Weather types and rainfall microstructure in Leon, Spain

Fernández‐Raga, María; Castro, Amaya; Marcos, Elena; Palencia, Covadonga; Fraile, Roberto

doi:10.1002/joc.4816

Cited by 24 publications

(21 citation statements)

References 33 publications

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“…In a study carried out in Leon, Spain, Fernandez-Raga et al [53] found that rain drops associated with the northern flow direction had a smaller size compared to other flow directions. This is because most of the moisture transported from the north would precipitate before reaching the measurement site.…”

Section: Rain Microstructurementioning

confidence: 99%

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Rain Microstructure Parameters Vary with Large-Scale Weather Conditions in Lausanne, Switzerland

et al. 2018

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Rain properties vary spatially and temporally for several reasons. In particular, rain types (convective and stratiform) affect the rain drop size distribution (DSD). It has also been established that local weather conditions are influenced by large-scale circulations. However, the effect of these circulations on rain microstructures has not been sufficiently addressed. Based on DSD measurements from 16 disdrometers located in Lausanne, Switzerland, we present evidence that rain DSD differs among general weather patterns (GWLs). GWLs were successfully linked to significant variations in the rain microstructure characterized by the most important rain properties: rain intensity (R), mass weighted rain drop diameter (D m ), and rain drop concentration (N), as well as Z = AR b parameters. Our results highlight the potential to improve radar-based estimations of rain intensity, which is crucial for several hydrological and environmental applications.

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Section: Rain Microstructurementioning

confidence: 99%

“…Fernandez-Raga et al [53] provided convincing evidence that weather patterns with northern components are associated with smaller rain drops in Leon, Spain. On the other hand, western and southwestern components carry humidity from the Atlantic and have larger drops.…”

Section: Introductionmentioning

confidence: 97%

Rain Microstructure Parameters Vary with Large-Scale Weather Conditions in Lausanne, Switzerland

et al. 2018

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“…The gamma distribution is defined for all positive real numbers and depends on two parameters: α and β (Fernandez‐Raga et al, ), which may be computed following the method of moments, from the relations μ = α / β and σ 2 = α / β 2 , where μ and σ 2 are, respectively, the mean size of raindrops and the variance (Duhanyan and Roustan, ; Johnson, et al, ). Besides, when α > 1, we have determined the mode of the gamma distribution through ( α− 1)/ β (Fernandez‐Raga et al, ).…”

Section: Methodsmentioning

confidence: 99%

Below‐cloud scavenging of fine and coarse aerosol particles by rain: The role of raindrop size

Blanco-Alegre

Castro

Calvo

et al. 2018

Quart J Royal Meteoro Soc

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Below‐cloud aerosol scavenging is an important process to remove particles from the atmosphere. In this study, both precipitation (measured with a laser disdrometer registering drops between 0.125 and 8 mm) and atmospheric aerosol particles (measured with a Passive Cavity Aerosol Spectrometer Probe registering aerosol sizes between 0.1 and 24 µm) have been sampled on a 1 min basis. Based on 6 months of outdoor measurements in León (northwest Iberian Peninsula), the scavenging coefficients were calculated for the aerosol particles measured, with a mean value of 2.6 × 10−5 ± 6.0 × 10−5 s−1 for the fine mode and 5.8 × 10−5 ± 9.6 × 10−5 s−1 for the coarse mode in 54 rain events. Likewise, the particle concentration decreased during rain by 10%, and by 18% between the time before and after the rain. In the Greenfield Gap (sizes between 0.3 and 1 µm) the scavenging is less effective, mainly between 0.6 and 1 µm, than with smaller particles. The number of drops between 0.75 and 3 mm shows statistically significant (p < 0.05) negative correlations with the number of particles between 0.16 and 1.76 µm, thus illustrating the potential of those raindrops to favour the scavenging of particles of that size. In addition, there were statistically significant negative correlations between the total volume removed by falling drops (mm3/m3) and the variation of the number of particles in channels with diameters between 0.12 and 0.19 µm.

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“…On the Mediterranean coast precipitation is driven by easterly types, whereas in the Cantabrian coast northerly and north-westerly patterns dominate and cyclonic LWTs although result to be the less frequent are the most efficient in generating precipitation (Cortesi et al, 2014). Paredes et al (2006) Within Spain there exist a few LWTs studies focusing on the northwest in Galicia (Eiras- Barca et al, 2018;Lorenzo et al, 2008), Leon (Fernández-González et al, 2012;Fernandez-Raga et al, 2017) and the southeast (Goodess and Palutikof, 1998). In Galicia, Lorenzo et al (2008) found that the anticyclonic pattern is the most frequent across the whole year, with westerly and south-westerly types being significant during autumn and winter.…”

