Total precipitable water in the atmosphere over India     

S. Rangarajan  A. Mani 《Journal of Earth System Science》1982,91(3):189-207

Electromagnetic radiation, in its passage through the atmosphere, is attenuated by absorption and scattering by atmospheric gases, dust and aerosols. The most important absorber is water vapour and the most significant parameter in atmospheric absorption studies is the total precipitable water in the atmosphere. The present paper summarises the results of a study made to compute the total precipitable water in the atmosphere over India using radiosonde and other data, as part of a programme for the computation of direct, global and diffuse solar radiation at the ground from the solar constant. Using values of air temperature and dew point from the ground up to 250 mb at 19 radiosonde stations and surface water vapour mixing ratio values at 105 surface observatories in India, precipitable water amounts have been computed for 124 stations, for each month and for the whole year. The paper describes the techniques used to extend the total precipitable water amounts derived from radiosonde data at 19 stations to 124 stations covering the major climatic zones in the country and presents the results in the form of 12 maps showing the spatial and temporal distribution of total precipitable water over India  相似文献   

High time resolution monitoring of tropospheric temperature with a Radio Acoustic Sounding System (RASS)     

T. Tsuda  Y. Masuda  H. Inuki  K. Takahashi  T. Takami  T. Sato  S. Fukao  S. Kato 《Pure and Applied Geophysics》1989,130(2-3):497-507

We have observed the time-height variation of the temperature field in the upper troposphere using a Radio Acoustic Sounding System (RASS) which consists of the MU radar and a high-power acoustic transmitter. The fast beam steerability of the MU radar has made it possible to measure temperature profiles in a fairly wide height range in the upper troposphere (5–11 km), even under intense wind conditions. Observations were continued for about 32 hr on 24–26 December, 1986 with a time-height resolution of 30 min and 150 m. During the observation period, the tropospheric jet was so intense that the acoustic wavefronts were severely distorted. Using wind velocity profiles observed by the MU radar we have numerically estimated the propagation of acoustic wavefronts, and further determined favorable pointing directions for the MU radar to receive significant backscattering from refractive index fluctuations produced by the acoustic waves. Conventional radiosonde soundings were carried out every 6 hr, which showed a temperature decrease of 4 K/day in the upper troposphere during the observation period. Temperature profiles taken by RASS agree well with the radiosonde results.  相似文献   

A note on some early radiosonde temperature observations in the Antarctic lower stratosphere     

H. R. Phillpot 《Pure and Applied Geophysics》1989,130(2-3):171-180

The behaviour of the Southern Hemisphere stratosphere has attracted considerable interest, and been compared with the Northern Hemisphere, since the International Geophysical Year (1957–58) when the sudden (explosive or accelerated) springtime warming phenomenon in the Antarctic was first observed. Over the years studies of upper air temperature and wind observations have been made, principally through the spring months when the polar vortex breakdown occurs, utilising both ground-based (rawinsonde, rocket) and more recently, satellite-derived data. Although the radiosonde-derived temperature data are limited both by the number of reporting stations, and the practical difficulty of securing observations much above the 100 hPa level, useful records exist from 1956 or 1957. These have shown that in the 1959 southern spring, the lower stratosphere was relatively colder, and the warming rate through the season was essentially more regular, with little evidence of the marked but short-lived temperature fluctuations usually found. Similar, but not quite such wide-spread conditions occurred again in the 1961 spring. In another study, 30 hPa temperature fields over the Antarctic continent, which could be drawn for the 1967 spring, showed the complexity of the polar vortex breakdown. These features are recalled because extension of the 100 hPa springtime temperature series for the Australian Antarctic station at Casey (66.3°S, 110.5°E) shows that in 1985 and part of 1986, the temperature behaviour there was similar to, but not quite so extreme as that which occurred at Mirny (66.5°S, 93.0°E) in 1959.  相似文献   

The vertical structure of the atmospheric boundary layer over the central Arctic Ocean   总被引：2，自引：1，他引：1  

