Seasons of Change in the Arctic Environment

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。太阳辐射的极端年周期，北极与低纬度地区之间的相互作用，北极内部陆地、海洋和大气之间的相互作用，以及冻结和解冻的能量学，这些联合收割机结合在一起，使北极的季节性变得更加复杂和丰富，这在地球上的其他地方是看不到的。这种季节性正在发生变化。夏季海冰范围正在减少，伴随着秋季北冰洋气温的强劲上升。西伯利亚的活跃层冻结发生在冬季后期。这些和其他新出现的变化将在未来几十年变得更加突出，其影响有望通过系统的物理，化学，生物和社会经济组成部分级联。这项研究将确定主导气候强迫，反馈和驱动北极系统季节性变化的组件联系，它们将塑造整个世纪系统的演变。 这将需要考虑全球辐射强迫、从低纬度进入北极的能量和物质输送以及北极内陆地、海洋和大气之间的变化，以及这些变化如何影响北极？的物理、化学和生物过程。一个被动控制与主动控制相结合的框架将有助于组织调查。被动控制是通过背景升温进行的控制。一个例子是北极变暖将如何导致积雪季节性持续时间缩短。主动控制是指由从低纬度或北极本身进入北极的能量或物质输送的变化所驱动的季节性改变。一个例子是秋季海冰范围的减少如何导致海洋变暖，然后通过区域大气传输，可能导致邻近陆地变暖。季节性的变化可能经常反映被动和主动控制。诊断，如季节性异常结构，定义为一个或多个给定年份的状态变量的季节性周期相对于长期气候，将被用来评估如何在不同的系统元素的季节性已经通过仪器记录演变。这些观测分析将指导建模实验，以检查状态变量对主动和被动控制的敏感性，以及季节性变化将如何塑造系统的未来。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The Arctic system is strongly defined by its seasonality. The extreme annual cycle of solar radiation, interactions between the Arctic and lower latitudes, within-Arctic interactions between the land, ocean, and atmosphere, and the energetics of freeze and thaw, combine to lend a complexity and richness to Arctic seasonality not seen elsewhere on the planet. This seasonality is changing. Summer sea ice extent is declining, attended by strong autumn rises in air temperature over the Arctic Ocean. Active layer freeze-up in Siberia is occurring later in the winter. These and other emerging changes will become more prominent in coming decades, with impacts promising to cascade through the physical, chemical, biological, and socio-economic components of the system.This research will identify the dominant climate forcings, feedbacks, and component linkages driving change in Arctic system seasonality, and they will shape the evolution of the system through the 21st century. This will require consideration of changes in global radiative forcing, energy and mass transports from lower latitudes into the Arctic, and between the land, ocean, and atmosphere within the Arctic, and how these influence the Arctic?s physical, chemical, and biological processes. A framework of passive versus active controls will help to organize the investigations. A passive control is the control by background warming. An example is how Arctic warming will lead to shorter seasonal duration of snow cover. An active control refers to altered seasonality driven by changes in energy or mass transports into the Arctic from lower latitudes or within the Arctic itself. An example is how reduced autumn sea-ice extent leads to warming over the ocean, which then, through regional atmospheric transport, may lead to warming over adjacent land. Changes in seasonality will likely often reflect both passive and active controls. Diagnostics such as seasonal anomaly structures, defined as the seasonal cycle of a state variable for a given year or years relative to the long-term climatology, will be used to evaluate how seasonality in different system elements has evolved through the instrumental record. These observational analyses will guide modeling experiments to examine the sensitivity of state variables to active and passive controls and how changing seasonality will shape the future of the system.