A spatio‐temporal structure‐based approach to drought characterisation

作者：Benjamin Lloyd‐Hughes · 发表于：International Journal of Climatology · 年份：2011 · DOI：10.1002/joc.2280 · 被引用次数：248 · 研究领域：Hydrology and Drought Analysis、Climate variability and models、Climate change impacts on agriculture

Abstract Drought characterisation is an intrinsically spatio‐temporal problem. A limitation of previous approaches to characterisation is that they discard much of the spatio‐temporal information by reducing events to a lower‐order subspace. To address this, an explicit 3‐dimensional (longitude, latitude, time) structure‐based method is described in which drought events are defined by a spatially and temporarily coherent set of points displaying standardised precipitation below a given threshold. Geometric methods can then be used to measure similarity between individual drought structures. Groupings of these similarities provide an alternative to traditional methods for extracting recurrent space‐time signals from geophysical data. The explicit consideration of structure encourages the construction of summary statistics which relate to the event geometry. Example measures considered are the event volume, centroid, and aspect ratio. The utility of a 3‐dimensional approach is demonstrated by application to the analysis of European droughts (15°W to 35°E, and 35°N to 70°N) for the period 1901–2006. Large‐scale structure is found to be abundant with 75 events identified lasting for more than 3 months and spanning at least 0.5 × 10 6 km 2 . Near‐complete dissimilarity is seen between the individual drought structures, and little or no regularity is found in the time evolution of even the most spatially similar drought events. The spatial distribution of the event centroids and th...