scholarly journals Low CO2 evasion rate from the mangrove-surrounding waters of the Sundarbans

2021 ◽  
Author(s):  
Anirban Akhand ◽  
Abhra Chanda ◽  
Kenta Watanabe ◽  
Sourav Das ◽  
Tatsuki Tokoro ◽  
...  
Keyword(s):  
Bay Of Bengal ◽  
Dissolved Inorganic Carbon ◽  
Monsoon Season ◽  
Buffering Capacity ◽  
Marine Water ◽  
High Temporal Resolution ◽  
Post Monsoon Season ◽  
Biogeochemical Parameters ◽  
Northern Bay Of Bengal ◽  
The Sundarbans

AbstractGlobally, water bodies adjacent to mangroves are considered significant sources of atmospheric CO2. We directly measured the partial pressure of CO2 in water [pCO2(water)] and related biogeochemical parameters with high temporal resolution, covering both diel and tidal cycles, in the mangrove-surrounding waters around the northern Bay of Bengal during the post-monsoon season. Mean pCO2(water) was marginally oversaturated in two creeks (470 ± 162 µatm, mean ± SD) and undersaturated in the adjoining estuarine stations (387 ± 58 µatm) compared to atmospheric pCO2, and was considerably lower than the global average. We further estimated the pCO2(water) and buffering capacity of all possible sources of the mangrove-surrounding waters and concluded that their character as a CO2 sink or weak source is due to the predominance of marine water from the Bay of Bengal with low pCO2 and high buffering capacity. Marine water with high buffering capacity suppresses the effect of pCO2 increase within the mangrove system and lowers the CO2 evasion even in creek stations. The δ13C of dissolved inorganic carbon (DIC) in the mangrove-surrounding waters indicated that the DIC sources were a mixture of mangrove plants, pore-water, and groundwater, in addition to marine water. Finally, we showed that the CO2 evasion rate from the estuaries of the Sundarbans is much lower than the recently estimated world average. Our results demonstrate that mangrove areas having such low emissions should be considered when up-scaling the global mangrove carbon budget from regional observations.

scholarly journals The relationship between geopotential height and movement & landfall of tropical cyclone in the Bay of Bengal region

MAUSAM ◽  
2022 ◽  
Vol 63 (3) ◽  
pp. 469-474
Author(s):  
G.K. DAS ◽  
S.K. MIDYA ◽  
G.C. DEBNATH ◽  
S.N. ROY
Keyword(s):  
Tropical Cyclone ◽  
Bay Of Bengal ◽  
Geopotential Height ◽  
Monsoon Season ◽  
Simple Relationship ◽  
Post Monsoon ◽  
Post Monsoon Season ◽  
The Relationship

In this paper a simple relationship is employed to investigate relative impacts on the movement and landfall of tropical cyclone in the Bay of Bengal region when geopotential height of different troposphere levels is used as an input. Five tropical cyclone during pre-monsoon and post-monsoon season over the Bay of Bengal region has been selected for the study. The RS/RW data of coastal stations namely Kolkata (Dumdum), Dhaka, Agartala, Bhubaneswar, Visakhapatnam, Machlipatnam, Chennai and Karaikal has been collected for the period of the cyclones under study. The geopotential height of different standard levels has been plotted against the time for the stations for every cyclone. The study suggests that the cyclone moves towards and cross near the station having relatively steeper decrease in geopotential height upto mid tropical level followed by increased in geopotential height.

scholarly journals Decadal Changes of Radiocarbon in the Surface Bay of Bengal: Three Decades After Geosecs and One Decade After WOCE

Radiocarbon ◽  
2010 ◽  
Vol 52 (3) ◽  
pp. 1191-1196 ◽  
Author(s):  
Koushik Dutta ◽  
G V Ravi Prasad ◽  
Dinesh K Ray ◽  
Sanjeev Raghav
Keyword(s):  
Bay Of Bengal ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Surface Seawater ◽  
Decline Rate ◽  
C Distribution ◽  
Northern Bay Of Bengal

Radiocarbon was measured in the surface seawater dissolved inorganic carbon (DIC) of the Bay of Bengal during November 2006. A meridional transect of the Δ14C in DIC was obtained from measurements in closely spaced samples collected roughly along 88°E. The Δ14C of these samples ranged from 44‰ to 57.7‰ (mean 51.8 ± 1.1‰, n = 12), and 38‰ at one station in the northern Bay of Bengal. The overall pattern of 14C distribution in DIC of surface Bay of Bengal during 2006 was roughly similar to that during the WOCE expedition of 1995. These results indicate a Δ14C decline rate of ∼4‰ per decade since WOCE in the surface Bay of Bengal, which is much smaller compared to a decline rate of ∼25‰ per decade observed in the 2 decades between the GEOSECS and WOCE expeditions, due to the smaller atmosphere-ocean Δ14C gradient.

scholarly journals Modulation of environmental conditions on the significant difference in the super cyclone formation rate during the pre- and post-monsoon seasons over the Bay of Bengal

2021 ◽  
Author(s):  
Zhi Li ◽  
Yuhuan Xue ◽  
Yue Fang ◽  
Kuiping Li
Keyword(s):  
Bay Of Bengal ◽  
Monsoon Season ◽  
Formation Rate ◽  
Specific Humidity ◽  
Global Maximum ◽  
Tropical Ocean ◽  
Post Monsoon ◽  
Significant Difference ◽  
Post Monsoon Season ◽  
Upper Level

