Ocean Surfaces on Snowball Earth
Ocean Surfaces on Snowball Earth
批准号:
1142963
负责人:
Stephen Warren
金额:
$50.0万
依托单位:
依托单位国家:
美国
项目类别:
Standard Grant
财政年份:
2012
资助国家:
美国
项目状态:
已结题
起止时间:
2012-09-01 至 2016-08-31
中文摘要
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英文摘要
The climatic changes of late Precambrian time, 600-800 million years ago, included episodes of extreme glaciation, during which ice may have covered nearly the entire ocean for several million years, according to the Snowball Earth hypothesis. These episodes would hold an important place in Earth?s evolutionary history; they could have encouraged biodiversity by trapping life forms in small isolated ice-free areas, or they could have caused massive extinctions that cleared the path for new life forms to fill empty niches. What caused the Earth to become iced over, and what later caused the ice to melt? Scientific investigation of these questions will result in greater understanding of the climatic changes that the Earth can experience, and will enable better predictions of future climate. This project involves Antarctic field observations as well as laboratory studies and computer modeling.The aim of this project is not to prove or disprove the Snowball Earth hypothesis but rather to quantify processes that are important for simulating snowball events in climate models. The principal goal is to identify the types of ice that would have been present on the frozen ocean, and to determine how much sunlight they would reflect back to space. Reflection of sunlight by bright surfaces of snow and ice is what would maintain the cold climate at low latitudes. The melting of the ocean required buildup of greenhouse gases, but it was probably aided by deposition of desert dust and volcanic ash darkening the snow and ice. With so much ice on the Earth?s surface, even small differences in the amount of light that the ice absorbed or reflected could cause significant changes in climate. The properties of the ice would also determine where, and in what circumstances, photosynthetic life could have survived. Some kinds of ice that are rare on the modern Earth may have been pivotal in allowing the tropical ocean to freeze. The ocean surfaces would have included some ice types that now exist only in Antarctica: bare cold sea ice with precipitated salts, and "blue ice" areas of the Transantarctic Mountains that were exposed by sublimation and have not experienced melting. Field expeditions were mounted to examine these ice types, and the data analysis is underway. A third ice type, sea ice with a salt crust, is being studied in a freezer laboratory. Modeling will show how sunlight would interact with ice containing light-absorbing dust and volcanic ash. Aside from its reflection of sunlight, ice on the Snowball ocean would have been thick enough to flow under its own weight, invading all parts of the ocean. Yet evidence for the survival of photosynthetic life indicates that some regions of liquid water were maintained at the ocean surface. One possible refuge for photosynthetic organisms is a bay at the far end of a nearly enclosed tropical sea, formed by continental rifting and surrounded by desert, such as the modern Red Sea. A model of glacier flow is being developed to determine the dimensions of the channel, connecting the sea to the ocean, necessary to prevent invasion by the flowing ice yet maintain a water supply to replenish evaporation.
