Role of surface heat fluxes underneath cold pools

Abstract This study examines the role of surface heat fluxes, particularly in relation to the wind-induced surface heat exchange (WISHE) mechanism, in the rapid intensification (RI) of tropical cyclones (TCs). Sensitivity experiments with capped surface fluxes and thus reduced WISHE exhibit delayed RI and weaker peak intensity, while WISHE could affect the evolutions of TCs both before and after the onset of RI. Before RI, more WISHE leads to faster increase of equivalent potential temperature in the lower levels, resulting in more active and stronger convection. In addition, TCs in experiments with more WISHE reach a certain strength earlier, before the onset of RI. During the RI period, more surface heat fluxes could provide convective instability in the lower levels, and cause a consequent development in the convective activity. More efficient intensification in a TC is found with higher surface heat fluxes and larger inertial stability, leading to a stronger peak intensity, more significant and deeper warm core in TC center, and the axisymmetrization of convection in the higher levels. In both stages, different levels of WISHE alter the thermodynamic environment and convective-scale processes. In all, this study supports the crucial role of WISHE in affecting TC intensification rate for TCs with RI.

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The Role of Clouds and Surface Heat Fluxes in the Maintenance of the 2013–2016 Northeast Pacific Marine Heatwave

Journal of Geophysical Research Atmospheres ◽

10.1029/2019jd030780 ◽

2019 ◽

Vol 124 (20) ◽

pp. 10772-10783 ◽

Cited By ~ 4

Author(s):

Lauren Schmeisser ◽

Nicholas A. Bond ◽

Samantha A. Siedlecki ◽

Thomas P. Ackerman

Keyword(s):

Surface Heat ◽

Heat Fluxes ◽

Surface Heat Fluxes ◽

Northeast Pacific

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Numerical Study of the Role of Microphysical Latent Heating and Surface Heat Fluxes in a Severe Precipitation Event in the Warm Sector over Southern China

Asia-Pacific Journal of Atmospheric Sciences ◽

10.1007/s13143-017-0061-0 ◽

2018 ◽

Vol 54 (1) ◽

pp. 77-90 ◽

Cited By ~ 4

Author(s):

Jin-Fang Yin ◽

Dong-Hai Wang ◽

Zhao-Ming Liang ◽

Chong-Jian Liu ◽

Guo-Qing Zhai ◽

...

Keyword(s):

Numerical Study ◽

Southern China ◽

Surface Heat ◽

Heat Fluxes ◽

Precipitation Event ◽

Latent Heating ◽

Surface Heat Fluxes ◽

Warm Sector

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The role of surface heat fluxes in tropical intraseasonal oscillations

Nature Geoscience ◽

10.1038/ngeo312 ◽

2008 ◽

Vol 1 (10) ◽

pp. 653-657 ◽

Cited By ~ 80

Author(s):

Adam H. Sobel ◽

Eric D. Maloney ◽

Gilles Bellon ◽

Dargan M. Frierson

Keyword(s):

Surface Heat ◽

Heat Fluxes ◽

Surface Heat Fluxes ◽

Intraseasonal Oscillations ◽

Tropical Intraseasonal Oscillations

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Characteristics of a Hailstorm over the Andean La Paz Valley

10.5194/nhess-2019-27 ◽

2019 ◽

Author(s):

Marcelo Zamuriano ◽

Andrey Martynov ◽

Luca Panziera ◽

Stefan Brönnimann

Keyword(s):

Deep Convection ◽

Local Features ◽

Surface Heat ◽

Heat Fluxes ◽

Lake Breeze ◽

Shallow Convection ◽

La Paz ◽

Surface Heat Fluxes ◽

Cold Pools ◽

Lake Temperature

Abstract. The iconic hailstorm and flash flood episode of 19 February 2002 over La Paz city is numerically investigated in this article. Large scale atmospheric circulation is dynamically downscaled in order to take into account the complex orography forcing and local features. Satellite observations suggests late morning shallow convection over the Altiplano that becomes deep convection in the early afternoon around complex orography. The control simulation captures well the cloud evolution and suggest a two-stage precipitation mechanism. First, early convection occurred around 1200 LST and originated from thermodynamic instability combined with lake breeze and orographic lifting. Rainfall discharge then generated cold pools. During the second stage, cold pools around complex orography were propagated by lake breeze and encountered the La Paz Valley breeze, triggering the deep convection near La Paz city around 1400 LST. We assess the importance of local features through numerical experiments, which include modification of orography, suppression of surface heat fluxes, changes of surface lake temperature and removal of the lake. We show the importance of orographic configuration as triggering mechanism for convection initiation and for mesoscale circulation, the role of lake temperature for frontal breeze and propagation of cold pools, and of surface heat fluxes for atmospheric instability. This study highlights the complex interaction between lakes, surface heating and orography that favour deep convection and hailstorm formation, which is especially relevant around the Titicaca lake region.

