Diverse Characteristics of U.S. Summer Heat Waves

Abstract Heat waves are climate extremes having significant environmental and social impacts. However, there is no universally accepted definition of a heat wave. The major goal of this study is to compare characteristics of continental U.S. warm season (May–September) heat waves defined using four different variables—temperature itself and three variables incorporating atmospheric moisture—all for differing intensity and duration requirements. To normalize across different locations and climates, daily intensity is defined using percentiles computed over the 1979–2013 period. The primary data source is the U.S. Historical Climatological Network (USHCN), with humidity data from the North American Regional Reanalysis (NARR) also tested and utilized. The results indicate that heat waves defined using daily maximum temperatures are more frequent and persistent than when based on minimum temperatures, with substantial regional variations in behavior. For all four temperature variables, heat waves based on daily minimum values have greater spatial coherency than for daily maximum values. Regionally, statistically significant upward trends (1979–2013) in heat wave frequency are identified, largest when based on daily minimum values, across variables. Other notable differences in behavior include a higher frequency of heat waves based on maximum temperature itself than for variables that include humidity, while daily minimum temperatures show greater similarity across all variables in this regard. Overall, the study provides a baseline to compare with results from climate model simulations and projections, for examining differing regional and large-scale circulation patterns associated with U.S. summer heat waves and for examining the role of land surface conditions in modulating regional variations in heat wave behavior.

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Analysis of the extreme heat events in Iran

International Journal of Climate Change Strategies and Management ◽

10.1108/ijccsm-04-2016-0046 ◽

2017 ◽

Vol 9 (4) ◽

pp. 418-432 ◽

Cited By ~ 1

Author(s):

Hojjatollah Yazdanpanah ◽

Josef Eitzinger ◽

Marina Baldi

Keyword(s):

Trend Analysis ◽

Heat Wave ◽

Heat Waves ◽

Temporal Variations ◽

Maximum Temperature ◽

Daily Maximum Temperature ◽

Daily Maximum ◽

Positive Trend ◽

Content Type ◽

Hot Days

Purpose The purpose of this paper is to assess the spatial and temporal variations of extreme hot days (H*) and heat wave frequencies across Iran. Design/methodology/approach The authors used daily maximum temperature (Tmax) data of 27 synoptic stations in Iran. These data were standardized using the mean and the standard deviation of each day of the year. An extreme hot day was defined when the Z score of daily maximum temperature of that day was equal or more than a given threshold fixed at 1.7, while a heat wave event was considered to occur when the Z score exceeds the threshold for at least three continuous days. According to these criteria, the annual frequency of extreme hot days and the number of heat waves were determined for all stations. Findings The trend analysis of H* shows a positive trend during the past two decades in Iran, with the maximum number of H* (110 cases) observed in 2010. A significant trend of the number of heat waves per year was also detected during 1991-2013 in all the stations. Overall, results indicate that Iran has experienced heat waves in recent years more often than its long-term average. There will be more frequent and intense hot days and heat waves across Iran until 2050, due to estimated increase of mean air temperature between 0.5-1.1 and 0.8-1.6 degree centigrade for Rcp2.6 and Rcp8.8 scenarios, respectively. Originality/value The trend analysis of hot days and heat wave frequencies is a particularly original aspect of this paper. It is very important for policy- and decision-makers especially in agriculture and health sectors of Iran to make some adaptation strategies for future frequent and intense hot days over Iran.

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A Stepwise-Clustered Simulation Approach for Projecting Future Heat Wave Over Guangdong Province

Frontiers in Ecology and Evolution ◽

10.3389/fevo.2021.761251 ◽

2021 ◽

Vol 9 ◽

Author(s):

Jiayan Ren ◽

Guohe Huang ◽

Yongping Li ◽

Xiong Zhou ◽

Jinliang Xu ◽

...

