URBANIZATION EFFECTS ON OBSERVED CHANGES IN SUMMER EXTREME HEAT EVENTS OVER ZHEJIANG PROVINCE, EAST CHINA

Although the urban heat island(UHI) is a well-documented phenomenon, relatively little information in the literature is available about its impact on summer extreme heat event(EHE). As UHI is characterized by increased temperature, it can potentially increase the magnitude and duration of EHEs within cities. Based on daily maximum temperature records from 62 observation stations in Zhejiang province from the period 1971-2011 and satellite-measured nighttime light imagery from the Defense Meteorological Satellite Program(DMSP) Operational Linescan System(OLS) during 1992-2010, we analyzed the long-term change of summer EHEs and its association with the rapid urbanization process. The results could be concluded as follows:(1) Zhejiang has experienced rapid urbanization and dramatic growth in urban areas in the past two decades, especially after 2000.(2) The summer mean maximum temperature and the 95 th percentile of summer daily maximum temperature in most of its stations have increased, with the most significant increase occurring in the highly urbanized areas including the city belt around Hangzhou Bay, Taizhou-Wenzhou and Jinghua-Yiwu city belts.(3) The hot days and hot-day degrees, defined by both daily 95 th percentile and the threshold of 35℃, show that the UHI effect causes additional hot days and heat stress in urban stations compared to rural stations.The results in this study suggest that the UHI effect should be determined and incorporated in preparing high temperature forecasts in cities.

Linkage of the Decadal Variability of Extreme Summer Heat in North China with the IPOD since 1981

Extreme summer heat can have serious socioeconomic impacts in North China.Here,we explore the decadal variability of the number of extreme heat days in early-to-mid summer(June and July)and a related potential mechanism consistent with the major seasonal occurrence period of extreme heat events in North China(NCSH).Observational analyses show significant decadal variability in NCSH for 1981–2021,potentially linked to the Indo-Pacific warm pool and Northwest Pacific Ocean dipole(IPOD)in early-to-mid summer.Dynamic diagnostic analysis and the linear baroclinic model(LBM)show that the positive IPOD in early-to-mid summer can excite upward vertical wind anomalies in the South China-East China Sea region,shifting the position of the western Pacific subtropical high(WPSH)to the east or weakening the degree of its control of the South China-East China Sea region,thus generating a positive geopotential height quadrupole(EAWPQ)pattern in the East Asia-Northwest Pacific region.Subsequently,the EAWPQ can cause air compression(expansion)over North China by regulating the tropospheric thickness anomalies in North China,thus increasing(decreasing)NCSH.Finally,an empirical model that incorporates the linear trend can better simulate the decadal NCSH compared to an empirical model based solely on the IPOD index,suggesting that the decadal variability of NCSH may be a combined contribution of the decadal IPOD and external linear forcing.

Gastrointestinal manifestations of critical ill heatstroke patients and their associations with outcomes:A multicentre,retrospective,observational study

BACKGROUND Extreme heat exposure is a growing health problem,and the effects of heat on the gastrointestinal(GI)tract is unknown.This study aimed to assess the incidence of GI symptoms associated with heatstroke and its impact on outcomes.AIM To assess the incidence of GI symptoms associated with heatstroke and its impact on outcomes.METHODS Patients admitted to the intensive care unit(ICU)due to heatstroke were included from 83 centres.Patient history,laboratory results,and clinically relevant outcomes were recorded at ICU admission and daily until up to day 15,ICU discharge,or death.GI symptoms,including nausea/vomiting,diarrhoea,flatulence,and bloody stools,were recorded.The characteristics of patients with heatstroke concomitant with GI symptoms were described.Multivariable regression analyses were performed to determine significant predictors of GI symptoms.RESULTS A total of 713 patients were included in the final analysis,of whom 132(18.5%)patients had at least one GI symptom during their ICU stay,while 26(3.6%)suffered from more than one symptom.Patients with GI symptoms had a significantly higher ICU stay compared with those without.The mortality of patients who had two or more GI symptoms simultaneously was significantly higher than that in those with one GI symptom.Multivariable logistic regression analysis revealed that older patients with a lower GCS score on admission were more likely to experience GI symptoms.CONCLUSION The GI manifestations of heatstroke are common and appear to impact clinically relevant hospitalization outcomes.

