Model representation of boundary-layer convergence triggering deep convection over complex terrain: A case study from COPS

2010 ◽  
Vol 95 (2-3) ◽  
pp. 172-185 ◽  
Author(s):  
Christian Barthlott ◽  
Janus Willem Schipper ◽  
Norbert Kalthoff ◽  
Bianca Adler ◽  
Christoph Kottmeier ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Complex Terrain ◽  
Deep Convection ◽  
Model Representation

scholarly journals The impact of a foehn wind on PM10 concentrations and the urban boundary layer in complex terrain: a case study from Kraków, Poland

Tellus B ◽  
2021 ◽  
Vol 73 (1) ◽  
pp. 1-26
Author(s):  
Piotr Sekuła ◽  
Anita Bokwa ◽  
Zbigniew Ustrnul ◽  
Mirosław Zimnoch ◽  
Bogdan Bochenek
Keyword(s):  
Boundary Layer ◽  
Complex Terrain ◽  
Urban Boundary Layer ◽  
The Impact

scholarly journals Influence of corona discharge on the ozone budget in the tropical free troposphere: a case study of deep convection during GABRIEL

2014 ◽  
Vol 14 (17) ◽  
pp. 8917-8931 ◽  
Author(s):  
H. Bozem ◽  
H. Fischer ◽  
C. Gurk ◽  
C. L. Schiller ◽  
U. Parchatka ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Corona Discharge ◽  
Deep Convection ◽  
Convective Transport ◽  
Free Troposphere ◽  
Direct Production ◽  
Model Calculations ◽  
Mixing Ratios ◽  
Outflow Region

Abstract. Convective redistribution of ozone and its precursors between the boundary layer (BL) and the free troposphere (FT) influences photochemistry, in particular in the middle and upper troposphere (UT). We present a case study of convective transport during the GABRIEL campaign over the tropical rain forest in Suriname in October 2005. During one measurement flight the inflow and outflow regions of a cumulonimbus cloud (Cb) have been characterized. We identified a distinct layer between 9 and 11 km altitude with enhanced mixing ratios of CO, O3, HOx, acetone and acetonitrile. The elevated O3 contradicts the expectation that convective transport brings low-ozone air from the boundary layer to the outflow region. Entrainment of ozone-rich air is estimated to account for 62% (range: 33–91%) of the observed O3. Ozone is enhanced by only 5–6% by photochemical production in the outflow due to enhanced NO from lightning, based on model calculations using observations including the first reported HOx measurements over the tropical rainforest. The "excess" ozone in the outflow is most probably due to direct production by corona discharge associated with lightning. We deduce a production rate of 5.12 × 1028 molecules O3 flash−1 (range: 9.89 × 1026–9.82 × 1028 molecules O3 flash−1), which is at the upper limit of the range reported previously.

scholarly journals Influence of corona discharge on the ozone budget in the tropical free troposphere: a case study of deep convection during GABRIEL

2014 ◽  
Vol 14 (4) ◽  
pp. 5233-5270 ◽  
Author(s):  
H. Bozem ◽  
H. Fischer ◽  
C. Gurk ◽  
C. L. Schiller ◽  
U. Parchatka ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Corona Discharge ◽  
Deep Convection ◽  
Convective Transport ◽  
Free Troposphere ◽  
Direct Production ◽  
Model Calculations ◽  
Mixing Ratios ◽  
Steady State Model

Abstract. Convective redistribution of ozone and its precursors between the boundary layer (BL) and the free troposphere (FT) influences photochemistry, in particular that of the middle and upper troposphere (UT). We present a case study of convective transport during the GABRIEL campaign over the tropical rain forest in Suriname in October 2005. During a measurement flight on 12 October the inflow and outflow regions of a cumulonimbus cloud (Cb) have been characterized, providing evidence of convective transport. We identified a distinct layer between 9 and 11 km altitude with enhanced mixing ratios of CO, O3, HOx, acetone and acetonitrile. The elevated O3 contradicts the expectation that convective transport brings low ozone air from the boundary layer to the outflow region. The enhanced mixing ratio of ozone in the outflow was mainly of dynamical origin. Entrainment of ozone rich air at the outflow level into the convective outflow accounts for 62% (range: 33–91%) of the observed O3. Ozone is enhanced by only 5–6% by photochemical production in the outflow due to enhanced NO from lightning, based on steady state model calculations, using in-situ observations including the first reported HOx measurements over the tropical rainforest. The "excess" ozone in the outflow is most probably due to direct production by corona discharge associated with lightning. We deduce a production rate of 5.12 × 1028 molecules O3 flash−1 (range: 9.89 × 1026–9.82 × 1028 molecules O3 flash−1), which is at the upper limit of the range of the values reported previously.

scholarly journals Cloud-scale modelling of the impact of deep convection on the fate of oceanic bromoform in the troposphere: a case study over the west coast of Borneo

2020 ◽  
Author(s):  
Paul D. Hamer ◽  
Virginie Marécal ◽  
Ryan Hossaini ◽  
Michel Pirre ◽  
Gisèle Krysztofiak ◽  
...  
Keyword(s):  
Boundary Layer ◽  
West Coast ◽  
Deep Convection ◽  
Convective System ◽  
The West ◽  
Upper Troposphere ◽  
Convective Systems ◽  
Mixing Ratios ◽  
The Impact

