scholarly journals Observation-Based Estimates of Surface Cooling Inhibition by Heavy Rainfall under Tropical Cyclones

2013 ◽  
Vol 43 (1) ◽  
pp. 205-221 ◽  
Author(s):  
Nicolas C. Jourdain ◽  
Matthieu Lengaigne ◽  
Jérome Vialard ◽  
Gurvan Madec ◽  
Christophe E. Menkes ◽  
...  
Keyword(s):  
Tropical Cyclones ◽  
Bay Of Bengal ◽  
Cold Water ◽  
Mixed Layer Depth ◽  
Vertical Mixing ◽  
Dilution Effect ◽  
Global Scale ◽  
Surface Cooling ◽  
Ocean Reanalysis ◽  
The Impact

Abstract Tropical cyclones drive intense ocean vertical mixing that explains most of the surface cooling observed in their wake (the “cold wake”). In this paper, the authors investigate the influence of cyclonic rainfall on the cold wake at a global scale over the 2002–09 period. For each cyclone, the cold wake intensity and accumulated rainfall are obtained from satellite data and precyclone oceanic stratification from the Global Eddy-Permitting Ocean Reanalysis (GLORYS2). The impact of precipitation on the cold wake is estimated by assuming that cooling is entirely due to vertical mixing and that an extra amount of energy (corresponding to the energy used to mix the rain layer into the ocean) would be available for mixing the ocean column in the hypothetical case with no rain. The positive buoyancy flux of rainfall reduces the mixed layer depth after the cyclone passage, hence reducing cold water entrainment. The resulting reduction in cold wake amplitude is generally small (median of 0.07 K for a median 1 K cold wake) but not negligible (>19% for 10% of the cases). Despite similar cyclonic rainfall, the effect of rain on the cold wake is strongest in the Arabian Sea and weak in the Bay of Bengal. An analytical approach with a linearly stratified ocean allows attributing this difference to the presence of barrier layers in the Bay of Bengal. The authors also show that the cold wake is generally a “salty wake” because entrainment of subsurface saltier water overwhelms the dilution effect of rainfall. Finally, rainfall temperature has a negligible influence on the cold wake.

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.

Numerical Investigation of the Upper Ocean Response to the Typhoon Winnie (1997) Using an Air-Sea Coupled Model

2013 ◽  
Vol 726-731 ◽  
pp. 3443-3446
Author(s):  
Li Wen Huang ◽  
Yi Jun Ge
Keyword(s):  
Mixed Layer ◽  
Mixed Layer Depth ◽  
Vertical Mixing ◽  
Coupled Model ◽  
Upper Ocean ◽  
Surface Mixed Layer ◽  
Large Area ◽  
Surface Cooling ◽  
Sea Temperature ◽  
The Impact

In order to investigate the impact of air-sea interaction on the ocean surface mixed layer, Typhoon Winnie (1997) was numerical simulated with a two-way air-sea coupled model MCM (Mesoscale Coupled Model). It shows that the Sea Surface Temperature (SST) decreases over a large area with a magnitude up to 4°C. The sea temperature at 30-50 m depth increases about 1°C corresponding to the surface cooling. Moreover, the oceanic mixed layer depth deepens by 20-30 m. It can be included that these variations in the upper ocean are mainly due to vertical mixing induced by the wind stress of the typhoon.

scholarly journals Impact of Cyclonic Ocean Eddies on Upper Ocean Thermodynamic Response to Typhoon Soudelor

2019 ◽  
Vol 11 (8) ◽  
pp. 938 ◽  
Author(s):  
Jue Ning ◽  
Qing Xu ◽  
Han Zhang ◽  
Tao Wang ◽  
Kaiguo Fan
Keyword(s):  
Vertical Mixing ◽  
Heat Content ◽  
Mesoscale Eddies ◽  
Upper Ocean ◽  
Surface Cooling ◽  
Ocean Eddies ◽  
Horizontal Advection ◽  
Content Change ◽  
Order Of Magnitude ◽  
The Impact

