with sensible and latent heat fluxes anomalies
Simulation Period ( 1917-2006)
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Projected Change (Projected Change (PCM.A1 (2070-2099) PCM.A1 (2070-2099) – Observed Forcing (1917-2006) )– Observed Forcing (1917-2006) )
Seasonal Average Fluxes Annual Average Fluxes
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Projected Climate Impact on Land Projected Climate Impact on Land Surface Variables (Avg. of 16 sites)Surface Variables (Avg. of 16 sites)
IPCC AR3 Climate model output (PCM, HadCM3, GFDL)
Scenarios: A1, B1 and SresA1F1, SersB1
____Observed (1917-2006)
___ GFDL (2070-2099)___ PCM (2070 -2099)____HadCM3 (2070-2099)Projections: Decrease
in soil moisture – increase in soil temp- increase in ET- increase in LHF- decrease in SHF
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Conclusions:Conclusions:VIC model simulates surface soil moisture,
soil temperature and other variables which are in good agreement with observations
Soil moisture anomalies of observed data show good correlation with other climatic variables
Climate model projections show decrease in soil moisture, increase in ET, increase in ST which might lead to significant changes in energy fluxes
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