scholarly journals Presence of continental and Bay of Bengal moisture in rainfall at Kolkata, revealed through simultaneous observation from land and sea during South-West monsoon of 2004

2016 ◽  
Author(s):  
Shaakir Shabir Dar ◽  
Prosenjit Ghosh
Keyword(s):  
Isotopic Composition ◽  
Bay Of Bengal ◽  
Indian Subcontinent ◽  
Isotopic Signature ◽  
Peninsular India ◽  
Gangetic Plain ◽  
Prevailing Wind Direction ◽  
South West Monsoon ◽  
Continental Source ◽  
Sw Monsoon

Abstract. The backward air mass trajectory analysis (HYSPLIT) during the summer monsoon suggests that the rain which precipitates at Kolkata is generated from a moisture parcel which originates from the Arabian Sea and moves inland over the dry Indian subcontinent or over the Bay of Bengal. We used monthly satellite and ground based measurements of the hydro-meteorological variables together with isotope data from Bangalore, Bay of Bengal and Kolkata and other locations to quantify the contribution of different moisture sources during the SW Monsoon. The vapor mass as it moves under the prevailing wind direction was subjected to isotopic modification due to addition of evaporated moisture from Bay of Bengal and rainout process. This was simulated using Craig and Gordon model and Rayleigh fractionation model respectively. The moisture generated during the process of evaporation from Bay of Bengal surface ocean gets advected towards the continent and precipitates as rainfall or snowfall over the Indo-Gangetic plain. We assumed based on our observation that the initial isotopic composition of vapor originating from the peninsular continental source is similar to our observation recorded at Bangalore station. It is found that the isotopic signature of Bangalore is completely lost albeit the significant contribution of the moisture from Bay of Bengal. To explain the isotopic composition of precipitation at Kolkata during the SW-Monsoon, it was necessary to invoke 75–80 % moisture contribution from the Bay of Bengal whereas the evaporated moisture parcel from the Peninsular India contribute 25 %–35 %.

scholarly journals High-Resolution Monsoon Records Since Last Glacial Maximum: A Comparison of Marine and Terrestrial Paleoarchives from South Asia

2011 ◽  
Vol 2011 ◽  
pp. 1-12 ◽  
Author(s):  
Manish Tiwari ◽  
Ashutosh K. Singh ◽  
Rengaswamy Ramesh
Keyword(s):  
High Resolution ◽  
Bay Of Bengal ◽  
Arabian Sea ◽  
Indian Subcontinent ◽  
Water Discharge ◽  
River System ◽  
The Holocene ◽  
The Past ◽  
South West Monsoon ◽  
Eastern Arabian Sea

Agricultural production and the availability of fresh water in Indian subcontinent critically depend on the monsoon rains. Therefore it is vital to understand the causal mechanisms underlying the observed changes in the Indian monsoon in the past. Paleomonsoon reconstructions show that the water discharge from the Ganges-Brahmaputra River system to the Bay of Bengal was maximum in the early to mid-Holocene; data from the Western Arabian Sea and Omanian speleothems indicate declining monsoon winds during the Holocene, whereas records from the South West Monsoon (SWM) precipitation dominated eastern Arabian Sea show higher runoff from the Western Ghats indicating gradually increasing monsoon precipitation during the Holocene. Thus there exists considerable spatial variability in the monsoon in addition to the temporal variability that needs to be assessed systematically. Here we discuss the available high resolution marine and terrestrial paleomonsoon records such as speleothems and pollen records of the SWM from important climatic regimes such as Western Arabian Sea, Eastern Arabian Sea, Bay of Bengal to assess what we have learnt from the past and what can be said about the future of water resources of the subcontinent in the context of the observed changes.

Neotypification of Terminalia paniculata (Combretaceae)

Phytotaxa ◽  
2017 ◽  
Vol 326 (1) ◽  
pp. 88
Author(s):  
TAPAS CHAKRABARTY ◽  
VENKATACHALAM SAMPATH KUMAR
Keyword(s):  
World War Ii ◽  
Indian Subcontinent ◽  
Original Material ◽  
World War ◽  
Botanical Survey ◽  
Peninsular India ◽  
The Family ◽  
Central National Herbarium ◽  
Terminalia Paniculata ◽  
Southern Regional