By using multiplatform satellite datasets, Argo observations and numerical model data, the upper ocean thermodynamic responses to Super Typhoon Soudelor are investigated with a focus on the impact of an ocean cyclonic eddy (CE). In addition to the significant surface cooling inside the CE region, an abnormally large rising in subsurface temperature is observed. The maximum warming and heat content change (HCC) reach up to 4.37 °C and 1.73 GJ/m2, respectively. Moreover, the HCC is an order of magnitude larger than that calculated from statistical analysis of Argo profile data in the previous study which only considered the effects caused by typhoons. Meanwhile, the subsurface warming outside the CE is merely 1.74 °C with HCC of 0.39 GJ/m2. Previous studies suggested that typhoon-induced vertical mixing is the primary factor causing subsurface warming but these studies ignored an important mechanism related to the horizontal advection caused by the rotation and movement of mesoscale eddies. This study documents that the eddy-induced horizontal advection has a great impact on the upper ocean responses to typhoons. Therefore, the influence of eddies should be considered when studying the responses of upper ocean to typhoons with pre-existing mesoscale eddies.

scholarly journals Impact of ocean mixed‐layer depth initialization on the simulation of tropical cyclones over the Bay of Bengal using the WRF‐ARW model

2019 ◽  
Vol 27 (1) ◽  
Author(s):  
Viswanadhapalli Yesubabu ◽  
Vijaya Kumari Kattamanchi ◽  
Naresh Krishna Vissa ◽  
Hari Prasad Dasari ◽  
Vijaya Bhaskara Rao Sarangam
Keyword(s):  
Tropical Cyclones ◽  
Mixed Layer ◽  
Bay Of Bengal ◽  
Mixed Layer Depth ◽  
Ocean Mixed Layer ◽  
Layer Depth ◽  
Arw Model ◽  
Ocean Mixed Layer Depth

scholarly journals Assimilating synthetic Biogeochemical-Argo and ocean colour observations into a global ocean model to inform observing system design

2021 ◽  
Vol 18 (2) ◽  
pp. 509-534
Author(s):  
David Ford
Keyword(s):  
Global Scale ◽  
Ocean Model ◽  
Point Of View ◽  
Global Ocean ◽  
Ocean Colour ◽  
Ocean Reanalysis ◽  
Argo Data ◽  
Argo Floats ◽  
Improved Model ◽  
The Impact

Abstract. A set of observing system simulation experiments was performed. This assessed the impact on global ocean biogeochemical reanalyses of assimilating chlorophyll from remotely sensed ocean colour and in situ observations of chlorophyll, nitrate, oxygen, and pH from a proposed array of Biogeochemical-Argo (BGC-Argo) floats. Two potential BGC-Argo array distributions were tested: one for which biogeochemical sensors are placed on all current Argo floats and one for which biogeochemical sensors are placed on a quarter of current Argo floats. Assimilating BGC-Argo data greatly improved model results throughout the water column. This included surface partial pressure of carbon dioxide (pCO2), which is an important output of reanalyses. In terms of surface chlorophyll, assimilating ocean colour effectively constrained the model, with BGC-Argo providing no added benefit at the global scale. The vertical distribution of chlorophyll was improved by assimilating BGC-Argo data. Both BGC-Argo array distributions gave benefits, with greater improvements seen with more observations. From the point of view of ocean reanalysis, it is recommended to proceed with development of BGC-Argo as a priority. The proposed array of 1000 floats will lead to clear improvements in reanalyses, with a larger array likely to bring further benefits. The ocean colour satellite observing system should also be maintained, as ocean colour and BGC-Argo will provide complementary benefits.

scholarly journals Financial Analysis of the Use of Two Horizontal Drain Water Heat Recovery Units

