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Title: Addition of Tropospheric Chemistry and Aerosols to the NCAR Community Climate System Model

Abstract

Atmospheric chemistry and aerosols have several important roles in climate change. They affect the Earth's radiative balance directly: cooling the earth by scattering sunlight (aerosols) and warming the Earth by trapping the Earth's thermal radiation (methane, ozone, nitrous oxide, and CFCs are greenhouse gases). Atmospheric chemistry and aerosols also impact many other parts of the climate system: modifying cloud properties (aerosols can be cloud condensation nuclei), fertilizing the biosphere (nitrogen species and soil dust), and damaging the biosphere (acid rain and ozone damage). In order to understand and quantify the effects of atmospheric chemistry and aerosols on the climate and the biosphere in the future, it is necessary to incorporate atmospheric chemistry and aerosols into state-of-the-art climate system models. We have taken several important strides down that path. Working with the latest NCAR Community Climate System Model (CCSM), we have incorporated a state-of-the-art atmospheric chemistry model to simulate tropospheric ozone. Ozone is not just a greenhouse gas, it damages biological systems including lungs, tires, and crops. Ozone chemistry is also central to the oxidizing power of the atmosphere, which destroys a lot of pollutants in the atmosphere (which is a good thing). We have also implemented a fast chemical mechanismmore » that has high fidelity with the full mechanism, for significantly reduced computational cost (to facilitate millennium scale simulations). Sulfate aerosols have a strong effect on climate by reflecting sunlight and modifying cloud properties. So in order to simulate the sulfur cycle more fully in CCSM simulations, we have linked the formation of sulfate aerosols to the oxidizing power of the atmosphere calculated by the ozone mechanisms, and to dimethyl sulfide emissions from the ocean ecosystem in the model. Since the impact of sulfate aerosols depends on the relative abundance of other aerosols in the atmosphere, we also implemented interactive simulation of nitrate, sea-salt, black carbon, and both primary and secondary organic aerosols into CCSM (using assumed size distributions). These new capabilities are opening the door to studies of the role atmospheric chemistry and aerosols in climate change, and their impact on the biosphere, that were previously impossible.« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
881068
Report Number(s):
UCRL-TR-217228
TRN: US200612%%772
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
03 NATURAL GAS; 54 ENVIRONMENTAL SCIENCES; AEROSOLS; ATMOSPHERIC CHEMISTRY; BIOSPHERE; CHEMISTRY; CLIMATES; DIMETHYL SULFIDE; ECOSYSTEMS; GREENHOUSE GASES; METHANE; NITROGEN; NITROUS OXIDE; OZONE; POLLUTANTS; SULFATES; SULFUR CYCLE; THERMAL RADIATION

Citation Formats

Cameron-Smith, P, Lamarque, J, Connell, P, Chuang, C, Rotman, D, and Taylor, J. Addition of Tropospheric Chemistry and Aerosols to the NCAR Community Climate System Model. United States: N. p., 2005. Web. doi:10.2172/881068.
Cameron-Smith, P, Lamarque, J, Connell, P, Chuang, C, Rotman, D, & Taylor, J. Addition of Tropospheric Chemistry and Aerosols to the NCAR Community Climate System Model. United States. doi:10.2172/881068.
Cameron-Smith, P, Lamarque, J, Connell, P, Chuang, C, Rotman, D, and Taylor, J. Mon . "Addition of Tropospheric Chemistry and Aerosols to the NCAR Community Climate System Model". United States. doi:10.2172/881068. https://www.osti.gov/servlets/purl/881068.
@article{osti_881068,
title = {Addition of Tropospheric Chemistry and Aerosols to the NCAR Community Climate System Model},
author = {Cameron-Smith, P and Lamarque, J and Connell, P and Chuang, C and Rotman, D and Taylor, J},
abstractNote = {Atmospheric chemistry and aerosols have several important roles in climate change. They affect the Earth's radiative balance directly: cooling the earth by scattering sunlight (aerosols) and warming the Earth by trapping the Earth's thermal radiation (methane, ozone, nitrous oxide, and CFCs are greenhouse gases). Atmospheric chemistry and aerosols also impact many other parts of the climate system: modifying cloud properties (aerosols can be cloud condensation nuclei), fertilizing the biosphere (nitrogen species and soil dust), and damaging the biosphere (acid rain and ozone damage). In order to understand and quantify the effects of atmospheric chemistry and aerosols on the climate and the biosphere in the future, it is necessary to incorporate atmospheric chemistry and aerosols into state-of-the-art climate system models. We have taken several important strides down that path. Working with the latest NCAR Community Climate System Model (CCSM), we have incorporated a state-of-the-art atmospheric chemistry model to simulate tropospheric ozone. Ozone is not just a greenhouse gas, it damages biological systems including lungs, tires, and crops. Ozone chemistry is also central to the oxidizing power of the atmosphere, which destroys a lot of pollutants in the atmosphere (which is a good thing). We have also implemented a fast chemical mechanism that has high fidelity with the full mechanism, for significantly reduced computational cost (to facilitate millennium scale simulations). Sulfate aerosols have a strong effect on climate by reflecting sunlight and modifying cloud properties. So in order to simulate the sulfur cycle more fully in CCSM simulations, we have linked the formation of sulfate aerosols to the oxidizing power of the atmosphere calculated by the ozone mechanisms, and to dimethyl sulfide emissions from the ocean ecosystem in the model. Since the impact of sulfate aerosols depends on the relative abundance of other aerosols in the atmosphere, we also implemented interactive simulation of nitrate, sea-salt, black carbon, and both primary and secondary organic aerosols into CCSM (using assumed size distributions). These new capabilities are opening the door to studies of the role atmospheric chemistry and aerosols in climate change, and their impact on the biosphere, that were previously impossible.},
doi = {10.2172/881068},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Nov 14 00:00:00 EST 2005},
month = {Mon Nov 14 00:00:00 EST 2005}
}