AbstractUnlike other tropical ocean basins, the Bay of Bengal (BoB) has two tropical cyclone (TC) seasons: a pre-monsoon season (Pre-MS) and a post-monsoon season (Post-MS). More interestingly, during the period from 1981 to 2016, the global maximum and minimum formation rates of super cyclones (SCs, categories 4 and 5) occurred in the Pre-MS and Post-MS, respectively, in the BoB. Methods including Butterworth filter, box difference index analysis and quantitative diagnosis were utilized herein to detect what and how background environmental factors cause significantly different SC formation rates between the Pre- and Post-MS. Diagnosis results revealed that the vertical temperature difference (VTD) mainly determines whether TCs can develop into SCs during the Post-MS, similar to Pre-MS. It’s in agreement with previous studies demonstrating that the VTD is controlled by the low-level temperature during the Post-MS but is determined by the upper-level temperature during the Pre-MS. The results also revealed that the background sea surface temperature is much higher in the Pre-MS than in the Post-MS and forces higher 1000 hPa-level air temperature. Additionally, there is higher saturated specific humidity (qs) due to the higher temperature in the Pre-MS. The differences in the bottom-level temperature and qs cooperate to predominantly contribute to the significant difference in Vpot2, which could denote the maximum potential intensity of TC, eventually leading to the remarkably different SC formation rates between the Pre- and Post-MS in the BoB.

scholarly journals Seasonal and annual variability in chlorophyll-a in the shelf region of the Northern Bay of Bengal using MODIS-Aqua data

2020 ◽  
Vol 49 (4) ◽  
pp. 398-407
Author(s):  
Muhammad Abdur Rouf ◽  
Al-Hasan Antu ◽  
Imran Noor
Keyword(s):  
Satellite Data ◽  
Bay Of Bengal ◽  
River Discharge ◽  
Monsoon Season ◽  
Northeast Monsoon ◽  
Discharge Data ◽  
Annual Variability ◽  
Northern Bay Of Bengal ◽  
Shelf Region

AbstractChlorophyll-a (Chl-a) concentration is an important issue in ocean ecosystem management and research. This study investigates seasonal and annual variability in Chl-a and its relationship with sea surface temperature (SST) and river discharge in the shelf region of the Northern Bay of Bengal (BoB), as well as validates satellite data against in-situ data. Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua satellite data on Chl-a concentration and SST from 2002–2018 were used in this study. River discharge data were obtained from the Bangladesh Water Development Board (BWDB). The annual Chl-a concentration ranged from 2.08 to 2.94 mg m−3, with an average of 2.43 ± 0.24 mg m−3. The Chl-a concentration was found higher (2.21 ± 0.56 mg m−3) during the northeast monsoon (October–February) and lower (1.81 ± 1.14 mg m−3) during the pre-monsoon season (March–May). The study revealed a declining trend in Chl-a concentration from 2002 to 2018, and the rate of change was −0.0183 mg m−3 year−1. Chl-a concentration showed a weak inverse relationship with SST, both annually and seasonally, especially in the pre-monsoon season. River discharge masked the effect of SST on Chl-a variability during the southwest and northeast monsoon. A reasonable correlation (r = 0.78) was found between the MODIS-Aqua data and in-situ Chl-a observations.

scholarly journals Low CO<sub>2</sub> evasion rate from the mangrove surrounding waters of Sundarban

2019 ◽  
Author(s):  
Anirban Akhand ◽  
Abhra Chanda ◽  
Kenta Watanabe ◽  
Sourav Das ◽  
Tatsuki Tokoro ◽  
...  
Keyword(s):  
Dissolved Inorganic Carbon ◽  
Monsoon Season ◽  
Co2 Flux ◽  
Co2 Concentration ◽  
Atmospheric Co2 ◽  
High Pco2 ◽  
Weak Source ◽  
Post Monsoon Season ◽  
Coastal Sea ◽  
Up Scaling

Abstract. Globally, water bodies adjacent to mangroves are considered sources of atmospheric CO2. We directly measured the partial pressure of CO2 in water, pCO2(water), and other related biogeochemical parameters with very high (1-min) temporal resolution at Dhanchi Island in India’s Sundarbans during the post-monsoon season. We used elemental, stable isotopic, and optical signatures to investigate the sources of dissolved inorganic carbon (DIC) and organic matter (OM) in these waters. Diel mean pCO2(water) was marginally oversaturated in creeks (efflux, 69 ± 180 µmol m−2 h−1) and undersaturated along the island boundary and in the main river (influx, −17 ± 53 and −31 ± 73 µmol m−2 h−1, respectively) compared to the atmospheric CO2 concentration. The possibility in earlier studies of over- or underestimating the CO2 flux because of an inability to capture tidal minima and maxima was minimized in the present study, which confirmed that the waters surrounding mangroves in this region can act as a sink or a very weak source of atmospheric CO2. δ13C values for DIC suggest a mixed DIC source, and a three-end-member stable isotope mixing model and optical signatures of OM suggest negligible riverine contribution of freshwater to OM. We conclude that the CO2 sink or weak source character was due to a reduced input of riverine freshwater [which usually has high pCO2(water)] and the predominance of pCO2-lean water from the coastal sea, which eventually increases the buffering capacity of the water as evidenced by the Revelle factor. Up-scaling the CO2 flux data for all seasons and the entire estuary, we propose that the CO2 evasion rate observed in this study is much lower than the recently estimated world average. Mangrove areas having such low emissions should be given due emphasis when up-scaling the global mangrove carbon budget from regional observations.

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