COASTAL UPWELLING AT TERENGGANU AND PAHANG COASTAL WATERS: INTERACTION OF HYDROGRAPHY, CURRENT CIRCULATION AND PHYTOPLANKTON BIOMASS

2016 ◽  
Vol 78 (8) ◽  
Author(s):  
Zuraini Zainol ◽  
Mohd Fadzil Mohd Akhir
Keyword(s):  
Coastal Waters ◽  
Phytoplankton Biomass ◽  
Current Flow ◽  
Coastal Upwelling ◽  
Transition Period ◽  
Southwest Monsoon ◽  
Good Evidence ◽  
Spatial And Temporal Variability ◽  
Seasonal Influence ◽  
Current Circulation

The hydrographic characteristics and current circulation in Terengganu and Pahang coastal waters were examined for their spatial and temporal variability based on the seasonal influence during the transition period (April 2014) and southwest monsoon (June and August, 2014). The results of this study demonstrated the presence of slightly cooler water during June and August, 2014 compared to April, 2014, which indicate the existence of coastal upwelling. Furthermore, the uplifting of isotherms towards the coast during the study trip was also a good evidence of upwelling. The current flow generated by the wind was the possible reason of the features. Furthermore, this study also makes the first attempt to observe the coupling effects between coastal upwelling and the phytoplankton biomass in Terengganu and Pahang coastal waters, which is still sparse. Interestingly, apart from the nutrient availability, the coastal upwelling was believed to influence the phytoplankton biomass at the study area.

Frontal variability and its impact on chlorophyll in the Arabian Sea

2020 ◽  
Author(s):  
Yuntao Wang ◽  
Wentao Ma ◽  
Feng Zhou ◽  
Chai Fei
Keyword(s):  
Arabian Sea ◽  
Coastal Upwelling ◽  
Cold Water ◽  
Southwest Monsoon ◽  
Ocean Dynamics ◽  
Ekman Transport ◽  
Spatial And Temporal Variability ◽  
Anomalous Field ◽  
The North ◽  
The Impact

<p>Sixteen years satellite observations are used to investigate the frontogenesis, frontal variability and its impact on chlorophyll in the Arabian Sea. Large frontal probability (FP) and high chlorophyll mainly happens near the coast, e.g., near Somalia and Oman, and its value generally decreases with offshore distance. An Empirical Orthogonal Function (EOF) is used to disentangle the spatial and temporal variability of front and chlorophyll. Prominent seasonal cycle of frontal activities is identified, peaking in summer when southwest wind prevails. The seasonality for chlorophyll is same with wind and front near Somalia, which largely impacted by monsoon. During summer, the southwest monsoon drives offshore Ekman transport and induces coastal upwelling. It transports subsurface cold water and nutrients to the surface layer, which generates fronts and enhances chlorophyll, respectively. The frontal activities can be used as an indicator to determine the chlorophyll level that high chlorophyll happens when frontal probability gets higher than 2%. At anomalous field, stronger wind can induce higher frontal activities and chlorophyll. The impact of wind on frontogenesis can extend 1,000km offshore and a simplified linear regression is applied to quantify their relationship. The variability of wind leads chlorophyll by lags increasing with distance, indicating a horizontal offshore transport of coastal water. In winter, the northeast wind is not upwelling favorable, thus the frontal activities and chlorophyll are greatly reduced off Somalia. During this period, large chlorophyll is found in the north off Oman because of mixing, thus its relationship with front is less pronounced. In the upwelling regions, fronts act as an intermedia process that connecting the wind forcing and responses of ecosystem. The frontal activities in Arabian Sea is fundamentally important to improve our understanding of monsoon related ocean dynamics.</p>

Wind speed data analysis for predictions of sea waves in Bitung Coastal Waters

2013 ◽  
pp. 35 ◽  
Author(s):  
Joanes E Koagouw ◽  
Gybert E Mamuaya ◽  
Adrie A Tarumingkeng ◽  
P A Angmalisang
Keyword(s):  
Data Analysis ◽  
Wind Speed ◽  
Coastal Waters ◽  
Transition Period ◽  
Marine Resources ◽  
Land Uses ◽  
Sea Waves ◽  
North West ◽  
North Sulawesi ◽  
The Waves

