Continual tropical cyclone and extreme urban heat (TC-Heat) compound events under East Asian metropolitan cities’ footprint

Trends in the number of extreme hot days (days with SST anomalies higher than the 95% percentile) were analyzed along the Canary Upwelling Ecosystem (CUE) over the period 1982- 2012 by means of SST data retrieved from NOAA OI1/4 Degree. The analysis will focus on the Atlantic Iberian sector and the Moroccan sub- region where upwelling is seasonal (spring and summer) are permanent, respectively. Trends were analyzed both near coast and at the adjacent ocean where the increase in the number of extreme hot days is higher. Changes are clear at annual scale with an increment of 9.8±0.3 (9.7±0.1) days dec-1 near coast and 11.6±0.2 (13.5±0.1) days dec-1 at the ocean in the Atlantic Iberian sector (Moroccan sub-region). The differences between near shore and ocean trends are especially patent for the months under intense upwelling conditions. During that upwelling season the highest differences in the excess of extreme hot days between coastal and ocean locations (Δn(#days dec-1)) occur at those regions where coastal upwelling increase is high. Actually, Δn and upwelling trends have shown to be significantly correlated in both areas, R=0.88 (p<0.01) at the Atlantic Iberian sector and R=0.67 (p<0.01) at the Moroccan sub-region.

Major Tropical Cyclone (TC) events cause extensive damage in coastal regions of the western North Atlantic Basin. The short instrumental record leaves significant gaps in understanding long‐term trends in TC recurrence and intensity, creating uncertainty about future storm trends. Analysis of an ∼520‐year core record from Harvey Lake, located &gt;80 km from the Atlantic coast in southwestern New Brunswick, Canada was carried out using: (a) end‐member mixing analysis (EMMA) of lake sediment grain size data to identify storm‐linked sedimentological processes; and (2) ITRAX X‐ray fluorescence (XRF) derived element/ratios (Fe, Ti, Ca/Sr, Zr/Rb, K/Rb, and Br + Cl/Al) associated with precipitation, weathering, catchment runoff, and air masses. Three derived end members were correlated to heavy rainfall events (EM01), spring freshet (EM02), and TCs (EM03). CONISS analysis of the EMMA and XRF core data resulted in recognition of four unique climatic zones distinguished by distinct distributions of TC and rainfall/weathering/runoff/and air masses. Numerous, major (EM01) rainfall events and (EM03) TC events characterized the basal core record during the early Little Ice Age (LIAa; Zone 1) phase, terminating at ∼1645. A near cessation of heavy rainfall and TC events differentiated the subsequent colder LIAb (∼1645–1825; Zone 2) and subsequent Little Ice Age Transition (∼1825–1895; Zone 3). A resurgence of major rainfall and TC events occurred during recovery from the LIA starting in ∼1895 (Zone 4). EMMA provides a robust tool for recognition of TC and major rainfall events, and greatly expands the potential for paleo‐storm activity research well inland from coastal regions.

This study assesses how well the Community Climate System Model version 4 (CCSM4) simulates the large scale conditions needed for extreme hot surface temperatures in the California Central Valley (CV). Extreme hot summer days in the CV are associated with a large scale meteorological pattern (LSMP) described in Grotjahn and Faure (2008). The strength and sign of that pattern are assessed using a circulation index developed in Grotjahn (2011). The circulation index is strongly linked to daily maximum surface temperature normalized anomalies at stations spanning the CV. (Extreme heat events in the CV also affect a wider area of California and United States west coast). This study makes two primary points. First, the approach used in Grotjahn (2011) can be applied as a novel tool to evaluate how skillfully a model simulates conditions present during CV hot spells by evaluating how well the LSMP is simulated. The circulation index is calculated from historical simulations by CCSM4 and its distribution compared with that of the observed circulation index. Second, values of the CCSM4 based circulation index have smaller standard deviation than observed in reanalysis data. CCSM4 can generate a few comparably large circulation index values (implying high surface temperature anomalies) but not as often as in reanalysis data. Correct simulation of this large scale pattern is a necessary condition for successful simulation of California extreme hot days by a regional climate model. Also, the CCSM4 topography does not have a CV, but a broad topographic slope instead. Various choices of CCSM4 grid points were tested and none satisfactorily represented the CV maximum temperatures. These results should discourage use of CCSM4 surface data directly but encourage use of a regional climate model driven by the CCSM4 to capture hot spells in the CV.