Section: Weather Patternsmentioning

confidence: 99%

Concurrent Hydroclimatic Hazards from Catchment to Global Scales

Luca¹

2020

Preprint

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Interactions between multiple hazards can cause socio-economic damages that exceed those expected by the individual hazard components. Over the past decade, the multi-hazards paradigm has emerged to the extent that the Sendai Framework for Disaster Risk Reduction 2015-2030 advocated a multi-hazard approach. This thesis examines three types of concurrent hydroclimatic hazards that can occur at catchment to global scales. The first multi-hazard is the link between multi-basin flooding (MBF) and extra-tropical cyclones (ETCs) over Great Britain during the period 1975-2014. Results show that during the most geographically widespread MBF episode, up to 108 river catchments (or ~46% of the study area) recorded a peak flow annual maximum within a 16-day window. Most extreme MBF episodes were linked to cyclonic Lamb Weather Types (LWTs), atmospheric rivers and very severe gales. These episodes were associated with significant socio-economic impacts due to widespread flooding. The second hazard was observed (1971-2000) and projected (2011-2100) LWTs, whose seasonal frequency and persistence are associated with multi-hazards over the British Isles. Daily sea-level-pressure data from two reanalyses products, one subjective weather pattern catalogue and an ensemble of 10 Atmosphere-Ocean General Circulation Models (AOGCMs) were used to compute LWTs. Results showed that the AOGCMs are overall able to reproduce historical weather pattern persistence, which, along with annual frequency, is projected to significantly increase anticyclonic and decrease cyclonic LWTs, in summer and autumn respectively. This implies a higher risk of drought, heatwaves and air pollution events in summer but reduced likelihood of flooding and severe gales in autumn by the end of the 21st century. By 2100, the AOGCMs suggest an increased risk of concurrent flood-wind hazards during winter. In summer, the strength of the nocturnal Urban Heat Island (UHI) of London is expected to intensify by the end of the century, contributing to higher chances of combined heatwave-air pollution events. The third type of multi-hazard investigated was the spatio-temporal concurrence of global wet and dry hydrological extremes, during the 1950-2014 period. The analysis was conducted using the monthly self-calibrated Palmer Drought Severity Index based on the Penman-Monteith model (sc_PDSI_pm). Results showed that the land area impacted by extreme dry and wet-dry events significantly increased over the observational period. The most geographically widespread wet-dry event covered a total area of 21 million km2 (or 14% of the global land area) with documented flood and drought impacts over diverse regions. Two new metrics were developed to provide more insight into the combined wet and dry hazards: the wet-dry (WD) ratio and the extreme transitions (ET) time interval. The former quantifies the predominance of wet or dry extremes over a given area, whereas the ET measures the average separation time between the opposite extremes (i.e. between wet to dry or dry to wet transitions). The WD-ratio reveals a predominance of wet over dry extremes in the USA, northern and southern south America, northern Europe, north Africa, western China and most of Australia. The ET median for wet to dry is ~27 months, and 21 months for dry to wet. Global correlations between wet-dry hydrological extremes and El Niño Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO) and American Multidecadal Oscillation (AMO) were also investigated. ENSO and PDO showed similar correlation patterns, with the former significantly impacting a larger area. On the other hand, the AMO showed an almost inverse spatial correlation pattern, with an overall larger area impacted. The findings presented in this thesis could be informative for emergency responders and relief agencies, disaster risk reduction practitioners, and (re)insurance companies. For instance, multi-basin flooding co-occurring with ETCs could overwhelm emergency response that depends on support from neighbouring regions that are similarly affected. Economic damages could exceed those insured by households and businesses. Projected rises in nocturnal UHI intensity in London could exacerbate heat-stress and, when combined with episodes of poor air quality, increase the likelihood of health problems amongst vulnerable groups. Furthermore, concurrent wet and dry hydrological extremes could be significant for organizations with global assets or sensitive supply chains, and the hydropower, agricultural and transport sectors. Global maps generated of major wet-dry events and the WD-ratio could also be integrated into a seasonal forecasting product, to help stakeholders in hedging the risk. Key opportunities for further research on multi-hazards are future hydroclimatic projections in the light of anthropogenic climate change and the application of new statistical techniques that could help in discerning the driving physical processes.

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Weather types and rainfall microstructure in Leon, Spain

Cited by 24 publications

References 33 publications

Rain Microstructure Parameters Vary with Large-Scale Weather Conditions in Lausanne, Switzerland

Rain Microstructure Parameters Vary with Large-Scale Weather Conditions in Lausanne, Switzerland

Below‐cloud scavenging of fine and coarse aerosol particles by rain: The role of raindrop size

Concurrent Hydroclimatic Hazards from Catchment to Global Scales

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