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利用1980～1994年NCEP/NCAR月平均高度场和我国测站降水量资料,通过奇异值分解方法探讨了华北汛期降水与500,200 hPa欧亚中高纬大气环流异常的关系,得到与华北汛期旱涝有关的两类异常环流型。     

Predicting June Mean Rainfall in the Middle/Lower Yangtze River Basin

We demonstrate that there is significant skill in the GloSea5 operational seasonal forecasting system for predicting June mean rainfall in the middle/lower Yangtze River basin up to four months in advance. Much of the rainfall in this region during June is contributed by the mei-yu rain band. We find that similar skill exists for predicting the East Asian summer monsoon index(EASMI) on monthly time scales, and that the latter could be used as a proxy to predict the regional rainfall. However, th...     

Contrasting Regional Responses of Indian Summer Monsoon Rainfall to Exhausted Spring and Concurrently Emerging Summer El Ni?o Events

The inverse relationship between the warm phase of the El Ni?o Southern Oscillation(ENSO) and the Indian Summer Monsoon Rainfall(ISMR) is well established. Yet, some El Ni?o events that occur in the early months of the year(boreal spring) transform into a neutral phase before the start of summer, whereas others begin in the boreal summer and persist in a positive phase throughout the summer monsoon season. This study investigates the distinct influences of an exhausted spring El Ni?o(springtime)...     

Another Year of Record Heat for the Oceans

Changes in ocean heat content(OHC), salinity, and stratification provide critical indicators for changes in Earth’s energy and water cycles. These cycles have been profoundly altered due to the emission of greenhouse gasses and other anthropogenic substances by human activities, driving pervasive changes in Earth’s climate system. In 2022, the world’s oceans, as given by OHC, were again the hottest in the historical record and exceeded the previous 2021 record maximum.According to IAP/CAS data, ...     

Skilful Forecasts of Summer Rainfall in the Yangtze River Basin from November

Variability in the East Asian summer monsoon(EASM) brings the risk of heavy flooding or drought to the Yangtze River basin, with potentially devastating impacts. Early forecasts of the likelihood of enhanced or reduced monsoon rainfall can enable better management of water and hydropower resources by decision-makers, supporting livelihoods and major economic and population centres across eastern China. This paper demonstrates that the EASM is predictable in a dynamical forecast model from the pr...     

垂直指向多卜勒雷达测量大气垂直运动和雨滴谱等物理量的方法

在假定雨滴谱为指数分布的基础上,本文提出用垂直指向多卜勒雷达同时测量与雨和风有关的参量的新方法,即用多卜勒谱的倾斜率M_3(也就是谱的三阶中心距)和反射因子Z估计谱参量N_0和λ、大气垂直速度、由风切变和乱流引起的多卜勒谱宽、降雨含水量M和雨强R。这方法的主要优点在于乱流和风切变对M3的影响很小。作者在理论上和用数值模拟分析讨论了这方法的原理和误差。对一实例计算表明,M_3确实是与实测多卜勒谱有关的信号。最后对文中提出的由M3选择确切的λ值的技术作了初步讨论。     

河谷地区日降水量与中尺度环流之间的关系

到目前为止,世界上对降水量日变化已进行了几十年的研究,这些研究包括对强风暴进行的研究,以及对降水频繁的热带和中纬度地区的夏季强对流的研究。尽管这些研究充分揭示了十二小时内的降水变化,并发现了强对流发生频率最大的地区,但是对盆地及山谷的降水仍缺乏详细的研究。     

厄尔尼诺-南方涛动模式研究

研制了一个海-气耦合模式,并用于讨论ENSO现象。在没有异常的外部强迫作用的条件下,该耦合模式再现了观测现象的某些关键特征,其中包括增暖事件多以3—4年的不规则时间间隔重新出现。研究表明,平均海平面温度、风和洋流场确定ENSO距平的特征空间结构。距平的锁相(phase-locking)趋势可以用与平均场年变程有关的耦合强度的变化来解释。敏感性研究发现,振荡的振幅和时间尺度对于影响海-气耦合强度的几个参数是敏感的。较强的耦合意味着较大、较长时间尺度的振荡。模式振荡的关键性因素是赤道海水上部含热量的变化率,赤道地区含热量在增暖事件之前增加,在增暖过程中急剧减少。给出了这种变化率和有关El Nino与非El Nino状态之间转化的理论。还讨论了预报El Nino事件的模式结果的含意。     

从短期风记录进行风能的估算

1.引言为便于判断是否适合安装风能转换系统(WECS)和对候选地点作出选择,需要定点的长期平均风能资料。由于常常不可能在每个地点上都有长期可用的平均资料,所以切合实际的办法是依靠短期的测量(但足以作出适当的估算)或者是依靠别的可替换的估算方法。 Corotis等人(1977)发现,由一年的数据     

有关森林天然火灾的低层风和温度廓线

1.引言对负责森林火险天气预报人员来说,查看一下简单的气象图表,并确定气象条件是否有利于星星之火发展到不可控制的大火那将是非常必要的。由于近地面天气状况是受制于高层天气过程的,而火灾又是一种三度空间现象,与大气的铅直剖面关系密切。风和温度随高度变化影响大气对流的强弱,也影响林火的发生和发展。近年来,人们一直在探讨这些因素对森林天然火灾的影响。 1954年,拜厄姆(Byram)提出了在“点燃”林火的上空是某些特殊的风廓线。其要点之一是在火场的上空,风力由近地面的最大值一直到大约2400米附近的高度,而后随高度递减。他认为这样有利于火场上空对流柱的发展,由此能增强在地面火势的强度。