Compound extreme events can potentially cause deadlier socio-economic consequences. Although several studies focused on individual extreme climate events, the occurrence of compound extreme events is still not well studied in the upper Midwestern United States. In this study, compound extreme precipitation preceded by extreme hot day events was investigated. Results showed a strong linkage between extreme precipitation events and extreme hot days. A significant increasing trend was noticed mainly in Iowa (10.1%), northern parts of Illinois (5.04%), and Michigan (5.04%). Results also showed a higher intensity of extreme precipitation events preceded by an extremely hot day compared to the intensity of extreme precipitation events not preceded by an extremely hot day, mostly in the central and lower parts of Minnesota, western and upper parts of Iowa, lower and upper parts of Illinois, parts of Ohio, Michigan, and Wisconsin for 1950–2010. In other words, extreme heat contributed to more extreme precipitation events. Our findings would provide important insights related to flood management under future climate change scenarios in the region.

Trends in the number of extreme hot days (days with SST anomalies higher than the 95% percentile) were analyzed along the Canary upwelling ecosystem (CUE) over the period 1982–2012 by means of SST data retrieved from NOAA OI1/4 Degree. The analysis will focus on the Atlantic Iberian sector and the Moroccan subregion where upwelling is seasonal (spring and summer) and permanent, respectively. Trends were analyzed both near coast and at the adjacent ocean where the increase in the number of extreme hot days is higher. Changes are clear at annual scale with an increment of 9.8 ± 0.3 (9.7 ± 0.1) days dec−1 near coast and 11.6 ± 0.2 (13.5 ± 0.1) days dec−1 at the ocean in the Atlantic Iberian sector (Moroccan subregion). The differences between near shore and ocean trends are especially patent for the months under intense upwelling conditions. During that upwelling season the highest differences in the excess of extreme hot days between coastal and ocean locations (Δn(# days dec−1)) occur at those regions where coastal upwelling increase is high. Actually, Δn and upwelling trends have shown to be significantly correlated in both areas, R = 0.88 (p < 0.01) at the Atlantic Iberian sector and R = 0.67 (p < 0.01) at the Moroccan subregion.

PurposeThe 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/approachThe 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.FindingsThe 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/valueThe 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.

Background Extreme weather and climate events impact public health in multiple ways and extreme heat is one of the major environmental challenges for public health in Thailand. Objective We assessed the effects of heat stress on occupational health among agricultural workers who are exposed to the heat at different levels for both males and females in different age groups. We further investigated the responses to extreme heat among the government agencies. Methods A cross-sectional study was used to identify heat exposure situations that create heat stress-related health risks. The question guidelines have been developed to assess occupational heat impacts in the study site and used semi-structured interviews to describe how agricultural workers experience heat exposures where they work. The Wet Bulb Globe Temperature (WBGT) index and temperatures were measured by WBGT monitors in both winter and summer. Twenty-nine participants aged 24–76 were recruited to the study. Results All participants had one or more signs and symptoms of heat stress; however, they had concerns about work-related heat stress prevention. Outdoor WBGT was found to be highest between 11:00 AM and 11:59 AM, and 13:00 PM and 13:59 PM in winter and summer, respectively. Our findings revealed that study sites had heat indices necessitating extreme caution, where sunstroke, muscle cramps, and/or heat exhaustion were possible with prolonged exposure. Conclusions A heat health warning system is essential to reduce the negative impacts of extreme weather.

Extreme ambient heat and outcomes of assisted reproduction in the continental United States, 1996 to 2018.

