Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Introduction to Land Surface Modeling
Document related concepts
Transcript
Introduction to Land Surface Modeling Zong-Liang Yang The University of Texas at Austin Prepared for the TCEQ Meeting May 24, 2006 www.geo.utexas.edu/climate Why Land Surface Modeling? • An important component of the weather, climate or environmental system. – exchanges of momentum, energy, water vapor, CO2, VOC, and other trace gases between land surface and the overlying atmosphere – states of land surface (e.g., soil moisture, soil temperature, canopy temperature, snow water equivalent) – characteristics of land surface (e.g., roughness, albedo, emissivity, soil texture, vegetation type, cover extent, leaf area index, and seasonality) • Critical for weather, climate, hydrological, and environmental forecasts. NCAR CLM Website The Development of Climate models, Past, Present and Future Mid 1950s Late 1960s Early 1980s Mid 1990s Present day Atmosphere Atmosphere Atmosphere Atmosphere Atmosphere Atmosphere Land surface Land surface Land surface Land surface Land surface Ocean & sea-ice Ocean & sea-ice Ocean & sea-ice Sulphate aerosol Sulphate aerosol Non-sulphate aerosol Sulphate aerosol Non-sulphate aerosol Carbon cycle Carbon cycle Ocean & sea-ice Late 2000s? Atmospheric chemistry Ocean & sea-ice Off-line model model development Strengthening colours denote improvements in models Sulphur cycle model Land carbon cycle model Ocean carbon cycle model Atmospheric chemistry Non-sulphate aerosols Carbon cycle model Atmospheric chemistry John Houghton Integrated Environmental Modeling Framework Climate Change and Variability Remote Sensing and GIS Water Resources Applications Coupled Ocean-Atmosphere Models Air Quality Air Quality Models Mesoscale Soil-Vegetation-Atmosphere Transfer Models E Policy P Qs D Ss Ig D Sg In Situ Data Water Quality and Quantity Qg Hydrologic/Routing Models Accurate Land Surface Modeling Is Critical for Seamless Suite of Forecasts Forecast Uncertainty Years Outlook Seasons Boundary Conditions Months Hours Commerce Health Energy Ecosystem Recreation Reservoir Control Agriculture Hydropower Fire Weather Protection of Life & Property Benefits Environment Initial Conditions Minutes State/Local Planning Warnings & Alert Coordination Days Transportation Watches 1 Week Space Operation Forecasts 2 Week Flood Mitigation & Navigation Threats Assessments Forecast Lead Time Guidance Paul Houser Land-Atmosphere Coupling Strength Koster et al. (2004), Science What Are Land Surface Processes Land surface processes function as – lower boundary condition in Atmospheric Models • Atmospheric Boundary Layer Simulation • Climate Simulation • Numerical Weather Prediction • 4-D Data Assimilation – upper boundary condition in Hydrological Models • Water Resources Estimation • Crop Water Use • Runoff Simulation – interface for coupled Atmospheric / Hydrological / Ecological Models Land Surface Models (LSMs) • Computer code describing land surface processes (also called LSSs, LSPs, SVATs) – FORTRAN, C, … ... – Tens to thousands of lines • There are a huge number of LSMs (100+ examples in literature) – many are just “research models’’, local-scale oriented, with specific process emphasis – up to ~100 canopy, ~100 soil, ~100 snow, even ~100 atmosphere layers! • LSMs in GCMs and Hydrological Models are less diverse – one dimensional, with 1-2 canopy, 1-10 soil, 1-10 snow layers – three general classes • “Bucket” Models (no vegetation canopy) • “Micrometeorological” Models (detailed soil/snow/canopy processes) + Greening • “Intermediate” Models (some soil/snow/canopy features) Four Basic Requirements Frequently-sampled (hourly or sub-hourly) weather “forcing data” to “drive” LSMs • • • • • • precipitation (rate; coverage, large-scale/convective) radiation (shortwave, longwave) temperature wind components (u, v) specific