Spatiotemporal Evaluation and Future Projection of Diurnal Temperature Range over the Tibetan Plateau in CMIP6 Models

The diurnal temperature range(DTR) serves as a vital indicator reflecting both natural climate variability and anthropogenic climate change. This study investigates the historical and projected multitemporal DTR variations over the Tibetan Plateau. It assesses 23 climate models from phase 6 of the Coupled Model Intercomparison Project(CMIP6) using CN05.1 observational data as validation, evaluating their ability to simulate DTR over the Tibetan Plateau. Then, the evolution of DTR over the Tibetan Plateau under different shared socioeconomic pathway(SSP) scenarios for the near,middle, and long term of future projection are analyzed using 11 selected robustly performing models. Key findings reveal:(1) Among the models examined, BCC-CSM2-MR, EC-Earth3, EC-Earth3-CC, EC-Earth3-Veg, EC-Earth3-Veg-LR,FGOALS-g3, FIO-ESM-2-0, GFDL-ESM4, MPI-ESM1-2-HR, MPI-ESM1-2-LR, and INM-CM5-0 exhibit superior integrated simulation capability for capturing the spatiotemporal variability of DTR over the Tibetan Plateau.(2) Projection indicates a slightly increasing trend in DTR on the Tibetan Plateau in the SSP1-2.6 scenario, and decreasing trends in the SSP2-4.5, SSP3-7.0, and SPP5-8.5 scenarios. In certain areas, such as the southeastern edge of the Tibetan Plateau, western hinterland of the Tibetan Plateau, southern Kunlun, and the Qaidam basins, the changes in DTR are relatively large.(3) Notably, the warming rate of maximum temperature under SSP2-4.5, SSP3-7.0, and SPP5-8.5 is slower compared to that of minimum temperature, and it emerges as the primary contributor to the projected decrease in DTR over the Tibetan Plateau in the future.

Association Between Diurnal Temperature Range and Respiratory Tract Infections

Objective This study aimed to assess the association between emergency-room visits for respiratory tract infection （RTI） with diurnal temperature range （DTR）, a weather parameter closely associated with urbanization and global climate change. Methods We conducted a semiparametric time-series analysis to estimate the percentage increase in emergency-room visits for RTI associated with changes in DTR after adjustment for daily weather conditions （temperature and relative humidity） and outdoor air pollution. Results DTR was significantly associated with daily emergency-room visits for RTI. An increase of 1 ~C in the current-day （LO） and in the 2-day moving average （L01） DTR corresponded to a 0.94% [95% confidence interval （CI）, 0.34%-1.55%] and 2.08% （95% CI, 1.24%-2.93%） increase in emergency-room visits for RTI, respectively. Conclusion DTR was associated with increased risk of RTI. More studies are needed to understand the impact of DTR on respiratory health.

Correlation between Atmospheric Water Vapor and Diurnal Temperature Range over China

Diurnal temperature range （DTR） is an im- portant measure in studies of climate change and variability. The changes of DTR in different regions are affected by many different factors. In this study, the degree of correlation between the DTR and atmospheric precipitable water （PW） over China is explored using newly homogenized surface weather and sounding observations. The results show that PW changes broadly reflect the geographic patterns of DTR long-term trends over most of China during the period 1970-2012, with significant anticorrelations of trend patterns between the DTR and PW, especially over those regions with higher magnitude DTR trends. PW can largely explain about 40% or more （re 0.40） of the DTR changes, with a d（PW）/d（DTR） slope of -2% to -10% K^-1 over most of northwestern and southeastern China, despite certain seasonal dependencies. For China as whole, the significant anticorrelations between the DTR and PW anomalies range from -0.42 to -0.75, with a d（PW）/d（DTR） slope of-6% to -11% K^-1. This implies that long-term DTR changes are likely to be associated with opposite PW changes, approximately following the Clausius-Clapeyron equation. Furthermore, the relationship is more significant in the warm season than in the cold season. Thus, it is possible that PW can be considered as one potential factor when exploring long-term DTR changes over China. It should be noted that the present study has a largely statistical focus and that the underlying physical processes should therefore be examined in future work.

