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Diurnal Temperature Range (diurnal + temperature_range)
Selected AbstractsDiurnal temperature range as a novel risk factor for COPD deathRESPIROLOGY, Issue 7 2008Guixiang SONG Background and objective: Although the relationship between day-to-day temperature changes and COPD mortality is well established, it is not known whether temperature variation within one day, that is diurnal temperature range (DTR), is a risk factor for acute COPD death, independent of the absolute temperature level. Methods: In a time-series study, the relationship between DTR and daily COPD mortality between 2001 and 2004 in Shanghai, China was assessed. A semi-parametric generalized additive model was used to allow for long-term and seasonable trends in COPD mortality, as well as variation in air pollution and weather. Results: There was a significant association between DTR and daily COPD mortality. A 1°C increase in the 4-day moving average for DTR corresponded to a 1.25% (95% confidence interval: 0.35,2.15) increase in COPD mortality. Conclusion: These findings suggest that DTR is a novel risk factor for acute COPD death. [source] Human modification of the landscape and surface climate in the next fifty yearsGLOBAL CHANGE BIOLOGY, Issue 5 2002R. S. Defries Abstract Human modification of the landscape potentially affects exchanges of energy and water between the terrestrial biosphere and the atmosphere. This study develops a possible scenario for land cover in the year 2050 based on results from the IMAGE 2 (Integrated Model to Assess the Greenhouse Effect) model, which projects land-cover changes in response to demographic and economic activity. We use the land-cover scenario as a surface boundary condition in a biophysically-based land-surface model coupled to a general circulation model for a 15-years simulation with prescribed sea surface temperature and compare with a control run using current land cover. To assess the sensitivity of climate to anthropogenic land-cover change relative to the sensitivity to decadal-scale interannual variations in vegetation density, we also carry out two additional simulations using observed normalized difference vegetation index (NDVI) from relatively low (1982,83) and high (1989,90) years to describe the seasonal phenology of the vegetation. In the past several centuries, large-scale land-cover change occurred primarily in temperate latitudes through conversion of forests and grassland to highly productive cropland and pasture. Several studies in the literature indicate that past changes in surface climate resulting from this conversion had a cooling effect owing to changes in vegetation morphology (increased albedo). In contrast, this study indicates that future land-cover change, likely to occur predominantly in the tropics and subtropics, has a warming effect governed by physiological rather than morphological mechanisms. The physiological mechanism is to reduce carbon assimilation and consequently latent relative to sensible heat flux resulting in surface temperature increases up to 2 °C and drier hydrologic conditions in locations where land cover was altered in the experiment. In addition, in contrast to an observed decrease in diurnal temperature range (DTR) over land expected with greenhouse warming, results here suggest that future land-cover conversion in tropics could increase the DTR resulting from decreased evaporative cooling during the daytime. For grid cells with altered land cover, the sensitivity of surface temperature to future anthropogenic land-cover change is generally within the range induced by decadal-scale interannual variability in vegetation density in temperate latitudes but up to 1.5 °C warmer in the tropics. [source] What are daily maximum and minimum temperatures in observed climatology?INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 3 2008X. Lin Abstract Instrumental daily maximum and minimum temperatures are reported and archived from various surface thermometers along with different average algorithms in historical and current U.S. surface climate networks. An instrumental bias in daily maximum and minimum temperatures caused by surface temperature sensors due to the different sampling rates, average algorithms, and sensor's time constants was examined using a Gaussian-distributed function of surface air temperature fluctuations in simulation. In this study, the field observations were also included to examine the effects of average algorithms used in reporting daily maximum and minimum temperatures. Compared to the longest-recorded and standard liquid-in-glass maximum and minimum thermometers, some surface climate networks produced a systematic warming (cooling) bias in daily maximum (minimum) temperature observations, thus, resulting biases made the diurnal temperature range (DTR) more biased in extreme climate studies. Our study clarified the ambiguous concepts on daily maximum and minimum temperature observations defined by the World Meteorological Organization (WMO) in terms of sensor's time constants