Intercomparison of Air–Sea Interface Fluxes over the Yellow Sea and Korea Strait: Impact of Tsushima Warm Current     

D. Bala Subrahamanyam  Radhika Ramachandran  S. Indira Rani  P. K. Kunhikrishnan  B. Prasad Kumar 《Boundary-Layer Meteorology》2008,127(2):333-344

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   

Spatio-temporal Variability of Surface-layer Turbulent Fluxes Over the Bay of Bengal and Arabian sea During the ICARB Field Experiment     

Denny P. Alappattu  D. Bala Subrahamanyam  P. K. Kunhikrishnan  Radhika Ramachandran  K. M. Somayaji  R. Venkatesh  G. S. Bhat  A. Bhagavath Singh 《Boundary-Layer Meteorology》2008,126(2):297-309

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.

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Vertical structure of sea-breeze circulation over Thumba (8.5°N,?76.9°E,?India) in the winter months and a case study during W-ICARB field experiment     

T. J. Anurose  D. Bala Subrahamanyam  C. B. S. Dutt  N. V. P. Kiran Kumar  Sherine Rachel John  Sandhya K. Nair  M. Santosh  Mannil Mohan  P. K. Kunhikrishnan  S. Sijikumar  S. S. Prijith 《Meteorology and Atmospheric Physics》2012,115(3-4):113-121

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   

Albedo enhancement over land to counteract global warming: impacts on hydrological cycle     

Govindasamy Bala  Bappaditya Nag 《Climate Dynamics》2012,39(6):1527-1542

A recent modelling study has shown that precipitation and runoff over land would increase when the reflectivity of marine clouds is increased to counter global warming. This implies that large scale albedo enhancement over land could lead to a decrease in runoff over land. In this study, we perform simulations using NCAR CAM3.1 that have implications for Solar Radiation Management geoengineering schemes that increase the albedo over land. We find that an increase in reflectivity over land that mitigates the global mean warming from a doubling of CO₂ leads to a large residual warming in the southern hemisphere and cooling in the northern hemisphere since most of the land is located in northern hemisphere. Precipitation and runoff over land decrease by 13.4 and 22.3%, respectively, because of a large residual sinking motion over land triggered by albedo enhancement over land. Soil water content also declines when albedo over land is enhanced. The simulated magnitude of hydrological changes over land are much larger when compared to changes over oceans in the recent marine cloud albedo enhancement study since the radiative forcing over land needed (?8.2?W?m^?2) to counter global mean radiative forcing from a doubling of CO₂ (3.3?W?m^?2) is approximately twice the forcing needed over the oceans (?4.2?W?m^?2). Our results imply that albedo enhancement over oceans produce climates closer to the unperturbed climate state than do albedo changes on land when the consequences on land hydrology are considered. Our study also has important implications for any intentional or unintentional large scale changes in land surface albedo such as deforestation/afforestation/reforestation, air pollution, and desert and urban albedo modification.  相似文献   

Modeling of SH-Wave Propagation in a Pre-stressed Highly Anisotropic Layered Structure     

Sahu  Sanjeev A.  Pankaj  Kamlesh K.  Kumari  Shreeta 《Mathematical Geosciences》2019,51(4):419-436

Mathematical Geosciences - The present study presents the propagation of horizontally polarized shear waves (SH-waves) in highly anisotropic layered media under the effect of horizontal and...  相似文献   

GIS application to determine the effect of topography on landuse in Ashwani Khad watershed     

Sudhir Mahajan  Pankaj Panwar  Deepak Kaundal 《Journal of the Indian Society of Remote Sensing》2001,29(4):243-248

The landuse status of Ashwani Khad watershed has been obtained using 1RS-ID satellite data for 1999 and further topographic analysis has been carried out using GIS software-ARC/ INFO and ARCVIEW. It has been found that of the total geographical area (85.30 sq. km) of the Ashwani Khad watershed which lies between 30°50′ to 31°N latitude and 77°05′ to 77° 15′E longitude in Himachal Pradesh, 54.53 % constituted wasteland, 33.55% agriculture and least 11.92 % forest. The altitude, aspect and slope have exhibited marked effect on land utilization. Agriculture and wasteland have been found maximum in mid altitude (1300-1500 m) and moderate slopes (13.2-26.4 degree), whereas, agriculture and forest have been maximum in flat and north aspect.  相似文献   