Observed trends in diurnal temperature range over Nigeria

The long-term trend of diurnal temperature range(DTR)over Nigeria was examined using daily station-based datasets for the period 1971–2013.The results show that the regionally averaged DTR has decreased significantly(-0.34°C per decade)over the Nigerian Sahel(north of 10°N),but there has been a slight increasing trend(0.01°C per decade)over the Nigerian Guinea Coast.The annual decreasing trend of DTR in the Nigerian Sahel is mainly attributable to the significant increasing trend in daily minimum temperature(Tmin,0.51°C per decade),which far outstrips the rate of increase in the daily maximum(Tmax,0.17°C per decade).In contrast,the comparable trends in Tmin(0.19°C per decade)and Tmax(0.20°C per decade)may explain the non-significant trend of the DTR averaged over the Guinea Coast region.It is observed that the DTR has decreased more in boreal summer(June–July–August)than in boreal winter(December–January–February)for the regions.Furthermore,it is found that the significant DTR declining trend over the Nigerian Sahel is closely associated with an increasing trend of annual and summer precipitation in the region,but the increasing DTR trend in the Nigerian Guinea Coast region can be attributed to the decreasing trend of cloud cover over the region.

Diurnal Temperature Range and Daily Emergency Room Admissions among the Elderly in Beijing,China

In recent years, more attentions have been paid to the association between climate change and human health. Increasing and more variable global surface temperature is one of the key climatic change factors which have been consistently reported about the effect on human health. So far, more researches have revealed that temperature lead not only to direct deaths and illnesses but also to aggravation of cardiovascular and respiratory diseases. Typically, the relationship between temperature and mortality or morbidity is V-, U-, or J- shaped, with optimum temperature corresponding to the lowest point in the temperature mortality curve.

Characteristic Analysis of Diurnal Temperature Range in Guigang

[ Objective] The aim was to analyze diurnal temperature range in Guigang from 1960 to 2009. [Method] Based on the conventional me- teorological data （mean daily temperature, mean maximum temperature, and mean minimum temperature） of Guigang region during 1960 -2009, the Diurnal Temperature Range （DTR） and the DTR trend were studied. [ Result] The annual minimum temperatures and the annual maximum temperature were significantly increasing. The maximum temperature rose less than minimum temperature and spatial changes of daily temperature narrowed gradually from the Tropic of Cancer to the two sides. The extreme diurnal temperature decreased mostly in stations far away from the Tropic of Cancer and the significance was strong. The extreme diurnal temperature decreased little in stations close to the Tropic of Cancer. Influ- ences of different factors on daily difference varied. DTR positively correlated with sunshine duration, and negatively related to total cloudiness, rel- ative humidity and precipitation. DTR had insignificant relation with average wind speed. [ Conclusion] The study provided basis for the understand- ing of climate changes in Guigang.

Diurnal Temperature Range as a Novel Risk Factor for Sudden Infant Death

Objective To assess the relationship between diurnal temperature range （DTR） and sudden infant death （SID） between 2001 and 2004 in Shanghai,China.Methods We conducted a time‐stratified case‐crossover analysis to estimate the percent increase of SID associated with changes in DTR after adjustment for daily weather conditions （temperature and relative humidity） and outdoor air pollution.Results DTR was significantly associated with daily SID.An increase of 1 °C in the current‐day （L0） and in the 2‐day moving average （L01） DTR corresponds to a 1.56% （95% CI：0.97%,2.15%） and a 1.89% （95% CI：1.17%,2.60%） increase in SID,respectively.Conclusion An increased DTR was associated with an increased risk of SID in Shanghai.More studies are needed to understand the effect of DTR on infant deaths.

Impact of Direct Radiative Forcing of Anthropogenic Aerosols on Diurnal Temperature Range in January in Eastern China

This study investigates the changes in January diurnal temperature range(DTR) in China during 1961-2000.The observed DTR changes during 1981-2000 relative to 1961-80 are first analyzed based on the daily temperature data at 546 weather stations.These observed DTR changes are classified into six cases depending on the changes in daily maximum and minimum temperatures,and then the occurrence frequency and magnitude of DTR change in each case are presented.Three transient simulations are then performed to understand the impact of greenhouse gases(GHGs) and aerosol direct forcing on DTR change:one without anthropogenic radiative forcing,one with anthropogenic GHGs,and another one with the combined forcing of GHGs and five species of anthropogenic aerosols.The predicted daily DTR changes during the years 1981-2000 are also classified into six cases and are compared with the observations.Results show that the previously proposed reason for DTR reduction,a stronger nocturnal warming than a daytime warming,explains only 19.8%of the observed DTR reduction days.DTR reductions are found to generally occur in northeastern China,coinciding with significant regional warming.The simulation with GHG forcing alone reproduces this type of DTR reduction with an occurrence frequency of 32.9%,which is larger than the observed value.Aerosol direct forcing reduces DTR mainly by daytime cooling.Consideration of aerosol cooling improves the simulation of occurrence frequencies of different types of DTR changes as compared to the simulation with GHGs alone,but it cannot improve the prediction of the magnitude of DTR changes.

