滇西澜沧变质带中白云母的研究及其地质意义

本文以滇西澜沧变质带中最为广泛分布的造岩矿物——白云母为对象,详细研究和分析了其成分、多型类型及b_0值等,探讨了白云母的发育规律。研究结果表明,本带中绝大多数白云母为多硅白云母,且为3T+2M_1型,与蓝闪石共生的则以3T多硅白云母为主。此外,澜沧变质带经历了蓝闪石片岩亚相的高压变质作用,与古特提斯构造演化密切相关,并可与世界著名的高压带对比。     

临界值可变的抗差估计等价权函数

抗差估计等价权函数一般由正态分布统计量构造,其临界值(或称准则)一般由实际经验确定。首先分析了正态分布统计量和学生化残差统计量的区别,然后分别讨论了基于这两种统计量构造的等价权函数的区别。研究表明,利用学生化残差统计量构造的等价权函数以及顾及误差显著性水平确定的临界值,不仅考虑了观测误差的大小,而且还可以顾及了实际观测的图形强度和多余观测数,可以克服人为确定临界值可能带来的参数估计的有效性和抗差性方面的风险。     

云、雨水酸度和离子浓度与其微物理参数的关系

本文1987年5-6月和1989年5-6月庐山地区的实测资料,分析了云、雨水酸度和离子浓度与其微物理量间的关系。结果表明,云、雨滴大小、含水量、谱宽等微物理量的演变直接影响着其酸度和离子浓度。     

气候变化下极端水文事件的研究进展

气候异常变化导致洪涝灾害、干旱等极端水文事件的发生及其增加的水灾害风险正成为人类生存所面临的重大挑战。近年来,开展气候变化背景下流域极端水文事件的变化趋势、发生机理及其对气候变化的响应与预测研究正逐渐受到国内外众多学者的关注。本文从极端水文事件的定义、研究方法、水文极值分布函数、观测事实及模拟研究等方面分析评述了极端水文事件问题的研究现状和研究成果。在此基础上,讨论了研究现状存在的问题并对该领域未来研究方向进行了展望。     

基于SHAP值机器学习的江西暖季暴雨预报因子重要性分析

机器学习模型（Machine Learning,ML）的不可解释性给其在气象业务中的应用带来了挑战。模型解释和可视化是解决这一问题的有效途径。文中将SHAP值应用于天气预报ML模型解释,研究了江西省暖季暴雨模型的预报因子对预报结果的影响。分别选取2016—2020年、2021—2022年4—9月ECWMF（European Centre for Medium-Range Weather Forecasts）高分辨率数值模式物理量及国家站降水观测数据进行XGBoost 建模与模型解释。结果表明,全局重要性排名前4位依次是总降水（重要性42.70%）、850 hPa比湿（重要性11.17%）、925 hPa相对湿度（重要性10.44%）、500 hPa相对湿度（重要性 9.16%）。个例分析表明,命中个例中高重要性物理因子在暴雨区的 SHAP 值较大,漏报（空报）个例在漏报（空报）区域高重要性物理因子的SHAP值偏小（偏大）。SHAP值从全局和局部可定量给出ML模型有物理意义的解释,解释结果与天气学原理和业务经验较一致,有利于ML在气象业务中的深入应用。     

Optimal lake-marsh pattern determination in lake-marsh systems based on the eco-hydrological processes management

The major hydrological factors in lake-marsh systems are water level (depth), water surface area, and water volume. The key index for determining the lake-marsh pattern is water level, which leads to the variation of lake-marsh patterns under natural hydrological alternations. In addition, the vegetation structure also affects the lake-marsh pattern. With socioeconomic development and climate change, the ‘land use’ and ‘water use’ competitions appear more seriously between a lake-marsh system and its surrounding socioeconomic system, also inside the lake-marsh system. The possible optimal lake-marsh pattern could solve the contradictions mentioned above. As few studies focus on this issue, this study proposed an optimal lake-marsh pattern determination method with eco-hydrological management on relieving the land use and water use competitions. The optimal lake-marsh pattern determination method considers the protection objects (water depth demands), water supply (precipitation, surface water, and groundwater), and water demand (especially evapotranspiration) in the system at annual and monthly scales. Calculation and analysis were performed for the optimal pattern of the Wolonghu Wetlands as an example. The results mainly showed that the lake-marsh pattern of the Wolonghu Wetlands cannot be achieved on meeting both the maximum ecological services values and minimum water shortage amount under present natural condition. With artificial regulation measures, the possible optimal annual lake-marsh patterns can be obtained based on both ecological and hydrological objectives, with the area ratio of lake and marsh in the range of 0.650:0.350 and 0.726:0.274, the corresponding water level of lake body was of 86.85 to 87.0 m. This study could provide references for the Wolonghu Wetlands management, also for similar lake-marsh systems and other ecological systems.     

