The Experts below are selected from a list of 41685 Experts worldwide ranked by ideXlab platform
Laurent Bopp - One of the best experts on this subject based on the ideXlab platform.
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around one third of current arctic ocean primary production sustained by rivers and Coastal Erosion
Nature Communications, 2021Co-Authors: Jens Terhaar, Ronny Lauerwald, Pierre Regnier, Nicolas Gruber, Laurent BoppAbstract:Net primary production (NPP) is the foundation of the oceans' ecosystems and the fisheries they support. In the Arctic Ocean, NPP is controlled by a complex interplay of light and nutrients supplied by upwelling as well as lateral inflows from adjacent oceans and land. But so far, the role of the input from land by rivers and Coastal Erosion has not been given much attention. Here, by upscaling observations from the six largest rivers and using measured Coastal Erosion rates, we construct a pan-Arctic, spatio-temporally resolved estimate of the land input of carbon and nutrients to the Arctic Ocean. Using an ocean-biogeochemical model, we estimate that this input fuels 28-51% of the current annual Arctic Ocean NPP. This strong enhancement of NPP is a consequence of efficient recycling of the land-derived nutrients on the vast Arctic shelves. Our results thus suggest that nutrient input from the land is a key process that will affect the future evolution of Arctic Ocean NPP.
N Panapitukkul - One of the best experts on this subject based on the ideXlab platform.
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Coastal Erosion and mangrove progradation of southern thailand
Estuarine Coastal and Shelf Science, 2006Co-Authors: Udomluck Thampanya, Jan E Vermaat, S Sinsakul, N PanapitukkulAbstract:Approximately 60% of the southern Thai coastline used to be occupied by mangroves according to the first mangrove forest assessment in 1961. During the past three decades, these mangrove areas have been reduced to about 50% with less than 10% left on the east coast. Coastal Erosion and accretion occur irregularly along the coast but an intensification of Erosion has been noticed during the past decade. This study assessed the relationship between mangrove presence and changes in Coastal area. Mangrove colonization rates were assessed using in situ transects and remote sensing time series. Both methods led to comparable estimates ranging between 5 and 40 m y � 1 . Quantitative data on changes of Coastal segments along southern Thai coastlines as well as available possible factors responsible for these changes were compiled. Overall, net Erosion prevailed (1.3 � 0.4 m y � 1 ). The Gulf of Thailand coastline in the East of the country was found to be most dynamic: change occurred along more Coastal segments than in the West (43% vs. 16%). Rates of Erosion and accretion were also higher, 3.6 versus 2.9 m y � 1 and 2.6 versus 1.5 m y � 1 , respectively. Total area losses accounted for 0.91 km 2 y � 1 for the Gulf coast and 0.25 km 2 y � 1 for the West. Coasts with and without mangroves behaved differently: in the presence of mangroves less Erosion was observed whilst expansion occurred at particular Coastal types with mangrove existence, i.e. river mouths and sheltered bays. Possible underlying causes were examined using multivariate analysis. Eroded areas were found to increase with increased area of shrimp farms, increased fetch to the prevailing monsoon, and when dams reduced riverine inputs. Notably, however, in areas where Erosion prevailed, the presence of mangroves reduced these Erosion rates. Mangrove loss was found to be higher in the presence of shrimp farms and in areas where mangrove forests used to be extensive in the past. 2006 Elsevier Ltd. All rights reserved.
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Coastal Erosion and mangrove progradation of southern thailand
Estuarine Coastal and Shelf Science, 2006Co-Authors: Udomluck Thampanya, Jan E Vermaat, S Sinsakul, N PanapitukkulAbstract:Approximately 60% of the southern Thai coastline used to be occupied by mangroves according to the first mangrove forest assessment in 1961. During the past three decades, these mangrove areas have been reduced to about 50% with less than 10% left on the east coast. Coastal Erosion and accretion occur irregularly along the coast but an intensification of Erosion has been noticed during the past decade. This study assessed the relationship between mangrove presence and changes in Coastal area. Mangrove colonization rates were assessed using in situ transects and remote sensing time series. Both methods led to comparable estimates ranging between 5 and 40 m y � 1 . Quantitative data on changes of Coastal segments along southern Thai coastlines as well as available possible factors responsible for these changes were compiled. Overall, net Erosion prevailed (1.3 � 0.4 m y � 1 ). The Gulf of Thailand coastline in the East of the country was found to be most dynamic: change occurred along more Coastal segments than in the West (43% vs. 16%). Rates of Erosion and accretion were also higher, 3.6 versus 2.9 m y � 1 and 2.6 versus 1.5 m y � 1 , respectively. Total area losses accounted for 0.91 km 2 y � 1 for the Gulf coast and 0.25 km 2 y � 1 for the West. Coasts with and without mangroves behaved differently: in the presence of mangroves less Erosion was observed whilst expansion occurred at particular Coastal types with mangrove existence, i.e. river mouths and sheltered bays. Possible underlying causes were examined using multivariate analysis. Eroded areas were found to increase with increased area of shrimp farms, increased fetch to the prevailing monsoon, and when dams reduced riverine inputs. Notably, however, in areas where Erosion prevailed, the presence of mangroves reduced these Erosion rates. Mangrove loss was found to be higher in the presence of shrimp farms and in areas where mangrove forests used to be extensive in the past. 2006 Elsevier Ltd. All rights reserved.
