北京暴雨与旱涝关系的分析   总被引：11，自引：1，他引：10       下载免费PDF全文

吴正华  储锁龙 《应用气象学报》1998,9(4):492-495

根据北京近百年的逐日降水资料,分析了汛期暴雨与汛期旱涝的关系。指出:汛期暴雨多少和强度对汛期降水丰歉具有决定性作用;在给出的3种暴雨指数中,相当暴雨日数与旱涝级别的相关性最好。文中还讨论了旱涝短期气候预测与暴雨过程的短期气候预测相结合的必要性。  相似文献   

“地气图”方法用于省级旱涝预测的实践     

郭维栋  赵红岩  李栋梁  郭英香 《干旱气象》1998,(4)

简要介绍用“地气图”方法进行降水预测的基本思路,总结此方法的预报实践,指出省级尺度旱涝预测需要解决的几个关键问题,强调除加密观测外,上游地热涡增强的能量频散作用是下游地热涡发展的重要原因  相似文献   

甘肃中部雨养农业区土壤水分预测模式的研究   总被引：5，自引：0，他引：5  

杨兴国  柯晓新  张旭东  万信 《干旱气象》1998,(4)

采用联合国粮农组织（ＦＡＯ）最新推荐的计算农田蒸散量的彭曼－蒙蒂斯公式（ＦＡＯ－ＰＭ）,选取甘肃中部雨养农业区定西１９８０～１９９５年的常规气象资料和１９９０～１９９５年固定地段０～１００ｃｍ的土壤湿度资料,对水平衡和Ｙ．Ｍ安格斯坦土壤水分预测模式进行对比分析,认为后者适宜于本地区的土壤水分预测,并分析了误差原因  相似文献   

Lichens and the determination of river channel capacity     

Ken J. Gregory 《地球表面变化过程与地形》1976,1(3):273-285

The identification of channel capacity associated with a particular frequency of peak discharges is necessary for discharge estimation for planning purposes at ungauged sites. Although lichen limits have been suggested to be useful for this purpose, previous studies have not elaborated their hydrological significance. Lichen limits are clearly defined on the sides of rock channels in New England. Australia and they are analyzed in relation to discharge at 6 gauging stations with up to 52 years of continuous record. It is demonstrated that the lowest lichen limit is maintained by peak discharges which occur on average at least once or twice each year. Recurrence intervals based on Annual Series and on Annual Exceedance Series are calculated and for the annual series are fairly consistent for the lowest lichen limit and range from 1·14 to 1·37 years. Lichenometry can be applied to the analysis of river channels in relation to the frequency of peak discharges. By reference to growth curves based upon lichens on Armidale tombstones it is shown that lichenometry may be employed to indicate dates for channel modification due to the removal of blocks and to dam construction and also to date the rock surface between lichen limits. Detailed analysis of the record from gauging stations indicates that where several lichen limits occur in a channel cross section each limit is related to periods when peak discharges exceeded the limits on at least 5 occasions. The lichen-free surfaces were then recolonized by Parmelia spp. and the size of the lichen thalli indicates the time elapsing since these frequent high discharges.  相似文献   

Numerical weather prediction relevant to the monsoon problem     

T. N. Krishnamurti  John Molinari  Hua-Lu Pan  Vince Wong 《Pure and Applied Geophysics》1977,115(5-6):1357-1372

In this short paper we have identified some of the modelling groups that have the capability of simulating or carrying out short range numerical weather prediction over the monsoon belt. We have next outlined some of the important and desirable ingredients for a multilevel primitive equation model over the tropics, with most of the emphasis on the present version of Florida State University's Tropical Prediction Model. Finally, we present briefly some important results based on the present version of our prediction models that relate to the NWP efforts over the monsoon belt. Here we have identified the importance of mountains, convection, the radiative heating balance of the earth's surface, and the planetary boundary layer over the Arabian Sea.  相似文献   

STUDY OF RED TIDE PREDICTION MODEL FOR THE CHANGJIANG ESTUARY     

王正方  吕海燕  张庆  卢勇  曾江宁  周青松 《中国海洋湖沼学报》2000,18(4):350-354

ＩＮＴＲＯＤＵＣＴＩＯＮＡｑｕｉｃｕｌｔｕｒｅａｒｅａｒｅｄｔｉｄｅｓｉｇｎａｌｓｏｃｅａｎｐｏｌｌｕｔｉｏｎａｎｄｄｉｓａｓｔｅｒ.Ａｌｔｈｏｕｇｈｅｎｖｉｒｏｎｍｅｎｔｓｃｉｅｎｔｉｓｔｓｈａｖｅｃｏｎｄｕｃｔｅｄｍａｎｙｉｎ ｄｅｐｔｈｒｅｓｅａｒｃｈｅｓｏｎｔｈｅｃａｕｓｅａｎｄｆｏｒｍａｔｉｏｎｍｅｃｈａｎｉｓｍｏｆｒｅｄｔｉｄｅ ,ｍａｎｙｏｆｉｔｓａｓｐｅｃｔｓａｒｅｓｔｉｌｌｕｎｋｎｏｗｎｂｅｃａｕｓｅｒｅｄｔｉｄｅｉｓａｃｏｍｐｌｅｘｐｈｅｎｏｍｅｎｏｎａｎｄｔｈｅｅｃｏｌｏｇｉｃ…  相似文献   

