Simple Models of the Role of Surface Fluxes in Convective Cold Pool Evolution

We argue that the Cambridge capital theory controversies of the 1950s to 1970s were the latest in a series of still-unresolved controversies over three deep issues: explaining and justifying the return to capital; Joan Robinson's complaint that, due to path dependence, equilibrium is not an outcome of an economic process and therefore an inadequate tool for analyzing accumulation and growth; and the role of ideology and vision in fuelling controversy when results of simple models are not robust. We predict these important and relevant issues, latent in endogenous growth and real business cycle theories, will erupt in future controversy.

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Cold Pools and Their Influence on the Tropical Marine Boundary Layer

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-16-0264.1 ◽

2017 ◽

Vol 74 (4) ◽

pp. 1149-1168 ◽

Cited By ~ 26

Author(s):

Simon P. de Szoeke ◽

Eric D. Skyllingstad ◽

Paquita Zuidema ◽

Arunchandra S. Chandra

Keyword(s):

Boundary Layer ◽

Marine Boundary Layer ◽

Sensible Heat Flux ◽

Surface Flux ◽

Active Phase ◽

Surface Fluxes ◽

Cold Pool ◽

Madden Julian Oscillation ◽

Cold Pools ◽

Central Indian Ocean

Abstract Cold pools dominate the surface temperature variability observed over the central Indian Ocean (0°, 80°E) for 2 months of research cruise observations in the Dynamics of the Madden–Julian Oscillation (DYNAMO) experiment in October–December 2011. Cold pool fronts are identified by a rapid drop of temperature. Air in cold pools is slightly drier than the boundary layer (BL). Consistent with previous studies, cold pools attain wet-bulb potential temperatures representative of saturated downdrafts originating from the lower midtroposphere. Wind and surface fluxes increase, and rain is most likely within the ~20-min cold pool front. Greatest integrated water vapor and liquid follow the front. Temperature and velocity fluctuations shorter than 6 min achieve 90% of the surface latent and sensible heat flux in cold pools. The temperature of the cold pools recovers in about 20 min, chiefly by mixing at the top of the shallow cold wake layer, rather than by surface flux. Analysis of conserved variables shows mean BL air is composed of 51% air entrained from the BL top (800 m), 22% saturated downdrafts, and 27% air at equilibrium with the ocean surface. The number of cold pools, and their contribution to the BL heat and moisture, nearly doubles in the convectively active phase compared to the suppressed phase of the Madden–Julian oscillation.

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Peering into the internal structure of cold pools and their interactions with a dense observational network

10.5194/dach2022-51 ◽

2021 ◽

Author(s):

Cathy Hohenegger ◽

Jaemyeong Seo ◽

Hannes Nevermann ◽

Bastian Kirsch ◽

Nima Shokri ◽

...

Keyword(s):

Internal Structure ◽

Land Surface ◽

Surface Fluxes ◽

Cold Pool ◽

Convective Clouds ◽

Cold Pools ◽

Soil Sensors ◽

Modelling Studies ◽

Surface Network ◽

Shed Light

Melting and evaporation of hydrometeors in and below convective clouds generates cold, dense air that falls through the atmospheric column and spreads at the surface like a density current, the cold pool. In modelling studies, the importance of cold pools in controlling the lifecycle of convection has often been emphasized, being through their organization of the cloud field or through their sheer deepening of the convection. Larger, longer-lived cold pools benefit convection, but little is actually known on the size and internal structure of cold pools from observations as the majority of cold pools are too small to be captured by the operational surface network. &#160;One aim of the field campaign FESSTVaL was to peer into the internal structure of cold pools and their interactions with the underlying land surface by deploying a dense network of surface observations. This network consisted of 80 self-designed cold pool loggers, 19 weather stations and 83 soil sensors deployed in an area of 15 km around Lindenberg. FESSTVaL took place from 17 May to 27 August 2021. In principle, cold pool characteristics are affected both by the atmospheric state, which fuels cold pools through melting and evaporation of hydrometeors, and the land surface, which acts to destroy cold pools through friction and warming by surface fluxes. In this talk, the measurements collected during FESSTVaL will be used to shed light on these interactions. &#160;We are particularly interested to assess how homogeneous the internal structure of cold pools is and whether heterogeneities of the land surface imprint themselves on this internal structure. The results will be compared to available model simulations.

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Assessment of the role of sea surface fluxes on eastern Mediterranean explosive cyclogenesis with the aid of the limited-area model COSMO.GR

Atmospheric Research ◽

10.1016/j.atmosres.2017.10.005 ◽

2018 ◽

Vol 208 ◽

pp. 132-147 ◽

Cited By ~ 1

Author(s):

John Kouroutzoglou ◽

Euripides N. Avgoustoglou ◽

Helena A. Flocas ◽

Maria Hatzaki ◽

Panagiotis Skrimizeas ◽

...