Delineation of surface waterlogged areas in parts of bihar using IRS-1C LISS-III data     

Chandranath Chatterjee  Rakesh Kumar  Pankaj Mani 《Journal of the Indian Society of Remote Sensing》2003,31(1):57-65

Pre-monsoon and post-monsoon surface waterlogged areas were delineated using satellite remote sensing data for Muzaffarpur, Vaishali and Saran districts of North Bihar. Digital data of IRS-1C LISS-III sensor acquired on December 7, 1998 and April 6, 1999 were analyzed using digital image processing software-ERDAS Imagine 8.3.1. The surface waterlogged areas were delineated using modeling technique which is the most advanced and accurate method. Using the modeling technique, a pixel is classified as water if the digital number (DN) value of its Near Infra Red (NIR) band is less than the DN value of the Red band and the Green band, and the Normalized Difference Water Index (NDWI) is greater than or equal to 0.32. The pre-monsoon surface waterlogged areas are found to be 14.02, 23.61 and 9.61 km² while the post-monsoon surface waterlogged areas are found to be 231.83, 118.19 and 176.06 km² for Muzaffarpur, Vaishali and Saran districts, respectively. Also, land use/land cover maps were prepared.  相似文献   

Land use changes in ashwani khad watershed using GIS techniques     

Sudhir Mahajan  Pankaj Panwar 《Journal of the Indian Society of Remote Sensing》2005,33(2):227-232

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Sustainable Community-Based Forestry Development: A Policy and Programme Framework to Enhance Women's Participation     

Derek R. Armitage  & Bala Hyma 《Singapore journal of tropical geography》1997,18(1):1-19

Conventional development theory and practice have often failed to recognise the centrality of women in sustainable resource management. A conceptual shift in environment and resource policies, planning and programmes is required to affirm that women are active participants rather than passive recipients of change. To address the need for enhanced women's participation in community-based forestry development, this paper focuses on the policy and programme elements important in the design and implementation of successful community forestry projects. Consequently, the intention of this paper is to increase the awareness of planners and decision-makers regarding methods of operationalising women's participation in community-based forestry. Building upon previous work from aid agencies and other researchers, a range of institutional, organisational, socio-cultural and project elements are identified. These elements provide a comprehensive framework of the policy and programme issues requiring consideration when promoting women's participation in successful community-based forestry activities.  相似文献   

Solar wind velocity distribution on the heliospheric current sheet during Carrington rotations 1787-1795     

B. Bala  S. R. Prabhakaran Nayar 《Annales Geophysicae》1995,13(8):807-814

The solar wind velocity distribution in the heliosphere is best represented using a v-map, where velocity contours are plotted in heliographic latitude-longitude coordinates. It has already been established that low-speed regions of the solar wind on the source surface correspond to the maximum bright regions of the K-corona and the neutral line of the coronal magnetic field. In this analysis, v-maps on the source surface for Carrington rotations (CRs) 1787-1795, during 1987, have been prepared using the interplanetary scintillation measurements at Research Institute of Atmospherics (RIA), Nagoya Univ., Japan. These v-maps were then used to study the time evolution of the low-speed (\leq450 km s⁻¹) belt of the solar wind and to deduce the distribution of solar wind velocity on the heliospheric current sheet. The low-speed belt of the solar wind on the source surface was found to change from one CR to the next, implying a time evolution. Instead of a slow and systematic evolution, the pattern of distribution of solar wind changed dramatically at one particular solar rotation (CR 1792) and the distributions for the succeeding rotations were similar to this pattern. The low-speed region, in most cases, was found to be close to the solar equator and almost parallel to it. However, during some solar rotations, they were found to be organised in certain longitudes, leaving regions with longitudinal width greater than 30^○ free of low-speed solar wind, i.e. these regions were occupied by solar wind with velocities greater than 450 km s⁻¹. It is also noted from this study that the low-speed belt, in general, followed the neutral line of the coronal magnetic field, except in certain cases. The solar wind velocity on the heliospheric current sheet (HCS) varied in the range 300–585 km s⁻¹ during the period of study, and the pattern of velocity distribution varied from rotation to rotation.  相似文献