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Shallow-to-Deep Transition of Continental Moist Convection: Cold Pools, Surface Fluxes, and Mesoscale Organization

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-18-0031.1 ◽

2018 ◽

Vol 75 (12) ◽

pp. 4071-4090 ◽

Cited By ~ 8

Author(s):

Marcin J. Kurowski ◽

Kay Suselj ◽

Wojciech W. Grabowski ◽

Joao Teixeira

Keyword(s):

Surface Heat ◽

Surface Fluxes ◽

Heat Fluxes ◽

Cloud Base ◽

Moist Convection ◽

Near Surface ◽

Surface Heat Fluxes ◽

Cold Pools ◽

Interactive Surface ◽

Convection Parameterization

Abstract Large-eddy simulation is used to investigate the effects of cold pools driven by rain evaporation on the shallow-to-deep convection transition over land. The physically consistent methodologies are developed to obtain a time-dependent reference ensemble without cold pools and to apply interactive surface heat fluxes without modeling of surface energy and water budgets. Three different simulation ensembles are contrasted. The reference ensemble, in the spirit of one-dimensional single-column models, eliminates cold pools by horizontally homogenizing negative buoyancy production due to rain evaporation. The additional ensembles complement the reference cold-pool-free ensemble by including cold pools and by applying either interactive or prescribed surface fluxes. Contrasting these ensembles suggests possible improvements of convection parameterization in large-scale models of weather and climate. Without cold pools, the reference ensemble preserves key features of buoyancy-driven cellular convection associated with a field of convective plumes, as assumed in a typical convection parameterization. With cold pools, a significant enhancement of surface heat and moisture fluxes and about an hour delay of their daily maximum is simulated. Cold pools enhance near-surface temperature and moisture standard deviations as well as maxima of the near-surface updraft velocity. They also lead to the reduction of cloud lateral entrainment, deeper vertical development of the cloud layer, and a few-times-larger accumulated surface precipitation. Interactive surface fluxes provide a damping mechanism that noticeably suppresses all these effects. Perhaps surprisingly, cold pools do not significantly change the cloud-base convective mass flux that approximately follows the evolution of surface heat fluxes.

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The Role of WISHE in Secondary Eyewall Formation

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-17-0236.1 ◽

2018 ◽

Vol 75 (11) ◽

pp. 3823-3841 ◽

Cited By ~ 6

Author(s):

Chieh-Jen Cheng ◽

Chun-Chieh Wu

Keyword(s):

Control Experiment ◽

Inner Core ◽

Surface Wind ◽

Surface Heat ◽

Heat Fluxes ◽

Surface Heat Fluxes ◽

Secondary Eyewall Formation ◽

Tangential Wind ◽

The Impact

Abstract Numerical simulations are conducted to examine the role of the wind-induced surface heat exchange (WISHE) mechanism in secondary eyewall formation (SEF). The control experiment exhibits a coherent secondary eyewall structure as quantified by various parameters (e.g., the azimuthal-mean tangential wind and vertical velocity). Prior to SEF, an area characterized by increasing diabatic heating, enhanced inertial stability, and increasing supergradient winds at the top of the boundary layer is observed outside the eyewall. While these characteristics offer the possibility of both balanced and unbalanced dynamical pathways to SEF, the focus of this study is to evaluate the impact of WISHE. To examine the sensitivity of SEF to WISHE, the surface wind used for the calculation of surface heat fluxes is capped at several designated values and at different radial intervals. When the heat fluxes are moderately suppressed around and outside the SEF region observed in the control experiment, sensitivity experiments show that the formation of the outer eyewall is delayed, and the intensity of both eyewalls is weaker. When the heat fluxes are strongly suppressed in the same region, SEF does not occur. In contrast, suppressing the surface heat fluxes in the storm’s inner-core region has limited effect on the evolution of the outer eyewall. This study provides important physical insight into SEF, indicating that WISHE plays a crucial role in SEF and tropical cyclone evolution.

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