Cloud top height retrieval using polarizing remote sensing data of POLDER          下载免费PDF全文

HE Xianqiang  BAI Yan  PAN Delu  ZHU Qiankun  GONG Fang 《大气和海洋科学快报》2009,2(2):73-78

A retrieval method of cloud top heights using polarizing remote sensing is proposed in this paper. Using the vector radiative transfer model in a coupled atmosphere-ocean system, the factors influencing the upwelling linear polarizing radiance at top-of-atmosphere are analyzed, which show that the upwelling linear polarizing radiance varies remarkably with the cloud top height, but has negligible sensitivity with cloud albedo and aerosol scattering above the cloud layer. Based on this property, a cloud top height retrieval algorithm using polarizing remote sensing was developed. The algorithm has been applied to the polarizing remote sensing data of Polarization and Directionality of the Earth＇s Reflectances-2 （POLDER-2）. The retrieved cloud top height from POLDER-2 compares well with the Moderate Resolution Imaging Spectroradiometer （MODIS） operational product with a bias of-0.83 km and standard deviation of 1.56 km.  相似文献   

南海九章环礁中牛轭礁和西门礁新生沙洲沉积特征与动态     

许眸莹  高抒  葛晨东  黄梅 《热带海洋学报》2020,39(2):44-53

南沙群岛的珊瑚礁以环礁形式存在, 拥有各具特色的地貌形态。九章环礁中的牛轭礁和西门礁是两座发育有新生沙洲的环礁, 代表灰沙岛形成前一个重要的过渡性地貌演化阶段。这两处新生沙洲表层沉积物样品的粒度分析表明: 沉积物主要组分为珊瑚碎屑, 长轴中值粒径在14~45mm之间, 属于砾石级别; 样品分选系数在4.5~31之间, 分选性很差; 球度值为0.52~0.68, 球度差。粒度特征值中, 中值粒径具有随着到水边线距离的增大而升高的趋势, 而分选性和球度与距水边线距离关系不大。整体上中值粒径与分选系数呈正相关关系, 而与球度呈负相关关系。历史文献记载和卫星图像表明, 牛轭礁和西门礁上的新生沙洲都是近年来才形成的, 与风暴过程及冬季风有关。牛轭礁上沙洲向北迁移, 同时其长轴向东南方向延伸; 西门礁上沙洲整体向东南方向迁移, 并形成回弯形沙嘴形态。新生沙洲的出现与珊瑚碎屑物质供给变化或风暴浪作用变化的关系还需进一步探讨。  相似文献   

Favorable Environments for the Occurrence of Overshooting Tops in Tropical Cyclones     

Liangxiao SUN  Xiaoyong ZHUGE  Yuan WANG 《大气科学进展》2017,34(4):532-544

Based on Multifunctional Transport Satellite data and the infrared window-texture detection algorithm, the level of overshooting top(OT) activity within a tropical cyclone(TC), which is defined as the hourly mean number of OT occurrence,was statistically investigated in the western North Pacific basin for the period 2005–12. Based on the level of OT activity,the samples were divided into OT and non-OT cases or high-activity-OT(HA-OT) and low-activity-OT(LA-OT) cases. The differences in large-scale environmental variables between OT(HA-OT) and non-OT(LA-OT) cases were examined 12 hours prior to the OT occurrence. Statistical analysis showed that environmental differences did exist between the OT and non-OT cases. The OTs were more skewed towards the early stage of the TC life cycle, and mostly concentrated in low latitudes.Meanwhile, a sufficiently deep warm-water layer, large temperature difference between the upper- and lower-level troposphere, large humidity at the middle and upper levels, and large atmospheric instability, were favorable for OT occurrence.The differences in large-scale environmental characteristics between HA-OTs and LA-OTs were not as significant as those between OTs and non-OTs, but the HA-OT samples tended to occur when the vertical shear was weak and the TC intensity was low. Finally, statistical models were designed to predict the OT and HA-OT. When at least three OT(HA-OT) predictor thresholds were satisfied, the Peirce skill score reached a maximum value of 0.49(0.30).  相似文献   

利用LAP-3000型风廓线雷达资料对深圳地区湍流耗散率特征的研究     

王晓芳  王成刚  卜令兵  蒋德海 《气象科学》2011,(S1):1-6

利用2010年1-2月深圳LAP3000型风廓线雷达资料, 对湍流耗散率进行了估算, 针对典型晴天条件下的湍流耗散率  相似文献