Coastal area of Bitung Municipality is one of the economical activities centers in North Sulawesi Province such as for land-uses and the exploitation of natural resources. Those activities are exaggerating day bay day and tended to be uncontrollable. The excess of those conditions, it has been recorded the change of waves in Bitung waters that has impacts to coastal areas and can affect the utilization of coastal and marine resources. This research was aimed to observe waves altitude variations in Bitung waters with Svedrup Munk and Bretchsneider (SMB) method that had been used to predict waves altitudes. The results showed that the wind speed during West Season was 0.33 m and were dominant to the East, while during East season was 0.91m from South-East to North-West, and then on transition period (March to May) was 1.08m from South-East to East. The results of those wind speed to the waves altitudes in Bitung waters is discussed in this paper© Pesisir pantai Kota Bitung merupakan salah satu pusat aktivitas ekonomi (misalnya pemanfaatan lahan dan eksploitasi sumberdaya) di Provinsi Sulawesi Utara. Aktivitas tersebut semakin hari semakin meningkat dan memiliki kecenderungan tidak terkontrol. Akibat dari keadaan tersebut, telah terjadi perubahan fenomena gelombang di perairan Bitung yang berdampak pada keberadaan daerah pesisir pantai di mana hal ini dapat mengganggu aktivitas pemanfaatan sumberdaya pesisir dan laut tersebut. Penelitian ini bertujuan untuk mengetahui variasi tinggi gelombang di perairan Bitung dengan menggunakan metode Svedrup Munk and Bretchsneider (SMB) yang biasa digunakan untuk peramalan tinggi gelombang signifikan. Hasil penelitian menunjukkan bahwa kecepatan angin pada Musim Barat sebesar 0,33 meter dan dominan ke arah Timur, sementara pada Musim Timur sebesar 0,91 meter dari arah Tenggara ke Barat Laut, serta pada Musim Peralihan (antara bulan Maret-Mei) adalah sebesar 1,08 meter dari arah Tenggara dan Timur. Pengaruh kecepatan angin tersebut terhadap gelombang laut di perairan Bitung dibahas dalam tulisan ini©

Southwest Monsoon of 1979: Chemical and Biological Response of Somali Coastal Waters

Science ◽  
1980 ◽  
Vol 209 (4456) ◽  
pp. 597-600 ◽  
Author(s):  
S. L. SMITH ◽  
L. A. CODISPOTI
Keyword(s):  
Coastal Waters ◽  
Biological Response ◽  
Southwest Monsoon

Coastally trapped waves, baroclinic eddies, internal tides and oceanic fronts at the shelf break: their implications for exchanges between shelf and oceanic waters

1981 ◽  
Vol 302 (1472) ◽  
pp. 661-661 ◽  
Keyword(s):  
Coastal Waters ◽  
Coastal Upwelling ◽  
Shelf Break ◽  
Internal Tides ◽  
Oceanic Fronts ◽  
Run Off ◽  
Break Surface ◽  
Seaward Edge ◽  
Coastally Trapped Waves ◽  
Topographic Rossby Waves

The seaward edge of the continental shelf, or shelf break, is the locus of strong physical variability in the overlying waters. Near the shelf-break, surface tides scatter energy into internal modes that propagate both onshore and offshore and produce strong vertical shears. Atmospheric forcing generates subinertial-frequency topographic Rossby waves, which propagate parallel to the coastline and are strongly trapped near the shelf break. Relative to the sloping topography, wind-driven coastal upwelling generates prograde fronts, and river run-off generates retrograde fronts. Located near the shelf break, these fronts are boundaries between oceanic and coastal waters. Oceanic eddies impinge on, and move along, the shelf-break entraining coastal waters. Eddies may also be shed by shelf-break fronts. Submarine capes and canyons contort the shelf break and significantly modify the enumerated processes. Based on observational evidence from a few coastal regimes, the shelf break is a zone where several mesoscale and synoptic-scale processes operate and probably produce significant turbulent transfers.

