Atmospheric boundary layer structures associated with the Ora del Garda wind in the Alps as revealed from airborne and surface measurements

Laiti, Lavinia; Zardi, Dino; Franceschi, Massimiliano de; Rampanelli, G.

doi:10.1016/j.atmosres.2013.07.006

Cited by 33 publications

(29 citation statements)

References 70 publications

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“…3.2.1). They confirm the development of a well-defined lake-breeze front at the Ora del Garda onset, as speculated by Laiti et al (2013b) only on the basis of local atmospheric thermal structures observed in the afternoon and surface measurements at RDG. Furthermore, the surface data reveal that the inland penetration of the lake breeze in the easternmost part of the Sarca Valley (i.e.…”

Section: The Onset Of the Ora Del Gardasupporting

confidence: 68%

“…Furthermore, it focuses on the coupled surface and ABL processes occurring in two key areas for the development of the circulation, i.e. Lake Garda's shoreline and the junction between the Lakes and Adige valleys, which were not investigated in detail by Laiti et al (2013b). These include the lake-breeze front propagation in the Sarca Valley and the phenomena associated with the breeze overflow at the end of the Lakes Valley.…”

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confidence: 99%

“…Moreover, different flow depths, stratifications and asymmetric cross-valley circulations were observed for the two synoptic situations. Laiti et al (2013b) also speculated about the development of a hydraulic jump associated with the Ora del Garda overflow into the Adige Valley. This hypothesis was formulated on the basis of the observed features of the ABL structure, resembling those found in connection with gap flows in the Alps (as described, among others, by Armi and Mayr, 2007;Flamant et al, 2002;Gohm and Mayr, 2004;Mayr et al, 2007) or with downslope windstorms (see for example Liu at al., 2000).…”

mentioning

confidence: 99%

“…A first contribution, based on both airborne and surface observations, is provided in Laiti et al (2013b). In particular, that paper examined two flights of an instrumented motorglider (de Franceschi et al, 2003) performed in different weather situations, but with similar timings and flight trajectories.…”

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confidence: 99%

“…Differently from Laiti et al (2013b), here the first flight was performed in the morning and the second in the afternoon, to appreciate the diurnal evolution of the wind. Moreover, the data set also includes intensive surface observations collected during a targeted field campaign in the Terlago saddle area (de Franceschi et al, 2002), as well as standard data from a richer set of routinely operated surface stations than in Laiti et al (2013b). Indeed, the present study aims at analysing not only the ABL thermal structures associated with the Ora del Garda flow in its mature stage, but also their diurnal evolution.…”

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confidence: 99%

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Analysis of the diurnal development of a lake-valley circulation in the Alps based on airborne and surface measurements

et al. 2014

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Abstract. This study investigates the thermal structures of the atmospheric boundary layer (ABL) and the near-surface wind field associated with a lake-valley circulation in the south-eastern Italian Alps -the so-called Ora del Garda. Two flights of an equipped motorglider allowed for the exploration of the diurnal evolution of this circulation, from the onset, on Lake Garda's shoreline, throughout its development along the Sarca Valley and Lakes Valley (Valle dei Laghi), to the outflow into the Adige Valley. At the same time, surface observations, both from a targeted field campaign and from routinely operated weather stations, supported the analysis of the development of the Ora del Garda at the valley floor.In particular, in the valleys typical ABL vertical structures, characterized by rather shallow convective mixed layers (∼ 500 m) and (deeper) weakly stable layers above, up to the lateral crest height, are identified in the late morning. In contrast, close to the lake the ABL is stably stratified down to very low heights, as a consequence of the intense advection of colder air associated with the Ora del Garda flow (up to 6 m s −1 ). The combined analysis of surface and airborne observations (remapped over 3-D high-resolution grids) suggests that the lake-breeze front propagating up-valley from the shoreline in the late morning penetrates slightly later at the eastern end of the valley inlet (delay: ∼ 1 h), probably due to the asymmetric radiative forcing caused by the N-S valley orientation. On the other hand, in the early afternoon the Ora del Garda overflows through an elevated gap, producing an anomalous, strong cross-valley wind (5 m s −1 ) at the Adige Valley floor north of Trento, which overwhelms the local upvalley wind. This feature is associated with a strong deepening of the local mixed layer (from 400 to 1300 m). The potential temperature 3-D field suggests that the intense turbulent mixing may be attributed to the development of a downslope wind across the gap, followed by a hydraulic jump downstream.

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Section: The Onset Of the Ora Del Gardasupporting

confidence: 68%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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Analysis of the diurnal development of a lake-valley circulation in the Alps based on airborne and surface measurements

et al. 2014

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Climatological characteristics of the Ora del Garda wind in the Alps

Giovannini

Laiti

Zardi

et al. 2015

Intl Journal of Climatology

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The relation between circulation types and regional Alpine climate. Part I: synoptic climatology of Trentino

Panziera

Giovannini

Laiti

et al. 2015

Intl Journal of Climatology

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A comprehensive data set of surface temperature, rainfall, solar radiation and wind measurements was composed to investigate the relation between synoptic circulation types and the climate of Trentino, a mountainous region in the South-Eastern Alps. Synoptic patterns are classified over different levels by means of an existing classification method according to their degree of zonality, meridionality and vorticity. Distinct seasonal anomalies of mean daily temperature, total daily rainfall, daily solar irradiation and mean daily wind intensity are associated with most circulation types. Their magnitude varies not only among weather types, but also within the same type for different isobaric levels and seasons. The largest positive temperature anomalies are observed in correspondence with high-pressure and westerly circulations, whereas southerly circulation in the upper levels and low-pressure systems at lower altitudes produce the largest positive deviations of daily rainfall. Daily solar irradiation and mean daily wind intensity are larger than average with northerly circulations. Particular emphasis is given to extreme meteorological events, which occur with preferential circulation types. In fact, the frequency of occurrence of extremes of any variable for each synoptic pattern rarely coincides with the climatological value. Even though extremes in daily rainfall are observed with almost all synoptic circulations, most of them occur with the south-westerly circulation at 500 hPa, a frequent configuration contributing more than 50% to the total rainfall. Moreover, they occur with a larger variety of weather types at the lower levels and in spring and summer with respect to the upper levels and the colder seasons. The large number of statistical indices presented in this paper reveals that the climate of Trentino is strongly influenced not only by the synoptic circulation, but also by the mesoscale mechanisms resulting from the interaction of the large-scale flow with the local orography.

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Atmospheric boundary layer structures associated with the Ora del Garda wind in the Alps as revealed from airborne and surface measurements

Cited by 33 publications

References 70 publications

Analysis of the diurnal development of a lake-valley circulation in the Alps based on airborne and surface measurements

Analysis of the diurnal development of a lake-valley circulation in the Alps based on airborne and surface measurements

Climatological characteristics of the Ora del Garda wind in the Alps

The relation between circulation types and regional Alpine climate. Part I: synoptic climatology of Trentino

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