HadISDH.extremes Part Ⅱ:Exploring Humid Heat Extremes Using Wet Bulb Temperature Indices

Heat events may be humid or dry.While several indices incorporate humidity,such combined indices obscure identification and exploration of heat events by their different humidity characteristics.The new HadISDH.extremes global gridded monitoring product uniquely provides a range of wet and dry bulb temperature extremes indices.Analysis of this new data product demonstrates its value as a tool for quantifying exposure to humid verses dry heat events.It also enables exploration into“stealth heat events”,where humidity is high,perhaps enough to affect productivity and health,while temperature remains moderate.Such events may not typically be identified as“heat events”by temperature-focused heat indices.Over 1973-2022,the peak magnitude of humid extremes(maximum daily wet bulb temperature over a month;T_(w)X)for the global annual mean increased significantly at 0.13±0.04℃(10 yr)^(−1),which is slightly slower than the global annual mean T_(w) increase of 0.22±0.04℃(10 yr)^(−1).The frequency of moderate humid extreme events per year(90th per-centile daily maxima wet bulb temperature exceedance;T_(w)X90p)also increased significantly at 4.61±1.07 d yr^(−1)(10 yr)^(−1).These rates were slower than for temperature extremes,TX and TX90p,which respectively increased significantly at 0.27±0.04℃(10 yr)^(−1) and 5.53±0.72 d yr^(−1)(10 yr)^(−1).Similarly,for the UK/Europe focus region,JJA-mean T_(w)X increased significantly,again at a slower rate than for TX and mean T_(w).HadISDH.extremes shows some evidence of“stealth heat events”occurring where humidity is high but temperature remains more moderate.

Regional changes in extreme heat events in China under stabilized 1.5℃ and 2.0℃ global warming

Extreme heat events(EHEs)have a significant impact on the social economy and human health.China is a country with a large population and diverse terrain,and it is necessary to project future extreme heat changes in the sub-regions.This study used a specially designed dataset,the Community Earth System Model(CESM)simulations,namely CESM low-warming,to investigate the EHEs in China under 1.5℃ and 2.0℃ global warming.The results indicate that the regional mean warming over China will exceed the global average,about 1.63℃ and 2.24℃ in 1.5℃ and 2.0℃ warmer futures.Compared to the present-day(1976–2005),the frequency and duration of the EHEs in South China are projected to increase the most among the sub-regions.For example,the frequency of EHEs in South China at 1.5℃ and 2.0℃ warming will exceed 3 and 3.5 times the present-day level.However,when global warming rises from 1.5℃ to 2.0℃,the increased impacts relative to the 1.5℃ warming level will be the lowest in South China(less than 40%),and the highest increased impacts are projected to appear in Northeast China(53%-84%)and Northwest China(53%–107%).The main reason for this situation is that compared with the 1.5℃ scenario,the upper zonal westerly in northern China weakens and the continental high pressure enhances under the 2.0℃ scenario.Therefore,limiting global warming at 1.5℃ instead of 2.0℃ is beneficial for eliminating extreme heat events,especially for Northeast China and Northwest China.

HadISDH.extremes Part Ⅰ:A Gridded Wet Bulb Temperature Extremes Index Product for Climate Monitoring

HadISDH.extremes is an annually updated global gridded monthly monitoring product of wet and dry bulb temperature–based extremes indices,from January 1973 to December 2022.Data quality,including spatial and temporal stability,is a key focus.The hourly data are quality controlled.Homogeneity is assessed on monthly means and used to score each gridbox according to its homogeneity rather than to apply adjustments.This enables user-specific screening for temporal stability and avoids errors from inferring adjustments from monthly means for the daily maximum values.For general use,a score(HQ Flag)of 0 to 6 is recommended.A range of indices are presented,aligning with existing standardised indices.Uniquely,provision of both wet and dry bulb indices allows exploration of heat event character—whether it is a“humid and hot”,“dry and hot”or“humid and warm”event.It is designed for analysis of long-term trends in regional features.HadISDH.extremes can be used to study local events,but given the greater vulnerability to errors of maximum compared to mean values,cross-validation with independent information is advised.

Amplification effect of intra-seasonal variability of soil moisture on heat extremes over Eurasia

Drying soil has been conducive to a high frequency of extreme high-temperature events over many regions worldwide in recent decades.However,changes in the intraseasonal variability of soil moisture can also influence the likelihood of extremely high temperatures.Although previous investigators have examined the association between extremely high temperatures and large-scale atmospheric circulation variability,the role of land-atmosphere coupling dominated by soil moisture variability in extremely high temperatures,particularly over the Eurasian continent,is not well understood.In this study,on the basis of the Land Surface,Snow,and Soil Moisture Model Intercomparison Project,we found that land-atmosphere feedback amplified the variability of soil moisture in most regions of Eurasia during summer from 1980 to 2014.This amplification of soil moisture variability is closely correlated with more intensive intraseasonal variability of surface air temperature and more frequent occurrences of extreme high-temperature events,particularly in Europe,Siberia,Northeast Asia,and the Indochina Peninsula.This correlation implies that increasing the intraseasonal variability of soil moisture results in a high likelihood of heat extremes during summer in most parts of Eurasia except Asian desert areas.On the intraseasonal timescale,the land-atmosphere coupling increases the variability of surface sensible heat flux and net long-wave radiation heating the atmosphere by intensifying the soil moisture variability,thus amplifying the variability of surface air temperature and enhancing the extreme high-temperature days.This finding demonstrates the importance of changes in intraseasonal soil moisture variability for the increasing likelihood of heat extremes in summer.

