Understanding Long-term Variations in Stratospheric Water Vapor

了解平流层水蒸气的长期变化

• 批准号: 1261948
• 负责人: Andrew Dessler
• 金额: $ 25.91万
• 依托单位: Texas A&M University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-04-01 至 2017-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1261948&HistoricalAwards=false
• 关键词: Understanding; Long; term; Variations; Stratospheric

This project seeks to understand changes in tropical stratospheric water vapor seen in observations and in model simulations of future climate change. Simulations of future climate consistently show an increasing trend in tropical stratospheric water vapor due to greenhouse gas increases, but satellite data since the 1980s show interannual and decadal variability but little trend. In addition, comparison of monthly stratospheric water vapor and 100hPa heating rate are negatively correlated in observational data, but positively correlated in future climate simulations. Negative correlations are expected if changes in water vapor and heating rates are linked to variations in the Brewer-Dobson circulation, as a stronger BD circulation is associated with stronger tropical heating (i.e. stronger diabatic upwelling) and colder tropical stratospheric temperatures. But future climate simulations show increases in both water vapor and the strength of the BD circulation. Moreover, increases in surface temperature are expected to produce increases in stratospheric water vapor, but surface temperatures rose over the observed record while tropical stratospheric water vapor did not. This project uses a suite of models including a domain-filling trajectory model, the Whole Atmosphere Community Climate Model (WACCM), and a one-dimensional radiative transfer model, to understand the underlying processes responsible for the changes in observed and simulated water vapor changes.The work has broader impacts due to the climatic effects of stratospheric water vapor, and the relationship between stratospheric ozone and water vapor. In addition, the PI will conduct outreach to general audiences through new-media outlets, thereby working to increase public understanding of the phenomena addressed in this research. The project also supports and trains a graduate student, thereby providing for the development of the scientific workforce in this research area.

该项目试图了解热带平流层水汽在观测和未来气候变化模型模拟中所见的变化。对未来气候的模拟一直表明，由于温室气体的增加，热带平流层水汽有增加的趋势，但自20世纪80年代以来的卫星资料显示出年际和年代际变化，但趋势很小。此外，月平流层水汽与100hPa加热率的比较在观测资料中呈负相关，但在未来气候模拟中呈正相关。如果水汽和加热率的变化与布鲁尔-多布森环流的变化有关，预计会出现负相关，因为更强的BD环流与更强的热带加热(即更强的非绝热上升流)和更低的热带平流层温度有关。但未来的气候模拟显示，水汽和北半球环流的强度都在增加。此外，地表温度的升高预计会导致平流层水蒸气的增加，但地表温度的上升超过了观测记录，而热带平流层的水蒸气却没有。该项目使用了一套模式，包括区域填充轨迹模式、全大气社区气候模式(WACCM)和一维辐射传输模式，以了解导致观测和模拟的水汽变化的潜在过程。由于平流层水汽的气候效应，以及平流层臭氧和水汽的关系，该工作具有更广泛的影响。此外，宣传局将通过新媒体渠道向普通受众进行宣传，从而努力增加公众对本研究中涉及的现象的了解。该项目还支持和培训一名研究生，从而为这一研究领域的科学队伍的发展提供支持。