Role of surface heat fluxes underneath cold pools

Gentine, Pierre; Garelli, Alix; Park, Seung-Bu; Nie, Ji; Torri, Giuseppe; Kuang, Zhiming

doi:10.1002/2015gl067262

Cited by 67 publications

(103 citation statements)

References 38 publications

(63 reference statements)

Supporting

Mentioning

100

Contrasting

Order By: Relevance

“…Describing extremes may be accomplished by our model, by coupling precipitation intensity and gust front speed, thereby relaxing the assumption of constant speed c 0 . Further, due to the effect of surface heat fluxes and energy conservation, the speed of spreading should decrease with radius (Grant & van den Heever, 2016, 2018Gentine et al, 2016;Romps & Jeevanjee, 2016). Here, h denotes the effective CP height, and g is the gravitational acceleration.…”

Section: Discussionmentioning

confidence: 99%

Circling in on Convective Organization

Haerter

Böing

Henneberg

et al. 2019

Geophysical Research Letters

View full text Add to dashboard Cite

Cold pools (CPs) contribute to convective organization. However, it is unclear by which mechanisms organization occurs. By using a particle method to track CP gust fronts in large eddy simulations, we characterize the basic collision modes between CPs. Our results show that CP interactions, where three expanding gust fronts force an updraft, are key at triggering new convection. Using this, we conceptualize CP dynamics into a parameter‐free mathematical model: circles expand from initially random points in space. Where two expanding circles collide, a stationary front is formed. However, where three expanding circles enclose a single point, a new expanding circle is seeded. This simple model supports three fundamental features of CP dynamics: precipitation cells constitute a spatially interacting system, CPs come in generations, and scales steadily increase throughout the diurnal cycle. Finally, this model provides a framework for how CPs act to cause convective self‐organization, clustering, and extremes.

show abstract

Section: Discussionmentioning

confidence: 99%

Circling in on Convective Organization

Haerter

Böing

Henneberg

et al. 2019

Geophysical Research Letters

View full text Add to dashboard Cite

show abstract

“…5. Domain size is 64 km by 64 km, with the model output saved every 30 min over 2.5 days of the thermodynamics to the cold pool dynamics as well as conceivably interaction with surface fluxes (Ross et al 2004;Gentine et al 2016;Grant and van den Heever 2016). Future challenges also remain on the modeling front.…”

Section: Thermodynamic Secondary Initiation Processesmentioning

confidence: 99%

A Survey of Precipitation-Induced Atmospheric Cold Pools over Oceans and Their Interactions with the Larger-Scale Environment

et al. 2017

Self Cite

View full text Add to dashboard Cite

Pools of air cooled by partial rain evaporation span up to several hundreds of kilometers in nature and typically last less than 1 day, ultimately losing their identity to the large-scale flow. These fundamentally differ in character from the radiatively-driven dry pools defining convective aggregation. Advancement in remote sensing and in computer capabilities has promoted exploration of how precipitation-induced cold pool processes modify the convective spectrum and life cycle. This contribution surveys current understanding of such cold pools over the tropical and subtropical oceans. In shallow convection with low rain rates, the cold pools moisten, preserving the near-surface equivalent potential temperature or increasing it if the surface moisture fluxes cannot ventilate beyond the new surface layer; both conditions indicate downdraft origin air from within the boundary layer. When rain rates exceed $ 2 mm h À1 , convective-scale downdrafts can bring down drier air of lower equivalent potential temperature from above the boundary layer. The resulting density currents facilitate the lifting of locally thermodynamically favorable air and can impose an arc-shaped mesoscale cloud organization. This organization allows clouds capable of reaching 4-5 km within otherwise dry environments. These are more commonly observed in the northern hemisphere trade wind regime, where the flow to the intertropical 123Surv Geophys (2017) 38:1283-1305 https://doi.org/10.1007/s10712-017-9447-x convergence zone is unimpeded by the equator. Their near-surface air properties share much with those shown from cold pools sampled in the equatorial Indian Ocean. Cold pools are most effective at influencing the mesoscale organization when the atmosphere is moist in the lower free troposphere and dry above, suggesting an optimal range of water vapor paths. Outstanding questions on the relationship between cold pools, their accompanying moisture distribution and cloud cover are detailed further. Near-surface water vapor rings are documented in one model inside but near the cold pool edge; these are not consistent with observations, but do improve with smaller horizontal grid spacings.

show abstract

“…Moreover, cold pools are distributed along the front and continuously fed by precipitation events, similarly to what happens in squall lines. Given this spatial organization, their strength and propagation do not depend on the surface state, as in the case for isolated convection (Gentine et al, 2016). Instead they solely depend on the state of the mid-to upper-troposphere (Peters and Hohenegger, 2017), which is also insignificantly modified by surface fluxes over the course of one diurnal cycle.…”

Section: Advectionmentioning

confidence: 99%

A simplified model of precipitation enhancement over a heterogeneous surface

Hohenegger

2018

Hydrol. Earth Syst. Sci.

View full text Add to dashboard Cite

Abstract. Soil moisture heterogeneities influence the onset of convection and subsequent evolution of precipitating systems through the triggering of mesoscale circulations. However, local evaporation also plays a role in determining precipitation amounts. Here we aim at disentangling the effect of advection and evaporation on precipitation over the course of a diurnal cycle by formulating a simple conceptual model. The derivation of the model is inspired by the results of simulations performed with a high-resolution (250 m) large eddy simulation model over a surface with varying degrees of heterogeneity. A key element of the conceptual model is the representation of precipitation as a weighted sum of advection and evaporation, each weighed by its own efficiency. The model is then used to isolate the main parameters that control precipitation variations over a spatially drier patch. It is found that these changes surprisingly do not depend on soil moisture itself but instead purely on parameters that describe the atmospheric initial state. The likelihood for enhanced precipitation over drier soils is discussed based on these parameters. Additional experiments are used to test the validity of the model.

show abstract

Role of surface heat fluxes underneath cold pools

Cited by 67 publications

References 38 publications

Circling in on Convective Organization

Circling in on Convective Organization

A Survey of Precipitation-Induced Atmospheric Cold Pools over Oceans and Their Interactions with the Larger-Scale Environment

A simplified model of precipitation enhancement over a heterogeneous surface

Contact Info

Product

Resources

About