Abstract. Coastal oceans emit bromoform (CHBr3) that can be transported rapidly to the upper troposphere by deep convection. In the troposphere, the spatial and vertical distribution of CHBr3 and its product gases (PGs) depend on emissions, chemical processing, transport by large scale flow, convection, and associated washout. This paper presents a modelling study on the fate of CHBr3 and its PGs in the troposphere. A case study at cloud scale was conducted along the west coast of Borneo, when several deep convective systems triggered in the afternoon and early evening of November 19th 2011. These systems were sampled by the Falcon aircraft during the field campaign of the SHIVA project. We analyse these systems using a simulation with the cloud-resolving meteorological model C-CATT-BRAMS at 2 × 2 km resolution that describes transport, photochemistry, and washout of CHBr3. We find that simulated CHBr3 mixing ratios and the observed values in the boundary layer and the outflow of the convective systems agree. However, the model underestimates the background CHBr3 mixing ratios in the upper troposphere, which suggests a missing source. An analysis of the simulated chemical speciation of bromine within and around each simulated convective system during the mature convective stage reveals that > 85 % of the bromine derived from CHBr3 and its PGs is transported vertically to the point of convective detrainment in the form of CHBr3 and that the remaining small fraction is in the form of organic PGs, principally insoluble brominated carbonyls produced from the photo-oxidation of CHBr3. The model simulates that within the boundary layer and free troposphere, the inorganic PGs are only present in soluble forms, i.e., HBr, HOBr, and BrONO2, and consequently, within the convective clouds, the inorganic PGs are almost entirely removed by wet scavenging. For the conditions of the simulated case study Br2 plays no significant role in the vertical transport of bromine. This likely results from the small simulated quantities of inorganic bromine involved, the presence of HBr in large excess compared to HOBr and the less soluble BrO, and the relatively quick removal of soluble compounds within the convective column. This prevalence of HBr is a result of the wider simulated regional atmospheric composition whereby background tropospheric ozone levels are exceptionally low.

A case study of the nocturnal boundary layer over a complex terrain

1993 ◽  
Vol 66 (3) ◽  
pp. 303-324 ◽  
Author(s):  
Matthew J. Parker ◽  
Sethu Raman
Keyword(s):  
Boundary Layer ◽  
Complex Terrain ◽  
Nocturnal Boundary Layer

scholarly journals Cloud-scale modelling of the impact of deep convection on the fate of oceanic bromoform in the troposphere: a case study over the west coast of Borneo

2021 ◽  
Vol 21 (22) ◽  
pp. 16955-16984
Author(s):  
Paul D. Hamer ◽  
Virginie Marécal ◽  
Ryan Hossaini ◽  
Michel Pirre ◽  
Gisèle Krysztofiak ◽  
...  
Keyword(s):  
Boundary Layer ◽  
West Coast ◽  
Deep Convection ◽  
Regional Scale ◽  
Convective System ◽  
The West ◽  
Convective Systems ◽  
Mixing Ratios ◽  
The Impact

Abstract. This paper presents a modelling study on the fate of CHBr3 and its product gases in the troposphere within the context of tropical deep convection. A cloud-scale case study was conducted along the west coast of Borneo, where several deep convective systems were triggered on the afternoon and early evening of 19 November 2011. These systems were sampled by the Falcon aircraft during the field campaign of the SHIVA project and analysed using a simulation with the cloud-resolving meteorological model C-CATT-BRAMS at 2×2 km resolution that represents the emissions, transport by large-scale flow, convection, photochemistry, and washout of CHBr3 and its product gases (PGs). We find that simulated CHBr3 mixing ratios and the observed values in the boundary layer and the outflow of the convective systems agree. However, the model underestimates the background CHBr3 mixing ratios in the upper troposphere, which suggests a missing source at the regional scale. An analysis of the simulated chemical speciation of bromine within and around each simulated convective system during the mature convective stage reveals that >85 % of the bromine derived from CHBr3 and its PGs is transported vertically to the point of convective detrainment in the form of CHBr3 and that the remaining small fraction is in the form of organic PGs, principally insoluble brominated carbonyls produced from the photo-oxidation of CHBr3. The model simulates that within the boundary layer and free troposphere, the inorganic PGs are only present in soluble forms, i.e. HBr, HOBr, and BrONO2, and, consequently, within the convective clouds, the inorganic PGs are almost entirely removed by wet scavenging. We find that HBr is the most abundant PG in background lower-tropospheric air and that this prevalence of HBr is a result of the relatively low background tropospheric ozone levels at the regional scale. Contrary to a previous study in a different environment, for the conditions in the simulation, the insoluble Br2 species is hardly formed within the convective systems and therefore plays no significant role in the vertical transport of bromine. This likely results from the relatively small quantities of simulated inorganic bromine involved, the presence of HBr in large excess compared to HOBr and BrO, and the relatively efficient removal of soluble compounds within the convective column.

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