and average lengths and an accurate description of daily maximum and minimum temperatures is recommended to avoid the uncertainties occurred in the observed climatology. Copyright © 2007 Royal Meteorological Society [source] Uncertainties in central England temperature 1878,2003 and some improvements to the maximum and minimum seriesINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 9 2005David Parker Abstract We assess the random and systematic uncertainties affecting the central England temperature (CET) record since 1878 on daily, monthly and annual time scales. The largest contribution to uncertainty in CET on all these time scales arises from areal sampling, followed for annual and monthly CET by thermometer calibration. For the daily series, random thermometer precision and screen errors are the second largest source of uncertainty. Annual CETs are least uncertain, whereas daily CETs are most uncertain. Despite the uncertainties in annual mean CET, the trend of 0.077 °C per decade since 1900 is significant at the 1% level. In an additional investigation, we detect biases in the published series of central England maximum and minimum temperatures, and implement systematic adjustments of up to ±0.2 °C to the values up to 1921 and up to ±0.1 °C to the values since 1980. These adjustments are of opposite sign in maximum and minimum temperature, so they do not affect mean CET, but they improve the homogeneity of the diurnal temperature range, which then shows little trend before 1980 and a reduced rising trend thereafter. The uncertainties in maximum and minimum temperature make the data inadequate for the task of establishing the magnitude of the recent increase of diurnal range. © Crown Copyright 2005. Reproduced with the permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd. [source] An improved method of constructing a database of monthly climate observations and associated high-resolution gridsINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 6 2005Timothy D. Mitchell Abstract A database of monthly climate observations from meteorological stations is constructed. The database includes six climate elements and extends over the global land surface. The database is checked for inhomogeneities in the station records using an automated method that refines previous methods by using incomplete and partially overlapping records and by detecting inhomogeneities with opposite signs in different seasons. The method includes the development of reference series using neighbouring stations. Information from different sources about a single station may be combined, even without an overlapping period, using a reference series. Thus, a longer station record may be obtained and fragmentation of records reduced. The reference series also enables 1961,90 normals to be calculated for a larger proportion of stations. The station anomalies are interpolated onto a 0.5° grid covering the global land surface (excluding Antarctica) and combined with a published normal from 1961,90. Thus, climate grids are constructed for nine climate variables (temperature, diurnal temperature range, daily minimum and maximum temperatures, precipitation, wet-day frequency, frost-day frequency, vapour pressure, and cloud cover) for the period 1901,2002. This dataset is known as CRU TS 2.1 and is publicly available (http://www.cru.uea.ac.uk/). Copyright © 2005 Royal Meteorological Society [source] Changes in seasonal and annual high-frequency air temperature variability in the Arctic from 1951 to 1990INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 9 2002Rajmund Przybylak Abstract A detailed analysis of intraseasonal (within season) and interannual (between years) temperature variability for the whole Arctic for the period 1951,90 is provided. For this purpose four temperature variables were used: average (TMEAN), maximum (TMAX) and minimum (TMIN) temperatures, and the diurnal temperature range (DTR). The source data for the analysis were the daily TMAX and TMIN for ten stations representing almost all climatic regions in the Arctic. The methods of calculation of temperature variability were mostly taken from Plummer (1996; Australian Meteorological Magazine45: 233). Thus the results presented for the Arctic can be fully compared with existing results for the other parts of the world (China, the former USSR, the USA and Australia). Regional trends in intraseasonal and interannual temperature variability were mixed and the majority of them were insignificant. Trends in intraseasonal variability were positive in the Norwegian Arctic and eastern Greenland and negative in the Canadian and Russian Arctic. Small increases in interannual variability for all temperature variables were observed annually in the Norwegian Arctic and eastern Greenland, and in the Canadian Arctic. These were largely a result of increases in winter and transitional seasons respectively. On the other hand, opposite tendencies, both on a seasonal and an annual basis, occurred in the Russian Arctic. Statistically significant negative trends in intraseasonal variability