Sahel Afforestation and Simulated Risks of Heatwaves and Flooding Versus Ecological Revegetation That Combines Planting and Succession

Studies simulating the large-scale afforestation of the African Sahel constantly find warning signals of increased risk of extreme temperatures and heatwaves resulting from changes in albedo and latent heat flow. We review the afforestation measures underlying three simulation studies, together with a restoration model in which compartments are formed by greenbelts to enable succession of savanna vegetation, protected from hot wind and drought. Savanna-like vegetation (around 20% woody plants) will show bright reflective surface and drying of leaves during dry season rather than constant green color, with very different impact on albedo and temperatures. We derive that the simulated risks of extreme heat and flooding from rain will strongly depend on species, shape and density of the new vegetation. Ecological restoration concepts are expected to mitigate or prevent such restoration related climatic risks. Compact afforestation of the Sahel does not appear to be necessary or feasible. A restoration model based on compartmentalization and the protected succession of diverse, climatically adaptable vegetation could also be used in populated drylands, as a sustainable and temperature balancing solution to desertification.

Planck’s Oscillators at Low Temperatures and Haken’s Perturbation Approach to the Quantum Oscillators Reconsidered

In the first step the extremal values of the vibrational specific heat and entropy represented by the Planck oscillators at the low temperatures could be calculated. The positions of the extrema are defined by the dimensionless ratios between the quanta of the vibrational energy and products of the actual temperature multiplied by the Boltzmann constant. It became evident that position of a local maximum obtained for the Planck’s average energy of a vibration mode and position of a local maximum of entropy are the same. In the next step the Haken’s time-dependent perturbation approach to the pair of quantum non-degenerate Schr?dinger eigenstates of energy is re-examined. An averaging process done on the time variable leads to a very simple formula for the coefficients entering the perturbation terms.

Dynamic Assessment of Global Maize Exposure to Extremely High Temperatures

Exposure to extreme heat can severely harm crop growth and development,and it is essential to assess such exposure accurately to minimize risks to crop production.However,the actual distribution of crops and its changes have neither been examined in sufficient detail nor integrated into the assessments of exposure to ensure their accuracy.By examining the distribution of maize at a high resolution through species distribution modeling,we assessed the past and future exposure of maize to temperatures above 37℃worldwide.Such exposure is likely to be widespread and severe,mainly in the subtropics,and may even expand to the mid-latitudes to encompass some major maize-producing areas.Many areas at both high and low latitudes may become exposed for the first time in the next 20 years.By the 2050 s,the total area exposed could increase by up to 185%to 308.18 million ha,of which the area exposed for over 60 days may increase nearly sevenfold.The average length of exposure may increase by 69%to 27 days,and areas optimally suited to maize planting may see the fastest increase by up to 772%.Extreme heat can threaten global maize production severely,and measures to mitigate that threat and to adapt to it are urgently needed.

气候变化背景下极端热事件劳动适龄人口暴露度的全球和区域变化

Despite recent progress in assessing future population exposure,few studies have focused on the exposure of certain vulnerable groups,such as working people.Working in hot environments can increase the heat-related risk to human health and reduce worker productivity,resulting in broad social and economic implications.Based on the daily climatic simulations from the Coupled Model Intercomparison Project phase 6(CMIP6)and the age group-specific population projections,we investigate future changes in working-age population exposure to heat extremes under multiple scenarios at global and continental scales.Projections show little variability in exposure across scenarios by mid-century(2031–2060),whereas significantly greater increases occur under SSP3-7.0 for the late century(2071–2100)compared to lower-end emission scenarios.Global exposure is expected to increase approximately 2-fold,6-fold and 16-fold relative to the historical time(1981–2010)under SSP1-2.6,SSP2-4.5 and SSP3-7.0,respectively.Asia will have the largest absolute exposure increase,while in relative terms,the most affected region is Africa.At the global level,future exposure increases are primarily caused by climate change and the combined effect of climate and working-age population changes.Climate change is the dominant driver in enhancing future continental exposure except in Africa,where the main contributor is the combined effect.