Lorenzo Vergni

Dr. Lorenzo Vergni

Department of Agricultural, Food and Environmental Sciences, University of Perugia, Borgo XX Giugno 74, 06121 Perugia, Italy
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Research Focus & Metrics

Academic Career Length

19Years (2008-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 March 2011 in Agricultural and Forest Meteorology
Verified
Journal Article
Closed access
LVLorenzo Vergni
Lorenzo Vergni
FTFrancesca Todisco
Francesca Todisco

7 May 2021 in Natural Hazards
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Journal Article
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LVLorenzo Vergni
Lorenzo Vergni
FTF. Todisco
F. Todisco
BLB. Di Lena
B. Di Lena
In the literature, numerous papers report comparative analyses of drought indices. In these types of studies, the similarity between drought indices is usually evaluated using the Pearson correlation coefficient, r, calculated between corresponding severity time series. However, it is well known that the correlation does not describe the strength of agreement between two variables. Two drought indices can exhibit a high degree of correlation but can, at the same time, disagree substantially, for example, if one index is consistently higher than the other. From an operational point of view, two indices can be considered in agreement when they indicate the same severity category for a given period (e.g. moderate drought). In this work, we compared six meteorological drought indices based on both correlation analysis and Cohen's Kappa test. This test is typically used in medical or social sciences to obtain a quantitative assessment of the degree of agreement between different methods or analysts. The indices considered are five timescale-dependent indices, i.e. the Percent of Normal Index, the Deciles Index, the Percentile Index, the Rainfall Anomaly Index, and the Standardised Precipitation Index, computed at the 1-, 3-, and 6-month timescales, and the Effective Drought Index, a relatively new index, which has a self-defined timescale. The indices were calculated for 15 stations in the Abruzzo region (central Italy) during 1951–2018. We found that the strength of agreement depends on both the criteria of drought severity classification and the different indices' calculation method. The Cohen's Kappa test indicates a prevailing moderate or fair agreement among the indices considered, despite the generally very high correlation between the corresponding severity times series. The results demonstrate that the Cohen's Kappa test is more effective than the correlation analysis in discriminating the actual strength of agreement/disagreement between drought indices.

20 March 2013 in Theoretical and Applied Climatology
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Journal Article
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BLB. Di Lena
B. Di Lena
LVLorenzo Vergni
Lorenzo Vergni
FAF. Antenucci
F. Antenucci
FTFrancesca Todisco
Francesca Todisco
FMF. Mannocchi
F. Mannocchi

1 January 2008 in Agricultural and Forest Meteorology
Verified
Journal Article
Closed access
FTFrancesca Todisco
Francesca Todisco
LVLorenzo Vergni
Lorenzo Vergni

19 March 2015 in Water Resources Management
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Journal Article
Closed access
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LVLorenzo Vergni
Lorenzo Vergni
FTFrancesca Todisco
Francesca Todisco
FMF. Mannocchi
F. Mannocchi

13 October 2012 in Natural Hazards
Verified
Journal Article
Closed access
PDF file
FTFrancesca Todisco
Francesca Todisco
FMF. Mannocchi
F. Mannocchi
LVLorenzo Vergni
Lorenzo Vergni