Ronny Lauerwald - One of the best experts on this subject based on the ideXlab platform.
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around one third of current arctic ocean primary production sustained by rivers and Coastal Erosion
Nature Communications, 2021Co-Authors: Jens Terhaar, Ronny Lauerwald, Pierre Regnier, Nicolas Gruber, Laurent BoppAbstract:Net primary production (NPP) is the foundation of the oceans' ecosystems and the fisheries they support. In the Arctic Ocean, NPP is controlled by a complex interplay of light and nutrients supplied by upwelling as well as lateral inflows from adjacent oceans and land. But so far, the role of the input from land by rivers and Coastal Erosion has not been given much attention. Here, by upscaling observations from the six largest rivers and using measured Coastal Erosion rates, we construct a pan-Arctic, spatio-temporally resolved estimate of the land input of carbon and nutrients to the Arctic Ocean. Using an ocean-biogeochemical model, we estimate that this input fuels 28-51% of the current annual Arctic Ocean NPP. This strong enhancement of NPP is a consequence of efficient recycling of the land-derived nutrients on the vast Arctic shelves. Our results thus suggest that nutrient input from the land is a key process that will affect the future evolution of Arctic Ocean NPP.
Hugues Lantuit - One of the best experts on this subject based on the ideXlab platform.
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Coastal Erosion and mass wasting along the canadian beaufort sea based on annual airborne lidar elevation data
Geomorphology, 2017Co-Authors: Jaroslav Obu, Frank Gunther, Guido Grosse, Hugues Lantuit, Torsten Sachs, Veit Helm, Michael FritzAbstract:Abstract Erosion of permafrost coasts has received increasing scientific attention since 1990s because of rapid land loss and the mobilisation potential of old organic carbon. The majority of permafrost Coastal Erosion studies are limited to time periods from a few years to decades. Most of these studies emphasize the spatial variability of Coastal Erosion, but the intensity of inter-annual variations, including intermediate Coastal aggradation, remains poorly documented. We used repeat airborne Light Detection And Ranging (LiDAR) elevation data from 2012 and 2013 with 1 m horizontal resolution to study Coastal Erosion and accompanying mass-wasting processes in the hinterland. Study sites were selected to include different morphologies along the coast of the Yukon Coastal Plain and on Herschel Island. We studied elevation and volume changes and coastline movement and compared the results between geomorphic units. Results showed simple uniform Coastal Erosion from low coasts (up to 10 m height) and a highly diverse Erosion pattern along coasts with higher backshore elevation. This variability was particularly pronounced in the case of active retrogressive thaw slumps, which can decrease Coastal Erosion or even cause temporary progradation by sediment release. Most of the extremes were recorded in study sites with active slumping (e.g. 22 m of coastline retreat and 42 m of coastline progradation). Coastline progradation also resulted from the accumulation of slope collapse material. These occasional events can significantly affect the coastline position on a specific date and can affect Coastal retreat rates as estimated in long term by coastline digitalisation from air photos and satellite imagery. These deficiencies can be overcome by short-term airborne LiDAR measurements, which provide detailed and high-resolution information about quickly changing elevations in Coastal areas.
