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Modeling Land and atmosphere interactions Yongkang Xue Dept. Geography and Dept. Atmospheric &Oceanic Sciences University of California, Los Angeles, USA The 2nd Summer School on Land Surface Observing, Modeling and Data Assimilation, 13-16 July 2010 Beijing Normal University, Beijing, China PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn AEROSOL PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn More variable than ocean for coupling processes: (1) Moisture variability. (2) Low heat capacity leads to high diurnal and seasonal variations; more response to net radiation. (3) Absorbed solar radiation varies with surface albedo. (4) Heterogeneity. PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Shortcomings of the early modeling approaches: (1) Independent specification of surface attributes; (2) Unrealistic specification of surface albedo; (3) Unrealistic specification of roughness length, confusion of momentum and heat/vapor transfer pathways; (4) Unrealistic specification of soil hydrology; (5) Unrealistic description of the evapotranspiration processes PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Motivation for better land surface modeling 1) Considerable advances in the 1970s – 1990s in understanding of land surface processes in the presence of vegetation 2) GCM studies show considerable sensitivity of model simulations to drastic changes in the formulation of land evaporation 3) More land data available from remote sensing and field measurements 4) Environmental concerns about the consequences of land cover changes and global warming. PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Land surface process studies: 1.Development, validation, and calibration of land surface processes parameterization 2.land data development and application 3. land surface atmosphere interactions studies (1). Land/atmosphere coupling (2). Sensitivity studies (including land use & land cover changes) (3). Prediction studies PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Land surface process studies: 1.Development, validation, and calibration of land surface processes parameterization PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn The Climatic System Biophysical feedback Temperature, humidity, precipitation, and atmospheric circulation Radiation balance Momentum transfer Heat transfer Water cycle (Snow, Frozen soil) Distribution Structure Terrestrial ecosystems PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Schematic Diagram of Simplified Simple Biosphere Model (SSiB) PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn ECOPHYSIOLOGY LINKING THE RATE OF CARBON DIOXIDE AND WATER EXCHANGE EvapoTranspiration α gc gc = Ahs/cs ET=PLANT-WATER EXCHANGE A = PAR UPTAKE = FAPARxPAR hs = SURFACE RELATIVE HUMIDITY cs = SURFACE CO2 CONCENTRATION C12H4O6 PAR = PHOTOSYNTHETICALLY ACTIVE RADIATION Piers J. Sellers, Mark D. Heiser and Forrest G. Hall, “Relations Between Surface Conductance and Spectral Vegetation Indices at Intermediate (100m2 -15km2) Length Scales”, Journal of Geophysical Research, 97:-D17,19,033-19,061. 10µm PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn The Climatic System Biophysical feedback Temperature, humidity, precipitation, and atmospheric circulation Greenhouse gases (CO2) Radiation balance Momentum transfer Photosynthesis Respiration Heat transfer Water cycle Distribution Structure Terrestrial ecosystems PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Schematic diagram of SSiB evaporation Sensible heat flux PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Carbon flux The Climatic System Greenhouse gases (CO2, CH4, N2O) and aerosols Radiation balance Nutrient cycles Momentum transfer Biomass burning Heat transfer Photosynthesis Respiration Decomposition Water cycle Distribution Composition Terrestrial ecosystems PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Structure Biogeochemical feedback Biophysical feedback Temperature, humidity, precipitation, and atmospheric circulation PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn OFF-Line tests PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Land surface process studies: 1.Development, validation, and calibration of land surface processes parameterization 2.land data development and application PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Initial Conditions for Simplified Simple Biosphere Model version 1 PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn 13 land cover types 1 2 3 4 5 6 7 8 9 10 11 12 13 tropical rainforest broadleaf deciduous trees