humidity surface pressure Initialization of state variables • soil moisture (liquid, frozen) • deep soil temperature Specification of surface characteristics • • • • • • vegetation cover percent and composition (ET, BVOC…) soil type (soil moisture & hydrology) topography (hydrology) albedo (solar radiation & energy balance) roughness (turbulence & momentum exchange) root depth (water holding capacity & hydrology) Validation of simulations of state variables and fluxes • soil moisture • sensible/latent heat fluxes • skin temperature Best Known Examples – “Biosphere-Atmosphere Transfer Scheme (BATS)” – “Simple Biosphere Model (SiB)” – Community Land Model (CLM) – Noah Community Land Model Reflected Solar Radiation Absorbed Solar Radiation Photosynthesis Sensible Heat Flux Latent Heat Flux Longwave Radiation Hydrology Momentum Flux Wind Speed 0 ua Precipitation Evaporation Interception Canopy Water Transpiration Emitted Longwave Radiation Diffuse Solar Radiation Biogeophysics Throughfall Stemflow Sublimation Melt Evaporation Infiltration Surface Runoff Snow Soil Heat Flux Soil Water Heat Transfer Redistribution Drainage Snow River Flow Soil Water Surface Runoff Ground Water Lake Ocean NCAR CLM Website Community Land Model Dynamic Vegetation 0 500 1000 PPFD (molm-2s-1) g CO2g-1s-1 0 -1 -2 6 4 2 0 0 1500 3000 0 -10 25 60 Temperature (C) Vegetation Dynamics g CO2g-1s-1 0 -10 25 60 Temperature (C) Root 0.3 0 -10 25 60 Temperature (C) 0 15 30 Autotrophic Respiration Temperature (C) 6 4 2 0 Foliage Water Potential (MPa) g CO2g-1s-1 Growth Respiration Sapwood 0.01 Litterfall 0 500 1000 Heterotrophic Respiration Ambient CO2 (ppm) 0 1 2 Vapor Pressure Foliage Deficit (Pa) Nitrogen (%) Nutrient Uptake 8 1 0 15 30 Temperature (C) Relative Rate 6 4 2 0 Foliage 0.5 Relative Rate g CO2g-1s-1 g CO2g-1s-1 Photosynthesis g CO2g-1s-1 Ecosystem Carbon Balance 1 0 0 100 Soil Water (% saturation) NCAR CLM Website Noah NCEP Noah Website Research Issues • Obtaining and applying relevant “pure biome” data to test or calibrate LSMs • Dealing with spatial/temporal heterogeneity • area-average parameters or tiling of land covers? • defining space-time structure of atmospheric inputs • Making best use of remote sensing data for initialization, specification and validation • Improving key processes • Snow/Frozen soil • Runoff generation/routing • “Greening” of LSMs (carbon balance and vegetation dynamics) • Urban CLM Subgrid Structure Gridcell Landunits Glacier Wetland Vegetated Lake Urban Columns Soil Type 1 PFTs Keith Oleson CLM Subgrid Structure Gridcell Landunits Glacier Wetland Urban Lake Vegetated Industrial Columns/PFTs Medium Density Suburban Roof Keith Oleson Sunlit Wall Shaded Wall Pervious Impervious Canyon Floor Climate Science Program at UT-Austin www.geo.utexas.edu/climate NOAA, Understanding and Simulation of the Effects of American Monsoon Precipitation. NASA/NOAA, Parameterization of Snow Weather Prediction Models. Vegetation on North Cover Fraction in Climate and EPA, Impacts of Climate Change and Land Cover Change on Biogenic Volatile Organic Compounds (BVOCs) Emissions in Texas. DHS, Regional Scale Flood Modeling for the San Antonio River Basin, 3-yr Graduate Fellowship to Marla Knebl. NSF, Including Aquifer into the Community Land Model, 3-yr Graduate Fellowship to Lindsey Gulden. [Groundwater and Runoff] NASA, Using MODIS Data to Characterize Climate Model Land Surface Processes and the Impacts of Land Use/Cover Change on Surface Hydrological Processes. Integrated Environmental Modeling Framework Climate Change and Variability Remote Sensing and GIS Water Resources Applications Coupled Ocean-Atmosphere Models Air Quality Air Quality Models Mesoscale Soil-Vegetation-Atmosphere Transfer Models E Policy P Qs D Ss Ig D Sg In Situ Data Water Quality and Quantity Qg Hydrologic/Routing Models Coupling Land Surface with Other Processes NCAR CLM Website