Ninety five tropical cyclonic events (tropical storms, depressions and cyclones) between 2001 and 2010 were studied to determine their impact on dust outbreaks and long-range transport over the northern Indian Ocean and south Asia. In addition to the winter and summer Shamal Winds, tropical cyclones are an important mechanism of dust entrainment and transport of dust in this region. Elevated dust levels were observed in the northern Arabian Sea during most tropical cyclone events. During the study period, fifteen tropical cyclones migrated close to the dust source areas leading to major dust storms. Anti-clockwise winds associated with these storms were observed to entrain dust and transport it mostly towards the west or south-westerly direction. Tropical cyclones and storms, located further away from dust source areas, significantly alter the dispersal pathways of dust plumes raised by other mechanisms. The Northern Bay of Bengal cyclone events are shown to aid advection of dust plumes from southwest Asia and Thar Desert over highly populated regions of the Indian Subcontinent. Tropical cyclones also play an important role in dispersal of fine-mode aerosols over South Asia and formation of complex aerosol-dust mixtures.

This study cross-validates the radar reflectivity Z, the rainfall drop size distribution parameter (median volume diameter, Do ) and the rainfall rate R estimated from the Tropical Rainfall Measuring Mission (TRMM) satellite Precipitation Radar (PR), a combined PR and TRMM Microwave Imager (TMI) algorithm (COM) and a C-band dual-polarised ground-radar (GR) for TRMM overpasses during the passage of tropical cyclone (TC) and non-TC events over Darwin, Australia. Two overpass events during the passage of TC Carlos and eleven non-TC overpass events are used in this study and the GR is taken as the reference. It is shown that the correspondence is dependent on the precipitation type whereby events with more (less) stratiform rainfall usually have a positive (negative) bias in the reflectivity and the rainfall rate whereas in the Do the bias is generally positive but small (large). The COM reflectivity estimates are similar to the PR but it has a smaller bias in the Do for most of the greater stratiform events. This suggests that combining the TMI with the PR adjusts the Do towards the "correct" direction if the GR is taken as the reference. Moreover, the association between the TRMM estimates and the GR for the two TC events, which are highly stratiform in nature, is similar to that observed for the highly stratiform non-TC events (there is no significant difference) but it differs largely from that observed for the majority of the highly convective non-TC events.

Heat waves are increasing with global warming and have more dramatic biological effects on organisms in natural and agricultural ecosystems than mean temperature increase. However, predicting the impact of future heat waves on organisms and ecosystems is challenging because we still have a limited understanding of how the different components that characterize heat waves interact. Here we take an experimental approach to examine the individual and combine consequences of two important features that characterize heat waves: duration of successive hot days and recovery days between two hot spells. Specifically we exposed individuals of a global agricultural pest, the aphid Sitobion avenae to different heat wave scenarios by factorially manipulating the number of extreme hot days versus normal days and altered which period individuals experienced first in their life cycle. We found that effects of heat waves were driven by a delicate balance of damage during hot periods versus repair during normal periods. Increasing the duration of hot days in heat waves had a negative effect on various demographic rates and life‐time fitness of individuals, but magnitude of this effect was typically contingent on the temporal clustering of hot periods. Importantly, this interaction effect indicates that changes in the temporal distribution of extreme hot versus normal days can strongly alter the performance of organisms and dynamics of populations even when the total number of hot days during a given period remains unchanged. Together, these results emphasize the importance of accounting for the temporal distribution and quantitative patterns of extreme temperature events for predicting their consequences of natural and agricultural ecosystems.

As two prominent natural hazards, tropical cyclone (TC) and heat compound events seem irrelevant on most occasions. TC generally leads to cooling, but could induce extreme heat days (EHD) and heat compound hazard under certain circumstances. An EHD along the southeastern coast of China (SECC) associated with Typhoon Lekima (2019) is documented with its major contributing factors. The formation and intensity of the EHD were found to be closely related to the outer circulation of Lekima by comparing a series of WRF simulations. Via a boundary layer heat budget, we found local sensible heat flux was a necessary, but not sufficient condition for this EHD. Aided by a backward trajectory analysis, we found that upstream surface sensible heat flux, subsidence induced by Typhoon Lekima, and foehn effect due to local topography played approximately equal roles to the occurrence of the EHD. The retreat of regional land‐sea breeze circulation was also beneficial to the appearance of the EHD. Such TC‐heat events might be more overwhelming due to more vigorous TCs with warming in the future.

