The Coastal Convective Interactions Experiment (CCIE): Understanding the Role of Sea Breezes for Hailstorm Hotspots in Eastern Australia

Soderholm, Joshua; McGowan, Hamish A.; Richter, Harald; Walsh, Kevin; Weckwerth, Tammy M.; Coleman, Matthew A.

doi:10.1175/bams-d-14-00212.1

Cited by 18 publications

(22 citation statements)

References 46 publications

(40 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The higher occurrence of SEQ storm days during sea breeze conditions is consistent with Soderholm et al (2016).…”

Section: Static Stabilitysupporting

confidence: 79%

“…2.5 for locations) situated to minimise local influences (e.g., urban effects, tall vegetation). Out of the twenty AWSs, only three are located in proximity to the southwest region of frequent convective initiation and hailstorm development (Soderholm et al 2016). To fill this observational gap, two additional AWSs were deployed by The University of Queensland for the duration of CCIE (November 2013 to January 2015).…”

Section: Methodsmentioning

confidence: 99%

“…Mountains of eastern North American (Weisman 1990b), Andes Mountains of South America (Mezher et al 2012), Prebetic Ranges of the Iberian Peninsula (Azorin-Molina et al 2014a), and the Great Dividing Range of Australia (Potts et al 2000;Soderholm et al 2016) Convective storm environments are also influenced by the surface properties (e.g., albedo, heat capacity, moisture content). Wet landscapes increase near-surface humidity, potentially leading to great parcel instability (Segal et al 1995) and increased convective storm activity .…”

Section: Surface Effectsmentioning

confidence: 99%

“…Particulates are generally an indicator of a well-mixed air mass, therefore it is hypothesised that the return flow is coupled with an eastward advected inland CBL above the sea breeze. Synoptic winds with a westerly component are typical of SEQ storm environments above the PBL (Callaghan 1996;Peter et al 2015;Soderholm et al 2016), thus an advected CBL is likely to be of continental origin.…”

Section: Sea Breeze Structurementioning

confidence: 99%

“…A field campaign strategy was designed to investigate convective storm hotspots in SEQ using the guidance provided by the long-term climatology (Soderholm et al 2016). …”

Section: Overview Of Objectives and Major Findingsmentioning

confidence: 99%

See 4 more Smart Citations

The coastal convective interactions experiment

Soderholm¹

Self Cite

View full text Add to dashboard Cite

Prediction of convective storm environments relies principally upon the broad-scale meteorology (e.g., synoptic boundaries and air masses) in contrast to local-scale (2 -20 km) processes within the planetary boundary layer (PBL). Diurnal heating of the Earth's heterogeneous surface at these finer scales forces circulations (e.g., sea breezes, valley winds, urban heat island circulations) which have been related to trends in the meteorological and climatological activity of storms; however, a quantitative understanding of their interactions with deep convection is limited. This is especially true for physical settings which support a variety of PBL circulations that challenge our understanding of ii Detailed analysis of the CCIE climatology datasets provided an understanding of SEQ hailstorms across a range of spatiotemporal scales. At the inter-annual time scale, the ElNiño Southern Oscillation (ENSO) was shown to have a statistically significant relationship with both hailstorm and sea breeze frequency in SEQ. Synoptic scale southeasterly changes that were found to couple with sea breezes provide the most favourable environment for hailstorms, particularly for southwest SEQ. At the mesoscale, hail development within convective cells was found to be most frequent within the inland limb of maritime air masses on sea breeze days. It was concluded, that the maritime sea breeze air is potentially favourable for convection after modification through inland propagation and the associated entrainment of sensible heat.Investigation of the CCIE field campaign datasets show that diurnal modification of the coastal PBL by near-surface and boundary layer processes provide favourable preconditioning for convective storms. This includes: (1) early sea breeze onset for the city of Brisbane due an urban heat island enhanced land-sea thermal contrast, (2) significant afternoon warming and moistening above the sea breeze attributed to the advection of the inland convective boundary layer coastward under prevailing westerly flow, and (3) substantial variations in near-surface moisture likely associated with topography and landuse. For the 27 November 2014 Brisbane case study hailstorm event, which caused damages exceeding $1.5 billion AUD, these diurnal preconditioning processes are shown to be favourable for the development of a mesoscale convective environment capable of supporting large hailstone growth. The multicell-HP supercell storm mode identified for this event and previous similar events in SEQ is hypothesised to be more sensitive to variations in near-surface and boundary layer instability. This is in contrast to contemporary supercell storms, highlighting the importance of PBL observations for developing an understanding of convective storms in subtropical coastal environments.In summary, this thesis provides a substantial and original contribution towards understanding of subtropical coastal storm environments. The integration of meteorological and climatological datasets from the CCIE provided a wealth of evi...