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EAGER: An Oasis for Surface Life on the Ocean of Snowball Earth
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批准号:2041491
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项目类别:Standard Grant
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资助金额:$22.5万
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财政年份:2020
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负责人:Stephen Warren
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依托单位:
Imperial College Astrophysics Consolidated Grant 2016-2019
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批准号:ST/N000838/1
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项目类别:Research Grant
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资助金额:$263.88万
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财政年份:2016
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负责人:Stephen Warren
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依托单位:
Spectral and Broadband Albedo of Antarctic Sea-ice Types
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批准号:1141275
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项目类别:Standard Grant
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资助金额:$13.25万
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财政年份:2012
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负责人:Stephen Warren
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依托单位:
An Experiment Relating Black Carbon Content to Reduction of Snow Albedo
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批准号:1118460
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项目类别:Standard Grant
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资助金额:$32.47万
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财政年份:2011
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负责人:Stephen Warren
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依托单位:
Global Cloud Climatology from Surface Observations: Analyses and Decadal Update
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批准号:1021543
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项目类别:Continuing Grant
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资助金额:$25.79万
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财政年份:2010
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负责人:Stephen Warren
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依托单位:
Ocean Surfaces on Snowball Earth
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批准号:0739779
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项目类别:Continuing Grant
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资助金额:$95.63万
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财政年份:2008
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负责人:Stephen Warren
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依托单位:
Interaction of Clouds, Snow, and Solar Radiation on the East Antarctic Plateau
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批准号:0636993
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项目类别:Standard Grant
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资助金额:$26.76万
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财政年份:2007
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负责人:Stephen Warren
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依托单位:
Collaborative Research: Global Cloud Climatology from Surface Observations: Analyses and Decadal Update
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批准号:0630428
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项目类别:Continuing Grant
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资助金额:$16.48万
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财政年份:2007
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负责人:Stephen Warren
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依托单位:
Collaborative Research: Longwave Radiation Processes and Surface Energy Budget on the Antarctic Plateau
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批准号:0540090
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项目类别:Continuing Grant
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资助金额:$34.0万
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财政年份:2006
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负责人:Stephen Warren
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依托单位:
Black carbon in Arctic snow and ice and its effect on surface albedo
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批准号:0612636
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项目类别:Standard Grant
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资助金额:$92.57万
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财政年份:2006
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负责人:Stephen Warren
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依托单位:
Collaborative Research: Global Distribution of Diurnal Cycles and Long-term Changes in Cloud Amounts from Surface Observations
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批准号:0242124
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项目类别:Continuing Grant
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资助金额:$24.6万
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财政年份:2003
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负责人:Stephen Warren
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依托单位:
Longwave Radiation Processes on the Antarctic Plateau
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批准号:0230466
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项目类别:Continuing Grant
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资助金额:$34.02万
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财政年份:2003
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负责人:Stephen Warren
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依托单位:
Solar Radiation Processes on the East Antarctic Plateau
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批准号:0003826
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项目类别:Continuing Grant
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资助金额:$84.29万
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财政年份:2001
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负责人:Stephen Warren
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依托单位:
Collaborative Research: Global Distribution of Diurnal Cycles and Long Term Changes in Cloud Amounts from Surface Observations
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批准号:9908699
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项目类别:Standard Grant
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资助金额:$4.55万
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财政年份:2000
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负责人:Stephen Warren
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依托单位:
Collaborative Research: Solar Radiation Processes in the East Antarctic Sea Ice Zone
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批准号:9815156
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项目类别:Continuing Grant
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资助金额:$39.49万
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财政年份:1999
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负责人:Stephen Warren
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依托单位:
Collaborative Research: The Surface of the Antarctic Plateau as a Natural Laboratory for Radiation Processes in the Global Upper Troposphere: Water Vapor and Ice Clouds
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批准号:9813671
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项目类别:Continuing Grant
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资助金额:$55.65万
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财政年份:1998
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负责人:Stephen Warren
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依托单位:
Collaborative Research: Longwave Radiation Processes on the Antarctic Plateau
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批准号:9726676
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项目类别:Continuing Grant
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资助金额:$68.7万
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财政年份:1998
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负责人:Stephen Warren
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依托单位:
Solar Radiation Processes in the East Antarctic Sea Ice Zone
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批准号:9527245
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项目类别:Continuing Grant
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资助金额:$20.53万
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财政年份:1996
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负责人:Stephen Warren
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依托单位:
Climate Processes on the Antarctic Plateau
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批准号:9421096
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项目类别:Continuing Grant
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资助金额:$56.85万
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财政年份:1995
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负责人:Stephen Warren
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依托单位:
Global Distrubution of Diurnal Cycles and Long-term in Cloud Amounts from Surface Observations
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批准号:9510170
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项目类别:Standard Grant
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资助金额:$45.04万
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财政年份:1995
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负责人:Stephen Warren
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依托单位:
海外基金