Interannual variability of surface salinity and Ekman pumping in the Canada Basin during summertime of 2003−2017

2021 ◽  
Author(s):  
Jihai Dong ◽  
Meibing Jin ◽  
Yu Liu ◽  
Changming Dong
Keyword(s):  
Interannual Variability ◽  
Canada Basin ◽  
Ekman Pumping ◽  
Surface Salinity

Intraseasonal-to-Interannual Variability of South Indian Ocean Sea Level and Thermocline: Remote versus Local Forcing

2012 ◽  
Vol 42 (4) ◽  
pp. 602-627 ◽  
Author(s):  
Laurie L. Trenary ◽  
Weiqing Han
Keyword(s):  
Indian Ocean ◽  
Interannual Variability ◽  
Sea Level ◽  
Time Scales ◽  
Ekman Pumping ◽  
Remote Forcing ◽  
South Indian ◽  
The Pacific ◽  
The Indian Ocean ◽  
Thermocline Variability

Abstract The relative importance of local versus remote forcing on intraseasonal-to-interannual sea level and thermocline variability of the tropical south Indian Ocean (SIO) is systematically examined by performing a suite of controlled experiments using an ocean general circulation model and a linear ocean model. Particular emphasis is placed on the thermocline ridge of the Indian Ocean (TRIO; 5°–12°S, 50°–80°E). On interannual and seasonal time scales, sea level and thermocline variability within the TRIO region is primarily forced by winds over the Indian Ocean. Interannual variability is largely caused by westward propagating Rossby waves forced by Ekman pumping velocities east of the region. Seasonally, thermocline variability over the TRIO region is induced by a combination of local Ekman pumping and Rossby waves generated by winds from the east. Adjustment of the tropical SIO at both time scales generally follows linear theory and is captured by the first two baroclinic modes. Remote forcing from the Pacific via the oceanic bridge has significant influence on seasonal and interannual thermocline variability in the east basin of the SIO and weak impact on the TRIO region. On intraseasonal time scales, strong sea level and thermocline variability is found in the southeast tropical Indian Ocean, and it primarily arises from oceanic instabilities. In the TRIO region, intraseasonal sea level is relatively weak and results from Indian Ocean wind forcing. Forcing over the Pacific is the major cause for interannual variability of the Indonesian Throughflow (ITF) transport, whereas forcing over the Indian Ocean plays a larger role in determining seasonal and intraseasonal ITF variability.

scholarly journals Effects of Tropical Cyclones on Sea Surface Salinity in the Bay of Bengal Based on SMAP and Argo Data

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2975
Author(s):  
Huabing Xu ◽  
Rongzhen Yu ◽  
Danling Tang ◽  
Yupeng Liu ◽  
Sufen Wang ◽  
...  
Keyword(s):  
Tropical Cyclones ◽  
Bay Of Bengal ◽  
Vertical Mixing ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Ekman Pumping ◽  
Surface Salinity ◽  
Argo Data ◽  
Before And After ◽  
The Impact

This paper uses the Argo sea surface salinity (SSSArgo) before and after the passage of 25 tropical cyclones (TCs) in the Bay of Bengal from 2015 to 2019 to evaluate the sea surface salinity (SSS) of the Soil Moisture Active Passive (SMAP) remote sensing satellite (SSSSMAP). First, SSSArgo data were used to evaluate the accuracy of the 8-day SMAP SSS data, and the correlations and biases between SSSSMAP and SSSArgo were calculated. The results show good correlations between SSSSMAP and SSSArgo before and after TCs (before: SSSSMAP = 1.09SSSArgo−3.08 (R2 = 0.69); after: SSSSMAP = 1.11SSSArgo−3.61 (R2 = 0.65)). A stronger negative bias (−0.23) and larger root-mean-square error (RMSE, 0.95) between the SSSSMAP and SSSArgo were observed before the passage of 25 TCs, which were compared to the bias (−0.13) and RMSE (0.75) after the passage of 25 TCs. Then, two specific TCs were selected from 25 TCs to analyze the impact of TCs on the SSS. The results show the significant SSS increase up to the maximum 5.92 psu after TC Kyant (2016), which was mainly owing to vertical mixing and strong Ekman pumping caused by TC and high-salinity waters in the deep layer that were transported to the sea surface. The SSSSMAP agreed well with SSSArgo in both coastal and offshore waters before and after TC Roanu (2016) and TC Kyant (2016) in the Bay of Bengal.

scholarly journals Interannual Variability of the Lena River Plume Propagation in 1993–2020 during the Ice-Free Period on the Base of Satellite Salinity, Temperature, and Altimetry Measurements

2021 ◽  
Vol 13 (21) ◽  
pp. 4252
Author(s):  
Vladislav R. Zhuk ◽  
Arseny Alexandrovich Kubryakov
Keyword(s):  
Interannual Variability ◽  
Chemical Properties ◽  
River Plume ◽  
Sea Surface Salinity ◽  
Arctic Seas ◽  
Surface Salinity ◽  
Lena River ◽  
In Situ Data ◽  
The North ◽  
Infrared Measurements

