Presidential Address of Sir William Thomson Halcrow. President 1946-1947.

Halcrow, Sir W T

doi:10.1680/ijoti.1946.13785

Cited by 5 publications

(1 citation statement)

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“…The method was implemented using the R package POT (Ribatet, ) to provide a means for the objective determination of independent events, with the highest hourly value within a cluster used for each event. A practical indicator that relates extreme rainfall climatology to flood risk is the series of thresholds prescribed by the operational ERAs, which provide warnings of extreme rainfall based on intensities that are likely to cause severe surface water flooding in urban areas (Hurford et al , ). These were defined by Halcrow () to approximate the 1‐in‐30 year RP FEH rainfall intensities (Faulkner, ) for eight UK cities, and the 30‐year RP is used as the design standard for most urban drainage systems in the UK (WRc, ).…”

Section: Data Qc and Methodologymentioning

confidence: 99%

Quality‐control of an hourly rainfall dataset and climatology of extremes for the UK

Blenkinsop

Lewis

Chan

et al. 2016

Intl Journal of Climatology

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Sub‐daily rainfall extremes may be associated with flash flooding, particularly in urban areas but, compared with extremes on daily timescales, have been relatively little studied in many regions. This paper describes a new, hourly rainfall dataset for the UK based on ∼1600 rain gauges from three different data sources. This includes tipping bucket rain gauge data from the UK Environment Agency (EA), which has been collected for operational purposes, principally flood forecasting. Significant problems in the use of such data for the analysis of extreme events include the recording of accumulated totals, high frequency bucket tips, rain gauge recording errors and the non‐operation of gauges. Given the prospect of an intensification of short‐duration rainfall in a warming climate, the identification of such errors is essential if sub‐daily datasets are to be used to better understand extreme events. We therefore first describe a series of procedures developed to quality control this new dataset. We then analyse ∼380 gauges with near‐complete hourly records for 1992–2011 and map the seasonal climatology of intense rainfall based on UK hourly extremes using annual maxima, n‐largest events and fixed threshold approaches. We find that the highest frequencies and intensities of hourly extreme rainfall occur during summer when the usual orographically defined pattern of extreme rainfall is replaced by a weaker, north–south pattern. A strong diurnal cycle in hourly extremes, peaking in late afternoon to early evening, is also identified in summer and, for some areas, in spring. This likely reflects the different mechanisms that generate sub‐daily rainfall, with convection dominating during summer. The resulting quality‐controlled hourly rainfall dataset will provide considerable value in several contexts, including the development of standard, globally applicable quality‐control procedures for sub‐daily data, the validation of the new generation of very high‐resolution climate models and improved understanding of the drivers of extreme rainfall.

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Section: Data Qc and Methodologymentioning

confidence: 99%