The Mesoscale Structure of Severe Precipitation Systems in Switzerland

Schiesser, Hans-Heinrich; Houze, Robert A.; Huntrieser, H.

doi:10.1175/1520-0493(1995)123<2070:tmsosp>2.0.co;2

Cited by 57 publications

(46 citation statements)

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“…For the inter-arrival times, we choose an exponential distribution with parameter ω = 0.006261 h −1 (χ 2 = 239.7, df = 10, p = 0). In Lugano, storms are dominated by local-scale convective systems in the summer and fall, which produce mid-to high-intensity showers during a few hours, accentuated by orographic effects (Schiesser et al, 1995;Panziera et al, 2014). Consequently, a 4 h MIT was chosen, resulting in 3806 independent storms over the 1981-2012 period.…”

Section: Event Propertiesmentioning

confidence: 99%

Describing the interannual variability of precipitation with the derived distribution approach: effects of record length and resolution

Meier

Moraga

Pranzini

et al. 2016

Hydrol. Earth Syst. Sci.

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Abstract. Interannual variability of precipitation is traditionally described by fitting a probability model to yearly precipitation totals. There are three potential problems with this approach: a long record (at least 25-30 years) is required in order to fit the model, years with missing rainfall data cannot be used, and the data need to be homogeneous, i.e., one has to assume stationarity. To overcome some of these limitations, we test an alternative methodology proposed by Eagleson (1978), based on the derived distribution (DD) approach. It allows estimation of the probability density function (pdf) of annual rainfall without requiring long records, provided that continuously gauged precipitation data are available to derive external storm properties. The DD approach combines marginal pdfs for storm depths and inter-arrival times to obtain an analytical formulation of the distribution of annual precipitation, under the simplifying assumptions of independence between events and independence between storm depth and time to the next storm. Because it is based on information about storms and not on annual totals, the DD can make use of information from years with incomplete data; more importantly, only a few years of rainfall measurements should suffice to estimate the parameters of the marginal pdfs, at least at locations where it rains with some regularity.For two temperate locations in different climates (Concepción, Chile, and Lugano, Switzerland), we randomly resample shortened time series to evaluate in detail the effects of record length on the DD, comparing the results with the traditional approach of fitting a normal (or lognormal) distribution. Then, at the same two stations, we assess the biases introduced in the DD when using daily totalized rainfall, instead of continuously gauged data. Finally, for randomly selected periods between 3 and 15 years in length, we conduct full blind tests at 52 high-quality gauging stations in Switzerland, analyzing the ability of the DD to estimate the longterm standard deviation of annual rainfall, as compared to direct computation from the sample of annual totals.Our results show that, as compared to the fitting of a normal or lognormal distribution (or equivalently, direct estimation of the sample moments), the DD approach reduces the uncertainty in annual precipitation estimates (especially interannual variability) when only short records (below 6-8 years) are available. In such cases, it also reduces the bias in annual precipitation quantiles with high return periods. We demonstrate that using precipitation data aggregated every 24 h, as commonly available at most weather stations, introduces a noticeable bias in the DD. These results point to the tangible benefits of installing high-resolution (hourly, at least) precipitation gauges, next to the customary, manual rain-measuring instrument, at previously ungauged locations. We propose that the DD approach is a suitable tool for the statistical description and study of annual rainfall, not only when short records ...

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Section: Event Propertiesmentioning

confidence: 99%

Describing the interannual variability of precipitation with the derived distribution approach: effects of record length and resolution

Meier

Moraga

Pranzini

et al. 2016

Hydrol. Earth Syst. Sci.