Keyword(s):

Eastern Mediterranean ◽

Surface Fluxes ◽

Sea Surface ◽

Limited Area ◽

Limited Area Model ◽

Area Model

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Surface thermal inversion evolution in the bottom of a Pyrenean valley studied by observations and mesoscale simulations

10.5194/egusphere-egu2020-9919 ◽

2020 ◽

Author(s):

Maria A. Jiménez ◽

Joan Cuxart ◽

Alexandre Paci ◽

Laura Conangla ◽

Daniel Martínez-Villagrasa ◽

...

Keyword(s):

Surface Fluxes ◽

Cold Pool ◽

Daily Cycle ◽

Bottom Part ◽

Thermal Inversion ◽

Main Site ◽

Variable Surface ◽

Low Levels ◽

Small Cloud ◽

Mesoscale Simulations

Two experimental campaigns have been carried out in the Cerdanya valley at south side of the Pyrenees (E-W oriented, 35 km long and 9 km wide) during fall 2015 (Cerdanya Cold Pool experiment, CCP&#8217;15) and winter 2017 (CCP&#8217;17, as a part of the Cerdanya-2017 experiment) to study the cold pool that usually forms there at night. The main site (Das) is placed in the central bottom part of the basin. Conangla et al (2018, IJOC) showed that most cold pool events reported there have a daily cycle, being formed in the evening and destroyed by solar heating of the surface the morning after.The availability of vertical soundings performed by a tethered balloon and a WindRASS, together with measured surface fluxes of latent and sensible heat and momentum at the surface layer allows to inspect the establishment and evolution of the surface thermal inversion in Das. This area collects also downslope and downvalley flows accumulating cold air in the valley along the night. The organization of the flow at low levels is studied through mesoscale simulations of some selected Intensive Operational Periods (IOPs) and the surface observations at different locations along and across the valley.The selected IOPs comprise nights with only locally-generated winds and small cloud cover, and with variable surface state including grass, fresh snow and patches of old snow. The evolution of the strength and depth of the surface inversion as seen by the model are compared to the available data. Besides, the organization of the flow at low levels and the contribution of the air from the tributary valleys is analyzed in terms of temperature and wind speed budgets to properly characterize the differences in the strength of the cold pool for the selected studied IOPs.

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The Role of WISHE in the Rapid Intensification of Tropical Cyclones

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-20-0006.1 ◽

2020 ◽

Vol 77 (9) ◽

pp. 3139-3160

Author(s):

Chieh-Jen Cheng ◽

Chun-Chieh Wu

Keyword(s):

Tropical Cyclones ◽

Potential Temperature ◽

Surface Heat ◽

Surface Fluxes ◽

Heat Fluxes ◽

Rapid Intensification ◽

Surface Heat Fluxes ◽

Peak Intensity ◽

Before And After

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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Modeling the possible role of iodine oxides in atmospheric new particle formation

Atmospheric Chemistry and Physics ◽

10.5194/acp-6-505-2006 ◽

2006 ◽

Vol 6 (2) ◽

pp. 505-523 ◽

Cited By ~ 69

Author(s):

S. Pechtl ◽

E. R. Lovejoy ◽

J. B. Burkholder ◽

R. von Glasow

Keyword(s):

Marine Boundary Layer ◽

Hot Spot ◽

Coastal Region ◽

Particle Growth ◽

Particle Formation ◽

Surface Fluxes ◽

Laboratory Model ◽

New Particle Formation ◽

Iodine Oxides

Abstract. We studied the possible role of iodine oxides in atmospheric new particle formation with the one-dimensional marine boundary layer model MISTRA, which includes chemistry in the gas and aerosol phase as well as aerosol microphysics. The chemical reaction set focuses on halogen (Cl-Br-I) chemistry. We included a two-step nucleation parameterization, where in the first step, the "real" nucleation process is parameterized, i.e., the formation of cluster-sized nuclei via homogeneous condensation of gases. We considered both ternary sulfuric acid-ammonia-water nucleation and homomolecular homogeneous OIO nucleation. For the latter, we derived a parameterization based on combined laboratory-model studies. The second step of the nucleation parameterization treats the "apparent" nucleation rate, i.e., the growth of clusters into the model's lowest size bin by condensable vapors such as OIO. We compared different scenarios for a clean marine versus a polluted continental background atmosphere. In every scenario, we assumed the air to move, independent of its origin, first over a coastal region (where it is exposed to surface fluxes of different reactive iodine precursors) and later over the open ocean. According to these sensitivity studies, in the clean marine background atmosphere OIO can be responsible for both homogeneous nuclei formation and the subsequent growth of the clusters to detectable sizes. In contrast to this, in the continental case with its higher levels of pollutants, gas phase OIO mixing ratios, and hence related nucleation rates, are significantly lower. Compared to ternary H2SO4-NH3-H2O nucleation, homogeneous OIO nucleation can be neglected for new particle formation in this case, but OIO can contribute to early particle growth, i.e., to apparent nucleation rates. In general, we found OIO to be more important for the growth of newly formed particles than for the formation of new nuclei. According to our studies, observations of particle "bursts" can only be explained by hot spot-like, not by homogeneously distributed emissions.

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