Energies ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 4113 ◽  
Author(s):  
Kamil Pochwat ◽  
Sabina Kordana-Obuch ◽  
Mariusz Starzec ◽  
Beata Piotrowska
Keyword(s):  
Heat Exchanger ◽  
Water Temperature ◽  
Heat Recovery ◽  
Cold Water ◽  
Financial Analysis ◽  
Global Scale ◽  
Drain Water ◽  
Actual Distribution ◽  
Cold Water Temperature ◽  
The Impact

The growing interest in the use of unconventional energy sources is a stimulus for the development of dedicated devices and technologies. Drain water heat recovery (DWHR) units can be an example of such devices. They allow the recovery of part of the heat energy deposited in grey water. This paper describes the results of research on the assessment of the financial profitability of the use of two horizontal heat exchanger solutions, taking into account the actual distribution of cold water temperature during the operating year in the plumbing and two operating regimes of the premises as the residential and service facilities. The analysis showed that the use of a horizontal heat exchanger with increased efficiency in a dwelling in a 15-year life cycle allowed for achieving more than twice as much savings (reaching up to EUR 1427) compared to a classic horizontal heat exchanger. At the same time, it was shown that the installation of this type of equipment was more profitable the greater the water consumption of the premises. The article also notes the impact of cold water temperature in the installation on the results of the analysis. It was featured that taking temperature on the basis of installation design recommendations led to significant distortions in the financial analysis. On the other hand, comparing the method of averaging the cold water temperature (daily, monthly and yearly), it was determined that averaging the temperature over the annual cycle was an acceptable simplification of the model. The research results presented in the paper have a practical aspect and may constitute guidelines for designers and potential investors. In addition, they can be an incentive to continue research on heat exchangers by other scientific centers, which on a global scale will increase the universality of their use.

scholarly journals Deep-mixing and deep-cooling events in Lake Garda: Simulation and mechanisms

2021 ◽  
Vol 80 (2) ◽  
Author(s):  
Bouke Biemond ◽  
Marina Amadori ◽  
Marco Toffolon ◽  
Sebastiano Piccolroaz ◽  
Hans Van Haren ◽  
...  
Keyword(s):  
Water Temperature ◽  
Deep Water ◽  
Cold Water ◽  
Vertical Mixing ◽  
Three Dimensional ◽  
Surface Cooling ◽  
Deep Mixing ◽  
Lake Garda ◽  
Turbulence Production ◽  
Strong Winds

A calibrated three-dimensional numerical model (Delft3D) and in-situ observations are used to study the relation between deep-water temperature and deep mixing in Lake Garda (Italy). A model-observation comparison indicates that the model is able to adequately capture turbulent kinetic energy production in the surface layer and its vertical propagation during unstratified conditions. From the modeling results several processes are identified to affect the deep-water temperature in Lake Garda. The first process is thermocline tilting due to strong and persistent winds, leading to a temporary disappearance of stratification followed by vertical mixing. The second process is turbulent cooling, which acts when vertical temperature gradients are nearly absent over the whole depth and arises as a combination of buoyancy-induced turbulence production due to surface cooling and turbulence production by strong winds. A third process is differential cooling, which causes cold water to move from the shallow parts of the lake to deeper parts along the sloping bottom. Two of these processes (thermocline tilting and turbulent cooling) cause deep-mixing events, while deep-cooling events are mainly caused by turbulent cooling and differential cooling. Detailed observations of turbulence quantities and lake temperature, available at the deepest point of Lake Garda for the year 2018, indicate that differential cooling was responsible for the deep-water cooling at that location. Long-term simulations of deep-water temperature and deep mixing appear to be very sensitive to the applied wind forcing. This sensitivity is one of the main challenges in making projections of future occurrences of episodic deep mixing and deep cooling under climate change.

scholarly journals Surface processes in the 7 November 2014 medicane from air–sea coupled high-resolution numerical modelling

