| 项目编号: | 1660538
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| 项目名称: | Collaborative Research: Using SOCRATES Datasets to Improve Simulations of Clouds, Aerosols and their Climate Impacts |
| 作者: | Stephan Fueglistaler
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| 承担单位: | Princeton University
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| 批准年: | 2017
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| 开始日期: | 2017-06-15
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| 结束日期: | 2020-05-31
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| 资助金额: | 77410
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| 资助来源: | US-NSF
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| 项目类别: | Continuing grant
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| 国家: | US
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| 语种: | 英语
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| 特色学科分类: | Geosciences - Atmospheric and Geospace Sciences
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| 英文关键词: | so cloud
; model simulation
; model
; work
; project
; representation
; cloud
; atmospheric research
; impact
; campaign
; socrates campaign
; datum
; cloud process
; climate sensitivity
; shallow cumulus cloud
; scientific research community
; lower-tropospheric cloud
; nudged meteorology simulation
; socrates blog
; global climate change
; aerosol
; research community
; cloud ice
; cloud droplet
; cloud-aerosol interaction
; cloud particle
; scientific research
; large-eddy simulation
; southern ocean clouds
; cam6
; future climate projection
; cloud deficiency
; cloud water
; simulated cloud cover
; gv
; liquid droplet
; research aircraft
; research area
; cloud behavior
; cloud microphysic
; ancillary cloud
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| 英文摘要: | The Southern Ocean (SO), meaning the global ocean of the high latitude Southern Hemisphere, has a well-deserved reputation as the stormiest place on earth. The remoteness of the SO and its unforgiving conditions have severely limited observations of atmospheric processes occurring above it, including cloud processes in the cyclones traveling along the South Polar front. Yet these processes are of interest for a variety of reasons, including the fact that SO clouds are relatively free from the effects of continental and anthropogenic aerosols, and the region is thus a natural laboratory for the study of cloud behavior under pristine conditions. SO clouds also play a significant cooling role in the energy balance of the planet by reflecting incoming sunlight back to space. There is evidence to suggest that this cooling has a long-range effect on the distribution of the low-latitude rainfall associated with the intertropical convergence zone, and that changes in SO cloudiness due to global climate change will affect the location and strength of the Southern Hemisphere jet stream. One indicator of our lack of understanding of SO cloud processes is the inadequate SO cloud cover found in climate model simulations, which is accompanied by excessive absorption of sunlight by the ocean surface which may in turn cause errors in estimates of climate sensitivity. The deficiency in simulated cloud cover is most pronounced in boundary layer and lower-tropospheric clouds (tops below 3km) in the cold, dry sectors of frontal weather systems traveling along the SO storm track.
This project is a component of the Southern Ocean Clouds, Radiation, Aerosol, Transport Experimental Study (SOCRATES). The primary activity of the campaign is the deployment of a Gulfstream V (GV) research aircraft maintained by the Earth Observing Laboratory of the National Center for Atmospheric Research. The GV is based in Hobart, Australia and makes multiple flights across the South Polar front collecting data on SO clouds and the meteorological conditions in which they occur. The GV is equipped with dropsondes to record ambient meteorological conditions, radar and lidar to observe the clouds, and instruments mounted on the wings or positioned behind inlets to to sample, collect and analyze aerosols and cloud particles (liquid droplets and ice crystals). The SOCRATES campaign is complementary to SO activities planned internationally and by other US agencies, including surface observations taken on ships and on MacQuarie Island, a small uninhabited island at 54 degrees South.
Work supported here uses data collected in the SOCRATES campaign to improve the representation of SO clouds and cloud-aerosol interactions in climate and weather models. Several possible reasons for the cloud deficiencies are addressed, including deficiencies in the representation of cloud microphysics leading to overly rapid freezing of supercooled liquid water (SLW) cloud droplets, excessive precipitation from shallow cumulus clouds, errors in the representation of small-scale turbulent motions and their effects on the distribution of cloud water, and inaccurate representation of aerosols and their role as condensation nuclei for liquid droplets and nucleating particles for cloud ice. Much of the activity in the campaign is focused on the abundance of SLW in SO clouds, which are less glaciated than their Northern Hemisphere counterparts (i.e. they contain more very cold liquid droplets and fewer ice particles), and work in this project uses model simulations to understand this difference.
Two categories of models are used, global atmospheric models and large-eddy simulation (LES) models. Global models include the Community Atmosphere Model version 6 (CAM6), developed by and for the research community and hosted at the National Center for Atmospheric Research, and the Atmospheric Model version 4 (AM4), developed by the Geophysical Fluid Dynamics Laboratory. The LES model is the System for Atmospheric Modeling (SAM), developed by researchers at the State University of New York at Stony Brook and the Colorado State University. For the global models, a "nudged meteorology" strategy is used to facilitate comparisons between observations and model simulations. In this strategy the model is subjected to forcing terms which constrain it to remain close wind and temperature values produced by operational weather forecasting centers. The goal is to reproduce the large-scale meteorological conditions in which campaign observations were made, so that the cloud and aerosol observations from the campaign can be reasonably compared to their simulated counterparts. The project uses the understanding developed from these comparisons, and from the LES modeling, to develop a representation for ice nucleating particles in CAM6.
The work has broader impacts due to its potential value for improving models used for weather prediction and future climate projections. The work on model improvement also has broader impacts for the scientific research community, as CAM6 and AM4 are widely used tools for scientific research. The nudged meteorology simulations are available for community use as part of the long-term online archive of data collected in the campaign, along with the meteorological analyses used to nudge the models and ancillary cloud and sea surface observations from satellites. In addition to the broader impacts of the work performed, the project provides support and training for two postdocs, thereby providing for the development of the scientific workforce in this research area. The PIs also contribute to campaign outreach activities including a SOCRATES blog. |
| 资源类型: | 项目
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/90010
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| Appears in Collections: | 全球变化的国际研究计划
科学计划与规划
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| Recommended Citation: | |
Stephan Fueglistaler. Collaborative Research: Using SOCRATES Datasets to Improve Simulations of Clouds, Aerosols and their Climate Impacts. 2017-01-01.
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