首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:从到   被引次数:从到   他引次数:从到 提示：输入*表示无穷大
全文获取类型
  收费全文   19篇
  免费   0篇
专业分类
测绘学   2篇
大气科学   7篇
地球物理   3篇
地质学   4篇
海洋学   3篇
出版年
  2023年   1篇
  2013年   2篇
  2012年   1篇
  2010年   1篇
  2009年   2篇
  2008年   5篇
  2004年   2篇
  1998年   1篇
  1994年   1篇
  1992年   1篇
  1989年   1篇
  1986年   1篇
排序方式： 共有19条查询结果，搜索用时 625 毫秒
1.
Surface-layer features with different prevailing wind directions for two distinct seasons (Southwest Monsoon and Northeast Monsoon) on the west coast of India are studied using data obtained from tower-based sensors at a site located about 500 m from the coast. Only daytime runs have been used for the present analysis. The surface boundary-layer fluxes have been estimated using the eddy correlation method. The surface roughnessz 0 obtained using the stability-corrected wind profiles (Paulson, 1970) has been found to be low for the Southwest monsson season. For the other season,z 0 is relatively high. The drag coefficientC D varies with height in the NE monsoon season but not in the season with lowz 0. This aspect is reflected in the wind profiles for the two seasons and is discussed in detail. The scaling behaviour of friction velocityu * and the turbulence intensity of longitudinal, lateral and vertical winds u, v and w, respectively) are further examined to study their dependence on fetch. Our study shows that for the non-dimensional case, u/u* and v/u* do not show any surface roughness dependence in either season. On the other hand, for w/u* for the season with lowz 0, the values are seen to agree well with that of Panofskyet al. (1977) for homogeneous terrain whereas for the other season with highz 0, the results seem to conform more to the values observed by Smedman and Högström (1983) for coastal terrain. The results are discussed in the light of observations by other investigators.  相似文献   
2.
Satellite remote sensing technique can be effectively utilised in mapping and monitoring the river course changes and associated geomorphological features. Ravi river, flowing along the Indo-Pakistan border, has been in the limelight for its repeated flood havoc during monsoon and abrupt encroachment at some places in the Indian territory, where it was not flowing earlier. This river, meandering in zig-zag fashion along the International boundary in Amritsar and Gurdaspur districts of Punjab, poses perennial threats to the nations’s economy due to extensive destruction happening every year. An attempt has been made to map the shift of this river and the associated geomorphological features along its course using the Indian Remote Sensing Satellite data (IRS-IA and IB LISS-IIFCC) of the period 1991–1993 and the Survey of India topographic sheets of the period 1972–1973. The study shows that there has been drastic changes in the course of Ravi during a span of 20 years due to human activities along its course. The river has shifted its course considerably towards India since its topography is against it. River training structures/bundhs, built by the neighbouring country, across and very near to the earlier river course has been the main reason for this drastic shifting. It is estimated that such massive structures could turn the river course towards India by atleast 1 to 5 km in the border districts of Punjab. This shifting of Ravi along international border poses a serious threat to the Nation’s defence system.  相似文献   
3.
The local weather and air quality over a region are greatly influenced by the atmospheric boundary layer (ABL) structure and dynamics. ABL characteristics were measured using a tethered balloon-sonde system over Kharagpur (22.32°N, 87.32°E, 40m above MSL), India, for the period 7 December 2004 to 30 December 2004, as a part of the Indian Space Research Organization-Geosphere Biosphere Program (ISRO-GBP) Aerosol Land Campaign II. High-resolution data of pressure, temperature, humidity, wind speed and wind direction were archived along with surface layer measurements using an automatic weather station. This paper presents the features of ABL, like ABL depth and nocturnal boundary layer (NBL) depth. The sea surface winds from Quikscat over the oceanic regions near the experiment site were analyzed along with the NCEP/NCAR reanalysis winds over Kharagpur to estimate the convergence of wind, moisture and vorticity to understand the observed variations in wind speed and relative humidity, and also the increased aerosol concentrations. The variation of ventilation coefficient (V C), a factor determining the air pollution potential over a region, is also discussed in detail.  相似文献   
4.
In this article, we describe a simple yet effective method for insertion of observational datasets in a mesoscale atmospheric model used in one-dimensional configuration through Nudging. To demonstrate the effectiveness of this technique, vertical profiles of meteorological parameters obtained from GLASS Sonde launches from a tiny island of Kaashidhoo in the Republic of Maldives are injected in a mesoscale atmospheric model — Advanced Regional Prediction System (ARPS), and model simulated parameters are compared with the available observational datasets. Analysis of one-time nudging in the model simulations over Kaashidhoo show that incorporation of this technique reasonably improves the model simulations within a time domain of +6 to +12 Hrs, while its impact on +18 Hrs simulations and beyond becomes literally null.  相似文献   
5.