Analysis on Change Characteristics of Diurnal Temperature Range in Benxi County from 1958 to 2010

Based on annual mean maximum and minimum temperatures,diurnal temperature range,precipitation,sunshine,total cloud cover and water barometric pressure data in Benxi County from 1958 to 2010,using statistical analysis,the results show that the annual and seasonal diurnal temperature ranges present significant decreasing tendencies,and the reducing tendency is the most remarkable in winter. Autumn reducing tendency is stronger than that in spring,and it is the weakest in summer. Annual and seasonal average temperatures,average maximum and minimum temperatures all present the remarkable rising trends. Rising trend of the minimum temperature is more significant than that of the maximum temperature. The monthly mean diurnal temperature range also presents reducing tendency,and the most reducing scope appear in January and February. Annual and season diurnal temperature range changes are related to sunshine,mean minimum temperature,mean maximum temperature,precipitation,total cloud cover and water barometric pressure,but various essential factors are different in each season. Annual mean temperature,annual mean minimum temperature,annual mean maximum temperature and annual diurnal temperature range all have sudden changes,but the age is inconsistent.

Possible Combined Influences of Absorbing Aerosols and Anomalous Atmospheric Circulation on Summertime Diurnal Temperature Range Variation over the Middle and Lower Reaches of the Yangtze River

Based on the temperature data from the China Meteorological Administration, NCEP-NCAR reanalysis data, and the TOMS Aerosol Index （AI）, we analyze the variations in the summertime diurnal temperature range （DTR） and temperature maxima in the middle and lower reaches of the Yangtze River （MLRYR） in China. The possible relationships between the direct warming effect of the absorbing aerosol and temperature variations are further investigated, although with some uncertainties. It is found that the summertime DTR exhibits a decreasing trend over the most recent 50 years, along with a slight increasing tendency since the 1980s. The trend of the maximum temperature is in agreement with those of the DTR and the absorbing aerosols. To investigate the causes of the large anomalies in the temperature maxima, composite analyses of the circulation anomalies are performed. When anomalous AI and anomalous maximum temperature over the MLRYR have the same sign, an anomalous circulation with a quasi-barotropic structure occurs there. This anomalous circulation is modulated by the Rossby wave energy propagations from the regions northwest of the MLRYR and influences the northwestern Pacific subtropical high over the MLRYR. In combination with aerosols, the anomalous circulation may increase the maximum temperature in this region. Conversely, when the anomalous AI and anomalous maximum temperature in the MLRYR have opposite signs, the anomalous circulation is not equivalently barotropic, which possibly offsets the warming effect of aerosols on the maximum temperature changes in this region. These results are helpful for a better understanding of the DTR changes and the occurrences of temperature extremes in the MLRYR region during boreal summer.

Effects of diurnal temperature range on adult size and emergence times from diapausing pupae in Papilio glaucus and R canadensis （Papilionidae）

With recent climate warming trends, both the increase in thermal variance （i.e., diurnal temperature range; DTR） as well as increased mean temperature may impact many different organisms, especially poikilothermic invertebrates. Predictions of insect developmental rates using degree-days （thermal unit accumulations above the developmental base threshold of the insect） are based on daily mean temperatures, regardless of DTR. However, non-linearity and variance in the means and extremes are often ignored. The role of thermal variance （e.g., daily temperature extremes and DTR） was evaluated experimentally for two swallowtail butterfly sister species using a common day/night photoperiod of 18 ： 6 h photo ： scoto-phase and corresponding daytime thermophase and nighttime cryophase periods of 22 ： 22℃ （constant 22℃）, 24 ： 16℃, and 26 ： 10℃（all three treatments had the same daily mean and the same degree-day accumulations）. Although developmental rates ofpost-diapause pupae were largely unaffected for both species, our results show that sizes in P canadensis females （but not males） were smaller in the treatments with more variance （26℃ ： 10℃） compared to constant 22℃. Such potentially significant impacts of size reduction in P canadensis females were not observed in P glaucus males or females under the same series ofthermo-period treatments.

