Roles of Moist Static Energy Transport in the Changing Arctic System

北极系统似乎正在走向一种可能是史无前例的新状态，北极内部没有明显的反馈可以阻止这种凝聚力的变化。涉及较低纬度的负反馈机制能否抵消永久冰的广泛减少以及物理和生物成分的相应变化？可能的候选者是与水平传输的湿静态能量有关的反馈。北极变暖相对于低纬度的放大可能意味着，随着极地温度梯度的放松，热量传输应该会减少，但水分和势能的通量是如何反应的呢？它们能抵消减少的热量传输吗？厄尔尼诺南方涛动和热带海面温度变化等大尺度气候特征对平流有何影响？在哪些地区和季节运输受到的影响最大？本练习将尝试使用新的数据源组合来回答这些问题。欧洲中期天气预报再分析中心(ERA-40)将在北纬70度以南有大量无线电探空仪和其他观测的地区使用，然而，再分析可以同化的信息很少，这是造成许多参数的巨大不确定性和观测与独立测量偏差的原因。为了改善这一问题，从卫星提取的新产品将与ERA-40输出合并，以创建混合半球数据集。这项工作将利用这一资源来调查过去23年来水平能量通量的表现，在此期间，北极系统经历了广泛的变化。这项工作通过关注北极气候系统的初级能源，探索其作为北极变化可能的减缓者的作用，并研究其与全球气候系统的关系，有助于对系统的理解。该项目的目标和方法是：1.从卫星获取的北极地区温度剖面计算潜在能量的日平均通量。显热和水汽通量已经完成。计算ERA-40场的日平均能量和水汽通量，并将它们与70？N以北地区的卫星获取的通量合并，以创建整个北半球(NH)的混合数据集。利用各种空间统计技术和时间序列分析，调查全国各大气层次通量和汇合的空间和时间模式(年度和季节异常和趋势、主要变率模式)。利用多变量相关方法，将观测到的北极各种参数的变化与水平通量的变化联系起来，并将能量平流与大尺度环流模式(如ENSO和NAO)联系起来。

The Arctic system appears to be heading toward a new state that may be unprecedented, and there are no apparent feedbacks within the Arctic that can arrest the cohesive change. Can negative feedback mechanisms involving lower latitudes offset widespread reductions in permanent ice and corresponding changes in physical and biological components? Possible candidates are feedbacks related to horizontally transported moist static energy. The likely amplification of warming in the Arctic relative to lower latitudes implies that heat transport should decrease as the poleward temperature gradient relaxes, but how do the fluxes of moisture and potential energy respond? Can they offset the reduced heat transport? How is advection affected by large-scale climate features such as the El Nino Southern Oscillation and changes in tropical sea surface temperatures? In which regions and seasons are transports most affected? This activity will attempt to answer these questions using a new combination of data sources. The European Center for Medium-Range Weather Forecast Reanalysis (ERA-40) will be used in regions where radiosondes and other observations are plentiful south of 70?N. Over the Arctic, however, there is little information for the reanalyses to assimilate, which is responsible for large uncertainties in many parameters and observed discrepancies with independent measurements. To ameliorate this problem, new products derived from satellite retrievals will be merged with ERA-40 output to create a hybrid hemispheric data set. This effort will use this resource to investigate how horizontal energy fluxes have behaved during the past 23 years, a period during which the Arctic system underwent widespread change. The effort contributes to a system understanding by focusing on the primary energy source for the Arctic climate system, exploring its role as a possible mitigator of Arctic change, and investigating its relationships with the global climate system.The objectives and methods of this project are:1. Calculate daily mean fluxes of potential energy from satellite-derived temperature profiles for the Arctic region. Sensible heat and moisture fluxes have already been completed.2. Calculate daily mean energy and moisture fluxes from ERA-40 fields and merge them with satellite-derived fluxes for the region north of 70?N to create a hybrid data set for the entire Northern Hemisphere (NH).3. Investigate spatial and temporal patterns (annual and seasonal anomalies and trends, dominant modes of variability) in fluxes and convergences at several atmospheric levels throughout the NH using a variety of spatial statistical techniques and time series analysis.4. Relate observed changes in a variety of Arctic parameters to changes in horizontal fluxes and correlate energy advection with large-scale circulation patterns, such as the ENSO and NAO using multivariate correlation methods.