show abstract

“…The higher occurrence of SEQ storm days during sea breeze conditions is consistent with Soderholm et al (2016).…”

Section: Static Stabilitysupporting

confidence: 79%

Section: Methodsmentioning

confidence: 99%

Section: Surface Effectsmentioning

confidence: 99%

Section: Sea Breeze Structurementioning

confidence: 99%

“…A field campaign strategy was designed to investigate convective storm hotspots in SEQ using the guidance provided by the long-term climatology (Soderholm et al 2016). …”

Section: Overview Of Objectives and Major Findingsmentioning

confidence: 99%

See 3 more Smart Citations

The coastal convective interactions experiment

Soderholm¹

Self Cite

View full text Add to dashboard Cite

show abstract

An 18‐year climatology of hailstorm trends and related drivers across southeast Queensland, Australia

Soderholm

McGowan

Richter

et al. 2017

Quart J Royal Meteoro Soc

View full text Add to dashboard Cite

The southeast Queensland (SEQ) region of Australia is recognised for frequent thunderstorms documented through numerous studies including high-impact severe thunderstorm cases which have caused insured losses exceeding $1 billion AUD. Despite a modest body of scientific literature, basic questions regarding the role of climate, synoptic and local-scale (<10 km) processes affecting the variability of thunderstorms still remain. In an effort to advance these questions as part of the Coastal Convective Interactions Experiment (CCIE), this study integrates multiple datasets across an 18-year period (July 1997-June 2015) to provide a mesoscale climatological analysis of the SEQ hailstorms and associated environmental conditions. On a multi-year time-scale, the relationship between the El Niño Southern Oscillation and hailstorm frequency is consistent with previous studies. On synoptic scales, a southeasterly change situation coupled with a sea breeze was found to provide the most favourable environment for hailstorms, particularly for southwest SEQ. On the local scale, hail development within convective cells was found to be most frequent within the inland limb of the maritime air mass on sea-breeze days. This observation suggests the sea-breeze air masses may become favourable for convection after sufficient modification during inland propagation.

show abstract

Characteristics of colliding sea breeze gravity current fronts: a laboratory study

Wiel

Gille

Smith

et al. 2017

Quart J Royal Meteoro Soc

View full text Add to dashboard Cite

Sea and land breeze circulations driven by surface temperature differences between land and sea often evolve into gravity currents with sharp fronts. Along narrow peninsulas, islands and enclosed seas, sea/land breeze fronts from opposing shorelines may converge and collide and may initiate deep convection and heavy precipitation. Here we investigate the collision of two sea breeze gravity current fronts in an analogue laboratory setting. We examine these collisions by means of 'lock-exchange' experiments in a rectangular channel. The effects of differences in gravity current density and height are studied. Upon collision, a sharp front separating the two currents develops. For symmetric collisions (the same current densities and heights) this front is vertical and stationary. For asymmetric collisions (density differences, similar heights) the front is tilted, changes shape in time and propagates in the same direction as the heavier current before the collision. Both symmetric and asymmetric collisions lead to upward displacement of fluid from the gravity currents and mixing along the plane of contact. The amount of mixing along the collision front decreases with asymmetry. Height differences impact post-collision horizontal propagation: there is significant propagation in the same direction as the higher current before collision, independent of density differences. Collisions of two gravity current fronts force sustained ascending motions which increase the potential for deep convection. From our experiments we conclude that this potential is larger in stationary collision fronts from symmetric sea breeze collisions than in propagating collision fronts from asymmetric sea breeze collisions.

show abstract

The Coastal Convective Interactions Experiment (CCIE): Understanding the Role of Sea Breezes for Hailstorm Hotspots in Eastern Australia

Abstract: South East Queensland, Australia, is explored through an 18-yr radar climatology and a two-season field campaign.

Cited by 18 publications

References 46 publications

The coastal convective interactions experiment

The coastal convective interactions experiment

An 18‐year climatology of hailstorm trends and related drivers across southeast Queensland, Australia

Characteristics of colliding sea breeze gravity current fronts: a laboratory study

Contact Info

Product

Resources

About