On the Contrasting Decadal Changes of Diurnal Surface Temperature Range between the Tibetan Plateau and Southeastern China during the 1980s–2000s

The diurnal surface temperature range （DTR） has become significantly smaller over the Tibetan Plateau （TP） but larger in southeastern China, despite the daily mean surface temperature having increased steadily in both areas during recent decades. Based on ERA-Interim reanalysis data covering 1979-2012, this study shows that the weakened DTR over TP is caused by stronger warming of daily minimum surface temperature （Tmin） and a weak cooling of the daily maximum surface temper- ature （Tmax）; meanwhile, the enhanced DTR over southeastern China is mainly associated with a relatively stronger/weaker warming of Tmax/Tmin. A further quantitative analysis of DTR changes through a process-based decomposition method-- the Coupled Surface-Atmosphere Climate Feedback Response Analysis Method （CFRAM）--indicates that changes in radia- tive processes are mainly responsible for the decreased DTR over the TR In particular, the increased low-level cloud cover tends to induce the radiative cooling/warming during daytime/nighttime, and the increased water vapor helps to decrease the DTR through the stronger radiative wanning during nighttime than daytime. Contributions from the changes in all radiative processes （over -2℃） are compensated for by those from the stronger decreased surface sensible heat flux during daytime than during nighttime （approximately 2.5℃）, but are co-contributed by the changes in atmospheric dynamics （approximately -0.4℃） and the stronger increased latent heat flux during daytime （approximately -0.8℃）. In contrast, the increased DTR over southeastern China is mainly contributed by the changes in cloud, water vapor and atmospheric dynamics. The changes in surface heat fluxes have resulted in a decrease in DTR over southeastern China.

Quantifying the response of surface urban heat island to urbanization using the annual temperature cycle model

Urban heat island(UHI),driving by urbanization,plays an important role in urban sustainability under climate change.However,the quantification of UHI’s response to urbanization is still challenging due to the lack of robust and continuous temperature and urbanization datasets and reliable quantification methods.This study proposed a framework to quantify the response of surface UHI(SUHI)to urban expansion using the annual temperate cycle model.We built a continuous annual SUHI series at the buffer level from 2003 to 2018 in the Jing-Jin-Ji region of China using MODIS land surface temperature and imperviousness derived from Landsat.We then investigated the spatiotemporal dynamic of SUHI under urban expansion and examined the underlying mechanism.Spatially,the largest SUHI interannual variations occurred in suburban areas compared to the urban center and rural areas.Temporally,the increase in SUHI under urban expansion was more significant in daytime compare to nighttime.We found that the seasonal variation of SUHI was largely affected by the seasonal variations of vegetation in rural areas and the interannual variation was mainly attributed to urban expansion in urban areas.Additionally,urban greening led to the decrease in summer daytime SHUI in central urban areas.These findings deepen the understanding of the long-term spatiotemporal dynamic of UHI and the quantitative relationship between UHI and urban expansion,providing a scientific basis for prediction and mitigation of UHI.

Trends of Temperature Extremes in Summer and Winter during 1971–2013 in China

The diurnal temperature range(DTR) has decreased dramatically in recent decades, but it is not yet obvious whether the extreme values of DTR have also reduced. Based on the daily maximum and minimum temperature data of 653 stations in China, a set of monthly indices of warm extremes, cold extremes, and DTR extremes in summer(June, July, August) and winter(December, January, February) were studied for spatial and temporal features during the period 1971–2013. Results show that the incidence of warm extremes has been increasing in most parts of China, while the opposite trend was found in the cold extremes for summer and winter months. Both increasing and decreasing trends of monthly DTR extremes were identified in China for both seasons. For high DTR extremes, decreasing trends were identified in northern China for both seasons, but increasing trends were found only in southern China in summer, while in winter, they were found in central China. Monthly low DTR extreme indices demonstrated consistent positive trends in summer and winter, while significant increases(P < 0.05) were identified for only a few stations.

Observed and Future Changes in the Temperature of the State of Jalisco, México Using Climdex and PRECIS

In the present study we analyzed the average and extreme temperatures observed and simulated by regional models in the State of Jalisco, Mexico. Data of daily mean, minimum and maximum temperatures of 208 stations distributed all over the State during the period 1971-2000 have been used to study the observed changes in the values of average and extreme temperatures. In addition, an assessment of future scenarios for the average and extreme temperatures associated with the increase in the concentration of greenhouse gases (GHG) was performed using simulations of a PRECIS (Providing Regional Climate for Impact Studies) regional climate modeling to create the climate for present (1971-2000), and future projections for the years 2020, 2050 and 2080. Observational analysis of the 208 stations suggests warming through increased intensity and frequency of hot events, with a decrease in the frequency of cold events. More than 35% to 76% of the stations have a tendency to a decrease in the number of cold events and 39% to 64% of the stations show a growing trend in the hot events. The percentage of stations showing warming through the indices of intensity of the highest maximums, lowest minimum temperatures is 37% to 70% and 30% to 65% of the stations, respectively. Observational analysis for the State of Jalisco as a whole also shows similar results. Anomalies in the average and extreme temperatures per month during the data period show an increase (decrease) in the frequency of hot (cold) events for every month. In general, PRECIS simulations under both scenarios A1B and A2 indicate an increase in warm events and decrease of cold extreme events towards the end of the 21st century. Both show similar patterns, but the scenario A2 shows slightly lower magnitudes of projected changes. Temperatures are likely to increase all year, but it is expected that changes in summer will be more prominent.

