Boundary‐layer ventilation by baroclinic life cycles

Sinclair, Victoria A.; Gray, Suzanne L.; Belcher, Stephen E.

doi:10.1002/qj.293

Cited by 38 publications

(61 citation statements)

References 46 publications

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“…Davis, 2010). Also such simulations became a valuable tool to improve our understanding of the ventilation of the boundary layer by baroclinic eddies (Sinclair et al, 2008) and moisture transport in extratropical cyclones (Boutle et al, 2010;Boutle et al, 2011). Thus, it will be useful to successively add more realism to our channel simulations by the introduction of turbulent surface fluxes, the inclusion of moisture and a convection scheme, and to assess the influence of these processes on the energetic development of the downstream cyclone.…”

Section: Discussionmentioning

confidence: 99%

Development of an idealised downstream cyclone: Eulerian and Lagrangian perspective on the kinetic energy

Papritz

Schemm

2013

Tellus A: Dynamic Meteorology and Oceanography

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A B S T R A C TIn this idealised modelling study, the development of a downstream cyclone, which closely follows the life-cycle of a Shapiro-Keyser cyclone, is addressed from a quasi-geostrophic kinetic energy perspective. To this end a simulation of a dry, highly idealised, dispersive baroclinic wave, developing a primary and a downstream cyclone, is performed. Kinetic energy and processes contributing to its tendency Á in particular baroclinic conversion and ageostrophic geopotential fluxes Á are investigated in three dimensions both in an Eulerian and a Lagrangian framework from the genesis of the downstream cyclone as an upper-level kinetic energy centre, over frontal fracture to the fully developed cyclone showing the characteristic T-bone surface frontal structure, with a strong low-level jet along the bent-back front. Initially the downstream cyclone grows by the convergence of ageostrophic geopotential fluxes from the primary cyclone, but as vertical motions intensify this process is replaced by baroclinic conversion in the warm sector. We show that kinetic energy released in the warm sector is radiated away at all levels by ageostrophic geopotential fluxes: in the upper troposphere they are directed downstream, while in the lower troposphere they radiate kinetic energy to the rear of the cyclone. Thereby, vertical ageostrophic geopotential fluxes, their location and divergence, are identified to play a major role in the intensification of the cyclone in the lower troposphere and for the formation of the low-level jet. Low-level rearward ageostrophic geopotential fluxes converging along the bent-back front are shown to be a general characteristic of an eastward propagating baroclinic wave.

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Section: Discussionmentioning

confidence: 99%

Development of an idealised downstream cyclone: Eulerian and Lagrangian perspective on the kinetic energy

Papritz

Schemm

2013

Tellus A: Dynamic Meteorology and Oceanography

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“…Under such conditions, a significant part of boundary layer air masses originates from the European free troposphere (Lelieveld et al, 2002;Traub et al, 2003). Several previous studies have paid attention to the tropospheric vertical mixing processes to address ventilation of PBL pollutants into the free troposphere (Sinclair et al, 2008), by warm conveyor belt (Kowol-Santen et al, 2001), cloud and mountain venting (Cotton et al, 1995;Henne et al, 2005), land-sea exchange processes (Foret et al, 2006;Dacre et al, 2007) or deep convection (Doherty et al, 2005;Lawrence and Rasch, 2005). However, only few have considered the reverse problem (Fiore et al, 2002;Parrington et al, 2009), i.e.…”

Section: G Foret Et Al: Evaluating the Potential Of Iasi Ozone Obsementioning

confidence: 99%

Evaluating the potential of IASI ozone observations to constrain simulated surface ozone concentrations

et al. 2009

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Abstract.A tracer study has been performed for two summers in 2003 and 2004 with a regional chemistry-transport model in order to evaluate the potential constraint that tropospheric ozone observations from nadir viewing infrared sounders like IASI or TES exert on modelled near surface ozone. As these instruments show high sensitivity in the free troposphere, but low sensitivity at ground, it is important to know how much of the information gained in the free troposphere is transferred to ground through vertical transport processes. Within the European model domain, and within a time span of 4 days, only ozone like tracers initialised in vertical layers above 500 hPa are transported to the surface. For a tracer initialised between 800 and 700 hPa, seven percent reaches the surface within one to three days, on the average over the European model domain but more than double over the Mediterranean Sea. For this region, trajectory analysis shows that this is related to strong subsident transport. These results are confirmed by a second tracer study taking into account averaging kernels related to IASI retrievals, indicating the potential of these measurements to efficiently constrain surface ozone values.

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“…Iron contained within aerosol dust enhances biological productivity when transported to the open ocean where it can change oceanic uptake of the greenhouse gas carbon dioxide (CO 2 ) through changes to marine photosynthesis (Fung et al, 2000;Jickells et al, 2005;Mahowald, 2011). Ventilation of tracers, such as dust, out of the planetary boundary layer (PBL) for transport downwind is dependent upon PBL turbulent mixing (Sinclair et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Impact of planetary boundary layer turbulence on model climate and tracer transport

et al. 2015

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Abstract. Planetary boundary layer (PBL) processes are important for weather, climate, and tracer transport and concentration. One measure of the strength of these processes is the PBL depth. However, no single PBL depth definition exists and several studies have found that the estimated depth can vary substantially based on the definition used. In the Goddard Earth Observing System (GEOS-5) atmospheric general circulation model, the PBL depth is particularly important because it is used to calculate the turbulent length scale that is used in the estimation of turbulent mixing. This study analyzes the impact of using three different PBL depth definitions in this calculation. Two definitions are based on the scalar eddy diffusion coefficient and the third is based on the bulk Richardson number. Over land, the bulk Richardson number definition estimates shallower nocturnal PBLs than the other estimates while over water this definition generally produces deeper PBLs. The near-surface wind velocity, temperature, and specific humidity responses to the change in turbulence are spatially and temporally heterogeneous, resulting in changes to tracer transport and concentrations. Near-surface wind speed increases in the bulk Richardson number experiment cause Saharan dust increases on the order of 1 × 10 −4 kg m −2 downwind over the Atlantic Ocean. Carbon monoxide (CO) surface concentrations are modified over Africa during boreal summer, producing differences on the order of 20 ppb, due to the model's treatment of emissions from biomass burning. While differences in carbon dioxide (CO 2 ) are small in the time mean, instantaneous differences are on the order of 10 ppm and these are especially prevalent at high latitude during boreal winter. Understanding the sensitivity of trace gas and aerosol concentration estimates to PBL depth is important for studies seeking to calculate surface fluxes based on near-surface concentrations and for studies projecting future concentrations.

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Boundary‐layer ventilation by baroclinic life cycles

Cited by 38 publications

References 46 publications

Development of an idealised downstream cyclone: Eulerian and Lagrangian perspective on the kinetic energy

Development of an idealised downstream cyclone: Eulerian and Lagrangian perspective on the kinetic energy

Evaluating the potential of IASI ozone observations to constrain simulated surface ozone concentrations

Impact of planetary boundary layer turbulence on model climate and tracer transport

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