BIAN Lingen  MA Yongfeng  LU Changgui  LIN Xiang 《海洋学报(英文版)》2013,32(10):34-40

The tropopause height and the atmospheric boundarylayer （PBL） height as well as the variation of inversion layer above the floating ice surface are presented using GPS （global position system ） radiosonde sounding data and relevant data obtained by Chinas fourth arctic scientific expedition team over the central Arctic Ocean （86°-88°N, 144°-170°W） during the summer of 2010. The tropopause height is from 9.8 to 10.5 km, with a temperature range between -52.2 and -54.10C in the central Arctic Ocean. Two zones of maximum wind （over 12 m/s） are found in the wind profile, namely, low- and upper-level jets, located in the middle troposphere and the tropopause, respectively. The wind direction has a marked variation point in the two jets from the southeast to the southwest. The average PBL height determined by two methods is 341 and 453 m respectively. These two methods can both be used when the inversion layer is very low, but the results vary significantly when the inversion layer is very high. A significant logarithmic relationship exists between the PBL height and the inversion intensity, with a correlation coefficient of 0.66, indicating that the more intense the temperature inversion is, the lower the boundary layer will be. The observation results obviously differ from those of the third arctic expedition zone （800-85° N）. The PBL height and the inversion layer thickness are much lower than those at 870-88° N, but the inversion temperature is more intense, meaning a strong ice- atmosphere interaction in the sea near the North Pole. The PBL structure is related to the weather system and the sea ice concentration, which affects the observation station.  相似文献   

豫北一次局地雹暴天气的预警特征和触发机制   总被引：1，自引：0，他引：1       下载免费PDF全文

苏爱芳  梁俊平  崔丽曼  刘超 《气象与环境学报》2012,28(6):1-7

利用常规气象观测、多普勒雷达、卫星资料和区域自动站观测资料及NCEP再分析资料,对2011年6月11日豫北局地强对流天气的预报预警特征和触发机制进行分析。结果表明：局地强对流天气是在东北冷涡背景下产生的,高低层中尺度影响系统(槽、切变线、大风速轴)交汇处右侧是强对流发生潜势区。局地强对流天气发生前,CAPE较大,0-6 km垂直风切变达到中等偏强,有利于超级单体的形成和发展。高空冷平流南侵、低层暖平流北上,有利于大气对流不稳定度进一步加大。中-β尺度强对流云团在东北冷涡槽底后部形成,其发展演变对局地强对流天气预报预警有参考意义。强对流回波经历了细胞状、带状发展期和块状减弱期。回波带南侧形成的超级单体造成了局地强风雹天气,冰雹发生时伴有“三体散射”现象。冷空气和地面辐合线是强对流天气的主要触发机制;地面辐合线对强对流天气还有提示作用。  相似文献   

利用不同资料研究我国大陆上空柱水汽含量   总被引：2，自引：1，他引：1       下载免费PDF全文

彭艳秋  王卫国  刘煜  李维亮 《应用气象学报》2012,23(1):59-68

利用1971—2001年探空资料以及ERA-40和NCEP/NCAR再分析资料分别得到地面到300 hPa我国大陆上空大气柱水汽含量,对3种不同资料所得的柱水汽含量的空间分布特征以及线性趋势进行对比分析。结果表明:3种资料得到的柱水汽含量年平均和季节平均的空间分布特征一致;3种资料年平均的线性变化趋势在东北地区、内蒙古东部地区,西南地区北部、华南沿海和新疆北部地区均呈增加趋势;在华北和华东的部分地区,ERA-40和NCEP/NCAR再分析资料为降低趋势,而探空资料得到的柱水汽含量变化相对较小,但未通过信度检验;探空资料得到的柱水汽含量的相对变化显示我国东北地区、内蒙古东部地区、新疆地区的增加更显著。  相似文献   