Keyword(s):

Heat Wave ◽

Climate Models ◽

Extreme Event ◽

Heat Waves ◽

Extreme Temperature ◽

Global Climate Models ◽

Maximum Temperature ◽

Daily Maximum Temperature ◽

Daily Maximum ◽

Simulation Approach

A heat wave is an important meteorological extreme event related to global warming, but little is known about the characteristics of future heat waves in Guangdong. Therefore, a stepwise-clustered simulation approach driven by multiple global climate models (i.e., GCMs) is developed for projecting future heat waves over Guangdong under two representative concentration pathways (RCPs). The temporal-spatial variations of four indicators (i.e., intensity, total intensity, frequency, and the longest duration) of projected heat waves, as well as the potential changes in daily maximum temperature (i.e., Tmax) for future (i.e., 2006–2095) and historical (i.e., 1976–2005) periods, were analyzed over Guangdong. The results indicated that Guangdong would endure a notable increasing annual trend in the projected Tmax (i.e., 0.016–0.03°C per year under RCP4.5 and 0.027–0.057°C per year under RCP8.5). Evaluations of the multiple GCMs and their ensemble suggested that the developed approach performed well, and the model ensemble was superior to any single GCM in capturing the features of heat waves. The spatial patterns and interannual trends displayed that Guangdong would undergo serious heat waves in the future. The variations of intensity, total intensity, frequency, and the longest duration of heat wave are likely to exceed 5.4°C per event, 24°C, 25 days, and 4 days in the 2080s under RCP8.5, respectively. Higher variation of those would concentrate in eastern and southwestern Guangdong. It also presented that severe heat waves with stronger intensity, higher frequency, and longer duration would have significant increasing tendencies over all Guangdong, which are expected to increase at a rate of 0.14, 0.83, and 0.21% per year under RCP8.5, respectively. Over 60% of Guangdong would suffer the moderate variation of heat waves to the end of this century under RCP8.5. The findings can provide decision makers with useful information to help mitigate the potential impacts of heat waves on pivotal regions as well as ecosystems that are sensitive to extreme temperature.

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Heat Waves in Florida: Climatology, Trends, and Related Precipitation Events

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-18-0165.1 ◽

2019 ◽

Vol 58 (3) ◽

pp. 447-466 ◽

Cited By ~ 5

Author(s):

Shealynn R. Cloutier-Bisbee ◽

Ajay Raghavendra ◽

Shawn M. Milrad

Keyword(s):

Heat Wave ◽

Large Scale ◽

Climate Model ◽

Heat Waves ◽

Heavy Precipitation ◽

Daily Maximum ◽

Recent Climate ◽

Climate Model Simulations ◽

Southern Florida ◽

Precipitation Events

AbstractHeat waves are increasing in frequency, duration, and intensity and are strongly linked to anthropogenic climate change. However, few studies have examined heat waves in Florida, despite an older population and increasingly urbanized land areas that make it particularly susceptible to heat impacts. Heavy precipitation events are also becoming more frequent and intense; recent climate model simulations showed that heavy precipitation in the three days after a Florida heat wave follow these trends, yet the underlying dynamic and thermodynamic mechanisms have not been investigated. In this study, a heat wave climatology and trend analysis are developed from 1950 to 2016 for seven major airports in Florida. Heat waves are defined based on the 95th percentile of daily maximum, minimum, and mean temperatures. Results show that heat waves exhibit statistically significant increases in frequency and duration at most stations, especially for mean and minimum temperature events. Frequency and duration increases are most prominent at Tallahassee, Tampa, Miami, and Key West. Heat waves in northern Florida are characterized by large-scale continental ridging, while heat waves in central and southern Florida are associated with a combination of a continental ridge and a westward extension of the Bermuda–Azores high. Heavy precipitation events that follow a heat wave are characterized by anomalously large ascent and moisture, as well as strong instability. Light precipitation events in northern Florida are characterized by advection of drier air from the continent, while over central and southern Florida, prolonged subsidence is the most important difference between heavy and light events.

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Evaluation the WRF Model with Different Land Surface Schemes: Heat Wave Event Simulations and Its Relation to Pacific Variability over Coastal Region, Karachi, Pakistan

Sustainability ◽

10.3390/su132212608 ◽

2021 ◽

Vol 13 (22) ◽

pp. 12608

Author(s):

Adil Dilawar ◽

Baozhang Chen ◽

Lifeng Guo ◽

Shuan Liu ◽

Muhammad Shafeeque ◽

...