The Lena River plume significantly affects the thermohaline, optical and chemical properties of the eastern Arctic seas. We use sea surface salinity (SSS), temperature (SST), and altimetry measurements to study features of the Lena plume propagation during 1993–2020. A comparison of Soil Moisture Active Passive (SMAP) SSS measurements with in situ data obtained using the flow-through system in oceanographic surveys in 2018–2019 demonstrates good coincidence with correlation ~ 0.96 and RMSD ~ 1 psu. The SMAP data were used to reconstruct the plume evolution in 2015–2020 and to identify three main types of Lena plume propagation, which are mainly related to the variability of dominant zonal wind direction: «northern»—the plume moves to the north from the delta up to 78° N; «eastern»—the plume moves eastward along the Siberian coast up to 180° E; «mixed» between two main types. Brackish plume waters were characterized by increased temperature and sea level, which provides the opportunity for studying the Lena plume dynamics using satellite altimetry and infrared measurements. These data were analyzed to study the interannual variability of plume propagation during the ice-free period of 1993–2020. The obtained results show that the «northern» type is observed twice more often than the «eastern» one, but the «eastern» type has intensified since 2010.

scholarly journals Stationary Eddies and the Zonal Asymmetry of Net Precipitation and Ocean Freshwater Forcing

2015 ◽  
Vol 28 (13) ◽  
pp. 5115-5133 ◽  
Author(s):  
Robert C. Wills ◽  
Tapio Schneider
Keyword(s):  
Spatial Variability ◽  
Large Scale ◽  
Vertical Motion ◽  
Sea Surface Salinity ◽  
Specific Humidity ◽  
Ekman Pumping ◽  
Surface Salinity ◽  
The North ◽  
Freshwater Forcing ◽  
The Pacific

Abstract Transport of water vapor in the atmosphere generates substantial spatial variability of net precipitation (precipitation minus evaporation). Over half of the total spatial variability in annual-mean net precipitation is accounted for by deviations from the zonal mean. Over land, these regional differences determine differences in surface water availability. Over oceans, they account, for example, for the Pacific–Atlantic difference in sea surface salinity, with implications for the deep overturning circulation. This study analyzes the atmospheric water budget in reanalyses from ERA-Interim and MERRA, to investigate which physical balances lead to zonal variation in net precipitation. It is found that the leading-order contribution is zonal variation in stationary-eddy vertical motion. Transient eddies modify the pattern of zonally anomalous net precipitation by moving moisture from the subtropical and tropical oceans onto land and poleward across the Northern Hemisphere storm tracks. Zonal variation in specific humidity and stationary-eddy horizontal advection play a secondary role. The dynamics leading to net precipitation via vertical motion in stationary eddies can be understood from a lower-tropospheric vorticity budget. The large-scale variations of vertical motion are primarily described by Sverdrup balance and Ekman pumping, with some modification by transient eddies. These results suggest that it is important to understand changes in stationary eddies and their influence on the zonal variation of transient eddy fluxes, in order to understand regional changes in net precipitation. They highlight the relative importance of different atmospheric mechanisms for the freshwater forcing of the North Pacific and North Atlantic.

Global distribution and interannual variation in the winter halocline

2021 ◽  
Keyword(s):  
North Pacific ◽  
Interannual Variation ◽  
World Ocean ◽  
Correlation Coefficients ◽  
Gulf Of Alaska ◽  
Sea Surface Salinity ◽  
Ekman Pumping ◽  
Surface Salinity ◽  
The World ◽  
Definition Of

Abstract The distribution and interannual variation in the winter halocline in the upper layers of the world ocean were investigated via analyses of hydrographic data from the World Ocean Database 2013 using a simple definition of the halocline. A halocline was generally observed in the tropics, equatorward portions of subtropical regions, subarctic North Pacific and Southern Ocean. A strong halocline tended to occur in areas where the sea surface salinity (SSS) was low. The interannual variation in halocline strength was correlated with variation in SSS. The correlation coefficients were usually negative: the halocline was strong when the SSS was low. However, in the Gulf of Alaska in the northeastern North Pacific, the correlation coefficient was positive. There, halocline strength was influenced by interannual variation in Ekman pumping.

scholarly journals 334-year coral record of surface temperature and salinity variability in the greater Agulhas Current region

2021 ◽  
Author(s):  
Jens Zinke ◽  
Siren Rühs ◽  
Miriam Pfeiffer ◽  
Takaaki K. Watanabe ◽  
Stefan Grab ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Surface Temperature ◽  
Interannual Variability ◽  
Time Scales ◽  
Ice Age ◽  
Western Boundary ◽  
Surface Salinity ◽  
Agulhas Current ◽  
Salinity Variability ◽  
Current Region

