Urban e ffects of Chennai on sea breeze induced convection and precipitation
Matthew Simpson 1, ∗,SethuRaman 1 ,R Suresh 2 and U C Mohanty 3
1 Department of Marine,Earth and Atmospheric Sciences,North Carolina State University,
Raleigh,NC 27695-8208,USA.
2 India Meteorological Department,Chennai.
3 Indian Institute of Technology,New Delhi.
∗e-mail:msimpson@llnl.gov

Abstract: Doppler radar derived wind speed and direction pro files showed a well developed sea breeze circulation over the Chennai, India region on 28 June, 2003. Rainfall totals in excess of 100 mm resulted from convection along the sea breeze front. Inland propagation of the sea  breeze front was observed in radar re flectivity imagery. High-resolution MM5 simulations were used to investigate the in fluence of Chennai urban land use on sea breeze initiated convection and precipitation. A comparison of observed and simulated 10 m wind speed and direction over Chennai showed that the model was able to simulate the timing and strength of the sea breeze. Urban e ffects are shown to increase the near surface air temperature over Chennai by 3.0 K during the early morning hours. The larger surface temperature gradient along the coast due to urban e ffects increased onshore flow by 4 .−1 .Model sensitivity study revealed that precipitation totals were enhanced by 25 mm over a large region 150 km west of Chennai due to urban e ffects. De ficiency in model physics related to night-time forecasts are addressed.


Reply to the comments by Tarkan Erdik and Zekai S¸en on ‘A comparative study of ANN and neuro-fuzzy for the prediction of dynamic constant of rockmass’
T N Singh1,∗, R Kanchan2, A K Verma2 and K Saigal2
1Department of Earth Sciences, Indian Institute of Technology, Powai, Mumbai 400 076, India.
2Institute of Technology, Banaras Hindu University, Varanasi 221 005, India.
∗e-mail: tnsingh@iitb.ac.in



On the measurement of the surface energy budget over a land surface during the summer monsoon
G S Bhat* and S C Arunchandra
Center for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bangalore 560 012, India.
∗e-mail: bhat@caos.iisc.ernet.in

Abstract: The measurement of surface energy balance over a land surface in an open area in Bangalore is reported. Measurements of all variables needed to calculate the surface energy balance on time scales longer than a week are made. Components of radiative fluxes are measured while sensible and latent heat fluxes are based on the bulk method using measurements made at two levels on a micrometeorological tower of 10 m height. The bulk flux formulation is veri fied by comparing its fluxes with direct fluxes using sonic anemometer data sampled at 10 Hz.Soil temperature is measured at 4 depths. Data have been continuously collected for over 6 months covering pre-monsoon and monsoon periods during the year 2006. The study first addresses the issue of getting the fluxes accurately.It is shown that water vapour measurements are the most crucial. A bias of 0.25% in relative humidity,which is well above the normal accuracy assumed by the manufacturers but achievable in the field using a combination of laboratory calibration and field intercomparisons, results in about 20 W m −2 change in the latent heat flux on the seasonal time scale. When seen on the seasonal time scale,the net longwave radiation is the largest energy loss term at the experimental site. The seasonal variation in the energy sink term is small compared to that in the energy source term.


Anaerobic oxidation of methane in coastal sediment from Guishan Island (Pearl River Estuary), South China Sea
Zijun Wu 1,2, ∗, Huaiyang Zhou 1 , Xiaotong Peng 1 ,
Nan Jia 2 , Yuhong Wang 3 and Linxi Yuan 2
1 State Key Laboratory of Marine Geology, Tongji University, Shanghai 200 092, China.
2 Institute of Polar Environment, University of Science and Technology of China, Hefei, Anhui 230 026, China.
3 National Institute of Health, Bethesda, Maryland 20892, USA.
∗e-mail: wuzj@tongji.edu.cn

Abstract: The concentrations of CH 4 SO 2 −4 ,ΣCO 2 and the carbon isotope compositions of ΣCO 2 and CH 4 in the pore-water of the GS sedimentary core collected from Guishan Island (Pearl River Estuary), South China Sea,were determined. The methane concentration in the pore-water shows dramatic changes and sulfate concentration gradients are linear at the base of the sulfate reduction zone for the station. The carbon isotope of methane becomes heavier at the sulfate-methane transition (SMT)likely because of the Raleigh distillation e ffect; 12 CH 4 was oxidized faster than 13 CH 4 and this caused the enrichment of residual methane δ 13 Cand δ 13 C –ΣCO 2 minimum. The geochemical pro files of the pore-water support the existence of anaerobic oxidation of methane (AOM), which is mainly controlled by the quality and quantity of the sedimentary organic matter. As inferred from the index of δ 13 C –TOC value and TOC/TN ratio, the organic matter is a mix of mainly refractory terrestrial component plus some labile alga marine-derived in the study area. A large amount of labile organic matter (mainly labile alga marine-derived) is consumed via the process of sedimentary organic matter diagenesis, and this reduces the amount of labile organic matter incorporated into the base of the sulfate reduction zone. Due to the scarcity of labile organic matter, the sulfate will in turn be consumed by its reaction with methane and therefore AOM takes place.Based on a di ffussion model, the portion of pore-water sulfate reduction via AOM is 58.6%,and the percentage of ΣCO 2 in the pore-water derived from AOM is 41.4%. Thus, AOM plays an important role in the carbon and sulfur cycling in the marine sediments of Pearl River Estuary.


