Role of
biology in the air–sea carbon flux in the Bay of Bengal and Arabian Sea
M K Sharada*, P S Swathi, K S Yajnik
and C Kalyani Devasena
CSIR Centre for Mathematical
Modelling and Computer Simulation
(C-MMACS),
Wind Tunnel Road, Bangalore 560 037,
India.
∗e-mail: sharada@cmmacs.ernet.in
Abstract: A
physical-biological-chemical model (PBCM)is used for investigating
the seasonal cycle of air –sea carbon flux and for assessing
the e ffect of the biological
processes on seasonal time scale in the Arabian Sea (AS)and Bay of
Bengal (BoB),where the surface waters
are subjected to contrasting physical conditions.The formulation of
PBCM is given in
Swathi et al (2000),and evaluation of several ammonium-inhibited
nitrate uptake models is given
in Sharada et al (2005). The PBCM is here first evaluated against JGOFS
data on surface pCO 2 in
AS,Bay of Bengal Process Studies (BoBPS)data on column integrated
primary productivity
in BoB,and WOCE I1 data on dissolved inorganic carbon (DIC)and
alkalinity (ALK)in the
upper 500 meters at 9 ◦N in AS and at 10 ◦N in BoB in September
–October.There is good qualitative agreement with local quantitative
discrepancies.
The net e ffect of biological processes on air –sea carbon flux on
seasonal time scale is determined with an auxiliary computational
experiment,called the abiotic run,in
which the biological processes are turned o ff.The di fference between
the biotic run and abiotic run is interpreted as the net e ffect of
biological processes on the seasonal variability of chemical
variables.The net biological e ffect on air –sea carbon flux is found to
be highest in southwest monsoon
season in the northwest AS, where strong upwelling drives intense new
production.The biological e
ffect is larger in AS than in BoB,as seasonal upwelling and mixing are
strong in AS,especially in the
northeast,while coastal upwelling and mixing are weak in BoB.
Spatial
distribution of atmospheric carbon
monoxide over Bay of Bengal
and Arabian Sea:
Measurements during
pre-monsoon period of 2006
V R Aneesh G Mohankumar* and S Sampath
Atmospheric Sciences Division,Centre
for Earth Science Studies,PB
No.7250,Akkulam,
Thiruvananthapuram 695 031,India.
∗e-mail:gmk4833@yahoo.com
Abstract:
Indian Space Research Organization (ISRO)conducted the ‘Integrated
Campaign for Aerosols, gases and Radiation Budget
(ICARB)’for a two-month pre-monsoon period
in 2006 with the ocean segment covering Bay of Bengal and Arabian
Sea.During this campaign,carbon monoxide (CO) was continuously
monitored using a non-dispersive IR
analyser.Quantifying CO in ambient air is vital in determining the air
quality of a region.Being toxic,CO is a
criteria pollutant,but it is a weak green house gas.Globally,very few
measurements exist over marine
atmospheres to study its temporal pattern;particularly in situ CO
measurements are few over
the Bay of Bengal and Arabian Sea for comparison.Present measurements
indicate:(i)predominant
single peak in the diurnal pattern of CO over the marine atmosphere in
contrast to the
double peak over the continent, (ii)the mean diurnal CO over the marine
atmosphere showing an
increasing trend towards evening hours,(iii)the amplitude of the AN
peaks over the marine atmosphere was
∼100 ppbv,while at a remote island site in the Indian Ocean it was ∼5
ppbv and (iv)high CO
values were observed close to continent and the long range transport by
wind also caused CO
highs.
Wind speed
prediction using statistical regression and neural network
Makarand A Kulkarni 1, ∗,Sunil Patil
2 ,G VRama 3 and P NSen 1
1 Department of Atmospheric and Space
Sciences, University of Pune,
Pune 411 007, India.
2 Department of Physics, University
of Pune, Pune 411 007, India.
3 Meteorological Facility,
Sriharikota 524 124, Nellore (Dt), A.P.,
India.
∗e-mail: makarand
−kulkarni@hotmail.com
Abstract:
Prediction of wind speed in the atmospheric boundary layer is important
for wind energy assess- ment,satellite launching and aviation,etc.There
are a few techniques
available for wind speed prediction,which require a minimum number of
input parameters.Four di fferent statistical tech- niques,viz.,curve
fitting,Auto Regressive Integrated Moving Average
Model (ARIMA),extrapo- lation with periodic function and Arti ficial
Neural Networks (ANN)are
employed to predict wind speed.These methods require wind speeds of
previous hours as input.It
has been found that wind speed can be predicted with a reasonable
degree of accuracy using two
methods,viz.,extrapolation using periodic curve fitting and ANN and the
other two methods are not
very useful.