While preparing a revised treatment of the family Combretaceae for “Flora of India Project,” our attention was drawn on Terminalia paniculata Roth (1821: 383) which was described on the basis of a specimen collected by Benjamin Heyne from peninsular India. The species is well documented in Indian Floras (e.g. Wight & Arnott 1834, Beddome 1869, Brandis 1874, Clarke 1878, Cooke 1903, Talbot 1911, Gamble 1919 and Chandrabose 1983). Gangopadhyay & Chakrabarty (1997) in their revision of the family Combretaceae of Indian subcontinent mentioned that the type of this species is not extant. The type material of T. paniculata housed in the Berlin herbarium (B; herbaria acronyms follow Thiers 2017) was presumably destroyed during the World War II. In the Kew herbarium (K), there is a collection by Benjamin Heyne (K000786096: image!) identified and listed in Wallich’s Numerical List as T. triopteris B.Heyne ex Wallich (1831: no. 3980B). This material contains two twigs, one flowering and the other fruiting and this appears to be a specimen not seen by Roth (1821) since he clearly mentioned in the protologue: “Fructum non vidi.” Thus, as per the provisions of the Code (Mc Neill et al., 2012), as there is no other extant original material (Article 9.7) traceable, a neotype (Articles 9.11 and 9.13) is designated here for T. paniculata from Peninsular India, where Benjamin Heyne made botanical explorations (Burkill, 1965). The neotype specimen is housed in the Central National Herbarium, Botanical Survey of India, Howrah, India (CAL) and its duplicate in the Madras Herbarium, Botanical Survey of India, Southern Regional Centre, Coimbatore, India (MH).

New records of Cyanobacterial morphotypes with Leptolyngbya indica sp. nov. from terrestrial biofilms of the Lower Gangetic Plain, India

Phytotaxa ◽  
2017 ◽  
Vol 316 (2) ◽  
pp. 101 ◽  
Author(s):  
MANOJIT DEBNATH ◽  
TARKESHWAR SINGH ◽  
PUNYASLOKE BHADURY
Keyword(s):  
Rice Field ◽  
New Records ◽  
Indian Subcontinent ◽  
Culture Conditions ◽  
South East Asia ◽  
Gangetic Plain ◽  
Gangetic Plains ◽  
Rice Field Soil ◽  
Green Remediation ◽  
Mangrove Soils

Macroscopic cyanobacterial biofilms were collected from alluvial plain soils and estuarine mangrove soils representing the Lower Gangetic Plains of South East Asia (India). The composition of the biofilms was investigated using light microscopy and field emission scanning electron microscopy of collected samples. In this study four simple trichal non-heterocytous morphotypes were found to be unique. Out of four, three morphotypes clearly showed differences with respect to described taxa as based on most recent taxonomic classification and possibly represent new report from the Indian subcontinent. One morphotype was successfully established under culture conditions and described as Leptolyngbya indica sp. nov. isolated from the alluvial arsenic affected rice field soil. This study provides vital information on morphotypic diversity of Cyanobacteria from specific biotopes which can contribute key information on their biogeography and potential application in green remediation.

scholarly journals Seven year satellite observations of the mean structures and variabilities in the regional aerosol distribution over the oceanic areas around the Indian subcontinent

2005 ◽  
Vol 23 (6) ◽  
pp. 2011-2030 ◽  
Author(s):  
S. K. Nair ◽  
K. Parameswaran ◽  
K. Rajeev
Keyword(s):  
Indian Ocean ◽  
Southern Hemisphere ◽  
Bay Of Bengal ◽  
Arabian Sea ◽  
Indian Subcontinent ◽  
Monsoon Season ◽  
Dry Season ◽  
Aerosol Transport ◽  
Summer Monsoon Season ◽  
Aerosol Distribution

Abstract. Aerosol distribution over the oceanic regions around the Indian subcontinent and its seasonal and interannual variabilities are studied using the aerosol optical depth (AOD) derived from NOAA-14 and NOAA-16 AVHRR data for the period of November 1995–December 2003. The air-mass types over this region during the Asian summer monsoon season (June–September) are significantly different from those during the Asian dry season (November–April). Hence, the aerosol loading and its properties over these oceanic regions are also distinctly different in these two periods. During the Asian dry season, the Arabian Sea and Bay of Bengal are dominated by the transport of aerosols from Northern Hemispheric landmasses, mainly the Indian subcontinent, Southeast Asia and Arabia. This aerosol transport is rather weak in the early part of the dry season (November–January) compared to that in the later period (February–April). Large-scale transport of mineral dust from Arabia and the production of sea-salt aerosols, due to high surface wind speeds, contribute to the high aerosol loading over the Arabian Sea region during the summer monsoon season. As a result, the monthly mean AOD over the Arabian Sea shows a clear annual cycle with the highest values occurring in July. The AOD over the Bay of Bengal and the Southern Hemisphere Indian Ocean also displays an annual cycle with maxima during March and October, respectively. The amplitude of the annual variation is the largest in coastal Arabia and the least in the Southern Hemisphere Indian Ocean. The interannual variability in AOD is the largest over the Southeast Arabian Sea (seasonal mean AOD varies from 0.19 to 0.42) and the northern Bay of Bengal (seasonal mean AOD varies from 0.24 to 0.39) during the February–April period and is the least over the Southern Hemisphere Indian Ocean. This study also investigates the altitude regions and pathways of dominant aerosol transport by combining the AOD distribution with the atmospheric circulation. Keywords. Atmospheric composition and structure (Aerosols and particles) – Meteorology and atmospheric dynamics (Climatology) – Oceanography: physical (Ocean fog and aerosols)

scholarly journals An Optimized Snowmelt Lysimeter System for Monitoring Melt Rates and Collecting Samples for Stable Water Isotope Analysis