Upwelling Bays: How Coastal Upwelling Controls Circulation, Habitat, and Productivity in Bays

2020 ◽  
Vol 12 (1) ◽  
pp. 415-447 ◽  
Author(s):  
John L. Largier
Keyword(s):  
Ocean Acidification ◽  
Wind Stress ◽  
Coastal Waters ◽  
Coastal Upwelling ◽  
Coastal Currents ◽  
Local Wind ◽  
Phytoplankton Blooms ◽  
Local Extrema ◽  
High Recruitment

Bays in coastal upwelling regions are physically driven and biochemically fueled by their interaction with open coastal waters. Wind-driven flow over the shelf imposes a circulation in the bay, which is also influenced by local wind stress and thermal bay–ocean density differences. Three types of bays are recognized based on the degree of exposure to coastal currents and winds (wide-open bays, square bays, and elongated bays), and the characteristic circulation and stratification patterns of each type are described. Retention of upwelled waters in bays allows for dense phytoplankton blooms that support productive bay ecosystems. Retention is also important for the accumulation of larvae, which accounts for high recruitment in bays. In addition, bays are coupled to the shelf ecosystem through export of plankton-rich waters during relaxation events. Ocean acidification and deoxygenation are a concern in bays because local extrema can develop beneath strong stratification.

scholarly journals Spatial and temporal variability in coccolithophore abundance and distribution in the NW Iberian coastal upwelling system

2018 ◽  
Vol 15 (1) ◽  
pp. 245-262 ◽  
Author(s):  
Blanca Ausín ◽  
Diana Zúñiga ◽  
Jose A. Flores ◽  
Catarina Cavaleiro ◽  
María Froján ◽  
...  
Keyword(s):  
Water Column ◽  
Environmental Conditions ◽  
Temporal Variability ◽  
Coastal Upwelling ◽  
Spatial And Temporal Variability ◽  
Upwelling System ◽  
Subsurface Waters ◽  
Shelf Station ◽  
Abundance And Distribution ◽  
Upwelling Event

Abstract. A systematic investigation of the spatial and temporal variability in coccolithophore abundance and distribution through the water column of the NW Iberian coastal upwelling system was performed. From July 2011 to June 2012, monthly sampling at various water depths was conducted at two parallel stations located at 42∘ N. Total coccosphere abundance was higher at the outer-shelf station, where warmer, nutrient-depleted waters favoured coccolithophore rather than phytoplanktonic diatom blooms, which are known to dominate the inner-shelf location. In seasonal terms, higher coccosphere and coccolith abundances were registered at both stations during upwelling seasons, coinciding with high irradiance levels. This was typically in conjunction with stratified, nutrient-poor conditions (i.e. relaxing upwelling conditions). However, it also occurred during some upwelling events of colder, nutrient-rich subsurface waters onto the continental shelf. Minimum abundances were generally found during downwelling periods, with unexpectedly high coccolith abundance registered in subsurface waters at the inner-shelf station. This finding can only be explained if strong storms during these downwelling periods favoured resuspension processes, thus remobilizing deposited coccoliths from surface sediments, and hence hampering the identification of autochthonous coccolithophore community structure. At both locations, the major coccolithophore assemblages were dominated by Emiliania huxleyi, small Gephyrocapsa group, Gephyrocapsa oceanica, Florisphaera profunda, Syracosphaera spp., Coronosphaera mediterranea, and Calcidiscus leptoporus. Ecological preferences of the different taxa were assessed by exploring the relationships between environmental conditions and temporal and vertical variability in coccosphere abundance. These findings provide relevant information for the use of fossil coccolith assemblages in marine sediment records, in order to infer past environmental conditions, of particular importance for Paleoceanography. Both E. huxleyi and the small Gephyrocapsa group are proposed as proxies for the upwelling regime with a distinct affinity for different stages of the upwelling event: E. huxleyi was associated with warmer, nutrient-poor and more stable water column (i.e. upwelling relaxation stage) while the small Gephyrocapsa group was linked to colder waters and higher nutrient availability (i.e. early stages of the upwelling event), similarly to G. oceanica. Conversely, F. profunda is suggested as a proxy for the downwelling regime and low-productivity conditions. The assemblage composed by Syracosphaera pulchra, Coronosphaera mediterranea, and Rhabdosphaera clavigera may be a useful indicator of the presence of subtropical waters conveyed northward by the Iberian Poleward Current. Finally, C. leptoporus is proposed as an indicator of warmer, saltier, and oligotrophic waters during the downwelling/winter regime.