Dependence
of thermal conductivity of snow on microstructure
P K Satyawali 1, ∗and A KSingh 2
1 Snow and Avalanche Study
Establishment, Him Parisar Sector 37A,
Chandigarh, India.
2 Defence Institute of Advanced
Technology (Deemed University),
Girinagar, Pune, India.
∗e-mail: pramodsatyawali@hotmail.com
Abstract:
A geometrical model,including di fferent geometrical shapes in fluencing
thermal conductivity of snow is proposed.The geometrical model has been
assumed to comprise of
unit cells having solid (ice)inclusion as an aggregation of
spherical,cylindrical or cubical
shapes with vertical connection, arranged in a cubic packing.From the
geometrical model and
one-dimensional heat transfer theory, the e ffective thermal
conductivity has been computed.For this
purpose,coupled one-dimensional heat transfer equations have been
solved for steady-state condition to
account for conduction in ice, conduction in air and latent heat
transfer due to water vapour
sublimation through air.The model demonstrates the dependency of
thermal conductivity on
density,grain-spacing,grain contact ratio and temperature.Spherical
inclusions give highest conductivity while
cubical inclusion estimates lowest value for the same density.Thermal
conductivity has been found
increasing sharply near to the packing density for all three
shapes.Empirical model results and
results obtained from existing microstructure based models have also
been compared with the present
model.
Simultaneous
transport of water and solutes under transient unsaturated flow conditions
– A case study
B K Purandara*, N Varadarajan and B
Venkatesh
National Institute of Hydrology, Hard
Rock Regional Center, Belgaum 590
001, Karnataka, India.
∗e-mail: purandarabk@yahoo.com
Abstract:
The imbalance between incoming and outgoing salt causes salinization of
soils and sub-soils that result in increasing the salinity of
stream-flows and agriculture
land.This salinization is a serious environmental hazard particularly
in semi-arid and arid lands.In order
to estimate the magnitude of the hazard posed by salinity,it is
important to understand and
identify the processes that con- trol salt movement from the soil
surface through the root zone to the
ground water and stream flows.In the present study,Malaprabha sub-basin
(up to dam site)has been selected which has two distinct climatic
zones,sub-humid (upstream of Khanapur)and
semi-arid region (downstream of Khanapur).In the upstream,both surface
and ground waters are used
for irrigation,whereas in the downstream mostly groundwater is
used.Both soils and ground waters
are more saline in down- stream parts of the study area.In this study
we characterized the soil
salinity and groundwater quality in both areas.An attempt is also made
to model the distribution
of potassium concentra- tion in the soil pro file in response to varying
irrigation conditions
using the SWIM (Soil –Water In filtration and Movement)model.Fair
agreement was obtained between
predicted and measured results indicating the applicability of the
model.
Migration
of the Ganga river and its implication
on hydro-geological
potential of Varanasi
area, U.P., India
U K Shukla* and N Janardhana Raju
Department of Geology, Banaras Hindu
University, Varanasi 221 005,
India.
∗e-mail: shukla −umakant@yahoo.com
Abstract:
Borehole data reveals that during Late Quaternary,the Ganga river was
non-existent in its present location near Varanasi.Instead,it was
flowing further south towards
peripheral craton.Himalayan derived grey micaceous sands were being
carried by southward flowing
rivers beyond the present day water divide of Ganga and mixed with pink
arkosic sand brought by
northward flowing peninsular rivers.Subsequently,the Ganga shifted to
its present position and got
incised.Near Varanasi,the Ganga river is flowing along a NW –SE tectonic
lineament.The migration
of Ganga river is believed to have been in response to basin expansion
caused due to Himalayan
tectonics during Middle Pleistocene times. Multi-storied sand bodies
generated as a result of channel migration
provide excellent aquifers con fined by a thick zone of muddy sediments
near the surface.Good
quality potable water is available at various levels below about 70 m
depth in sandy aquifers.Craton derived gravelly coarse- to-medium
grained sand forms the main aquifer zones of tens of meter
thickness with enormous yield.In contrast,the shallow aquifers made up
of recycled inter fluve
silt and sandy silt occur under uncon fined conditions and show
water-level fluctuation of a few
meters during pre-and post- monsoon periods.
Indicator minerals as guides to base metal
sulphide mineralisation in
Betul Belt, central
India
Biswajit Ghosh 1, ∗and M N Praveen 2
1 Geological Survey of India,
Operation: WB-SK-AN, Bhu Bijnan Bhawan,
DK-6, Sector-II,
Salt Lake, Kolkata 700 091, India.
2 Geological Survey of India,
Operation: TNPK, Kerala Unit, Dharani
Bhawan,
Manikanteshwaram, Thiruvananthapuram
695 013, India.
