Climate Variability and Change—Hydrological Impacts (Proceedings of the Fifth FRIEND World Conference held at Havana, Cuba, November 2006), IAHS Publ. 308, 2006, 169–174.

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Drought indices suitable to study the linkages to large-scale climate drivers in regions with seasonal frost influence

ANNE K. FLEIG, LENA M. TALLAKSEN & HEGE HISDAL

Department of Geosciences, University of Oslo, PO Box 1047 Blindern, NO-0316 Oslo, Norway

a.k.fleig@geo.uio.no

Abstract Based on a literature study the suitability of several common drought indices is evaluated for application in regional drought forecasting in climates with seasonal frost influence. In these regions hydrological droughts caused by a deficit in precipitation (summer droughts) and frost (winter droughts) have to be distinguished. Suitable drought indices should be objective, spatially and temporally robust, sensitive, interpretable and practical. They also need to enable drought forecasting, which is in this study considered to be based on a statistical model linking the drought indices to large-scale ocean and atmosphere patterns. None of the studied indices were found to be optimal for regional forecasting mainly due to a lack of robustness. It is suggested to use a set of three or four indices, including the Standardized Precipitation Index for meteorological drought, a streamflow drought index based on the threshold level method with a constant seasonal threshold, and a flow anomaly index to detect deviations from normal hydrological conditions.

Key words drought indices; hydrological drought; cold climate; regional forecasting; SPI; PDSI; PDHI; threshold level method; flow anomaly; streamflow

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