青藏高原春夏季温度与太平洋海温的关系     

刘青春  时兴合  汪青春  冯蜀青  赵永业 《干旱气象》2008,26(3):29-33

从预测高原不同区域春、夏季温度趋势分布的需要出发,利用聚类分析法将高原温度场分为3个区域。通过对3个区春、夏季温度指数与前期太平洋海温相关普查,定义了与高原春、夏季温度指数相关关系清晰的海温分布型指数。冬季西太平洋海温偏高（偏低）的海温分布型造成后期高原Ⅱ区春季温度偏高（偏低）;冬季西太平洋海温、东太平洋海温同时偏高（偏低）的海温分布型造成后期高原Ⅱ区南部、Ⅲ区夏季温度偏高（偏低）。进一步分析这2种海温分布型与后期春夏季500hPa北半球高度场的相关关系,结果表明：当冬季西太平洋海温指数偏高（低）时,春季高度场高纬冷空气活动的势力弱（强）且路径偏北（南）,同时高原高度场较低（高）,有利于（不利于）偏南气流北上,有利于（不利于）冬季向夏季环流形势的转变,春季高原中部温度偏高（偏低）;而当冬季西太平洋、东太平洋海域海温综合指数偏高（低）时,同年夏季500hPa高度场高原北部至中西伯利亚南部脊加强（减弱）,高原及北部为高值（低值）系统活动,西太平洋副高偏强（弱）,夏季高原中部、南部温度偏高（偏低）。  相似文献   

CHARACTERISTICS OF MEI-YU PRECIPITATION AND SVD ANALYSIS OF PRECIPITATION OVER THE YANGTZE-HUAIHE RIVERS VALLEYS AND THE SEA SURFACE TEMPERATURE IN THE NORTHERN PACIFIC OCEAN     

毛文书  王谦谦  彭骏  李永华 《热带气象学报(英文版)》2008,14(2):129-132

Based on the precipitation data of Meiyu at 37 stations in the valleys of Yangtze and Huaihe Rivers from 1954 to 2001, the temporal-spatial characteristics of Meiyu precipitation and their relationships with the sea surface temperature in northern Pacific are investigated using such methods as harmonic analysis, empirical orthogonal function (EOF), composite analysis and singular value decomposition (SVD). The results show that the temporal evolution and spatial distribution of Meiyu precipitation are not homogeneous in the Yangtze-Huaihe Rivers basins but with prominent inter-annual and inter-decadal variabilities. The key region between the anomalies of Meiyu precipitation and the monthly sea surface temperature anomalies (SSTA) lies in the west wind drift of North Pacific, which influences the precipitation anomaly of Meiyu precipitation over a key period of time from January to March in the same year. When the SST in the North Pacific west wind drift is warmer (colder) than average during these months, Meiyu precipitation anomalously increases (decreases) in the concurrent year. Results of SVD are consistent with those of composite analysis which pass the significance test of Monte-Carlo at 0.05.  相似文献   

Position and velocity perturbations for the determination of geopotential from space geodetic measurements   总被引：10，自引：0，他引：10  

Peiliang Xu 《Celestial Mechanics and Dynamical Astronomy》2008,100(3):231-249

Although space geodetic observing systems have been advanced recently to such a revolutionary level that low Earth Orbiting (LEO) satellites can now be tracked almost continuously and at the unprecedented high accuracy, none of the three basic methods for mapping the Earth’s gravity field, namely, Kaula linear perturbation, the numerical integration method and the orbit energy-based method, could meet the demand of these challenging data. Some theoretical effort has been made in order to establish comparable mathematical modellings for these measurements, notably by Mayer-Gürr et al. (J Geod 78:462–480, 2005). Although the numerical integration method has been routinely used to produce models of the Earth’s gravity field, for example, from recent satellite gravity missions CHAMP and GRACE, the modelling error of the method increases with the increase of the length of an arc. In order to best exploit the almost continuity and unprecedented high accuracy provided by modern space observing technology for the determination of the Earth’s gravity field, we propose using measured orbits as approximate values and derive the corresponding coordinate and velocity perturbations. The perturbations derived are quasi-linear, linear and of second-order approximation. Unlike conventional perturbation techniques which are only valid in the vicinity of reference mean values, our coordinate and velocity perturbations are mathematically valid uniformly through a whole orbital arc of any length. In particular, the derived coordinate and velocity perturbations are free of singularity due to the critical inclination and resonance inherent in the solution of artificial satellite motion by using various types of orbital elements. We then transform the coordinate and velocity perturbations into those of the six Keplerian orbital elements. For completeness, we also briefly outline how to use the derived coordinate and velocity perturbations to establish observation equations of space geodetic measurements for the determination of geopotential.  相似文献   