2019 ◽  
Vol 67 (1) ◽  
pp. 20-31 ◽  
Author(s):  
Andrea Rücker ◽  
Massimiliano Zappa ◽  
Stefan Boss ◽  
Jana von Freyberg
Keyword(s):  
Isotopic Composition ◽  
Isotope Analysis ◽  
Ground Level ◽  
Isotopic Signature ◽  
Small Scale ◽  
Spatial And Temporal Variability ◽  
Environmental Tracers ◽  
Hydrograph Separation ◽  
Stable Water Isotopes ◽  
Restricted Volume

Abstract The contribution of snow meltwater to catchment streamflow can be quantified through hydrograph separation analyses for which stable water isotopes (18O, 2H) are used as environmental tracers. For this, the spatial and temporal variability of the isotopic composition of meltwater needs to be captured by the sampling method. This study compares an optimized snowmelt lysimeter system and an unheated precipitation collector with focus on their ability to capture snowmelt rates and the isotopic composition of snowmelt. The snowmelt lysimeter system consists of three individual unenclosed lysimeters at ground level with a surface of 0.14 m2 each. The unheated precipitation collector consists of a 30 cm-long, extended funnel with its orifice at 2.3 m above ground. Daily snowmelt samples were collected with both systems during two snowfall-snowmelt periods in 2016. The snowmelt lysimeter system provided more accurate measurements of natural melt rates and allowed for capturing the small-scale variability of snowmelt process at the plot scale, such as lateral meltwater flow from the surrounding snowpack. Because of the restricted volume of the extended funnel, daily melt rates from the unheated precipitation collector were up to 43% smaller compared to the snowmelt lysimeter system. Overall, both snowmelt collection methods captured the general temporal evolution of the isotopic signature in snowmelt.

Transition to Colonialism

2020 ◽  
pp. 17-65
Author(s):  
Tirthankar Roy
Keyword(s):  
Eighteenth Century ◽  
Private Property ◽  
Initial Conditions ◽  
Indian Subcontinent ◽  
Peninsular India ◽  
Highly Skilled ◽  
Fiscal Administration ◽  
The One ◽  
Territorial States

The eighteenth-century economy of the Indian subcontinent was an uneven one. On the one hand, there were present a rich indigenous commercial tradition; territorial states that respected private property in land and trade; a literate elite running the fiscal administration; and rich cities that were home to highly skilled artisans. But much of that wealth was confined to the riparian, deltaic, and seaboard regions. The greater part of peninsular India consisted of drylands, poor peasants, few roads, slow traffic, few towns, forests, waterless uplands, and uninhabited deserts. With such divergent initial conditions, the onset of globalization and the emergence of British power led to a variety of trajectories, as Chapter 2 shows.

scholarly journals Interannual variability of isotopic composition in water vapor over western Africa and its relationship to ENSO

2015 ◽  
Vol 15 (6) ◽  
pp. 3193-3204 ◽  
Author(s):  
A. Okazaki ◽  
Y. Satoh ◽  
G. Tremoy ◽  
F. Vimeux ◽  
R. Scheepmaker ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Southern Oscillation ◽  
Monsoon Season ◽  
Precipitation Amount ◽  
Isotopic Signature ◽  
Atmospheric Environment ◽  
Global Spectral Model ◽  
Near Surface ◽  
Western Africa ◽  
The Relationship

Abstract. This study was performed to examine the relationship between isotopic composition in near-surface vapor (δ18Ov) over western Africa during the monsoon season and El Niño–Southern Oscillation (ENSO) activity using the Isotope-incorporated Global Spectral Model. The model was evaluated using a satellite and in situ observations at daily to interannual timescales. The model provided an accurate simulation of the spatial pattern and seasonal and interannual variations of isotopic composition in column and surface vapor and precipitation over western Africa. Encouraged by this result, we conducted a simulation stretching 34 years (1979–2012) to investigate the relationship between atmospheric environment and isotopic signature on an interannual timescale. The simulation indicated that the depletion in the monsoon season does not appear every year at Niamey. The major difference between the composite fields with and without depletion was in the amount of precipitation in the upstream area of Niamey. As the interannual variation of the precipitation amount is influenced by the ENSO, we regressed the monsoon season averaged δ18Ov from the model and annually averaged NINO3 index and found a statistically significant correlation (R = 0.56, P < 0.01) at Niamey. This relationship suggests that there is a possibility of reconstructing past western African monsoon activity and ENSO using climate proxies.

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