High Diurnal Temperature Range Research Articles

The influence of diurnal temperature range on the incidence of respiratory syncytial virus in Japan.

The incidence of respiratory syncytial virus (RSV) has been reported to exhibit seasonal variation. However, the impact of diurnal temperature range (DTR) on RSV has not been investigated. After acquiring data related to cases of RSV and weather parameters of DTR in Fukuoka, Japan, between 2006 and 2012, we used negative binomial generalized linear models and distributed lag nonlinear models to assess the possible relationship between DTR and RSV cases, adjusting for confounding factors. Our analysis revealed that the weekly number of RSV cases increased with a relative risk of 3·30 (95% confidence interval 1·65-6·60) for every 1°C increase in DTR. Our study provides quantitative evidence that the number of RSV cases increased significantly with increasing DTR. We suggest that preventive measures for limiting the spread of RSV should be considered during extended periods of high DTR.

Lagged effect of diurnal temperature range on mortality in a subtropical megacity of China.

BackgroundMany studies have found extreme temperature can increase the risk of mortality. However, it is not clear whether extreme diurnal temperature range (DTR) is associated with daily disease-specific mortality, and how season might modify any association.ObjectivesTo better understand the acute effect of DTR on mortality and identify whether season is a modifier of the DTR effect.MethodsThe distributed lag nonlinear model (DLNM) was applied to assess the non-linear and delayed effects of DTR on deaths (non-accidental mortality (NAD), cardiovascular disease (CVD), respiratory disease (RD) and cerebrovascular disease (CBD)) in the full year, the cold season and the warm season.ResultsA non-linear relationship was consistently found between extreme DTR and mortality. Immediate effects of extreme low DTR on all types of mortality were stronger than those of extreme high DTR in the full year. The cumulative effects of extreme DTRs increased with the increment of lag days for all types of mortality in cold season, and they were greater for extreme high DTRs than those of extreme low DTRs. In hot season, the cumulative effects for extreme low DTRs increased with the increment of lag days, but for extreme high DTR they reached maxima at a lag of 13 days for all types of mortality except for CBD(at lag6 days), and then decreased.ConclusionsOur findings suggest that extreme DTR is an independent risk factor of daily mortality, and season is a modifier of the association of DTR with daily mortality.

NONLINEAR ASSOCIATION OF DIURNAL TEMPERATURE RANGE WITH OXIDATIVE AND PHYSIOLOGIC STRESS MARKERS IN THE KOREAN ELDERLY ENVIRONMENTAL PANEL STUDY (KEEPS)

Background and Aims: While diurnal temperature range (DTR) has been found to be a risk factor for mortality in a previous study with an assumption of linearity, some disease mortality, such as that associated with rheumatic heart disease (RHD), showed a threshold effect for DTR. To define the nonlinear relationship pathway between DTR and health effects, we investigated how physiologic and oxidative stress markers responded to DTR. Methods: This study was part of the Korean Elderly Environmental Panel Study (KEEPS). Data was obtained from 569 participants who regularly attended a community elderly care center located in Seoul, Korea. The study was conducted a total of five times over a three years period beginning in August, 2008. We examined physiologic stress markers including heart rate variability (HRV) and indices such as mean heart rate, standard deviation of normal-to-normal (SDNN), normalized low frequency (LF) and high frequency (HF), and low/high frequency ratio (LF:HF). Urinary malondialdehyde (MDA) was evaluated as an oxidative stress marker. Effects of DTR below or above the median level were estimated using a generalized linear mixed model. Results: Significant differences in effects of DTR above and below the median level indicated the presence of a threshold effect or a nonlinear association between DTR and HRV markers. Estimated effects for log-transformed SDNN were 0.211 (standard error [SE] 0.069, P =0.0021) below and -0.093 (SE 0.038, P =0.0129) above the median DTR. While the mean heart rate slope above median DTR was significant, slopes of normalized HF and LF:HF ratio below median DTR were statistically significant. In addition, log-transformed MDA showed a pattern similar to HRV indices. Conclusions: The study demonstrated that physiologic and oxidative stress increased at low and high DTR with minimal stress levels around the median level of DTR indicating a physiologic comfort point.

Feasibility Study of an Innovative Dry-Cooling System With Phase-Change Material Storage for Concentrated Solar Power Multi-MW Size Power Plant

This work concerns the economic potential assessment of an innovative hybrid-cooling system for steam condensation in concentrated solar power plants. The system consists of an air-cooled condenser (ACC) working in parallel to a latent heat storage with phase-change material (PCM). The purpose of the hybrid system is to store some of the latent heat of steam condensation during the turbine operation and reject it at night, in order to shift a share of the cooling work and exploit the high diurnal temperature range of desert areas. System’s energy and economic performances are assessed by the parametric analysis of a theoretical case study, referred to an existing solar power plant and based on historical meteorological data. The analysis considers an ideal “perfect” PCM storage system, namely with no technological barriers, and different cost scenarios. The simulation campaign outcome indicates how the innovative solution can provide just a slight improvement of the plant performance, which is anyway significant in qualitative terms since the risk of breakdowns of turbine operation during the hottest summer days is avoided. It is remarkable that the introduction of the heat storage allows for a reduction of the ACC installed power. The economic feasibility of the proposed solution follows on mainly from the comparison between the investment cost increase —due to the PCM storage—and savings—due to reduction of the installed ACC modules. The hybrid-cooling system would be an attractive alternative to standard systems if the PCM storage cost could be contained by increasing the conductivity of the PCM material. As an alternative, a cheaper heat storage technology (e.g., a water thermocline) could be coupled to an indirect-cooling system.