Elevational patterns of temperature and humidity in the middle Tianshan Mountain area in Central Asia

The vertical distribution of vegetation types along an elevational gradient in mountain areas largely depends on the elevational changes in air temperature and humidity. In this study, we presented the seasonal and diurnal variations in the elevational gradients of air temperature and humidity on the southern and northern slopes in the middle Tianshan Mountain Range using data collected throughout the year via HOBO data loggers. The measurements were conducted at 12 different elevations from 1548 to 3277 m from September 2004 to August 2005. The results showed that the annual mean air temperature decreased along the elevational gradients with temperature lapse rates of(0.71±0.20)°C/100 m and(0.59±0.05)°C/100 m on the northern and southern slopes, respectively. The annual mean absolute humidity significantly decreased with increasing elevation on the northern slope but showed no significant trend on the southern slope. The annual mean relative humidity did not show a significant trend on the northern slope but increased with increasing elevation on the southern slope. The mean air temperature lapse rate exhibited significant seasonal variation, which is steeper insummer and shallower in winter, and this value varied between 0.37°C/100 m and 0.75°C/100 m on the southern slope and between 0.30°C/100 m and 1.02°C/100 m on the northern slope. The mean absolute and relative humidity also exhibited significant seasonal variations on both slopes, with the maximum occurring in summer and the minimum occurring in winter or spring. The monthly diurnal range of air temperature on both slopes was higher in spring than in winter. The annual range of air temperature on the southern slope was higher than that on the northern slope. Our results suggest that significant spatiotemporal variations in humidity and temperature lapse rate are useful when analyzing the relationships between species range sizes and climate in mountain areas.

Trend in pan evaporation and its attribution over the past 50 years in China

Trends in pan evaporation are widely relevant to the hydrological community as indicators of hydrological and climate change. Pan evaporation has been decreasing in the past few decades over many large areas with differing climates globally. This study analyzes pan evaporation data from 671 stations in China over the past 50 years in order to reveal the trends of it and the corresponding trend attribution. Mann-Kendall test shows a significant declining trend in pan evaporation for most stations, with an average decrease of 17.2 mm/10a in China as a whole, the rate of decline was the steepest in the humid region （29.7 mm/10a）, and was 17.6 mm/10a and 5.5 mm/10a in the semi-humid/semi-arid region and arid region, respectively. Complete correlation coefficients of pan evaporation with 7 climate factors were computed, and decreases in diurnal temperature range （DTR）, SD （sunshine duration） and wind speed were found to be the main attributing factors in the pan evaporation declines. Decrease in DTR and SD may relate to the increase of clouds and aerosol as well as the other pollutants, and decrease in wind speed to weakening of the Asian winter and summer monsoons under global climate warming.

Examination of Archival Data for Inhomogeneities and Determination of Climate Change in North America

Numerous articles have examined archival weather observations and attributed climate changes on time scales ranging from centuries to decades and in one case even days to human activity. This article gives examples showing how climate variability and sudden changes in instruments affect trend determination. In particular, surface temperature and water vapor pressure trends in North America during 1948-2010 are discussed. Over 1/4 billion hourly observations taken at 309 stations, were first carefully examined for inhomogeneities. Positive and negative steps, for both temperature and water vapor pressure were found to not be evenly distributed in time. Inclusion of such data in a trend analysis would overstate decadal changes in temperature and water vapor. Time series free of such discontinuities show a statistically significant warming has primarily affected the western Arctic, Canadian prairies and the Midwestern U.S. during winter. Increases in water vapor pressure are most pronounced in summer in the eastern U.S. The decadal water vapor pressure trends are somewhat smaller than found in other studies that examined data for far shorter time periods. The claim of a change in the DTR （diurnal temperature range） during the 3 day flight ban following Sept. 11, 2011, is not substantiated. The observed change in the DTR was likely caused by a reduction in cloudiness during the flight ban.