Climatic regime shift and decadal anomalous events in China

Climatic time series from historical documents and instrumental records from China showed temporal and regional patterns in the last two to three centuries, including two multidecadal oscillations at quasi-20-year and quasi-70-year timescales revealed by signal analysis from wavelet transform. Climatic anomalous events on the decadal timescale were identified based on the two oscillations when their positive (or negative) phases coincide with each other to amplify amplitude. The coldest event occurred in the decade of 1965–1975 in eastern China, while the periods of 1920–1930, 1940–1950, and 1988–2000 appeared to be warmer in most parts of China. For the precipitation series in northern China, the dry anomalous event was found in the late 1920s, while the wet anomalous event occurred in the 1950s. A severe drought in 1927–1929 in northern China coincided with the anomalous warm and dry decade, caused large-scale famine in nine provinces over northern China. Climatic anomalous events with a warm-dry or cold-wet association in the physical climate system would potentially cause severe negative impacts on natural ecosystem in the key vulnerable region over northern China. The spatial pattern of summer rainfall anomalies in the eastern China monsoon region showed an opposite variations in phase between the Yellow River Valley (North China) and the mid-low Yangtze River Valley as well as accompanied the shift of the northernmost monsoon boundary. Climatic regime shifts for different time points in the last 200 years were identified. In North China, transitions from dry to wet periods occurred around 1800, 1875, and 1940 while the transitions from wet to dry periods appeared around 1840, 1910, and the late 1970s. The reversal transition in these time points can also be found in the lower Yangtze River. Climatic regime shifts in China were linked to the interaction of mid- and low latitude atmospheric circulations (the westerly flow and the monsoon flow) when they cross the Tibetan Plateau in East Asia.     

华南区域季节性降水的差异分析

运用EOF方法研究华南区域降水时空分布特征,结果表明：（1）华南地区各季节降水在年际和年代际的时间变化上有区域一致性,但有季节性差异,其中春季和秋季在20世纪80年代后降水明显减少,旱年增多;而夏季90年代后降水明显增加,涝年增多;冬季变化则不明显。（2）华南地区各季节降水在空间分布上也有差异,其中春季降水呈现东多西少的分布特征,大值中心位于广西东北部、广东中部及西南沿海。夏季和秋季降水相似,呈南多北少的分布特征,大值中心位于广西沿海和广东西南沿海。冬季降水呈东北多西南少的分布特征,大值中心位于粤北。     

利用掩星资料分析东亚地区云厚的分布特征

利用2007年1月至2009年1月COSMIC掩星湿空气数据,基于相对湿度廓线出入云层时发生突变反演云边界高度的思想,统计分析了东亚地区云厚的分布特征。结果表明,掩星最低探测高度集中在3km以下,主要影响部分中云和低云云厚的反演。云发生概率沿纬度和经度方向呈现不同的分布特征,各类云概率随高度也有不同的变化规律。东亚地区所有云的平均厚度为1.78km,其中单层云和顶层云分布相似,双层云与其他云层的地理差异不大,单层云在春秋季分布相对均匀,而在夏冬季差异较大。夏季和冬季顶层云云顶高与云厚的二维频率分布各异,主要在于夏季有更多云体较厚且位于对流层上部的高云存在。     

长江下游仪征河段汊道分流属性及航道滩槽演变机制

长江下游仪征河段处于枯季潮流界的上边界,揭示其汊道分流属性及滩槽联动演变机制,对河势控制工程及深水航道工程实践具有重要意义.本研究收集了1955—2021年水文泥沙及地形等资料,在汊道分流关系及调整成因上:世业洲右汊的分流属性为枯水倾向型汊道,即低流量时期分流比大于高流量时期;1959—2021年期间,世业洲右汊分流比经历了“稳定-下降-上升”的调整过程,上游河段滩槽格局调整及流域来沙减少引起的汊道间不均衡冲刷是分流关系调整的主因;流域流量过程调整、河道崩岸等综合影响引起1959—2017年期间世业洲右汊分流比为减小态势,航道工程实施起到了调控汊道关系的功能,世业洲右汊分流比为增加态势.在滩槽联动演变关系上:仪征河段进口段以展宽为主,世业洲左汊展宽程度大于右汊,左汊河床形态变化与进口段滩槽形态的一致性关系优于右汊,即上游进口段滩槽演变、流域来沙量减少等综合作用会加速了左汊发展;2015年南京以下12.5 m深水航道二期工程建设以来,工程区域淤积且洲体完整性增强,且深槽冲刷及河槽容积增大,表明航道工程已实现汊道分流关系及滩槽调控的功能.     

