An Objective Identification Technique for Regional Extreme Events

Ren, Fumin; Cui, Donglin; Gong, Zhiqiang; Wang, Yanjiao; Zou, Xu‐Bo; Li, Yiping; Wang, Shigong; Wang, Xiaoling

doi:10.1175/jcli-d-11-00489.1

Cited by 90 publications

(78 citation statements)

References 15 publications

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“…The extremeness of an event depends thus on the extent of the considered region (Konrad, 2001). Ren et al (2012) recently tried to combine both aspects together and identified regional extreme events as a string of daily impacted areas. They applied distinct thresholds to daily data to tailor the considered areas and time period to the real extent and duration of the event.…”

Section: Regional Evaluation Of the Extremeness Of Weather Eventsmentioning

confidence: 99%

Event-adjusted evaluation of weather and climate extremes

Müller

Kašpar

2014

Nat. Hazards Earth Syst. Sci.

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Abstract.After an overview of existing methods, we present a novel method of "event-adjusted" evaluation of extremeness of weather and climate events. It is based on optimization of both the considered area and the time duration for every event. The method consists of three steps: (i) estimation of return periods of a representative variable at individual sites, performed separately for various time windows; (ii) spatial interpolation of the point return period data; and (iii) searching the area and the time window in which the extremeness of the event was maximum. The extremeness is quantified as the common logarithm of the spatial geometric mean of the return periods multiplied by the radius of a circle of the same area as the one over which the geometric mean is taken. The maximum product is referred to as the weather extremity index (WEI). Two precipitation events, which affected the Czech Republic in May and in August 2010, were evaluated by the WEI for illustration. Validation of the method on sufficiently long data series is still needed. Moreover, the WEI is generally applicable regardless of the studied phenomenon (heavy rains, heat waves, windstorms, etc.). This makes it possible to study various weather and climate extremes from the viewpoint of possible recent and future changes in their frequency, seasonal distribution, and circulation conditions accompanying them.

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Section: Regional Evaluation Of the Extremeness Of Weather Eventsmentioning

confidence: 99%

Event-adjusted evaluation of weather and climate extremes

Müller

Kašpar

2014

Nat. Hazards Earth Syst. Sci.

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“…The OITREE method (Ren et al, 2012) for identifying regional heavy rainfall events (RHREs) has five steps: (1) select a daily index for each individual point (station) to represent rainfall conditions; (2) separate the daily heavy rainfall belts;…”

Section: Methodsmentioning

confidence: 99%

“…The following sections give a brief introduction to the procedure and the selection of parameters used in the OITREE method to identify RHREs (Table 1). The details of the method can be found in Ren et al (2012) and Wang et al (2013).…”

Section: Methodsmentioning

confidence: 99%

“…(2); , which had the values 0.18, 0.24, 0.21, 0.18, and 0.19, respectively. The larger the coefficient, the greater its influence on the integrated index (Ren et al, 2012):…”

Section: Procedures and Selection Of Parametersmentioning

confidence: 99%

“…Using cluster analysis and area-averaged rainfall series, Teixeira and Satyamurty (2011) developed an approach to identify heavy and extreme rainfall events in southern and southeastern Brazil during 1960-2004. Ren et al (2012 developed an objective identification technique for regional extreme events (OITREE) using daily observations and showed a simple example of applying it to identify regional heavy precipitation events in China.…”

Section: Introductionmentioning

confidence: 99%

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Changes in regional heavy rainfall events in China during 1961–2012

Zou

Ren

2015

Adv. Atmos. Sci.

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A new technique for identifying regional climate events, the Objective Identification Technique for Regional Extreme Events (OITREE), was applied to investigate the characteristics of regional heavy rainfall events in China during the period 1961-2012. In total, 373 regional heavy rainfall events (RHREs) were identified during the past 52 years. The East Asian summer monsoon (EASM) had an important influence on the annual variations of China's RHRE activities, with a significant relationship between the intensity of the RHREs and the intensity of the Mei-yu. Although the increase in the frequency of those RHREs was not significant, China experienced more severe and extreme regional rainfall events in the 1990s. The middle and lower reaches of the Yangtze River and the northern part of South China were the regions in the country most susceptible to extreme precipitation events. Some stations showed significant increasing trends in the southern part of the middle and lower reaches of the Yangtze River and the northern part of South China, while parts of North China, regions between Guangxi and Guangdong, and northern Sichuan showed decreasing trends in the accumulated intensity of RHREs. The spatial distribution of the linear trends of events' accumulated intensity displayed a similar so-called "southern flooding and northern drought" pattern over eastern China in recent decades.

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Spatial and temporal variations of regional high temperature events in China

2013

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An objective identification technique is applied to identify Regional High Temperature Events (RHTE) in China using daily maximum temperature data at 642 stations from 1961 to 2010. There are 213 RHTE identified. These events in general occur from May to September, with months from June to August being high season and the peak frequency appearing in July. Over the space, these events mainly occur in regions east of 90 • E, with higher frequencies and stronger intensities in the middle and lower valleys of the Yangtze River. Extreme and severe RHTE are more frequent in southern, central and eastern China and are less frequent in northern China. Statistics that characterize the regional events including annual frequency, annual sum of integrated index, annual sum of single indices (e.g. duration, accumulated high temperature intensity, accumulated impacted area and extreme high temperature) and annual maximum values of these single indices suggest that the RHTE are becoming more severe in both space and time and impacting more areas. A further analysis shows that the distribution patterns of the trend change of China RHTE, i.e. RHTE becoming more frequent and stronger in most China especially in northern China, but less frequent and weaker in eastern regions between the Yangtze River and the Yellow River during the past 50 years, is mainly a regional response to global warming. Meanwhile, the increasing trends in frequency and accumulated intensity of the RHTE in southern China may also be partly due to the western Pacific subtropical high westward extension and intensification in summer during the past decades. KEY WORDS regional high temperature event; objective identification technique; spatial and temporal variations; China

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An Objective Identification Technique for Regional Extreme Events

Cited by 90 publications

References 15 publications

Event-adjusted evaluation of weather and climate extremes

Event-adjusted evaluation of weather and climate extremes

Changes in regional heavy rainfall events in China during 1961–2012

Spatial and temporal variations of regional high temperature events in China

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