用日全食光谱探测太阳中低层大气对局部热动平衡的偏离          下载免费PDF全文

刘曦  屈中权  宋智明 《天文学报》2021,62(1):9-109

在太阳大气不同层次连续光谱中叠加有丰富的发射线或吸收线,对这些谱线轮廓进行反演分析可以探测太阳大气的化学成分和物理状态.太阳大气的色球及过渡区由于其密度低难以建立热动平衡,建立相应的大气模型需要采用非局部热动平衡(Non-Local Thermodynamic Equilibrium,N-LTE)理论.根据相对偏离因子计算来研究太阳中低层大气偏离局部热动平衡(Local Thermodynamic Equilibrium,LTE)分布的情况.首先对日全食观测过程中得到色球和过渡区不同高度形成的两条光谱数据进行反演,得到确定观测谱线的参数信息,如连续谱源函数、谱线源函数、多普勒宽度和由此推出的等效动力学温度;根据这些反演出的谱线参量计算出二维视场内每个空间采样点偏离LTE状态的定量结果;其次,根据用于观测的积分视场单元光纤排布阵列重构出辐射强度、等效动力学温度和相对偏离因子二维分布.结果显示:在局部小区域,温度分布和相对偏离因子的分布存在较强相关性,而与辐射强度分布无明显相关.从两条谱线导出的等效温度和相对偏离因子分布存在明显的差异.这两种二维分布揭示出太阳大气某些小尺度区域具有较强的结构性和复杂性,为进一步理解太阳中低层大气物理提供了一种新的视角.  相似文献   

基于回归模型的热带气旋条件下的海表降温参数化方案设计     

韦骏  刘欣  蒋国庆 《海洋学报(英文版)》2018,37(1):1-10

Combining a linear regression and a temperature budget formula, a multivariate regression model is proposed to parameterize and estimate sea surface temperature(SST) cooling induced by tropical cyclones(TCs). Three major dynamic and thermodynamic processes governing the TC-induced SST cooling(SSTC), vertical mixing, upwelling and heat flux, are parameterized empirically using a combination of multiple atmospheric and oceanic variables:sea surface height(SSH), wind speed, wind curl, TC translation speed and surface net heat flux. The regression model fits reasonably well with 10-year statistical observations/reanalysis data obtained from 100 selected TCs in the northwestern Pacific during 2001–2010, with an averaged fitting error of 0.07 and a mean absolute error of 0.72°C between diagnostic and observed SST cooling. The results reveal that the vertical mixing is overall the pre dominant process producing ocean SST cooling, accounting for 55% of the total cooling. The upwelling accounts for 18% of the total cooling and its maximum occurs near the TC center, associated with TC-induced Ekman pumping. The surface heat flux accounts for 26% of the total cooling, and its contribution increases towards the tropics and the continental shelf. The ocean thermal structures, represented by the SSH in the regression model,plays an important role in modulating the SST cooling pattern. The concept of the regression model can be applicable in TC weather prediction models to improve SST parameterization schemes.  相似文献   

基于卫星遥感海温数据的南海SST预报误差订正     

张培军  周水华  梁昌霞 《热带海洋学报》2020,39(6):57-65

尝试利用卫星遥感高分辨率海表温度资料GHRSST (Group for High Resolution Sea Surface Temperature) 与海表温度(sea surface temperature, SST)数值预报产品之间的误差, 建立一种南海SST模式预报订正方法。首先, 利用南海的Argo浮标上层海温数据对GHRSST 海温数据进行验证, 结果表明两者之间均方根误差约为0.3℃, 相关系数为0.98, GHRSST 海温数据可用于南海业务化数值预报SST的订正。预报订正后的SST与Argo浮标海温数据相比, 24h、48h和72h的均方根误差均由0.8℃左右下降到0.5℃以内。与GHRSST 海温数据相比, 南海北部海域(110°E—121°E, 13°N—23°N)订正后的24h、48h和72h的SST预报空间误差均显著减小, 在冷空气影响南海期间或中尺度涡存在的过程中, SST预报订正效果也较为显著。因此, 该方法可考虑在南海业务化SST数值预报系统中应用。  相似文献   

