东亚冬季风异常与广东前汛期旱涝关系的初步分析

利用500hPa北半球格点资料,参照历史平均东亚大槽位置,定义了东亚冬季风强度指数(I₅₀₀)。分析发现,近50年东亚冬季风强度有减弱趋势,特别是1987年以来冬季风明显减弱。根据广东48个站1954～2004年前汛期(4～6月)降水资料,用区域旱涝指数W对广东前汛期旱涝等级进行划分。51年内广东有9年前汛期出现大涝(或特涝),11年出现大旱(或特旱),旱涝发生频繁。冬季风异常对广东前汛期降水的影响比较大,强冬季风年后广东前汛期出现大旱的可能性较大,而出现大涝的可能性很小。     

华北平原中尺度低气压的若干事实

本文对产生在太行山东侧华北平原行星边界层内的中尺度低压系统进行了普查分析,同时还使用了专门的探测资料,基本弄清了有关中低压的若干事实;探讨了有利于产生中低压的天气条件和华北地形对形成中低压的重要作用;分析了中低压的某些生消规律。     

层状冷云数值模式

为了研究层状冷云自然降水和人工降水的机制建立了一维非定常的数值模式。考察了宏微观参数和冰的凝华、淞附和繁生等过程对云中要素分布和降水的影响。并作了不同条件下播云的数值试验。     

Past,present and future climatic forcing due to greenhouse gases

An advanced one-dimensional radiative-convective model (RCM) is used to estimate the past, present and fu-ture climatic forcings induced by greenhouse gases of anthropogenic origin, such as CO2, CH4, N2O and CFCs, in this paper. The results show that the decadal climatic forcing for the last decade is one-order bigger than that prior to the year 1900, and in the case of no control on the emission of the greenhouse gases the climatic forcing for the year 2100 will be almost 4 times as much as now.     

MM5模式中不同对流参数化方案的比较试验

应用MM5中尺度模式, 在60、20和10 km模式分辨率下, 分别选用4种不同对流参数化方案 (KUO方案、GRELL方案、KAIN-FRITSCH方案和BETTS-MILLER方案, 以下简称KU、GR、KF和BM方案) 对1996年8月3~4日石家庄暴雨过程进行数值模拟试验.模拟结果的对比分析及其与观测的比较表明:主要雨带位置对参数化方案并不是十分敏感, 但随分辨率提高, 雨带分布特征的模拟更接近实况; 当分辨率提高到10 km时, 虚假的降水中心也明显增加; 模拟的暴雨中心强度随分辨率的提高而增强并随参数化方案的不同有所变化, 但均比实况偏弱.分析还发现, MM5模式的GR、KF及BM方案的次网格降水对总降水的贡献率随分辨率的提高而减小, 而KU方案的情况则呈现出不合理的缓慢增加态势.虽然4种方案下模拟的水平环流特征有较好的一致性, 但模拟的云物理特征和垂直运动特征还是存在一定差别的, 这种差别对定点、定量降水和天空状况、地面气温、湿度等要素的准确预报都会产生影响.因此, 在预报和模拟中应考虑预报和研究对象的特点来选择对流参数化方案.     

中国海相油气田勘探实例之十三 塔里木盆地东河塘海相砂岩油田勘探与发现

东河塘油田位于新疆库车县,构造上隶属于塔里木盆地塔北隆起轮台凸起东河塘断裂构造带,是我国发现的第一个高产高丰度海相砂岩油田,它的发现是中国海相砂岩油气勘探理论和实践的一次重大突破。油田发现于1990年7月,至1994年探明石油地质储量3323.13×104t,天然气地质储量15.5×108m3,至2009年底累计产原油825.75×104t。石炭系东河砂岩油藏是东河塘油田的主体,其储层东河砂岩段是一套滨岸相砂体,具有厚度巨大、埋深大、储集性能好的特点;其油藏类型为块状底水背斜油藏,产能高,储量丰度高。论述了东河塘油田勘探与发现的历程,剖析了取得勘探成功的实践认识与意义。     

雷达在水文预报应用中的研究进展

雷达可随时跟踪雨区范围、暴雨走向和降雨量的变化,而降雨是水文预报最重要的输入信息,对于水文预报、水库蓄放及江河流域水量的短时洪水预报都是很重要的。本文在介绍雷达测雨及国内外雷达测雨业务系统的基础上,重点总结了国内雷达测雨在水文预报中的研究进展,并提出了雷达在水文预报中的应用思路,探讨了雷达测雨在我国水文应用中的前景及其发展方向。数字化雷达测雨、地理信息系统以及数字高程图等系列新信息,将进一步推动新一代分布式降雨—径流模型的开发,并将极大地拓宽水文预报研究的思路和方法,从而提高预报精度。     