Pleistocene climatic change in Southern Australia and its effect on speleothem deposition in some Nullarbor caves     

Albert Coede  Russell S. Harmon  Tim C. Atkinson  Peter J. Rowe 《第四纪科学杂志》1990,5(1):29-38

Activity ratios of ²³⁴U/²³⁸U, ²³⁰Th/²³⁴U, and ²³⁰Th/²³²Th have been determined for calcite, gypsum and halite speleothems from caves of the Nullarbor Plain, mostly in the area N and NW of Mundrabilla Station, for the purpose of U-series dating. All calcite speleothems contain adequate amounts of uranium for dating, but some show an excess of ²³⁰Th. Stratigraphic relationships indicate that there were at least three phases of calcium carbonate deposition in the Nullarbor caves. The calcite samples, with one possible exception, have ages in excess of ca. 400000 yrs BP. This suggests that no significant amounts of calcium carbonate deposition have taken place during the last 400ka. At present, active deposition of speleothems is restricted almost entirely to gypsum and halite. The only gypsum speleothem dated was found to have a finite age of ca. 185 ka. Six dates on a small halite speleothem containing insect and arachnid remains indicate that it formed rapidly during Holocene time.  相似文献   

Dissolved organic nitrogen dynamics in the North Sea: A time series analysis (1995–2005)     

T. Van Engeland  K. Soetaert  A. Knuijt  R.W.P.M. Laane  J.J. Middelburg 《Estuarine, Coastal and Shelf Science》2010

Dissolved organic nitrogen (DON) dynamics in the North Sea was explored by means of long-term time series of nitrogen parameters from the Dutch national monitoring program. Generally, the data quality was good with little missing data points. Different imputation methods were used to verify the robustness of the patterns against these missing data. No long-term trends in DON concentrations were found over the sampling period (1995–2005). Inter-annual variability in the different time series showed both common and station-specific behavior. The stations could be divided into two regions, based on absolute concentrations and the dominant times scales of variability. Average DON concentrations were 11 μmol l⁻¹ in the coastal region and 5 μmol l⁻¹ in the open sea. Organic fractions of total dissolved nitrogen (TDN) averaged 38 and 71% in the coastal zone and open sea, respectively, but increased over time due to decreasing dissolved inorganic nitrogen (DIN) concentrations. In both regions intra-annual variability dominated over inter-annual variability, but DON variation in the open sea was markedly shifted towards shorter time scales relative to coastal stations. In the coastal zone a consistent seasonal DON cycle existed with high values in spring–summer and low values in autumn–winter. In the open sea seasonality was weak. A marked shift in the seasonality was found at the Dogger Bank, with DON accumulation towards summer and low values in winter prior to 1999, and accumulation in spring and decline throughout summer after 1999. This study clearly shows that DON is a dynamic actor in the North Sea and should be monitored systematically to enable us to understand fully the functioning of this ecosystem.  相似文献   

浅谈三轮区划与地理信息系统     

李文鑫 《南方国土资源》1999,12(4):612

文章简单介绍了三轮区划的工作任务和技术要求 ,以及在三轮区划工作中运用地理信息系统实现多学科矿产综合预测的工作方法。  相似文献   

A comparative study of extensive machine learning models for predicting long-term monthly rainfall with an ensemble of climatic and meteorological predictors     

Zhengzheng Zhou  Jie Ren  Xiaogang He  Shuguang Liu 《水文研究》2021,35(11):e14424

Rainfall prediction is of vital importance in water resources management. Accurate long-term rainfall prediction remains an open and challenging problem. Machine learning techniques, as an increasingly popular approach, provide an attractive alternative to traditional methods. The main objective of this study was to improve the prediction accuracy of machine learning-based methods for monthly rainfall, and to improve the understanding of the role of large-scale climatic variables and local meteorological variables in rainfall prediction. One regression model autoregressive integrated moving average model (ARIMA) and five state-of-the-art machine learning algorithms, including artificial neural networks, support vector machine, random forest (RF), gradient boosting regression, and dual-stage attention-based recurrent neural network, were implemented for monthly rainfall prediction over 25 stations in the East China region. The results showed that the ML models outperformed ARIMA model, and RF relatively outperformed other models. Local meteorological variables, humidity, and sunshine duration, were the most important predictors in improving prediction accuracy. 4-month lagged Western North Pacific Monsoon had higher importance than other large-scale climatic variables. The overall output of rainfall prediction was scalable and could be readily generalized to other regions.  相似文献