Longitudinal dispersion with time-dependent source concentration in semi-infinite aquifer
Mritunjay Kumar Singh*, Nav Kumar Mahato and Premlata Singh
Department of Applied Mathematics,Indian School of Mines University,Dhanbad 826 004,India.
∗e-mail:drmks29@redi ffmail.com

Abstract: An analytical solution is obtained to predict the contaminant concentration along unsteady ground-water flow in semi-in finite aquifer. Initially,the aquifer is not supposed to be solute free ,i.e.,aquifer is not clean.A time-dependent source concentration is considered at the origin of the aquifer and at the other end of the aquifer, it is supposed to be zero. The time-dependent forms of unsteady velocities are considered in which one such form ,i.e., sinusoidal form represents the seasonal pattern in a year in tropical regions. The Laplace Transformation Technique (LTT)is used to get an analytical solution and a graphical representation is made through MATLAB.



Estimation of urban mixed layer height in Zanjan using LIDAR observations and numerical modeling
A A Bidokhti 1, ∗,MKhoshsima 1 , S Sabetghadam 1 and H M Khalesifard 2
1 Institute of Geophysics, University of Tehran, Tehran, P. O. Box: 14155-6466, Iran.
2 Institute of Advanced Studies in Basic Sciences, Zanjan, Iran.
∗e-mail: bidokhti@ut.ac.ir

Abstract: Air pollution predictions often require the height of atmospheric mixed layer in time especially in big cities. Here, the variation of the height of this layer is estimated from direct measurements and also from a numerical forecast model with a high resolution boundary layer scheme. The height of the daytime mixed layer for the city of Zanjan (48 .5 ◦N,36 .7 ◦E,1700 m above sea level)is measured using a LIDAR (532 nm)system, which works based on aerosols scattering of laser light. The mixed layer height (z i for Zanjan city,well above mean sea level compared to other major cities in the world,is found to be between 1.4 km typically in spring and 2.2 km in summer, for synoptic calm conditions. Also, the MM5 forecast model with a proper boundary layer scheme (MRF)is used to estimate z i which shows rather good agreement with direct observations using the LIDAR system. The entrainment zone of the mixed layer was also found to undergo some occasional temporal growth that may be attributed to shear instability that led to more mixed layer growth.


Wave propagation in thermoelastic saturated porous medium
M D Sharma
Department of Mathematics,Kurukshetra University,Kurukshetra 136 119,India.
e-mail:mohan −here@redi ffmail.com

Abstract: Biot ’s theory for wave propagation in saturated porous solid is modi fied to study the propagation  of thermoelastic waves in poroelastic medium. Propagation of plane harmonic waves is considered in isotropic poroelastic medium. Relations are derived among the wave-induced temperature in the medium and the displacements of fluid and solid particles. Christo ffel equations obtained are modi fied with the thermal as well as thermoelastic coupling parameters. These equations explain the existence and propagation of four waves in the medium. Three of the waves are attenuating longitudinal waves and one is a non-attenuating transverse wave. Thermal properties of the medium have no e ffect on the transverse wave. The velocities and attenuation of the longitudinal waves are computed for a numerical model of liquid-saturated sandstone. Their variations with thermal as well as poroelastic parameters are exhibited through numerical examples.


Uplift along the western margin of the Deccan Basalt Province: Is there any geomorphometric evidence?
Vishwas S Kale* and Nikhil Shejwalkar
Department of Geography, University of Pune, Pune 411 007, India.
∗e-mail: vskale@unipune.ernet.in

Abstract: In line with the passive margin landscape evolutionary model in vogue, sustained erosion and long-distance retreat of the Western Ghat escarpment are widely considered to be the results of erosionally-driven isostatic uplift since Tertiary by many workers. Others have postulated or adduced evidence for strong neotectonic activity in the Ghat region. An obvious question in this regard is whether there is any geomorphometric evidence in support of this widespread view? In order to test the hypothesis of ongoing post-rift fexural uplift or neotectonic activity in the western Deccan Basalt Province (DBP), geomorphometric analysis was carried out and commonly used geomorphic indices of active tectonics (GAT)were derived for 30 selected river basins on both sides of the Western Ghat. SRTM-DEM data and ArcGIS were used to derive the indices. Tectonic geomorphic analysis based on five proxy indicators suggests that the di fferences in GAT indices,  both along strike and across the Western Ghat,are statistically insigni ficant. The index values are nowhere close to the GAT values typically associated with drainage basins a ffected by active tectonics and deformation.Mapping of the indices reveals lack of discernable trends. The adduced results indicate that the western DBP belongs to the class of relatively low tectonic activity.


Comments on ‘A comparative study of ANN and neuro-fuzzy for the prediction of dynamic constant of rockmass’ by T N Singh, R Kanchan, A K Verma and K Saigal
(J. Earth Syst. Sci., 114, February 2005, 75–86)
Tarkan Erdik and Zekai S¸en
Istanbul Technical University, Faculty of Civil Engineering, Hydraulics and Water
Resources Division, Maslak 34469, Istanbul, Turkey.

Abstract: Singh et al (2005)examined the potential of the ANN and neuro-fuzzy systems application for the prediction of dynamic constant of rockmass. However,the model proposed by them has some drawbacks according to fuzzy logic principles.This discussion will focus on the main fuzzy logic principles which authors and potential readers should take into consideration.