Anomaly based analysis of extreme heat waves in Eastern China during 1981-2013

Abstract

This study shows applications of an anomaly based analysis method to describe extreme summer heat waves in Eastern China during 1981-2013 using two reanalysis products. These events are defined in an area of a spatial size larger than 300 × 500 km (0.15 × 10 6 km 2 ) when its daily maximum surface air temperature (DMSAT) exceeds 35 ∘ C, and the DMSAT anomaly is no less than 5 ∘ C for at least five consecutive days. Results show that by extracting the transient anomalies, the anomaly based method can substantially improve descriptions of key synoptic features of heat waves in their central location, spatial coverage, intensity, and duration as well as their spatial structure of geopotential height and temperature anomalies. They also show the capability of the method in helping identify and trace the early disturbances that evolved into extreme heat wave events in Eastern China in 12 summers during 1981-2013. Over that period, the statistics of heat waves indicate an increase in the number of extreme heat wave events in China, especially in the 21st century. The method is further applied to the National Centres for Environmental Prediction (NCEP) and European Centre for Medium-Range Weather Forecasts (ECMWF) model predictions to illustrate its usefulness in interpreting model predictions for heat waves.

Circulation Conditions’ Effect on the Occurrence of Heat Waves in Western and Southwestern Europe

“…Similar results were obtained by Chen et al [9], who investigated atmospheric circulation during the selected HWs in China between 1981 and 2013. They proved that a strong signal of positive geopotential height anomalies in the upper troposphere is responsible for the surface heat wave and indicated the possibility of predicting the occurrence of HWs on the basis of observations of disturbances in the higher layers of the troposphere.…”

“…As for the duration, the WMO advice is that a heat wave should be considered a hot period "persisting [for] at least two consecutive days" [25]. Different duration thresholds are chosen, from ≥2 consecutive days in Canada [29], ≥3 days in France [27], Greece [30], Hungary [31], ≥5 days in Ukraine [7], China [9], Australia [32] up to ≥6 consecutive days in Bulgaria [33]. In human biometeorology defining heat waves is usually more complex.…”

“…A manifestation of the observed warming is the increasing frequency of days with extreme temperatures and at the same time the increasing frequency, duration and severity of heat waves in many regions of Europe and around the world [7][8][9][10]. The heat waves of 2003 and 2010, defined as "mega heat waves," broke 500-year period air temperature records in approximately 50% of Europe [11].…”

Recent changes in heat waves and cold waves detected based on excess heat factor and excess cold factor in Romania

“…Even though there is no simple relationship between air temperature and morbidity and mortality, high correlation between certain extreme temperatures and mortality has been demonstrated worldwide (Knowlton et al, 2009;Barnett et al, 2012). HWs cause more deaths all over the world than any other natural hazards (Unkaševic and Tošic, 2009;D'Ippoliti et al, 2010;Peterson et al, 2013;Shaposhnikov et al, 2014;Liu et al, 2015;Nairn and Fawcett, 2015;Kim et al, 2016;Chen et al, 2017). Some previous studies showed an increase in the number of deaths during HWs: between 3.0 and 7.8% in the United States of America (Medina-Ramón and Schwartz, 2007;Anderson and Bell, 2009;Peng et al, 2011), 21.8% in the Mediterranean areas (D'Ippoliti et al, 2010), 16.5% in Spain , 5% in China (Ma et al, 2015).…”

Intra‐annual variability of heat wave episodes over the east coast of India

“…The common feature observed in all global heat wave cases is the presence of a high-pressure synoptic system (anticyclone) (Black et al, 2004;Dole et al, 2011;Barriopedro et al, 2011;Parker et al, 2014;Murari et al, 2015;Wang et al, 2017). In addition, the heat waves are in general associated with pressure, temperature, geopotential height, and wind anomalies (Deshpande and Ernestraj, 2007;Cerne et al, 2007;Murari et al, 2015;Lee and Lee, 2016;Qian et al, 2016;Rohini et al, 2016;Chen et al, 2017). Also, the occurrence and longevity of heat wave can be governed by specific synoptic conditions.…”