Keyword(s):

Heat Wave ◽

Land Surface ◽

Southern Oscillation ◽

Wrf Model ◽

Maximum Temperature ◽

Daily Maximum Temperature ◽

Daily Maximum ◽

Relative Role ◽

Heat Wave Event ◽

Wave Event

This study investigates the relative role of land surface schemes (LSS) in the Weather Research and Forecasting (WRF) model, Version 4, to simulate the heat wave events in Karachi, Pakistan during 16–23 May 2018. The efficiency of the WRF model was evaluated in forecasting heat wave events over Karachi using the three different LSS, namely NOAH, NOAH-MP, and RUC. In addition to this we have used the longwave (RRTM) and shortwave (Dudhia) in all schemes. Three simulating setups were designed with a combination of shortwave, longwave, and LSS: E1 (Dudhia, RRTM, and Noah), E2 (Dudhia, RRTM, and Noah-MP), and E3 (Dudhia, RRTM, and RUC). All setups were carried out with a finer resolution of 1 km × 1 km. Findings of current study depicted that E2 produces a more realistic simulation of daily maximum temperature T(max) at 2m, sensible heat (SH), and latent heat (LH) because it has higher R2 and lower errors (BIAS, RMSE, MAE) compared to other schemes. Consequently, Noah-MP (LSS) accurately estimates T(max) and land surface heat fluxes (SH&LH) because uses multiple physics options for land atmosphere interaction processes. According to statistical analyses, E2 setup outperforms other setups in term of T(max) and (LH&SH) forecasting with the higher Nash-Sutcliffe efficiency (NSE) agreement is 0.84 (0.89). This research emphasizes that the selection of LSS is of vital importance in the best simulation of T(max) and SH (LH) over Karachi. Further, it is resulted that the SH flux is taking a higher part to trigger the heat wave event intensity during May 2018 due to dense urban canopy and less vegetated area. El Niño-Southern Oscillation (ENSO) event played role to prolong and strengthen the heat wave period by effecting the Indian Ocean Dipole (IOD) through walker circulation extension.

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Heat waves characteristics and their relation to air quality in Athens

Global NEST Journal ◽

10.30955/gnj.001530 ◽

2014 ◽

Vol 16 (5) ◽

pp. 919-928 ◽

Cited By ~ 7

Keyword(s):

Air Quality ◽

Heat Wave ◽

Heat Waves ◽

City Centre ◽

Maximum Temperature ◽

Daily Maximum Temperature ◽

Annual Number ◽

Daily Maximum ◽

Daily Average ◽

Suburban Site

<div> This paper studies the characteristics of the heat waves that were observed in Athens, Greece since 1951. A heat wave is detected when two temperature criteria are fulfilled at the city centre: the daily maximum temperature value is at least 37 oC and the daily average temperature value is at least 31 oC. Information about the intensity, duration, timing in season and annual frequency of occurrence of heat waves were extracted. The slope of the linear fit of the annual number of heat wave days indicated that 1.30 more heat wave days per year were observed after 1992. The intensity and the duration of heat waves have also increased since 90s, while heat wave days have been detected during the whole summer since then, even during the first days of September. Additionally, air quality at the centre and at a suburb of Athens during the heat wave days that were identified during the last decade is examined. The daily average value of PM10 concentration exceeded 50 μg m-3 in 65% and 59% of the heat wave days at the urban and the suburban site, respectively, while the information and the alert O3 threshold were exceeded in 17% and 5% of the heat wave days, respectively, at the suburban site. The degradation of air quality during heat wave days is also verified by the means of the common air quality index. Moreover, it was found that O3 levels decrease when heat waves last more than 6 days.  </div>

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The Role of Circulation and Land Surface Conditions in Current and Future Australian Heat Waves

Journal of Climate ◽

10.1175/jcli-d-17-0265.1 ◽

2017 ◽

Vol 30 (24) ◽

pp. 9933-9948 ◽

Cited By ~ 11

Author(s):

Peter B. Gibson ◽

Andrew J. Pitman ◽

Ruth Lorenz ◽

Sarah E. Perkins-Kirkpatrick

Keyword(s):