were noted mainly in the Canadian Arctic, whereas such trends in interannual variability were noted mainly in the Russian Arctic. The absence of significant changes in intraseasonal and interannual variability of TMEAN, TMAX, TMIN and DTR is additional evidence (besides the average temperature) that in the Arctic in the period 1951,90 no tangible manifestations of the greenhouse effect can be identified. Copyright © 2002 Royal Meteorological Society. [source] The regional scale impact of land cover change simulated with a climate modelINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 3 2002Mei Zhao Abstract A series of 17-year integrations using the NCAR CCM3 (at about 2.8° × 2.8° resolution) were performed to investigate the regional-scale impact of land cover change. Our aim was to determine the impact of historical land cover change on the regional-scale climate over the regions where most change occurred: Europe, India and China. The change from natural to current land cover was estimated using BIOME3 to predict the natural vegetation type, and then using remotely sensed data to estimate the locations where land cover had been changed through human activity. Results show statistically significant changes in the 15-year averaged 1000 hPa wind field, mean near-surface air temperature, maximum near-surface air temperature and the latent heat flux over the regions where land cover change was imposed. These changes disappeared if the land cover over a particular region was omitted, indicating that our results cannot be explained by model variability. An analysis of changes on an averaged monthly time scale showed large changes in the maximum daily temperature in (Northern Hemisphere) summer and little change in the minimum daily temperature, resulting in changes in the diurnal temperature range. The change in the diurnal temperature range could be positive or negative depending on region, time of year and the precise nature of the land cover changes. Our results indicate that the inclusion of land cover change scenarios in simulations of the 20th century may lead to improved results. The impact of land cover changes on regional climates also provides support for the inclusion of land surface models that can represent future land cover changes resulting from an ecological response to natural climate variability or increasing carbon dioxide. Copyright © 2002 Royal Meteorological Society. [source] Direct and Indirect Climate Change Effects on Photosynthesis and TranspirationPLANT BIOLOGY, Issue 3 2004M. U. F. Kirschbaum Abstract: Climate change affects plants in many different ways. Increasing CO2 concentration can increase photosynthetic rates. This is especially pronounced for C3 plants, at high temperatures and under water-limited conditions. Increasing temperature also affects photosynthesis, but plants have a considerable ability to adapt to their growth conditions and can function even at extremely high temperatures, provided adequate water is available. Temperature optima differ between species and growth conditions, and are higher in elevated atmospheric CO2. With increasing temperature, vapour pressure deficits of the air may increase, with a concomitant increase in the transpiration rate from plant canopies. However, if stomata close in response to increasing CO2 concentration, or if there is a reduction in the diurnal temperature range, then transpiration rates may even decrease. Soil organic matter decomposition rates are likely to be stimulated by higher temperatures, so that nutrients can be more readily mineralised and made available to plants. This is likely to increase photosynthetic carbon gain in nutrient-limited systems. All the factors listed above interact strongly so that, for different combinations of increases in temperature and CO2 concentration, and for systems in different climatic regions and primarily affected by water or nutrient limitations, photosynthesis must be expected to respond differently to the same climatic changes. [source] Diurnal temperature range as a novel risk factor for COPD deathRESPIROLOGY, Issue 7 2008Guixiang SONG Background and objective: Although the relationship between day-to-day temperature changes and COPD mortality is well established, it is not known whether temperature variation within one day, that is diurnal temperature range (DTR), is a risk factor for acute COPD death, independent of the absolute temperature level. Methods: In a time-series study, the relationship between DTR and daily COPD mortality between 2001 and 2004 in Shanghai, China was assessed. A semi-parametric generalized additive model was used to allow for long-term and seasonable trends in COPD mortality, as well as variation in air pollution and weather. Results: There was a significant association between DTR and daily COPD mortality. A 1°C increase in the 4-day moving average for DTR corresponded to a 1.25% (95% confidence interval: 0.35,2.15) increase in COPD mortality. Conclusion: These findings suggest that DTR is a novel risk factor for acute COPD death. [source] | ||||||||||