Lugworms are important members of the macrobenthos of sheltered intertidal sediments, and this study assessed the abundance and distribution of Abarenicola affinis in Otago, southern New Zealand. Using a faecal cast:lugworm ratio (1.00:1.09) revealed a patchy distribution across inlets, with an overall mean abundance of 11.1 individuals/m2 (range: 3.8 to 21.3 individuals/m2). Distribution patterns varied among inlets, with lugworms mostly confined to the high intertidal zone, but spread across all intertidal zones in one inlet. The lugworm habitat was characterised by muddy to medium sand (55–233 µm mean grain size) with low organic matter (< 2%) and chlorophyll a (1–12 µg/g dry sediment) contents. Depending on the inlet, lugworm abundance was related to sediment parameters, indicating that their distribution across Otago inlets is habitat dependent. The present findings also indicate that factors other than those measured contribute to A. affinis distribution and abundance patterns in this region.  相似文献   
6.
Detailed measurements were carried out in the Marine Atmospheric Boundary Layer (MABL) during the Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB) which covered both Arabian Sea and Bay of Bengal during March to May 2006. In this paper, we present the meteorological observations made during this campaign. The latitudinal variation of the surface layer turbulent fluxes is also described in detail.  相似文献   
7.
This paper presents the observations of the thermodynamic structure of the Marine Atmospheric Boundary Layer (MABL) over Bay of Bengal (BoB), Northern Indian Ocean (NIO) and Arabian Sea (AS) regions, using radiosonde observations carried out as a part of the Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB) during March–May 2006. Most of the profiles show the general structure of tropical MABL which consists of surface layer, sub-cloud layer (mixed layer), transition layer, cloud layer and trade wind inversion (TWI). However, in few soundings over BoB and AS, it was observed that the cloud layer is remarkably well-mixed, forming a double mixed layer (DML) structure. This feature is seen to be closely associated with the low level anticyclonic system over these sectors. The average profiles of vertical wind (corresponding to the region of observation) obtained from NCEP showed that there is an increase in the vertical velocity on the days when such a double mixed layer was observed and the altitude region of this high ω coincides with that of the DML. The study also reveals some important differences in the MABL structure during convectively active and weak periods. The spatial variation of the parameters like mixed layer (ML) depth, height of lifting condensation level (LCL), level of free convection (LFC), and trade wind inversion (TWI) are presented and discussed in detail. The TWI observations are first of their kind from the BoB region. The TWI top is found to be at a higher height compared to the observations over other oceanic regions, and the relationship between the TWI altitude and lapse rate of specific humidity is used to explain why the TWI was formed at a higher height. The observations of the MABL parameters are also compared with those reported from the previous campaigns over these regions.  相似文献   
8.
Surface-layer meteorological observations obtained from oceanic buoys over the Korean Strait and the Yellow Sea are used to estimate surface-layer turbulent fluxes of heat, moisture and momentum over the East-Asian Marginal Seas. Special emphasis is paid towards explanation of the impact of the Tsushima warm current flowing through the Korean Strait on air–sea interface fluxes. During the active phase of the Tsushima warm current, when the difference in sea surface temperature and air temperature becomes as large as 8°C, the sensible heat flux increases to a value of about 135 W m−2, while the latent heat flux is around 200 W m−2. The study attempts to broaden our understanding on the air-sea interaction processes over the Yellow Sea and Korean Strait.  相似文献   
9.
We report the spatio-temporal variability of surface-layer turbulent fluxes of heat, moisture and momentum over the Bay of Bengal (BoB) and the Arabian Sea (AS) during the Integrated Campaign for Aerosols, gases Radiation Budget (ICARB) field experiment. The meteorological component of ICARB conducted during March – May 2006 onboard the oceanic research vessel Sagar Kanya forms the database for the present study. The bulk transfer coefficients and the surface-layer fluxes are estimated using a modified bulk aerodynamic method, and then the spatio-temporal variability of these air-sea interface fluxes is discussed in detail. It is observed that the sensible and latent heat fluxes over the AS are marginally higher than those over the BoB, which we attribute to differences in the prevailing meteorological conditions over the two oceanic regions. The values of the wind stress, sensible and latent heat fluxes are compared with those obtained for the Indian Ocean Experiment (INDOEX) period. The variation of drag coefficient (C D ), exchange coefficients of sensible heat and moisture (C H = C E ) and neutral drag coefficient (C DN ) with wind speed is also discussed.
  相似文献   
10.
This research article aims at characterization of the sea-breeze circulation over Thumba (8.5°N,?76.9°E,?India) in the winter season from December 2008 to February 2009, when this mesoscale circulation over the study domain was prominent. The characteristics of sea-breeze circulation cell comprising sea-breeze and compensatory return flow are investigated for clear-sky and cloudy days. The study indicated delayed onset of sea-breeze on the cloudy days as compared to the clear-sky days and the vertical thickness of sea-breeze circulation cell was found to be larger for the clear-sky days. Vertical thickness of the return flow for both clear-sky and cloudy days was larger than that of the sea-breeze flow. Simultaneous observations of upper-air meteorological parameters obtained through balloon-borne GPS sonde ascents carried out from Thumba and its adjoining coastal ocean on 29 January 2009 as part of the Winter phase of Integrated Campaign for Aerosols, gases and Radiation Budget (W-ICARB) are utilized for a case study towards investigation of diurnal evolution of the sea-breeze circulation cell. Results obtained from this study indicated systematic evolution of sea-breeze circulation over Thumba, however, it was not very clear over ocean which is attributed to cloudy conditions that prevailed on the day of measurement.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号