scholarly journals Evaluation of the Town Energy Balance Model in Cold and Snowy Conditions during the Montreal Urban Snow Experiment 2005

2010 ◽  
Vol 49 (3) ◽  
pp. 346-362 ◽  
Author(s):  
A. Lemonsu ◽  
S. Bélair ◽  
J. Mailhot ◽  
S. Leroyer
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Transition Period ◽  
Sensible Heat Flux ◽  
Heat Fluxes ◽  
Surface Radiation ◽  
Anthropogenic Heat ◽  
Balance Model ◽  
Spatial And Temporal Variability ◽  
The Town

Abstract Using the Montreal Urban Snow Experiment (MUSE) 2005 database, surface radiation and energy exchanges are simulated in offline mode with the Town Energy Balance (TEB) and the Interactions between Soil, Biosphere, and Atmosphere (ISBA) parameterizations over a heavily populated residential area of Montreal, Quebec, Canada, during the winter–spring transition period (from March to April 2005). The comparison of simulations with flux measurements indicates that the system performs well when roads and alleys are snow covered. In contrast, the storage heat flux is largely underestimated in favor of the sensible heat flux at the end of the period when snow is melted. An evaluation and an improvement of TEB’s snow parameterization have also been conducted by using snow property measurements taken during intensive observational periods. Snow density, depth, and albedo are correctly simulated by TEB for alleys where snow cover is relatively homogeneous. Results are not as good for the evolution of snow on roads, which is more challenging because of spatial and temporal variability related to human activity. An analysis of the residual term of the energy budget—including contributions of snowmelt, heat storage, and anthropogenic heat—is performed by using modeling results and observations. It is found that snowmelt and anthropogenic heat fluxes are reasonably well represented by TEB–ISBA, whereas storage heat flux is underestimated.

Seasonal to interannual variations of wind forcing in the Peruvian upwelling system

2020 ◽  
Author(s):  
Sadegh Yari ◽  
Volker Mohrholz
Keyword(s):  
Wind Stress ◽  
Coastal Upwelling ◽  
Temporal Variations ◽  
Wind Forcing ◽  
Enso Cycle ◽  
Spatial And Temporal Variability ◽  
Ekman Pumping ◽  
North West ◽  
Upwelling System ◽  
Peruvian Coast

<p>The Humboldt (Peruvian) Upwelling System (HUS) is the most productive among the main Eastern Boundary Upwelling Systems (EBUS), namely California, North West Africa, Benguela and itself. In spite of comparable upwelling intensity its fisheries production exceeds that of the other upwelling systems considerably (Chavez and Messie 2009). Wind is the major driving force of the coastal and curl driven upwelling, that controlls the nutrient supply from the deep water pool to the euphotic surface layer. Strength, spatial and temporal variability of the wind forcing are subjected to seasonal and interannual changes. The core of this study is describe the wind driven upwelling cells in the Peruvian coastal area in detail using long-term data which is not well understood. A better understanding of the state and dynamics of HUS seems essential for fututre regional climate predictions. ASCAT wind stress data for the period of 11 years (2008-2018) is analyzed to assess the spatio-temporal variations of the wind stress field, coastal upwelling and Ekman pumping along the Peruvian coast. The meridional component of wind stress off the peruvian coast, which is the main driver of offshore transport, has been marginally inensified over the entire priod. However, a high level of interannual variability is evident. The El-Niño years show anomalously high wind stress and associated Ekman transoprt. Our results indicate that the southern sector is more influenced by ENSO cycle than the northern sector. Additionally, a strong seasonality in the wind stress is observed. During the austral summer (December-February) the wind stress show the minimum value while the high values are observed in July-September.</p>

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