Project Summary:
Employment of subgrid upscaling anddownscaling methods for use in coupled weather, climate and ecosystem models
DavidJ. Gochis, Research Applications
NCARCollaborators:
Andrea N. Hahmann (RAL)
Gordon Bonan (CGD)
Mariana Vertenstein (CGD)
Tony Craig (CGD)
UniversityCollaborators:
Prof. Peter Troch (University of Arizona)
Background
Severalparallel activities at NCAR have a demonstrated need for land models to improvetheir spatial representation of key land-atmosphere exchange processes. Thereis a cross-disciplinary need for simulating and predicting land surfaceprocesses at length scales far finer than those of the parent atmosphericmodels. The goal of our research effortsis to provide a framework for ‘landscape-scale’ model of land surfacehydrological processes and land-atmosphere exchanges using NCAR community landmodels. Work completed during the FY2007 expanded upon efforts initiated during2006 and saw the initiation of two new efforts. Development of the fine-mesh model continued with completion of aprecipitation downscaling methodology within the CLM/CAM modeling system. With baseline testing of the fine-meshversion of CLM coupled to CAM now in completed, discussions have begun on thesetup and execution of a long-term land-surface re-analysis over North America to explore the influence of climaticvariations on terrestrial storages and fluxes of water carbon and nitrogenusing the CLM3.5/CN model at high resolution. Work was also initiated on a new effort to enhance the surface hydrologyin NCAR land surface models, namely ‘Noah’ and ‘CLM’. This work is planned to be a centerpiece ofthe upcoming BEACHON field and modeling and Colorado Headwaters research efforts. Specific progress on these projects isprovided below.
Completed Work
Workduring FY07 has proceeded in the following three areas:
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Completion of asub-grid land model with sub-grid scale topography and precipitation within CAM-CLM. The science questions that thisactivity addresses are: What is theaffect of fine-resolution, sub-grid land use/land cover specification on thesimulated climate? What is the influence of a fine-resolution, sub-gridrepresentation of topography on the simulated climate? and What is theinfluence of a fine-resolution, sub-grid representation of topography on thesimulated climate? Results from aseries of simulations show a comparatively modest effect on the global atmosphericcirculation and thermodynamic structure from a simple implementation ofsub-grid land use and land cover types, although regionally-specific responses,especially differences in land-atmosphere exchanges are more pronounced. By including sub-grid topography, three main changesto the model were required to permit a spatially-explicit sub-gridrepresentation of topography, which included: a) Implementation of fine-meshtopographic datasets; b) Implementation of a dynamic lapse rateinterpolation/extrapolation; and c) Partitioning of rain versus snow ontofine-mesh land model. Results fromsimulations with sub-grid topography showed significant changes to both thegeneral circulation and the model surface hydrological fields compared withthose where only subgrid land use and land cover was specified. The principal changes were an alteration ofthe Northern Hemisphere wintertime mid-latitude wave train in the NorthPacific. A relative increase in thestrength of the Aleutian low combined with changes land surface elevationsresult in widespread changes in the amount of total precipitation andpartitioning between rain and snow over the parts of western Canada and Alaska. Effects in other complex regionsappeared to be of lesser magnitudes. Changes in rain-snow partitioning also impart a lag-effect on thesurface hydrology by altering the timing and location of snowmelt and runofffrom cool season precipitation. Implementationof a precipitation disaggregation scheme into the fine-mesh model whichstochastically determines the sub-grid area occurrence and intensity ofprecipitation based on the coarse grid model precipitation was also completed. Results from simulations including thesubgrid precipitation aggregation show modest changes in the global circulationas well as the surface hydroclimate though regional changes were sometimesquite substantial. In the U.S.Great Plains there appears to be a distinct strengthening of the low-levelmoisture transport from the Gulf of Mexico occurring with a regional increaseand redistribution of rainfall and surface evaporation (See Figure 1, below). Detailed investigation of this modelsensitivity is currently under investigation. Portions of this work waspresented at the Fall 2006 AGU meeting and manuscript detailing these modelsimulations and enhancements is now nearing completion.
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Scoping fordevelopment of a high-resolution, uncoupled, 50-year land surface re-analysiswith the fine-mesh version of CLM3.5/CN: Upon completion of the fine-mesh version of CLM a proposal has beendeveloped between CGD, RAL and CISL to extend the fine-mesh tool to investigatelong-term changes and variability in North American water, carbon andnitrogen. A white paper was preparedwhich scopes out the modeling plan and computational resources required toperform a 50 year, 0.1 degree land re-analysis over North America.