ȱʧ�����»���EM�㷨��GPS�߳����

GPS????????????????????????????????????????????????????????????????????????ó??淽?????????????????????????????EM?????????????????????????????????????????????????????Ч????????????μ?GPS??????????     

A Case study of a snowstorm at the Great Wall Station,Antarctica

A case of a snowstorm at the Great Wall Station was studied using data of NCEP (National Centers for Environmental Prediction) analysis, in situ observations and surface weather charts. The storm occurred on August 29th,2006, and brought high winds and poor horizontal visibility to the region.It was found that the storm occurred under the synoptic situation of a high in the south and a low in the north. A low-level easterly jet from the Antarctic continent significantly decreased the air temperature and humidity.Warm air advection at high level brought sufficient vapor from lower latitudes for the snowstorm to develop.The dynamic factors relating to strong snowfall and even the developmentof a snowstorm were deep cyclonic vorticity at middle and low levels,the configuration of divergence at high level and convergence at low level, and strong verticaluplift. There was an inversion layer in the low-level atmosphere during the later phase of the storm.This vertical structure of cold air at low levels and warm air at high levels may have been important to the longevity of the snowstorm.     

Occurrence and Diversity of Candida Genus in Marine Environments

A total of 317 yeast isolates from seawater,sediments,mud of salterns,guts of marine fishes and marine algae wereobtained.The results of routine identification and molecular characterization showed that six isolates among these marine yeastsbelonged to Candida genus as Candida interrnedia for YA01a,Candida parapsilosis for 3eA2,Candida quercitrusa for JHSb,Can-die rugosa for wl8,Candida zeylanoides for TJY13a,and Candida membranifaciens for W14-3.Isolates YA01a (Candida interme-die),wl8 (Candida rugosa),3eA2 (Candida parapsilosis),and JHSb (Candida quercitrusa) were found producing cell-bound lipase,while isolate W14-3 (Candida membranifaciens) producing riboflavin.These marine yeast Candida spp.Seem to have wide potentialapplications in biotechnology.     

不同方法对冬小麦地块级估产的适用性研究

为了探究不同估产模型对冬小麦估产的精度和适用性,提高像元级和地块级冬小麦估产精度。利用机器学习方法支持向量机（SVM）模型、随机森林（RF）模型和深度学习方法长短期记忆（LSTM）模型,对冬小麦进行产量预估。结果表明：在像元级上,LSTM模型、RF模型估产精度高于SVM模型,LSTM模型不仅能够表征作物在生育期的生长变化,还能降低人为因素干扰,估产结果更加客观真实,而SVM模型、RF模型易受到特征共线性和过拟合的影响,因此SVM模型、RF模型更适用于区域性小范围估产。在地块级上,SVM模型、RF模型和LSTM模型地块级估产精度比像元级估产精度均有提高,且LSTM模型估产精度明显高于SVM模型和RF模型,因此LSTM模型更适用于地块级估产,且LSTM模型泛化能力强、普适性高,适用于大范围农作物估产。     

OC4漂浮式风电平台的水弹性响应及波浪载荷研究

漂浮式风电平台在波浪中的摇晃运动会导致塔架根部产生很大的弯矩,极大地威胁平台结构安全。同时流体的附连水质量效应对平台塔架结构的动响应有着较为显著的影响,因此充分考虑这种流固耦合效应有利于更加准确地评估平台塔架的结构动响应。采用三维频域线性水弹性方法计算塔架在流体作用下的结构共振频率特征以及各阶模态振动的主坐标响应特性,然后通过弹性模态叠加法获得塔架的弯矩载荷。并结合概率学手段,预报了短期极限海况下塔架弯曲载荷响应,为新一代漂浮式风电平台结构安全性评估和方案设计提供了技术支撑。