Abstract

An increase in warming in the Arctic relative to the rest of the Northern Hemisphere or the globe continues attracting attention, despite the large amount of research being conducted. Possible causes of the Arctic amplification have been considered and continue to be discussed in many articles and reviews. In this article, for the first time, a quantitative assessment of the role of atmospheric transports in the formation of variability and trends in the mean near-surface air temperature (SAT) in the Arctic and at adjacent latitudes of the Northern Hemisphere is carried out and an analytical description of amplification in high latitudes is proposed. For the study, data from NCEP and ERA5 reanalyses for 1989–2020 and a representation of the set of events of air exchange between latitudes in a simple hemispheric atmospheric model under constant conditions at the boundaries, on the basis of which analytical expressions are obtained for the standard deviation ratios (SDRs) and temperature trends in neighboring areas. The degree of closeness between the empirical and model ratios of SDR and trends is taken as a contribution measure of air exchange to the increase in SDR and trends during warming. It has been found that the exchange between the polar and adjacent regions reaches lower latitudes as the polar region expands from 70° N up to 60° N. The latitude to which the polar air propagates on average decreases with the trend taken into account in the SDR, which confirms the effect of warming on the increase in air mass exchange. The model value of the increase in the average air temperature trend in the polar region of an isolated homogeneous atmosphere above the hemisphere relative to the trend in the adjacent region is determined by the ratio of their areas multiplied by the ratio of the trend determination coefficients. An increase in the temperature trend in the polar region of the real atmosphere, according to the NCEP and ERA5 reanalyses for 1989–2020, was compared with the model value, thereby assessing the contribution of air mass exchange to the increase in the temperature trend in the polar region. It was found that the exchange explains 54% of the increase in the air temperature trend (Arctic amplification) in the region of 90–60° N on average per year and 66% in the cold year part relative to the rest of the Northern Hemisphere. If we take into account the established southern boundary of air mass exchange between the polar and adjacent regions, then the amplification of an air temperature trend in the area of 90–60° N relative to the trend in the adjacent area, with which the exchange of air masses occurs, will almost completely (by 93% on average per year) be the result of exchange and, in the area of 90°–70° N, it will mostly be the result of exchange (by 74% on average per year).

中文翻译：

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北极放大：大气中的跨纬度交换作用

摘要

尽管进行了大量研究，但北极相对于北半球其他地区或全球变暖的加剧继续引起人们的关注。许多文章和评论已经考虑并继续讨论了北极扩大的可能原因。在本文中，首次对大气输送在北极和北半球邻近纬度的平均近地表气温（SAT）变化和趋势形成中的作用进行了定量评估并提出了高纬度地区放大的分析描述。在这项研究中，对 1989 年至 2020 年 NCEP 和 ERA5 的数据进行了重新分析，并在边界恒定条件下，在简单的半球大气模型中表示了纬度之间空气交换的一组事件，在此基础上获得了解析表达式标准偏差比 (SDR) 和邻近地区的温度趋势。将SDR与趋势的经验比率和模型比率之间的接近程度作为变暖期间空气交换对SDR和趋势增加的贡献度量。研究发现，随着极地从北纬70°扩大到北纬60°，极地与邻近地区之间的交换达到了较低的纬度。极地空气平均传播的纬度随着考虑到的趋势而降低。 SDR，证实了变暖对空气质量交换增加的影响。半球上方孤立均匀大气的极地区域平均气温趋势相对于邻近区域趋势增加的模型值由它们的面积之比乘以趋势决定系数之比确定。根据 NCEP 和 ERA5 对 1989-2020 年的再分析，将真实大气极地地区温度趋势的增加与模型值进行比较，从而评估气团交换对极地地区温度趋势增加的贡献。极地地区。研究发现，相对于北半球其他地区，这种交换解释了每年平均 90-60° N 地区气温趋势增加的 54%，以及寒冷年份部分相对于北半球其他地区的 66% 。如果我们考虑到极地和邻近地区之间已建立的空气质量交换的南部边界，那么北纬 90-60° 地区的气温趋势相对于邻近地区的趋势会放大，从而交换量也随之增加。的气团发生，几乎完全（平均每年 93%）是交换的结果，在 90°–70° N 地区，大部分是交换的结果（平均每年 74%）年）。