View full text Add to dashboard Cite

show abstract

“…The lines must have also attained a 3:1 length-width ratio. Schiesser et al (1995) found 3-10 km shear was substantially larger for isolated CC compared to other categories.…”

Section: Chapter 2 Literature Reviewmentioning

confidence: 78%

“…Schiesser et al (1995) created classifications for lines with leading stratiform rain and lines with no stratiform rain at all. proposed nomenclature for linear MCSs with parallel stratiform rain, where the stratiform region moves parallel to the line and very little precipitation surrounds the convective line itself.…”

Section: Chapter 2 Literature Reviewmentioning

confidence: 99%

Prediction of Convective Morphology in Near-Cloud-Permitting WRF Model Simulations

Snively

Gallus

2014

Weather and Forecasting

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The Weather Research and Forecasting (WRF) model’s ability to forecast convective morphological evolution is examined for 37 convective systems. The simulations used Thompson microphysics with 3-km horizontal grid spacing. Ten convective mode classifications were used. An objective score was developed to determine the accuracy of the simulated morphologies considering a normalized duration of each mode simulated and its agreement with observations. Rapid Update Cycle analyses were used to compare larger-scale preinitiation conditions to simulated morphology accuracy, as well as to examine how the WRF model’s skill at predicting these larger-scale conditions influenced its prediction of morphology. Two case studies selected as representative of the most common simulated morphology deficiencies were examined in detail. The model simulated cellular systems relatively well but struggled more with linear systems, particularly bow echoes and squall lines having trailing stratiform rain regions. Morphological evolution was generally better simulated in environments with enhanced deep-layer shear and cooler potential temperatures at the level of maximum θe. Weaker deep-layer shear, cooler potential temperatures at the surface, and quickly warming potential temperatures with height increased the likelihood of timing errors. The first case study showed that a warmer cold pool, much larger line-normal shear, and excessive midlevel drying were present in the model run that failed to develop a trailing stratiform region. The second case study showed that weak shear and the absence of a well-developed cold pool may have played a role in the lack of bowing.

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“…3) when low-level warm and humid Adriatic air began feeding directly into the system from the east to form a mesoscale convective system (MCS, e.g. Weisman and Klemp, 1982;Schiesser et al, 1995). The flow configuration at this stage was such that the continuous regeneration of convective cells took place in the relatively circumscribed area of some 20 × 40 km 2 around and west of Venice Mestre.…”

Section: Synoptics Of the 26 September 2007 Casementioning

confidence: 99%

Quantitative comparison of radar QPE to rain gauges for the 26 September 2007 Venice Mestre flood

Rossa¹,

Cenzon²,

Monai³

2010

Nat. Hazards Earth Syst. Sci.

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Abstract. In this study consideration is given to the potential use of radar-derived quantitative precipitation estimates (QPE) as flash flood guidance in the context of the Italian Civil Protection flood risk management system. The interest in high precipitation intensities and accumulation motivated the case study of the 26 September 2007 event, in which a quasi-stationary mesoscale convective system brought within 3-6 h 40% of the mean annual precipitation to the wider Venice-Mestre area, i.e. 260 mm in Venice-Mestre and 325 mm in closeby Valle Averto.Comparison of the radar-derived QPE in the area with the rain gauge network revealed a good correspondence for warm season rainfall, both for daily accumulations in the longterm (about 2 years) and hourly accumulations for the case under consideration. The long term average radar to gauge ratio is very close to 0 dB with an uncertainty of approximately ±3 dB, i.e. roughly a factor of two, slightly better for higher precipitation intensities. For the hourly accumulations during this very intense event the spread is similar, while the average is slightly positive.The locations of the rainfall accumulation maximum as detected, respectively, by the radar and by the rain gauge network do not coincide. Given the relatively good quality of the precipitation estimation, it is argued that these areas effectively have received even larger rainfall amounts, and that it is worthwhile to further investigate the potential of radar to be used as flash flood guidance.

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The Mesoscale Structure of Severe Precipitation Systems in Switzerland

Cited by 57 publications

References 0 publications

Describing the interannual variability of precipitation with the derived distribution approach: effects of record length and resolution

Describing the interannual variability of precipitation with the derived distribution approach: effects of record length and resolution

Prediction of Convective Morphology in Near-Cloud-Permitting WRF Model Simulations

Quantitative comparison of radar QPE to rain gauges for the 26 September 2007 Venice Mestre flood

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