Abstract. The Agulhas Current (AC) off the southern tip of Africa is one of the strongest western boundary currents and a crucial chokepoint of inter-ocean heat and salt exchange between the Indian and the South Atlantic Ocean. However, large uncertainties remain concerning the sea surface temperature and salinity variability in the AC region and their driving mechanisms over longer time scales, due to short observational datasets and the highly dynamic nature of the region. Here, we present an annual coral skeletal Sr/Ca composite record paired with an established composite oxygen isotope record from Ifaty and Tulear reefs in southwestern Madagascar to obtain a 334 year-long (1661–1995) reconstruction of δ18Oseawater changes related to surface salinity variability in the wider Agulhas Current region. Our new annual δ18Oseawater composite record from Ifaty traces surface salinity of the southern Mozambique Channel and AC core region from the SODA reanalysis since 1958. δ18Oseawater appears mainly driven by large-scale wind forcing in the southern Indian Ocean on interannual to decadal time scales. The δ18Oseawater and SST at Ifaty show characteristic interannual variability of between 2 to 4 years, typical for ENSO. Lagged correlations with the Multivariate ENSO index reveals a 1–2 year lag of δ18Oseawater and salinity at Ifaty and the AC region, suggesting that propagation of anomalies by ocean Rossby waves may contribute to salinity changes in the wider southwestern Indian Ocean. The δ18Oseawater and SST reconstructions at Ifaty reveal the highest interannual variability during the Little Ice Age, especially around 1700, which is in agreement with other Indo-Pacific coral studies. Our study demonstrates the huge potential to unlock past interannual and decadal changes in surface ocean hydrology and ocean transport dynamics from coral δ18Oseawater beyond the short instrumental record.

scholarly journals A modeling study of processes controlling the Bay of Bengal sea surface salinity interannual variability

2016 ◽  
Vol 121 (12) ◽  
pp. 8471-8495 ◽  
Author(s):  
V. P. Akhil ◽  
M. Lengaigne ◽  
J. Vialard ◽  
F. Durand ◽  
M. G. Keerthi ◽  
...  
Keyword(s):  
Interannual Variability ◽  
Bay Of Bengal ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Surface Salinity ◽  
Modeling Study

Observed interannual variability of near-surface salinity in the Bay of Bengal

2015 ◽  
Vol 120 (5) ◽  
pp. 3315-3329 ◽  
Author(s):  
Vimlesh Pant ◽  
M. S. Girishkumar ◽  
T. V. S. Udaya Bhaskar ◽  
M. Ravichandran ◽  
Fabrice Papa ◽  
...  
Keyword(s):  
Interannual Variability ◽  
Bay Of Bengal ◽  
Surface Salinity ◽  
Near Surface

scholarly journals Surface salinity under transitioning ice cover in the Canada Basin: Climate model biases linked to vertical 2 distribution of freshwater

2021 ◽  
Author(s):  
Erica Rosenblum ◽  
Robert Fajber ◽  
Julienne Stroeve ◽  
Sarah Gille ◽  
Bruno Tremblay ◽  
...  
Keyword(s):  
Climate Model ◽  
Ice Cover ◽  
Canada Basin ◽  
Surface Salinity ◽  
Model Biases

scholarly journals Interannual Variability of the Mindanao Current/Undercurrent in Direct Observations and Numerical Simulations

2016 ◽  
Vol 46 (2) ◽  
pp. 483-499 ◽  
Author(s):  
Shijian Hu ◽  
Dunxin Hu ◽  
Cong Guan ◽  
Fan Wang ◽  
Linlin Zhang ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Interannual Variability ◽  
Western Pacific ◽  
Western Boundary ◽  
Western Pacific Ocean ◽  
Ekman Pumping ◽  
Wind Stress Curl ◽  
Boundary Currents ◽  
Mindanao Current ◽  
The Western Pacific

AbstractThe interannual variability of the boundary currents east of the Mindanao Island, including the Mindanao Current/Undercurrent (MC/MUC), is investigated using moored acoustic Doppler current profiler (ADCP) measurements combined with a series of numerical experiments. The ADCP mooring system was deployed east of the Mindanao Island at 7°59′N, 127°3′E during December 2010–August 2014. Depth-dependent interannual variability is detected in the two western boundary currents: strong and lower-frequency variability dominates the upper-layer MC, while weaker and higher-frequency fluctuation controls the subsurface MUC. Throughout the duration of mooring measurements, the weakest MC was observed in June 2012, in contrast to the maximum peaks in December 2010 and June 2014, while in the deeper layer the MUC shows speed peaks circa December 2010, January 2011, April 2013, and July 2014 and valleys circa June 2011, August 2012, and November 2013. Diagnostic analysis and numerical sensitivity experiments using a 2.5-layer reduced-gravity model indicate that wind forcing in the western Pacific Ocean is a driving agent in conditioning the interannual variability of MC and MUC. Results suggest that westward-propagating Rossby waves that generate in the western Pacific Ocean (roughly 150°–180°E) are of much significance in the interannual variability of the two boundary currents. Fluctuation of Ekman pumping due to local wind stress curl anomaly in the far western Pacific Ocean (roughly 120°–150°E) also plays a role in the interannual variability of the MC. The relationship between the MC/MUC and El Niño is discussed.

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