Identifying the source of atmospheric moisture over arid deserts using stable isotopes (2H and 18O) in precipitation

Precipitation is a major component of the hydrologic cycle in arid desert areas. To date, however, few studies have been conducted on investigating the isotope characteristics and moisture sources of precipitation in arid desert environments. The Alxa Desert Plateau is a critical arid desert area in North China. This study is the first to analyse the stable isotopic composition of precipitation to identify the sources of atmospheric moisture over this plateau. Our results show that the δD and δ¹⁸O values of precipitation across the plateau change greatly at both daily and monthly timescales, and exhibit seasonal variations. Among the main meteorological parameters, atmospheric temperature is the most predominant factor controlling the isotopic composition and the δD–δ¹⁸O relationship of local precipitation. Analyses of the precipitation isotopes with the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model reveal that (a) the westerly and polar moisture sources are the dominant controls on summer and winter precipitation and (b) the evaporation of local lake water significantly affects winter precipitation even though it only represents a small amount. Based on the isotope data of 2013–2016 precipitation, a local meteoric water line (LMWL) is derived: δD = (8.20 ± 0.22)·δ¹⁸O + (8.15 ± 2.16)‰ for the study site. Compared to the global meteoric water line, the LMWL has a greater slope and lower d‐excess. This can be explained by admixing of atmospheric moisture resulting from the evaporation of local lake water. Based on this LMWL, we are able to trace that groundwater of the Badain Jaran Desert originates from the surrounding mountains with altitudes of <4,000 m. The newly derived LMWL shows that the recharge altitudes of desert groundwater are overestimated on the basis of the previous LMWLs. This study not only provides insights into the hydrological cycle but also offers guidance for water resource management in arid desert areas of China. Additionally, this study provides techniques that can be applied to the analyses of precipitation isotopes in similar arid regions of the world.     

RESEARCHES ON SOIL ENVIRONMENTAL BACKGROUND VALUES IN TIBET

ＲＥＳＥＡＲＣＨＥＳＯＮＳＯＩＬＥＮＶＩＲＯＮＭＥＮＴＡＬＢＡＣＫＧＲＯＵＮＤＶＡＬＵＥＳＩＮＴＩＢＥＴ￥ＺｈａｎｇＸｉａｏｐｉｎｇ（张晓平）ＫｅＹａｎｇｃｈｕａｎ（科扬川）（ＣｈａｎｇｃｈｕｎＩｎｓｔｉｔｕｔｅｏｆＧｅｏｇｒａｐｈｙ，ｔｈｅＣｈｉｎ...     

BACKGROUND VALUES AND TREND DISTRIBUTION OF Cu, Zn AND Ni IN SOILS IN CHINA

The background values of Cu, Zn and Ni are discussed based on the analytical data of 21 main soil types collected from various regions in China. According to statistics of many samples, the background value of Cu is 23.4±10.2 mg/ kg (482 samples), Zn 77.9±2.39 mg/ kg (474 samples), Ni 30.0±12.8 mg/kg (482 samples).     

Mean values of particular functions in the elliptic motion

The mean values % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXafv3ySLgzGmvETj2BSbqefm0B1jxALjhiov2D% aebbfv3ySLgzGueE0jxyaibaiGc9yrFr0xXdbba91rFfpec8Eeeu0x% Xdbba9frFj0-OqFfea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs% 0dXdbPYxe9vr0-vr0-vqpWqaaeaabiGaciaacaqabeaadaqaaqGaaO% qaamaalaaabaGaaGymaaqaaiaaikdacqaHapaCaaWaa8qCaeaacaGG% OaacbaGaa8NKbiabgkHiTiaadYgacaGGPaGaa8hiaiGacogacaGGVb% Gaai4Caiaa-bcacaWGRbGaa8NKbiaa-bcacaWGKbGaamiBaaWcbaGa% aGimaaqaaiaaikdacqaHapaCa0Gaey4kIipakiaa-bcacaqGHbGaae% OBaiaabsgacaWFGaWaaSaaaeaacaaIXaaabaGaaGOmaiabec8aWbaa% daWdXbqaaiaacIcacaWFsgGaeyOeI0IaamiBaiaacMcacaWFGaGaci% 4CaiaacMgacaGGUbGaa8hiaiaadUgacaWFsgGaa8hiaiaadsgacaWG% SbaaleaacaaIWaaabaGaaGOmaiabec8aWbqdcqGHRiI8aaaa!6BC2!\[\frac{1}{{2\pi }}\int\limits_0^{2\pi } {(f - l) \cos kf dl} {\rm{and}} \frac{1}{{2\pi }}\int\limits_0^{2\pi } {(f - l) \sin kf dl}\] (where f and l are respectively the true anomaly and the mean anomaly in the elliptic motion and k is an integer) are given in closed form.