broadleaf and needleaf trees needleaf evergreen trees needleaf deciduous trees broadleaf trees with ground cover groundcover only broadleaf shrubs with ground cover broadleaf shrubs with bare soil dwaft trees with ground cover bare soil crops land ice PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn SURFACE PARAMETERS C C C C C C C C C C C C C C C C C C C C C C LEAF TRANSMITTANCE LEAF REFLECTANCE SOIL REFLECTANCE LEAF ANGLE DISTRIBUTION FACTOR OPTIMUM TEMPERATURE FOR STOMATAL FUNCTIONING LOWER TEMPERATURE LIMIT FOR STOMATAL FUNCTIONING UPPER TEMPERATURE LIMIT FOR STOMATAL FUNCTIONING VAPOR PRESSURE DEFICIT PARAMETER WILTING POINT SOIL MOISTURE “SLOP” PARAMETER ROOTING DEPTH SOIL WETNESS EXPONENT SOIL TENSION AT SATURATION HYDRAULIC CONDUCTIVITY AT SATURATION SOIL POROSITY DEPTH OF 3 SOIL MOISTURE LAYERS ROUGHNESS LENGTH ZERO PLANE DISPLACEMENT LEAF AREA INDEX (LAI) GREEN LEAF FRACTION VEGETATION COVER FRACTION VMAX MAXIMUM RUBISCO CAPACITY C REFERENCE HEIGHT FOR WIND, HYMIDITY, & TEMPERATURE PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Simplified Simple Biosphere Model (SSiB) output variables Canopy temperature Soil surface temperature Deep soil temperature Surface albedo (visible, NIR, diffuse, direct) Surface skin temperature Water interception by canopy Soil moisture at three layers Snow water equivalent at canopy and on ground (up to three layers) Snow temperature (up to three layers) Latent heat flux: interception loss, transpiration, evaporation from soil Sensible heat flux Ground heat flux Momentum flux Carbon flux and net photosynthesis rate Surface runoff and drainage PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Coordinated Enhanced Observing Period Three Unique Capabilities A Prototype of the Global Water Cycle Observation System of Systems PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn RSLAI (summer) FASIR GIMMS Kang et al., 2007 PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Land surface process studies: 1.Development, validation, and calibration of land surface processes parameterization 2.land data development and application 3. land surface atmosphere interactions studies (1). Land/atmosphere coupling PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Radiation transfer Net Radiation = (1-α) SW↓ +(LW↓-εσTs4) 1). Surface Albedo (for diffuse and direct radiation at different wavelength with diurnal variation) 2). Upward long wave radiation (1)LWt+1↑= εσ(Tts)4 +4εσ(Tts)3(Tt+1s – Tts) (2) LWt+1↑= εσ(Tts + (∆Tst+1))4 PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn In a surface layer with constant momentum flux, where U* is the friction velocity. k is the von Karman constant, 0.35-0.4. Z0 is the roughness length. Z0 is the intercept of the line with the vertical axis scale (the height above the surface at which the wind speed would go to zero if the turbulence layer extended completely to the ground), d is the zero plane displacement height. It is a datum level and is determined experimentally. U* z − d − 1 − 1 U= − ψ 1 = U (C U0 + C un ) Ln * k z0 ρ U (U − 0) ρ (U − 0) * τ = ρU = = * −1 ra C −1 + Cun u0 2 PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn (Tsfc − Tref ) H = ρair C P ra − 1 − 1 C u0 + C un (Ri) ra = U * PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn − 1 − 1 C u0 + C un (Ri) ra = U * k C = u0 z−d Ln( z 0 ) 0 0.315Ri,− 10 < Ri < 0 − 1 C un = 66.86,0 < Ri < 0.16 PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn How to couple with PBL ∂Θ / ∂t = ∂τθ / ∂z ∂ Tc = R nc − H C − λ E c ∂t C gs ∂ Tgs ∂t = Rngs − H gs − λE gs − G s PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn (T jsfc − T i lowest PBLlayer ) H = ρair C P ra PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn t =t t +1 Hc = Hc + t =t ∂ ( H c c ) t =t ∂q s t =t ∂Hc ∂Hc t +1 t t +1 t (Tc −Tc ) + (Tgs −Tgs) + ∂Tgs ∂Tc ( q st +1 t =t ∂ ( H ) c − q st ) + (θ ∂θ PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn t +1 −θ t) PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Land surface process studies: 1.Development, validation, and calibration of land surface processes parameterization 2.land data development and application 3. land surface atmosphere interactions studies (1). Land/atmosphere coupling (2). Sensitivity studies (including land use & land cover changes). PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn A. Different mechanisms Mechanisms I Albedo, Soil Moisture, Surface Roughness effect PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Net Radiation = SW ↓− albedo×SW ↓ +LW ↓ −εTs Net Radiation = LH + SH + GH PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn 4 Albedo feedback Net Radiation = SW ↓− albedo× SW ↑ +LW ↓ −εTs PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn 4 Soil Moisture feedback PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Surface roughness feedback PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Mechanisms II Land surface induced low atmospheric heating and moisture flux convergence change (Xue, 1996; Xue et al., 2004) PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Type 7: grasslands Type 11: bare ground PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Mechanisms III Changes in geostrophic balance Xue et al., 2004 (JGR) PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn *Surface Scheme – 2 Layer soil model with monthly mean vegetation albedo and surface roughness – SSiB – Two scheme use the same initial soil moisture and surface albedo PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Mechanisms IV Changes in moisture static energy Xue et al., 2006 (J. Climate) PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn B. Assess the effects of land/atmosphere interaction in global climate system Xue et. al., 2010 PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn (2008). Based on NDVI How to make assessment based on models? . PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Global and Regional Atmospheric Conditions Specified albedo, soil wetness UCLA land scheme No interactions Specified Bare ground vegetation hydrology albedo & Z0 NCEP GCM soil model Partial interactions PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Vegetation & Soil dynamics SSiB VBP/Climate interactions The choice of land models is crucial. Those models should incorporate physical principles in representing specific land surface processes and have been tested extensively and evaluated in AGCMs with reasonable results that this type of land processes can achieve. PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Method: Two AGCM (UCLA AGCM and NCEP AGCM) coupled with three land surface schemes : 1). No Interaction model: The UCLA GCM Land Scheme: Prescribing monthly-mean land surface characteristics such as surface albedo, roughness, and ground wetness, but without any interactions with the atmosphere. 2). Partial Interaction model: The NCEP Two Layer Soil model (SOIL): simulated ground soil moisture exchange, using prescribed monthly mean distribution of vegetation albedo and surface roughness. 3). The VBP model: Simplified Simple Biosphere Model (SSiB) PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Criteria Should VBP is important in a real climate system and the VBP model properly presents the VBP process, the simulations should be improved. VBP effect is identified by the statistically significant reduction of bias and RMSE. PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn UCLA GCM with two surface schemes (processes) – LA-NOVBP: Specified monthly mean soil moisture with monthly mean vegetation albedo (in the original UCLA GCM) – LA-VBP: SSiB: radiative transfer at canopy, transpiration, interception loss, vegetation-modified surface resistance, vegetation and soil property based on vegetation types, etc. PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Observed and the simulated JJA precipitation (mm day-1) PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Observed and simulated JJA precipitation (mm day-1) PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Differences of absolute bias of annual mean precipitation (mm day-1) between LA-VBP and LA-VBP -2.5 Monsoon regions Midlatitude Regs. H L -2.0 EA -1.5 TP -1.0 -1 -0.5 -0.5 0.0 W ca f ri A . E sia .A S sia .A Am o az n si Ba n E. ra st u A lia & C. E. ric Af a n ia ca au nn so fri te As a s a A . l v n o n E P E sa m n er N. S. ta th ica e r u ir ca b e e So Ti m Am A . S N. a sia .A HL: High latitudes PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn US E. S. pe ro u E W S .U da na a C al re o b ria be i S (2008, JGL). Based on NDVI assessment based on models For the Partial VBP effects (excluding soil moisture and vegetation albedo), our study shows that its effect on annual precipitation over land were about 13% (Xue et al., 2010) PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn Land surface process studies: 1.Development, validation, and calibration of land surface processes parameterization 2.land data development and application 3. land surface atmosphere interactions studies (1). Land/atmosphere coupling (2). Sensitivity studies (including land use & land cover changes) (3). Prediction studies PDF 文件使用 "pdfFactory Pro" 试用版本创建 www.fineprint.cn