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Coastal Erosion dynamics on the permafrost dominated bykovsky peninsula north siberia 1951 2006
Polar Research, 2011Co-Authors: Hugues Lantuit, Volker Rachold, Guido Grosse, David E Atkinson, Pier Paul Overduin, Mikhail S Grigoriev, Hanswolfgang HubbertenAbstract:This study investigates the rate of Erosion during the 1951-2006 period on the Bykovsky Peninsula, located north-east of the harbour town of Tiksi, north Siberia. Its coastline, which is characterized by the presence of ice-rich sediment (Ice Complex) and the vicinity of the Lena River Delta, retreated at a mean rate of 0.59 m/yr between 1951 and 2006. Rates ranged from 434 m of Erosion to 92 m of accretion during these 56 years and exhibited large variability (?=45.4). Ninety-seven percent of the rates observed were less than 2 m/yr and 81.6% were less than 1 m/yr. No significant trend in Erosion could be recorded despite the study of five temporal subperiods within 1951-2006. Erosion modes and rates actually appear to be strongly dependant on the nature of the backshore material, Erosion being stronger along low-lying Coastal stretches affected by past or current thermokarst activity. The juxtaposition of wind records monitored at the town of Tiksi and Erosion records yielded no significant relationship despite strong record amplitude for both data sets. We explain this poor relationship by the only rough incorporation of sea-ice cover in our storm extraction algorithm, the use of land-based wind records vs. offshore winds, the proximity of the Peninsula to the Lena River Delta freshwater and sediment plume and the local topographical constraints on wave development. Keywords: Coastal Erosion, permafrost, Arctic, climate change, Russia (Published: 15 September 2011) Citation: Polar Research 2011, 30 , 7341, DOI: 10.3402/polar.v30i0.7341
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fifty years of Coastal Erosion and retrogressive thaw slump activity on herschel island southern beaufort sea yukon territory canada
Geomorphology, 2008Co-Authors: Hugues Lantuit, Wayne H PollardAbstract:Abstract Patterns of Coastal Erosion in the Arctic differ dramatically from those coasts in more temperate environments. Thick sea ice and shore-fast ice limit wave-based Erosional processes to a brief open water season, however despite this, permafrost coasts containing massive ice, ice wedges and ice-bonded sediments tend to experience high rates of Erosion. These high rates of Erosion reflect the combined thermal–mechanical processes of thawing permafrost, melting ground ice, and wave action. Climate change in the Arctic is expected to result in increased rates of Coastal Erosion due to warming permafrost, increasing active layer depths and thermokarst, rising sea levels, reduction in sea ice extent and duration, and increasing storm impacts. With the most ice-rich permafrost in the Canadian Arctic, the southern Beaufort Sea coast between the Tuktoyaktuk Peninsula and the Alaskan border is subject to high rates of Erosion and retrogressive thaw slump activity. Under many climate change scenarios this area is also predicted to experience the greatest warming in the Canadian Arctic. This paper presents results of a remote sensing study on the long-term patterns of Coastal Erosion and retrogressive thaw slump activity for Herschel Island in the northern Yukon Territory. Using orthorectified airphotos from 1952 and 1970 and an Ikonos image from 2000 corrected with control points collected by kinematic differential global positioning system and processed using softcopy photogrammetric tools, mean Coastal retreat rates of 0.61 m/yr and 0.45 m/yr were calculated for the periods 1952–1970 and 1970–2000, respectively. The highest Coastal retreat rates are on north–west facing shorelines which correspond to the main direction of storm-related wave attack. During the period 1970–2000 Coastal retreat rates for south to south–east facing shorelines displayed a distinct increase even though these are the most sheltered orientations. However, south to south–east facing shorelines correspond to the orientations where the highest densities of retrogressive thaw slumps are observed. Differences in rates of headwall retreat of retrogressive thaw slumps and Coastal Erosion results in the formation of larger thermokarst scars and the development of polycyclic thaw slumps on south to south–east exposures. The number and the total area of retrogressive thaw slumps increased by 125% and 160%, respectively, between 1952 and 2000. As well, the proportion of active retrogressive thaw slumps increased dramatically. Polycyclic retrogressive thaw slumps appear to develop in a periodic fashion, related to retrogressive thaw slump stage and maximum inland extent.
Jens Terhaar - One of the best experts on this subject based on the ideXlab platform.
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around one third of current arctic ocean primary production sustained by rivers and Coastal Erosion
Nature Communications, 2021Co-Authors: Jens Terhaar, Ronny Lauerwald, Pierre Regnier, Nicolas Gruber, Laurent BoppAbstract:Net primary production (NPP) is the foundation of the oceans' ecosystems and the fisheries they support. In the Arctic Ocean, NPP is controlled by a complex interplay of light and nutrients supplied by upwelling as well as lateral inflows from adjacent oceans and land. But so far, the role of the input from land by rivers and Coastal Erosion has not been given much attention. Here, by upscaling observations from the six largest rivers and using measured Coastal Erosion rates, we construct a pan-Arctic, spatio-temporally resolved estimate of the land input of carbon and nutrients to the Arctic Ocean. Using an ocean-biogeochemical model, we estimate that this input fuels 28-51% of the current annual Arctic Ocean NPP. This strong enhancement of NPP is a consequence of efficient recycling of the land-derived nutrients on the vast Arctic shelves. Our results thus suggest that nutrient input from the land is a key process that will affect the future evolution of Arctic Ocean NPP.