Large Eddy Simulation of Ocean Boundary Layer Entrainment

2001 ◽  
Author(s):  
Ching-Long Lin ◽  
William E. Eichinger
Keyword(s):  
Boundary Layer ◽  
Large Eddy Simulation ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Ocean Boundary

scholarly journals Large-eddy simulation of the ice shelf-ocean boundary layer and heterogeneous refreezing rate by sub-ice shelf plume

2020 ◽  
Author(s):  
Ji Sung Na ◽  
Taekyun Kim ◽  
Emilia Kyung Jin ◽  
Seung-Tae Yoon ◽  
Won Sang Lee ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Large Eddy Simulation ◽  
Outer Region ◽  
Ice Shelf ◽  
Salinity Field ◽  
Eddy Simulation ◽  
Large Eddy ◽  
In Situ Observations ◽  
Ocean Boundary

Abstract. The role of the refreezing effect in the ice shelf–ocean boundary layer (IOBL) flow with a super-cooled, plume beneath the ice shelf is investigated using the large-eddy simulation. To reveal the detailed physical processes and characteristics of the IOBL flow, a model domain is initialized and forced by in situ observations and a comparison is made between two simulations, one with the refreezing effect and one without. The simulated velocity, potential temperature, and salinity field are validated with in situ observations performed in Terra Nova Bay in the western Ross Sea in 2016/2017, confirming that the vertical structures in the simulation results agree well with observations. In particular, it is evident that, when the refreezing effect is considered, the IOBL flow can be more realistically resolved, especially upward advection from the sub-ice shelf plume and the ice front eddy. Beneath the ice shelf, two district regions (the inner and outer regions) are identified based on flow characteristics and the refreezing pattern. In the inner region, stratification and stable conditions are observed with negative momentum flux and low refreezing rates. Meanwhile, in the outer region, high shear impact and unstable conditions with a heat flux of −9 to −52 W m−2 are observed, demonstrating the high refreezing rate and the entrainment of super-cooled water from the sub-ice shelf plume. A total of 94 % of the refreezing events occur in the outer region, with a maximum refreezing rate of 1.86 m yr−1 at the ice front.

scholarly journals Nocturnal Boundary Layer Erosion Analysis in the Amazon Using Large-Eddy Simulation during GoAmazon Project 2014/5

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 240
Author(s):  
Rayonil Carneiro ◽  
Gilberto Fisch ◽  
Theomar Neves ◽  
Rosa Santos ◽  
Carlos Santos ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Large Eddy Simulation ◽  
Rainy Season ◽  
Nocturnal Boundary Layer ◽  
Enso Event ◽  
Dry Season ◽  
Dry Period ◽  
Additional Energy ◽  
Eddy Simulation ◽  
Large Eddy

This study investigated the erosion of the nocturnal boundary layer (NBL) over the central Amazon using a high-resolution model of large-eddy simulation (LES) named PArallel Les Model (PALM) and observational data from Green Ocean Amazon (GoAmazon) project 2014/5. This data set was collected during four intense observation periods (IOPs) in the dry and rainy seasons in the years 2014 (considered a typical year) and 2015, during which an El Niño–Southern Oscillation (ENSO) event predominated and provoked an intense dry season. The outputs from the PALM simulations represented reasonably well the NBL erosion, and the results showed that it has different characteristics between the seasons. During the rainy season, the IOPs exhibited slow surface heating and less intense convection, which resulted in a longer erosion period, typically about 3 h after sunrise (that occurs at 06:00 local time). In contrast, dry IOPs showed more intensive surface warming with stronger convection, resulting in faster NBL erosion, about 2 h after sunrise. A conceptual model was derived to investigate the complete erosion during sunrise hours when there is a very shallow mixed layer formed close to the surface and a stable layer above. The kinematic heat flux for heating this layer during the erosion period showed that for the rainy season, the energy emitted from the surface and the entrainment was not enough to fully heat the NBL layer and erode it. Approximately 30% of additional energy was used in the system, which could come from the release of energy from biomass. The dry period of 2014 showed stronger heating, but it was also not enough, requiring approximately 6% of additional energy. However, for the 2015 dry period, which was under the influence of the ENSO event, it was shown that the released surface fluxes were sufficient to fully heat the layer. The erosion time of the NBL probably influenced the development of the convective boundary layer (CBL), wherein greater vertical development was observed in the dry season IOPs (~1500 m), while the rainy season IOPs had a shallower layer (~1200 m).

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