2019 ◽  
Author(s):  
Marie-Noëlle Bouin ◽  
Cindy Lebeaupin Brossier
Keyword(s):  
Tropical Cyclones ◽  
Surface Processes ◽  
Convective Precipitation ◽  
Surface Cooling ◽  
Air Masses ◽  
Low Level ◽  
Cold Pools ◽  
Ocean Atmosphere ◽  
Upper Level ◽  
The Impact

Abstract. A medicane, or Mediterranean cyclone with characteristics similar to tropical cyclones, is simulated using a kilometre-scale ocean–atmosphere coupled modelling platform. A first baroclinic phase of the cyclone leads to strong convective precipitation, with high potential vorticity anomalies aloft due to an upper-level trough. The deepening and tropicalization of the cyclone is due first to the crossing of the upper-level jet, then to low-level convergence and uplift of conditionally unstable air masses by cold pools, resulting either from rain evaporation or from advection of continental air masses from North Africa. Backtrajectories show that air–sea heat exchanges warm and moisten the low-level inflow feeding the latent heat release during the mature phase of the medicane. However, the impact of ocean–atmosphere coupling on the cyclone track, intensity and lifecycle is very weak, due to a surface cooling one order of magnitude weaker than for tropical cyclones, even on the area of strong enthalpy fluxes. Isolating the influence of the surface parameters on the surface fluxes at sea during the different phases of the cyclone confirms the impact of the cold pools on the surface processes. The evaporation is controlled mainly by the sea surface temperature and wind, with a significant additional impact of the humidity and temperature at first level during the development phase. The sensible heat flux is influenced mainly by the temperature at first level throughout the whole medicane lifetime. This study shows that the tropical transition, in this case, is dependent on processes widespread in the Mediterranean Basin, like advection of continental air, rain evaporation, and dry air intrusion.

scholarly journals Deep-mixing and deep-cooling events in Lake Garda: Simulation and Mechanisms

2021 ◽  
Author(s):  
Bouke Biemond ◽  
Marina Amadori ◽  
Marco Toffolon ◽  
Sebastiano Piccolroaz ◽  
Hans van Haren ◽  
...  
Keyword(s):  
Water Temperature ◽  
Deep Water ◽  
Cold Water ◽  
Vertical Mixing ◽  
Three Dimensional ◽  
Surface Cooling ◽  
Deep Mixing ◽  
Lake Garda ◽  
Entire Depth ◽  
Strong Winds

<div> <div> <div> <p>A calibrated three-dimensional numerical model <span>(Delft3D) and in-situ observations are used to study the relation between deep water temperature and mixing in Lake Garda (Italy). A model-observation comparison indicates that the model is able to adequately capture the production of turbulent kinetic energy in the surface layer and its vertical propagation during unstratified conditions. Here, the model is used as a support to identify the main processes causing deep water cooling and deep mixing in the lake. The analysis indicated that two processes cause mixing over the entire depth. The first process is thermocline tilting due to strong and persistent winds. This is found to generate a temporary disappearance of stratification followed by vertical mixing over the entire depth. The second process is turbulent cooling, which arises as a combination of negative-buoyancy produced by surface cooling and turbulence injection from strong winds. Turbulent cooling acts when vertical temperature gradients are absent over the whole depth and cools and mixes the lake over its entire vertical. The third identified process is associated to differential cooling between the shallow southern part and the deep northern trunk. This generates the advection of cold water from the southern, colder and well-mixed basin to the norther trunk along the sloping bottom of the lake. Such differential cooling is found to be a consequence of the turbulent cooling and is not associated with mixing over the entire depth in the northern trunk. Available observations indicate that the three processes identified from the model indeed occur in Lake Garda. Long- term simulations of deep water temperature and related deep mixing appear to be very sensitive to the atmospheric forcing, whose accurate reproduction is essential for the prediction of the future occurrence of deep mixing events.</span></p> </div> </div> </div>

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