Elevated surface ozone levels are often detected in the New York metropolitan area during summertime. Moreover, surface ozone in this region exhibits sharp spatial gradients and distinctive diurnal cycles under the influence of complex boundary layer circulations induced by the intricate coastal geometry. This study examines how surface ozone is impacted by local circulations spatially and temporally under different temperature scenarios (all summer days, hot summer days, and extreme heat days) with the help of cluster‐based meteorological conditions during the summertime of 2017–2019. The most polluted days are found to be highly associated with hot sea breeze days with weak background flow. When sea breeze development in the New York Bight is delayed and its penetration north is intercepted by the dominant westerlies during hot summer days, daily maximum 8‐hr average ozone (DMA8) in some ozone hot spots of New York City (NYC) and the south shore of Connecticut (CT) typically drops 9–10 ppb under comparable temperature levels. The average regional decrease of DMA8 for NYC and coastal CT is 6.7 and 8.3 ppb, respectively. Furthermore, we conclude that a change in early morning meridional wind direction is the most critical meteorological characteristic in controlling sea breeze onset type and helping modulate ozone exceedances in the region during extreme hot days when ozone exceedances are expected to be very common. The conclusion is further demonstrated with two case studies during the Long Island Sound Tropospheric Ozone Study 2018 field campaign.

High temperature accompanied with high humidity may result in unbearable and oppressive weather. In this study, future changes of extreme high temperature and heat stress in mainland China are examined based on daily maximum temperature (Tx) and daily maximum wet-bulb globe temperature (Tw). Tw has integrated the effects of both temperature and humidity. Future climate projections are derived from the bias-corrected climate data of five general circulation models under the Representative Concentration Pathways (RCPs) 2.6 and 8.5 scenarios. Changes of hot days and heat waves in July and August in the future (particularly for 2020–50 and 2070–99), relative to the baseline period (1981–2010), are estimated and analyzed. The results show that the future Tx and Tw of entire China will increase by 1.5–5°C on average around 2085 under different RCPs. Future increases in Tx and Tw exhibit high spatial heterogeneity, ranging from 1.2 to 6°C across different regions and RCPs. By around 2085, the mean duration of heat waves will increase by 5 days per annum under RCP8.5. According to Tx, heat waves will mostly occur in Northwest and Southeast China, whereas based on Tw estimates, heat waves will mostly occur over Southeast China and the mean heat wave duration will be much longer than those from Tx. The total extreme hot days (Tx or Tw > 35°C) will increase by 10–30 days. Southeast China will experience the severest heat stress in the near future as extreme high temperature and heat waves will occur more often in this region, which is particularly true when heat waves are assessed based on Tw. In comparison to those purely temperature-based indices, the index Tw provides a new perspective for heat stress assessment in China.

The ionosphere plays a critical role in the electromagnetic waves in communication systems such as the global positioning system (GPS). However, it is suspected that the strong convection during the tropical cyclone (TC) events can be a trigger to anomalous electron density variation in the ionosphere. This study analyzed the variation of three ionosphere-related parameters based on the GPS data including scintillation index S4, cycle slips, and total electron content (TEC) rate (TECR) during the tropical cyclone event (the 2013 TC Usagi) in the Hong Kong region. The results showed that the ionosphere-related parameters had a consistent significant increase on the second day after the Usagi made landfall near Hong Kong. Consequently, the positioning performance of GPS precise point positioning (PPP) and relative positioning modes was degraded. The degradation was ~ 138%, ~ 181%, and ~ 460% in the east (root mean square (RMS) 0.050 m), north (RMS 0.045 m), and up (RMS 0.185 m), respectively, compared with the RMS of 0.021 m in the east, 0.016 m in the north, and 0.033 m in the up on the normal day. Regarding the relative positioning, the positioning errors in the east (RMS 0.134 m) and north (RMS 0.118 m) directions were ~ 7.1 and ~ 7.9 times, respectively, as large as the RMS of 0.019 m in the east and 0.015 m in the north on the normal day. The positioning errors in the up (RMS 0.513 m) direction were ~ 12.2 times larger than the RMS of 0.042 m on the normal day.