Land surface temperature shaped by urban fractions in megacity region

The influence of spatial scales on surface fluxes is an interesting but not fully investigated question. This paper presents an analysis on the influence of spatial scales on surface fluxes in the north Tibetan Plateau based on eddy covariance (EC) and large aperture scintillometer (LAS) data at site Nagqu/BJ, combined with the land surface temperature (LST) and normalized difference vegetation index (NDVI) of moderate-resolution imaging spectroradiometer (MODIS). The analysis shows that sensible heat fluxes calculated with LAS data (H_LAS) agree reasonably well with sensible heat fluxes calculated with EC data (H_EC) in the rain and dry seasons. The difference in their footprints due to the wind direction is an important reason for the differences in H_EC and H_LAS. The H_LAS are statistically more consistent with H_EC when their footprints overlap than when their footprints do not. A detailed analysis on H_EC and H_LAS changes with net radiation and wind direction in rain and dry season indicates that the spatial heterogeneity in net radiation created by clouds contributes greatly to the differences in H_EC and H_LAS in short-term variations. A significant relationship between the difference in footprint-weighted averages of LST and difference in H_EC and H_LAS suggests that the spatial heterogeneity in LST at two spatial scales is a reason for the differences in H_EC and H_LAS and that LST has a positive correlation with the differences in H_EC and H_LAS. A significant relationship between the footprint-weighted averages of NDVI and the ratio of sensible heat fluxes at two spatial scales to net radiation (H/Rn) in the rain season supports the analysis that the spatial heterogeneity in canopy at two spatial scales is another reason for differences in H_EC and H_LAS and that canopy has a negative correlation with (H/Rn). An analysis on the influence of the difference in aerodynamic roughness lengths at two spatial scales on sensible heat fluxes shows that the influence is greater in the dry season and smaller in the rain season because the ratio of z_{0m_LAS} to z_{0m_EC} is big in the dry season and is close to 1.0 in the rain season. This study on spatial scales on surface fluxes in the Tibetan Plateau will be helpful in analyzing and understanding its influence on climate.     

The Representativeness of Air Quality Monitoring Sites in the Urban Areas of a Mountainous City

Lanzhou is a typical mountainous city with severe air pollution in northwestern China. This study uses hourly observational data of air pollutants at five air quality monitoring sites in Lanzhou from July to December 2015 to discuss data quality control and the representativeness of the monitoring sites(four urban sites and one suburban site). A fuzzy matrix is applied to study primary air pollutants. The results show that of the six routinely monitored pollutants,the primary pollutant is PM_10 during the study period. Based on lag correlation analysis and one-way analysis of variance, it is concluded that there are redundant observations at the four urban sites for the timely diffusion and transport of air pollutants from the same general area. The coefficient of divergence(COD) method is then used to evaluate the spatial distribution differences, and the primary air pollutant PM_10 shows differences at each site. COD can be used as a positive indicator to describe site representativeness. To evaluate the overall air pollution in the valley, correlation analysis is performed between the PM_10 concentration retrieved from aerosol optical depth satellite data and the concentration from the four urban monitoring sites. Among these, the correlation between the workers' hospital site data and the retrieval data is the highest, passing the 90% confidence level. A new representative evaluation model for air quality monitoring sites, R_s = 0.77 COD + 0.23R_(retrieval), is established by using COD and correlation coefficients between routine observations and satellite retrieval products. From this model, it can be concluded that the biological products institute site in Lanzhou is the most representative site for the evaluation of air pollution out of the four urban air quality monitoring sites from July to December 2015.     

关于直播水稻观测方法问题的探讨

根据湖北江夏国家农业气象观测一级站在最近几年水稻观测中实际遇到的情况以及调查发现,直播水稻已形成不推而广的迅猛发展趋势,作为农业气象观测已不可回避地会遇到直播水稻的生育进程观测问题。由于种植方式的改变,大田植株分布形式也发生了根本的变化,仅以传统的移栽水稻制定的现行《农业气象观测规范》已无法处理好直播水稻的观测问题。为此,笔者依据《农业气象观测规范》,结合实际观测经验,分析直播水稻与移栽水稻的差异以及由此引出的新问题,提出了新的观测处理方法,以供同行探讨。