(WEAVE) Changing Seasons? Detecting and Understanding Climate Change

（编织）季节变化？

• 批准号: 9720134
• 负责人: Upmanu Lall
• 金额: $ 26.12万
• 依托单位: Utah State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-09-15 至 2003-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9720134&HistoricalAwards=false
• 关键词: WEAVE; Changing; Seasons; Detecting; Understanding

9720134 Lall Recent research suggests that the seasonal patterns of continental U.S. temperature, precipitation and streamflow have been changing over the last century. The peak temperature and precipitation may have shifted forward by 10 to 90 days in a calendar year in high latitudes. Snow melt runoff may also be occurring earlier in the year. At interannual or interdecadal time scales, there is evidence of delay/advance of seasons related to El Nino events. Such trends have implications for projections of the timing and magnitude of regional agrarian and urban water and energy demand, water supply, reservoir operation, agricultural practice, ecologic productivity, critical periods and risks of environmental impacts on surface waters and air quality and the consequent economic impacts. The interpretation of warming or rainfall trends attributed to particular months or seasons is also called into question. The objectives of the proposed research are to: Identify spatially coherent patterns for changes in the seasonality of precipitation, temperature and streamflow in N. America using nearly century long instrumental hydroclimate records. Relate shifts in seasonality to anthropogenic factors (e.g., greenhouse gases, urbanization), latitude, continentality (i.e., distance from ocean), and orography. Explore connections between the seasonality trends and trends in atmospheric circulation (as indicated by sea level pressure changes) for a dynamical understanding of the changing climate. Explore the use of General Circulation Models to explain the trends in terms of natural variability of the climate system or greenhouse forcing. These objectives will be addressed by assembling a comprehensive data base of daily/monthly precipitation, temperature, streamflow and sea level pressure data for regions ranging from the continental U.S. to the N. Hemisphere and the analysis of these data using nonparametric statistical methods to assess seasonality and its shifts, spatial coherenc e and space-time structure of the variations, and to develop and explore empirical hypotheses relating ocean-atmosphere circulation to the trends in precipitation, temperature and streamflow.

小行星9720134 最近的研究表明， 在过去的世纪里，美国的气温、降水量和流量一直在变化。 在高纬度地区，一个日历年的最高气温和降水量可能提前10至90天。 融雪径流也可能在今年早些时候发生。 在年际或年代际时间尺度上，有证据表明与厄尔尼诺事件有关的季节延迟/提前。 这些趋势对预测区域农业和城市水和能源需求的时间和规模、供水、水库运作、农业做法、生态生产力、对地表沃茨和空气质量产生环境影响的关键时期和风险以及随之产生的经济影响具有影响。 对归因于特定月份或季节的变暖或降雨趋势的解释也受到质疑。拟议研究的目标是： 识别N.降水、温度和径流季节性变化的空间相干模式。美国使用近世纪长的仪器水文气候记录。 将季节性变化与人为因素联系起来（例如，温室气体、城市化）、纬度、大陆性（即，与海洋的距离）和地形。 探索季节性趋势和大气环流趋势（如海平面压力变化所示）之间的联系，以动态地了解气候变化。 探索使用大气环流模式来解释气候系统自然变率或温室强迫的趋势。 这些目标将通过收集从美国大陆到北大西洋地区的日/月降水、温度、流量和海平面气压数据的综合数据库来实现。半球和这些数据的分析，使用非参数统计方法来评估季节性及其变化，空间相干性和时空结构的变化，并开发和探索经验假说海洋大气环流的趋势，降水，温度和流量。