Atmospheric Circulation ◽

Heat Wave ◽

Land Surface ◽

Large Scale ◽

Heat Waves ◽

Synoptic Situation ◽

Large Scale Circulation ◽

Evaporative Fraction ◽

Surface Conditions ◽

Circulation Patterns

Understanding the physical drivers of heat waves is essential for improving short-term forecasts of individual events and long-term projections of heat waves under climate change. This study provides the first analysis of the influence of the large-scale circulation on Australian heat waves, conditional on the land surface conditions. Circulation types, sourced from reanalysis, are used to characterize the different large-scale circulation patterns that drive heat wave events across Australia. The importance of horizontal temperature advection is illustrated in these circulation patterns, and the pattern occurrence frequency is shown to reorganize through different modes of climate variability. It is further shown that the relative likelihood of a particular synoptic situation being associated with a heat wave is strongly modulated by the localized partitioning of available energy between surface sensible and latent heat fluxes (as measured through evaporative fraction) in many regions in reanalysis data. In particular, a several-fold increase in the likelihood of heat wave day occurrence is found during days of reduced evaporative fraction under favorable circulation conditions. The atmospheric circulation and land surface conditions linked to heat waves in reanalysis were then examined in the context of CMIP5 climate model projections. Large uncertainty was found to exist for many regions, especially in terms of the direction of future land surface changes and in terms of the magnitude of atmospheric circulation changes. Efforts to constrain uncertainty in both atmospheric and land surface processes in climate models, while challenging, should translate to more robust regional projections of heat waves.

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Factors Contributing to Record-Breaking Heat Waves over the Great Plains during the 1930s Dust Bowl

Journal of Climate ◽

10.1175/jcli-d-16-0436.1 ◽

2017 ◽

Vol 30 (7) ◽

pp. 2437-2461 ◽

Cited By ~ 16

Author(s):

Tim Cowan ◽

Gabriele C. Hegerl ◽

Ioana Colfescu ◽

Massimo Bollasina ◽

Ariaan Purich ◽

...

Keyword(s):

United States ◽

Heat Wave ◽

Great Plains ◽

Land Surface ◽

Heat Waves ◽

Circulation Pattern ◽

Dust Bowl ◽

Warm Advection ◽

Summer Heat ◽

Upper Level

Record-breaking summer heat waves were experienced across the contiguous United States during the decade-long “Dust Bowl” drought in the 1930s. Using high-quality daily temperature observations, the Dust Bowl heat wave characteristics are assessed with metrics that describe variations in heat wave activity and intensity. Despite the sparser station coverage in the early record, there is robust evidence for the emergence of exceptional heat waves across the central Great Plains, the most extreme of which were preconditioned by anomalously dry springs. This is consistent with the entire twentieth-century record: summer heat waves over the Great Plains develop on average ~15–20 days earlier after anomalously dry springs, compared to summers following wet springs. Heat waves following dry springs are also significantly longer and hotter, indicative of the importance of land surface feedbacks in heat wave intensification. A distinctive anomalous continental-wide circulation pattern accompanied exceptional heat waves in the Great Plains, including those of the Dust Bowl decade. An anomalous broad surface pressure ridge straddling an upper-level blocking anticyclone over the western United States forced substantial subsidence and adiabatic warming over the Great Plains, and triggered anomalous southward warm advection over southern regions. This prolonged and amplified the heat waves over the central United States, which in turn gradually spread westward following heat wave emergence. The results imply that exceptional heat waves are preconditioned, triggered, and strengthened across the Great Plains through a combination of spring drought, upper-level continental-wide anticyclonic flow, and warm advection from the north.

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Modeling Northern Hemisphere Summer Heat Extreme Changes and Their Uncertainties Using a Physics Ensemble of Climate Sensitivity Experiments

Journal of Climate ◽

10.1175/jcli3877.1 ◽

2006 ◽

Vol 19 (17) ◽

pp. 4418-4435 ◽

Cited By ~ 81

Author(s):

Robin T. Clark ◽

Simon J. Brown ◽

James M. Murphy

Keyword(s):