Climatic Warming in the Himalaya During Recent Decades

Analyses of daily average, maximum and minimum temperatures from 19 stations of 4 countries in the Himalayan region reveal warming trend in the Himalaya after 1973. The linear rate of average temperature increase over the Himalaya during the period 1973 to 2009 is 0.0570C/ year, which exceeds IPCC and NASA’s calculated global and the Northern Hemisphere trend over the same period. Rate of temperature increase was also pronounced with the elevation ranges, geographical regions and the elevation in the Himalaya: high elevation region, Central Himalaya and winter season exhibited higher rate of temperature increase in their categories. Diurnal temperature range (DTR) was calculated from the daily maximum and minimum temperature. The rate of change of DTR in the region was found to be 0.0250C/ year however it was marginal when studied separately for Eastern, Central and Western Himalayas. Winter month exhibited higher DTR than the summer month. Elevation range 1000-3000m with high urbanization rate in the region showed high DTR. Since this study covers temperature study over a period of 3 decades and only deals with some causes of climate warming in Himalaya, a detailed study on the region covering long-term data is necessary to conclude on the climate change in the region.

Recruitment of trees at tropical alpine treelines: Erica in Africa versus Polylepis in South America

Background: Constraints on tree regeneration have been described from several temperate treeline sites, however data from tropical mountains are few. Aim: We test the hypothesis that high altitude treelines are caused by constraints on tree regeneration. We report the results of recent studies on climatic variables and on the reproduction of Erica spp. in east Africa, and compare those with similar studies on treeline stands of Polylepis spp. in Ecuador and Bolivia. Methods: We established altitudinal and horizontal transects comprising sampling plots from forests to surrounding grasslands. Data on microclimate, vegetation structure and reproductive activity were collected in the field, and supplemented by tests on germination requirements in the field in permanent exclosures and in the laboratory. Results: Our measurements demonstrated that the number and severity of frost events and potential water stress were higher near the soil surface (0.5 m) than in free air (2.0 m). Seeds of Erica trimera did not germinate, as the necessary climatic requirements (high diurnal temperature range, but no frost) were rarely fulfilled in the field. Most studied species were capable of clonal growth, and the relative importance of vegetative persistence tended to increase with altitude. These effects were independent of the intensity of land use. Conclusions: The harsh microclimate near the soil surface at tropical treelines may be one reason why recruitment from seed is limited for treeline-forming species. This is important for restoration or conservation schemes as well as predictions of treeline dynamics under global change.

Cosmic ray flux impact on clouds? An analysis of radiosonde, cloud cover, and surface temperature records from the United States

¶Many scientists have suggested that variations in cosmic ray flux may impact cloudiness at regional, hemispheric, or global scales. However, considerable debate surrounds (a) whether high or low clouds are most strongly impacted by cosmic rays, (b) the degree of seasonality in cloud responses to cosmic rays, and (c) the determination of physical processes involved in cosmic ray/cloud interactions. Some scientists find strong correlation coefficients between cloud measurements and cosmic ray flux, while others find no relationship whatsoever; virtually all scientists working on this issue are hampered by the relatively short time period with accurate cloud and cosmic ray flux records. In an attempt to extend the period of record, we assembled surface and radiosonde data for the United States over the period 1957–1996 along with sunspot records which are known to be strongly, but inversely, related to cosmic ray flux. We also assembled cloud cover data and cosmic ray measurements over a reduced time period. We found that periods with low sunspot number (times with high cosmic ray flux) are associated with significantly higher dew point depressions, a higher diurnal temperature range, and less cloud cover. Our results do not support suggestions of increased cloud cover during periods of high cosmic ray flux.

Large asymmetrical temperature trends at Mount Wilson, California

We compiled and analyzed a daily time series of temperatures and precipitation totals from Mount Wilson, California from 1918 to 1998. Our results show a large decline in maximum temperature, no change or an upward trend in minimum temperature, and a substantial decline in the diurnal temperature range (DTR). The interannual variations in monthly maximum temperature and DTR are significantly correlated with monthly precipitation levels, sea-surface temperatures (SSTs) off the coast of Southern California, and the Southern Oscillation Index (SOI). El Nino periods and/or months with high SST anomalies tend to be wet with lower maximum temperatures and DTR while La Nina periods and/or months of lower SSTs are hotter and drier with higher DTR values. It is noteworthy that the SOI and SSTs have significant trends toward more El Nino-like conditions with higher SSTs off Southern California.

Changes in temperature extremes and their possible causes at the SE boundary of the Alps

A trend analysis is performed on the years 1954 to 1995 annual and seasonal mean maximum and minimum temperature, diurnal temperature range, air pressure, and occurrence of different weather types, grouped according to the related diurnal temperature ranges for two mountain stations in Croatia. During the last 42 years an increase in annual mean maximum and mean minimum temperature has occurred. At both stations the increase in mean maximum was faster than in the mean minimum, resulting in an increase in mean diurnal temperature range. At the same time mean annual air pressure shows a significant increase both at Zavižan and at Puntijarka. An increase in occurrence of weather types with high diurnal temperature range appears at both locations, but is significant only at the inland station of Puntijarka.