国产GTS1探空仪与VAISALA公司RS92探空仪对比分析   总被引：8，自引：1，他引：7  

李伟  邢毅  马舒庆 《气象》2009,35(10):97-102

文章从静态指标与动态对比两个方面,对中国国产GTS1探空仪与芬兰Vaisala公司RS92探空仪的综合性能进行对比.对比结果表明,GTS1探空仪温度存在滞后误差,RS92探空仪湿度测量结果明显好于GTS1探空仪,200hPa以上RS92探空仪气压变化低于GTS1探空仪,测风精度方面RS92探空仪高于GTS1探空仪,850hPa以下和150hPa以上GTS1探空仪测风与RS92探空仪存在1m·s-1以内的系统差,RS92探空仪在整体性能上高于GTS1探空仪.  相似文献   

利用GPS定位资料分析L波段雷达测风性能   总被引：3，自引：3，他引：0       下载免费PDF全文

姚雯  马颖  黄炳勋  郭亚田 《应用气象学报》2009,20(2):195-202

新研制的GPS探空仪是在我国高空站网上普遍使用的L波段雷达-数字探空仪系统中增加GPS定位模块,高空风数据不但可以通过GPS定位数据计算获得,同时还可以通过L波段雷达单测风方式进行计算,这样使其自身获得了多方面的动态比对试验。通过对23份对比施放记录分析发现:在一般情况下,经过同等的适当滑动平滑后,从L波段雷达和GPS定位两个独立系统得出的高空风廓线基本一致,说明L波段雷达的测风精度基本可以达到GPS测风水平。但在探空仪上升到高空小风速区且远离测站时,雷达测风精度明显较GPS测风精度低,需要对原始数据进行更大范围的平滑。对照分析表明:目前高空站的L波段雷达观测业务还有较大发展潜力。  相似文献   

青藏高原东部大气探空廓线的气候特征分析     

JIANG Xingwen  LI Yueqing  HE Guangbi 《四川气象》2008,(4)

通过对青藏高原东部地区近几年部分探空资料的分析,得出了一些有意义的结论。结果表明:冬季,青藏高原东侧地区在对流层下部存在明显的逆温现象,在逆温层之下,大气相对湿度大,水汽随高度减小的幅度小,大气处于中性层结状况;在此逆温层之上,大气相对湿度小。在逆温层底部有大量的水汽堆积,在空中形成明显的逆湿层,而在高原主体上并没有此逆温层的存在,高原东侧各站逆温层底的高度差别不大。夏季,青藏高原东侧地区20时可以存在明显的混合层,混合层的高度在成都站最小,重庆站最大,而高原主体混合层高度大于东侧地区。旱年混合层高度大于涝年。8时和20时,冬季大气温、湿垂直特性变化不明显,而夏季具有明显的变化。夏季,降水过程明显抑制混合层的发展,在暴雨过程及其前后,混合层有明显的成熟、消亡、重新建立的特征。  相似文献   

基于探空数据的南海表面波导统计特征研究   总被引：1，自引：0，他引：1  

成印河  周生启  王东晓  鲁远征  姚景龙 《海洋学报(英文版)》2015,34(11):63-70

Based on the global position system(GPS) radiosonde data near the sea surface, the surface duct characteristics over the South China Sea(SCS) were statistically analyzed. The annual surface duct occurrence over the SCS was about 64%. Of the observed surface ducts, duct heights mainly distributed between 18 and 42 m, with M slopes in the range of –0.3 to –0.2 M units/m. Those ducts accounted for about 80% of the ducting cases. For the total profiles, the duct occurrences in a day changed slowly and were more than 60% in all times. The surface ducts formed more easily in the daytime than in the nighttime and most of the duct height were at bellow about 32 m.Additionally, The seasonal variation of the SCS ducts appeared to be evident, except that the mean duct thickness was almost constant, about 33 m for all seasons. The highest occurrence was about 71% in the autumn, followed by in the summer, spring and winter. In spring, their top-height existed more often at a height of more than 48 m.Their mean duct strength became stronger trend from spring to winter, with the M-slope in the range between–0.26 and –0.18 M units/m. Those results agreed well with other studies, provided considering the data resolution.The statistical analysis was reliable and gave the duct estimation for the SCS. Such duct climatology not only has important implications for communication systems and the reliability of the radar observation, but also can provide useful information to improve the accuracy of the meteorological radar measurements.  相似文献