Technical Report:

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  • Convection and clouds affect atmospheric temperature, moisture and wind fields through the heat of condensation and evaporation and through redistributions of heat, moisture and momentum. Individual clouds have a spatial scale of less than 10 km, much smaller than the grid size of several hundred kilometers used in climate models. Therefore the effects of clouds must be approximated in terms of variables that the model can resolve. Deriving such formulations for convection and clouds has been a major challenge for the climate modeling community due to the lack of observations of cloud and microphysical properties. The objective of our DOEmore » CCPP project is to evaluate and improve the representation of convection schemes developed by PIs in the NCAR (National Center for Atmospheric Research) Community Climate System Model (CCSM) and study its impact on global climate simulations. • The project resulted in nine peer-reviewed publications and numerous scientific presentations that directly address the CCPP’s scientific objective of improving climate models. • We developed a package of improved convection parameterization that includes improved closure, trigger condition for convection, and comprehensive treatment of convective momentum transport. • We implemented the new convection parameterization package into several versions of the NCAR models (both coupled and uncoupled). This has led to 1) Improved simulation of seasonal migration of ITCZ; 2) Improved shortwave cloud radiative forcing response to El Niño in CAM3; 3) Improved MJO simulation in both uncoupled and coupled model; and 4) Improved simulation of ENSO in coupled model. • Using the dynamic core of CCM3, we isolated the dynamic effects of convective momentum transport. • We implemented mosaic treatment of subgrid-scale cloud-radiation interaction in CCM3.« less
  • A comprehensive model of land-surface processes has been under development suitable for use with various National Center for Atmospheric Research (NCAR) General Circulation Models (GCMs). Special emphasis has been given to describing properly the role of vegetation in modifying the surface moisture and energy budgets. The result of these efforts has been incorporated into a boundary package, referred to as the Biosphere-Atmosphere Transfer Scheme (BATS). The current frozen version, BATS1e is a piece of software about four thousand lines of code that runs as an offline version or coupled to the Community Climate Model (CCM).
  • Maintaining a balance of computational load over processors is a crucial issue in parallel computing. For efficient parallel implementation, complex codes such as climate models need to be analyzed for load imbalances. In the present study we focus on the load imbalances in the physics portion of the community climate model`s (CCM2) distributed-memory parallel implementation on the Intel Touchstone DELTA computer. We note that the major source of load imbalance is the diurnal variation in the computation of solar radiation. Convective weather patterns also cause some load imbalance. Land-ocean contrast is seen to have little effect on computational load inmore » the present version of the model.« less
  • The purpose of this project is to establish the climate record of four versions of the National Center for Atmospheric Research (NCAR) Community Climate Model (CCM). Since the public release of the initial version of the CCM (CCM0) in 1982, advances in our modeling of the climate system have led to the release of CCM1 in 1987 and CCM2 in 1992. Several other versions of the CCM have also been developed at NCAR, two examples of which are the Global Environmental and Ecological Simulation of Interactive Systems (GENESIS) model and the Climate Sensitivity and Carbon Dioxide (CSCO2) model. This studymore » documents and compares the mean January and July climates of CSCO2, GENESIS, and standard versions of CCM1 and CCM2. Each model was integrated for 10 years with a horizontal spectral resolution of rhomboidal 15 (R15), including a low-resolution R15 version of CCM2.« less
  • The report presents the details of the governing equations, physical parameterizations, and numerical algorithms defining the version of the NCAR Community Climate Model designated CCM2. The material provides an overview of the major model components, and the way in which they interact as the numerical integration proceeds. Details on the coding implementation, along with in-depth information on running the CCMe code, given in a separate technical report entitled User's Guide to NCAR CCMe (Bath et. a., 1992). As before, it is the authors objective that the model provide NCAR and the university research community with a reliable, well documented atmosphericmore » general circulation model. In contrast with earlier versions of the CCM, however, the CCM2 represents a wholly new state-of-the-art atmospheric general circulation model, both functionally and in terms of its implementation. As such, the version of the CCM represents a major break from the evolutionary nature of earlier releases, and should provide the research community with a significantly improved atmospheric modeling capability.« less