1960-2020年东北黑土区水蚀动力因子时空格局及其对主要大气海洋环流模式的响应

Response of Spatial and Temporal Patterns of Water Erosion Dynamic Factors to the Main Atmospheric and Oceanic Circulation Patterns in the Chinese Mollisol Region During 1960-2020

[目的]研究东北黑土区水蚀动力因子的时空格局及其对大气海洋环流模式的响应,对区域极端降水事件诱发的土壤侵蚀防治有重要意义。[方法]选用降雨侵蚀力(R)、暴雨雨量(R 50p)、极端强降水量(R 95p)、连续5日最大降水量(R 5d)表征水蚀动力因子,基于1960-2020年逐日降雨数据,采用滑动平均、小波分析、Sen斜率估计法、Mann-Kendall检验方法,分析1960-2020年东北黑土区水蚀动力因子的时空格局,解析水蚀动力因子对大气海洋环流模式的响应。[结果](1)东北黑土区的年降雨侵蚀力(R)为1145.36~3575.94(MJ·mm)/(hm^(2)·h·a),暴雨雨量(R 50p)为73.17~197.86 mm,极端强降水量(R 95p)为265.81~566.35 mm;连续5日最大降水量(R 5d)为69.67~124.95 mm。(2)东北黑土区4个水蚀动力因子在1960-2000年均呈不显著上升趋势,且均未发生整体突变,但2015年后上升趋势明显,表明研究区发生降雨侵蚀的潜在可能性增加。4个水蚀动力因子均存在以约44年为主周期,29年为小周期的周期性变化特征,并经历高低交替2次振荡过程。(3)各水蚀动力因子的空间分布均呈现南高北低,东西两侧低中部高的特征,各指标的最大值出现在长白山-完达山山地丘陵区,最小值出现在呼伦贝尔丘陵平原区。(4)东亚夏季风指数(EASMI)是对东北黑土区水蚀动力因子影响最显著的单一环流模式,北极涛动(AO)和多元ENSO-南方涛动指数(MEI)可以通过影响东亚夏季风间接影响水蚀动力因子。东亚夏季风指数-南海夏季风指数叠加(EASMI-SCSSMI)对各水蚀动力因子的影响均为最显著(ΔPSAC>5%);而东亚夏季风指数、南海夏季风指数和多元ENSO-南方涛动的大气海洋环流模式仅对降雨侵蚀力(R)影响显著(ΔPSAC>5%)。[结论]东北黑土区水蚀动力时空格局的影响因素主要包括地形、东亚夏季风和南亚夏季风等,需关注2014年后水蚀动力增强带来的潜在水蚀危害。

[Objective]A study on the spatial and temporal patterns of water erosion dynamic factors and their responses to atmospheric and oceanic circulation patterns in the Mollisol region of Northeast China is crucial for preventing and controlling soil erosion in the context of frequent extreme precipitation events.[Methods]Four water erosion dynamic factors,including rainfall erosivity(R),heavy rainfall(R 50p),very wet day precipitation(R 95p)and the maximum five-day rainfall(R 5d),were selected to characterize water erosion dynamic factors.Based on daily rainfall data from 1960 to 2020,the spatial and temporal patterns of the water erosion dynamic factors in the Chinese Mollisol region in 1960-2020 were analyzed using the moving average,wavelet analysis,Sen's method and Mann-Kendall test methods,and the responses of water erosion dynamic factors to atmospheric and ocean circulation patterns were analyzed.[Results](1)The annual rainfall erosivity R varied from 1145.36 to 3575.94(MJ·mm)/(hm^(2)·h·a),heavy rainfall amount R 50p was between 73.17 and 197.86 mm,very wet day precipitation R 95p varied from 265.81 to 566.35 mm,and maximum five-day rainfall R 5d varied from 69.67 to 124.95 mm in the Chinese Mollisol region from 1960 to 2000.(2)These water erosion dynamic factors in the study region did not show a significantly increasing trend over the past 61 years and did not show an overall abrupt change,but a noticeable upward trend was observed after 2015,which hinted that potential risk of rainfall erosion could rise in the near future.Moreover,the water erosion dynamic factors displayed periodic changes with a main cycle of approximately 44 years and a secondary cycle of 29 years,and they went through two oscillatory processes with high and low levels.(3)The spatial distributions of these water erosion dynamic factors showed high values in the south and central parts,and low values in the north,east and west parts.The maximum values occurred in the Changbai-Wanda hilly area,while the minimum values were in the Hulunbeier hilly plain area.(4)In addition,the East Asian Summer Monsoon Index(EASMI)was the most important single circulation pattern affected the water erosion dynamic factors,while the Arctic Oscillation(AO)and Multivariate ENSO Index(MEI)could indirectly affect the water erosion dynamic factors in the Chinese Mollisol region by influencing the East Asian summer monsoon.The superposition of the East Asian Summer Monsoon Index and the South China Sea Monsoon Index(EASMI-SCSSMI)had the most significant impact on water erosion dynamic factors(ΔPSAC>5%),while three circulation patterns of the East Asian Summer Monsoon Index,the South China Sea Monsoon Index and the Multivariate ENSO Index only significantly affected rainfall erosivity R(ΔPSAC>5%).[Conclusion]The factors that influence the spatial and temporal patterns of water erosion dynamics in the mollisol region of northeast China included topography,East Asian summer monsoon and South Asian summer monsoon,etc.Additionally,it is essential to be aware of the potential water erosion that may occur due to the rebound of water erosion dynamics after 2014.