∗e-mail: bghosh −geol@hotmail.com
Abstract:
Zn-bearing minerals that act as indicator minerals for base metal
sulphide mineralization from the Proterozoic Betul Belt,central
India with special emphasis on their
genetic signi ficance have been discussed.Sulphide mineralisation is
hosted by the felsic volcanic
rocks and has similarities with volcanic-hosted massive sulphide
deposits in other parts of the
world.Synvolcanic hydrothermal alteration is crudely zoned with an
inner high Mg-Ca core and an outer
wider envelop of Al-Fe rich mineral assemblage.Most of the prospects
have strata
bound,moderately to steeply dipping, multiple,sub-parallel sheet like
ore bodies composed of disseminated
and semi-massive to massive ores.Zn-bearing spinel,staurolite,biotite
and ilmenite typically occur
within the foot-wall altera- tion zones in close proximity to the
sulphide mineralization.Zincian spinel is ubiquitous irrespective of
the nature of alteration zone.Zincian staurolite is nearly absent in
Mg-Ca alteration zones but commonly present in Al-Fe alteration zone
along with zincian
ilmenite.Zn-bearing biotite in intimate association with zincian spinel
is generally found in Mg-Ca
alteration zone and in the transition to Al-Fe alteration zone.Most of
these indicator minerals
can be considered as products of desulphidation of sphalerite during
metamorphism.Mechanisms other
than desulphidation like formation of gahnite by overstepping of
the zinc saturation limit of
biotite during retrogression to chlorite and formation of zincian
staurolite at the expense of
gahnite is also recorded.Field presence of these minerals has immense
signi ficance in exploration in
Betul Belt as they occur in close spatial relationship with the
sulphide rich zones and therefore
act as direct vectors to ore.
Pattern of sedimentation during the Late
Paleozoic, Gondwanaland
glaciation: An example from the Talchir
Formation, Satpura Gondwana basin,
central India
Chandan Chakraborty 1, ∗and Sanjoy
Kumar Ghosh 2
1 Geological Studies Unit, Indian
Statistical Institute, 203 B.T. Road, Kolkata 700 108, India.
2 Shell International Exploration and
Production Inc. WCK# 6380, 200 North Dairy Ashford,
Houston, Texas 77079, USA.
∗e-mail: chandan@isical.ac.in
Abstract: The Talchir
Formation of Permian age is the lowermost lithostratigraphic unit of
the Indian Gondwana successions preserving a record of the Late
Paleozoic glaciation that a ffected the whole Gondwanaland.The formation
unconformably overlies the Precambrian basement in all the Gondwana
basins of India,and marks initiation of sedimentation after a long
hiatus since the Pro- terozoic.The Talchir Formation of the Satpura
Gondwana basin of central India shows features diagnostic of deposition
under glacial regime such as the presence of diamictites,boulder
pavements, bedding plane striation,faceted/striated
gravels,bullet-shaped clasts,dropstone,cryoturbation, etc.The Talchir
strata of the Satpura basin,in addition to tidal signatures,contain
marine bivalve and trace fossils.A proglacial marine environment is
thus inferred for their deposition.The dom- inant lithologies are
conglomerate,pebbly sandstone,sandstone and shale with little
limestone, which can be classi fied into the following major facies:
•matrix-supported conglomerate,
•clast-supported conglomerate,
•cross-strati fied,channel form pebbly sandstone,
•hummocky,swaley or low-angle cross-strati fied pebbly and non-pebbly
sandstone,
•turbidite/tempestite sheet sandstone,
•massive to fissile,green to black claystone with carbonate layers and
nodules.
The conglomerates are interpreted as deposits of a spectrum of
sub-aqueous sediment gravity
flows including debris flow,hyperconcentrated/concentrated density flow
and grain flow.The cross-
strati fied pebbly sandstone bodies,on the other hand,represent
braidplain delta deposits of glacial
outwash origin.Hummocky,swaley,low-angle cross-strati fied sediment
bodies were deposited by
storm-generated combined flows in a shoreface setting.In contrast,the
sheet sandstone bodies are
products of turbidity currents and storm-induced density currents in an
inner shelf setting below
fair weather wave base.The claystone facies is interpreted as a product
of suspension fallout from
hypopycnal sediment plumes in the outer shelf domain below storm wave
base.All the lithofacies
described above occur repetitively in the succession.Three
facies-associations have been recognized
in the Talchir Formation,representing ice-contact fandelta,outwash
braidplain delta and a virtu-
ally ice-free,non-deltaic open marine realm.The di fferent marine facies
of the Talchir Formation
de fine a number of shallowing-upward packages,which are arranged in the
succession with a ret-
rogradational trend to result in an overall fining-and deepening-upward
succession.The overlying
coal-bearing Barakar Formation has been interpreted to have formed in a
tide-wave in fluenced
Keywords. Gondwana glaciation;glacio-marine sedimentation;Talchir
Formation;Satpura basin.