热带东印度洋SST对气候变暖和变冷的响应     

徐杉  罗义勇 《海洋学报(英文版)》2019,38(5):76-85

The response of the eastern tropical Indian Ocean(ETIO) to heat fluxes of equal amplitude but opposite sign is investigated using the Community Earth System Model(CESM). A significant positive asymmetry in sea surface temperature(SST) is found over the ETIO—the warming responses to the positive forcing exceeds the cooling to the negative forcing. A mixed layer heat budget analysis is carried out to identify the mechanisms responsible for the SST asymmetry. Results show that it is mainly ascribed to the ocean dynamical processes, including vertical advections and diffusion. The net surface heat flux, on the contrary, works to reduce the asymmetry through its shortwave radiation and latent heat flux components. The former is due to the nonlinear relationship between SST and cloud, while the latter is resulted mainly from Newtonian damping and air-sea stability effects. Changes in the SST skewness are also evaluated, with more enhanced negative SST skewness over the ETIO found for the cooling than heating scenarios due to the asymmetric thermocline-SST feedback.  相似文献   

地理国情监测在领导干部自然资源资产离任审计工作中的应用探讨     

张峰 《测绘与空间地理信息》2017,(12):126-128

为积极配合审计部门开展领导干部自然资源资产离任审计工作,充分利用地理国情普查及监测成果,探索领导干部自然资源资产离任审计的内容、方法和评价指标体系,探讨了基于地理国情普查和监测数据成果、基础测绘及相关技术获取的各类自然资源资产基础数据。按专业部门现行标准与有关行业部门进行必要的专题数据整合和处理,建设市级自然资源本底数据库,摸清自然资源的存量与变量,为建立自然资源资产审计长效机制奠定扎实的基础。  相似文献   

阿留申低压一组环流指数与北半球海气异常的关系          下载免费PDF全文

智海  王盘兴  陈明璐  段明铿  王玉昆  张丽娜 《大气科学学报》2017,40(5):641-652

定义了一组描述冬季季、月平均1 000 h Pa位势高度上阿留申低压(Aleutian low,AL)状态的新环流指数,包括强度指数P、面积指数S及中心位置指数(λ_c,φ_c)。采用1948/1949—2007/2008年60个冬季的NCEP/NCAR平均高度场资料计算了上述环流指数,并据此分析了AL的气候及异常规律。结果表明:1)AL在1月最强,中心偏南、偏西;12月最弱,中心偏北、偏东;2月居中。2)AL指数P与λ_c之间存在负相关,强年('0)偏东(λ'0)、弱年偏西。AL年代际变化主要表现在自20世纪70年代以来持续偏强、偏东,但近年有反转的迹象。3)AL在强El Nio年偏强、偏东,在强La Nia年相反,该关系自1975年以后尤其明显;AL与中纬太平洋海表温度(SST)存在显著正相关,SST负异常年AL东移加强,反之亦然。4)AL指数P与同期北半球中高纬气温、降水的显著相关区呈现"+-+"大圆波列分布,相关中心分别位于中纬度北太平洋、北美西北部、北美南部,与太平洋—北美遥相关型(PNA)接近。  相似文献   

与冬季北太平洋大范围海温异常相联系的海气特征          下载免费PDF全文

徐海明  崔梦雪 《大气科学学报》2018,41(3):330-343

采用1948—2014年NCEP/NCAR大气再分析资料以及延伸重建海温资料,基于大气海洋间不同的主导关系对冬季北太平洋大范围海温异常进行分类,探究其相应的海气结构特征。结果表明:1)大气影响海洋的个例多于海洋影响大气的个例,即在冬季北太平洋大气强迫海洋占主要地位,但也存在海洋对大气的反馈作用。2)对于大气影响海洋而言,SST(Sea Surface Temperature)暖异常区上空主要伴随着东北—西南走向的相当正压高低压异常(东北高西南低),对应东南风异常以及显著的深厚暖异常,表现出相当正压暖/脊结构,冷异常情况与此相反。SST异常为净热通量异常与风速异常共同作用引起。3)对于海洋影响大气而言,在SST暖异常区上空西部为南北向高低压异常(北高南低),东部为低压异常,对应偏东风异常。在SST冷异常区上空为偶极型的南北向高低压异常(南高北低),对应偏西风异常;位势高度异常表现出相当正压结构且较大气影响海洋时相对偏弱,大气暖(冷)温度异常比较浅薄且主要局限于对流层低层。4)海洋温度结构异常主要表现为,在大气影响海洋时海温异常由表层下传,海洋影响大气时为上下一致的温度异常。  相似文献