Structural Changes ◽

Heat Waves ◽

Full Range ◽

Daily Maximum ◽

Model Parameters ◽

Mean Values ◽

Summer Heat ◽

Modeling Uncertainties ◽

Physics Ensemble ◽

Projected Changes

Abstract Changes in extreme daily temperature events are examined using a perturbed physics ensemble of global model simulations under present-day and doubled CO2 climates where ensemble members differ in their representation of various physical processes. Modeling uncertainties are quantified by varying poorly constrained model parameters that control atmospheric processes and feedbacks and analyzing the ensemble spread of simulated changes. In general, uncertainty is up to 50% of projected changes in extreme heat events of the type that occur only once per year. Large changes are seen in distributions of daily maximum temperatures for June, July, and August with significant shifts to warmer conditions. Changes in extremely hot days are shown to be significantly larger than changes in mean values in some regions. The intensity, duration, and frequency of summer heat waves are expected to be substantially greater over all continents. The largest changes are found over Europe, North and South America, and East Asia. Reductions in soil moisture, number of wet days, and nocturnal cooling are identified as significant factors responsible for the changes. Although uncertainty associated with the magnitude of expected changes is large in places, it does not bring into question the sign or nature of the projected changes. Even with the most conservative simulations, hot extreme events are still expected to substantially increase in intensity, duration, and frequency. This ensemble, however, does not represent the full range of uncertainty associated with future projections; for example, the effects of multiple parameter perturbations are neglected, as are the effects of structural changes to the basic nature of the parameterization schemes in the model.

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Heat waves in Africa 1981–2015, observations and reanalysis

Natural Hazards and Earth System Science ◽

10.5194/nhess-17-115-2017 ◽

2017 ◽

Vol 17 (1) ◽

pp. 115-125 ◽

Cited By ~ 34

Author(s):

Guido Ceccherini ◽

Simone Russo ◽

Iban Ameztoy ◽

Andrea Francesco Marchese ◽

Cesar Carmona-Moreno

Keyword(s):

Heat Wave ◽

Heat Waves ◽

Extreme Temperature ◽

Reanalysis Data ◽

Maximum Temperature ◽

Wave Analysis ◽

Land Area ◽

Spatial Coverage ◽

Temperature Records ◽

Numerical Index

Abstract. The purpose of this article is to show the extreme temperature regime of heat waves across Africa over recent years (1981–2015). Heat waves have been quantified using the Heat Wave Magnitude Index daily (HWMId), which merges the duration and the intensity of extreme temperature events into a single numerical index. The HWMId enables a comparison between heat waves with different timing and location, and it has been applied to maximum and minimum temperature records. The time series used in this study have been derived from (1) observations from the Global Summary of the Day (GSOD) and (2) reanalysis data from ERA-Interim. The analysis shows an increasing number of heat waves of both maxima and minima temperatures in the last decades. Results from heat wave analysis of maximum temperature (HWMIdtx) indicate an increase in intensity and frequency of extreme events. Specifically, from 1996 onwards it is possible to observe HWMIdtx spread with the maximum presence during 2006–2015. Between 2006 and 2015 the frequency (spatial coverage) of extreme heat waves had increased to 24.5 observations per year (60.1 % of land cover), as compared to 12.3 per year (37.3 % of land area) in the period from 1981 to 2005 for GSOD stations (reanalysis).

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Probabilistic Heat Wave Forecast Based on a Large-Scale Circulation Pattern Using the TIGGE Data

Weather and Forecasting ◽

10.1175/waf-d-19-0188.1 ◽

2020 ◽

Vol 35 (2) ◽

pp. 367-377

Author(s):

Hyun-Ju Lee ◽

Woo-Seop Lee ◽

Jong Ahn Chun ◽

Hwa Woon Lee

Keyword(s):

South Korea ◽

Heat Wave ◽

Large Scale ◽

Heat Waves ◽

Ensemble Prediction ◽

Multimodel Ensemble ◽

Large Scale Circulation ◽

Circulation Patterns ◽

Wave Forecast ◽

Prediction Systems

Abstract Forecasting extreme events is important for having more time to prepare and mitigate high-impact events because those are expected to become more frequent, intense, and persistent around the globe in the future under the warming atmosphere. This study evaluates the probabilistic predictability of the heat wave index (HWI) associated with large-scale circulation patterns for predicting heat waves over South Korea. The HWI, reflecting heat waves over South Korea, was defined as the vorticity difference at 200 hPa between the South China Sea and northeast Asia. The forecast of up to 15 days from five ensemble prediction systems and the multimodel ensemble has been used to predict the probabilistic HWI during the summers of 2011–15. The ensemble prediction systems consist of different five operational centers, and the forecast skill of the probability of heat waves occurrence was assessed using the Brier skill score (BSS), relative operating characteristics (ROC), and reliability diagram. It was found that the multimodel ensemble is capable of better predicting the large-scale circulation patterns leading to heat waves over South Korea than any other single ensemble system through all forecast lead times. We concluded that the probabilistic forecast of the HWI has promise as a tool to take appropriate and timely actions to minimize the loss of lives and properties from imminent heat waves.

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