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Implementationand testing of the community Noah-distributed hydrological model in theColorado Headwaters region: In conjunction with the newly developing BEACHONand Colorado Headwaters research efforts work has been initiated on testing andevaluating a distributed version of the Noah-distributed hydrological model foruse over the mountainous regions of Colorado. This work forms the baseline of land surfacemodel development which will occur under the BEACHON program. With visitorsupport from TIIMES, collaboration with Prof. Peter Troch of the U. of Arizonawas initiated in order to evaluate the representation of hillslope hydrologicalprocesses in the Noah-distributed hydrological modeling system. Simulations from the model development workcompleted during the summer of 2007 are now underway and are scheduled to bepresented at an upcoming conference in Australia.
Plans for FY08 and Beyond
Activitiesplanned for FY2007 include the following:
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Continue planning and development of the BEACHON and Colorado Headwaters research programs. Work on these administrative efforts is expected to accelerate over the next year as these projects initiate in earnest.
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Continued development and testing of the fine-mesh version of CLM to include the CLM/CN model, which includes representations of carbon and nitrogen processes. This work will be targeted towards execution of a long-term land reanalysis over NorthAmerica and in support of BEACHON research which will focus on terrestrial hydrobiogeochemical controls and biogenic emissions in complex terrain regions.
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Upon completion of testing of the Noah-distributed hydrological model over the Colorado Headwater region, work will initiate on adapting the distributed modeling framework to permit use of the CLM/CN land surface model instead of the Noah land surface model in detailed hydrobiogeochemical studies. This work is directly linked to that outlined in #2 above and is targeted for development and use within the BEACHON research program.
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Community Service:
- Chair - NAME Science Working Group, North American Monsoon Experiment (NAME)
- K-12 Activiy:Weather Lecture to 4th Grade Class, Whittier Elementary, Boulder, CO, USA
- member - CUAHSI Synthesis Team, Consortium of Universities for the Advancement of Hydrologic Science, Inc(CUAHIS)
- Thesis Committee: Angela Rowe, , Masters, CSU, Ft. Collins, CO USA
- Thesis Committee: Chunmei Zhu, , PhD, U. Washington, Seattle, WA USA
- Thesis Committee: Kazungu Maitaria, , PhD, U. of Arizona, Tucson, AZ USA
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TIIMES External Collaborators:
Luis Brito, Centro de Investigaciones Biológicas del Noroeste (CIBNOR)
Cedric David, University of Texas at Austin
Henry Diaz, National Oceanic & Atmospheric Administration (NOAA) - CDC
Jaime Garatuza, Instituto Tecnológico de Sonora (ITSON)
Greg Garfin, University of Arizona
Wayne Higgins, National Centers for Environmental Prediction-NOAA
Dennis Lettenmaier, University of Washington
Brant Liebman, National Oceanic & Atmospheric Administration (NOAA) - CDC
David Maidment, University of Texas at Austin
Kazungu Maitaria, University of Arizona
Steve Mullen, University of Arizona
Steve Nesbitt, University of Illinois
Andrea Ray, National Oceanic & Atmospheric Administration (NOAA) - CDC
Jim Shuttleworth, University of Arizona
Peter Troch, University of Arizona
Bob Varady, University of Arizona
Enrique Vivoni, New Mexico Institute of Technology
Christopher Watts, University of Sonora
Zong-Liang Yang, University of Texas at Austin
Chunmei Zhu, University of Washington
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Publications:
Gochis, D., L. Brito-Castillo, W. J. Shuttleworth, 2007:Correlations between sea-surface temperatures and warm seasonstreamflow in northwest Mexico. Int. J. Climat., 27, 883-901.
Hong, Y., D. J. Gochis, J.-T. Cheng, K.-L. Hsu, S. Soroshian, 2007:Evaluation of PERSIANN-CCS rainfall measurement using the NAME eventrain gauge network. J. Hydrometeorol., 8, 469-482.
Ray, A. J., G. M. Garfin, L. Brito-Castillo, M. Cortez-Vasquez, H.F. Diaz, J. Garatuza-Payan, D. J. Gochis, R. Lobato-Sanchez, R. Varady,C. J. Watts, 2007: Monsoon region climate applications: Integratingclimate science with regional planning and policy. Bull. Amer. Meteor. Soc., 88, 933-935.
Gochis, D. J., J. Garatuza-Payan, 2007: Spatial and temporalpatterns of precipitation intensity as observed by the NAME Event RainGauge Network from 2002 to 2004. J. Climate, 20, 1734-1750.
Higgins, R. W., D. J. Gochis, 2007: Synthesis of results from the North American Monsoon Experiment (NAME) Process Study. J. Climate, 20, 1601-1607.
Gochis, D. J., R. W. Higgins, 2007: The path to improving predictions of the North American Monsoon. Newsletter, U.S. CLIVAR Variations, 5(1), 39306. |
