The effect of precipitation and air temperature on land‐cover change in the Sahel

Vegetation changes in the Sahel region are strongly affected by variation in rainfall, but air temperature has been considered a relatively minor climatic factor in previous studies. However, soil moisture, the major water source for vegetation in arid and semiarid regions, is generally dependent on temperature‐controlled evaporation. Therefore, we can hypothesize that air temperature modifies the sensitivity of vegetation greenness to rainfall because water loss in soil is critically vulnerable to temperature, although Sahel plants can tolerate high temperatures. In this study, the annual mean of daily maximum air temperature was used as a constraint in analyzing the relationships between annual changes in the cumulative enhanced vegetation index (EVI) and total rainfall. We found that rainfall increase in hotter years could not well induce land greening, and decreased rainfall in cooler years did not necessarily cause vegetation degradation. This presents the importance of temperature as a climatic component in understanding the mechanism of rainfall‐induced land‐cover changes in the Sahel region.     

A METHOD FOR INVESTIGATING THE POTENTIAL IMPACTS OF CLIMATE-CHANGE SCENARIOS ON ANNUAL MINIMUM GROUNDWATER LEVELS

Previous approaches to assessing the impact of climate-change scenarios on groundwater levels and groundwater droughts have focused on modelling specific recharge processes or phenomena. However, statistical methods, based on correlations between historic groundwater level and rainfall time-series, provide an alternative and robust approach to predicting minimum groundwater levels and droughts. For the purposes of this study, groundwater droughts are defined in terms of the return period of a given groundwater level. A multiple linear regression model (regression of monthly rainfall totals for a given period against values of minimum annual groundwater levels for the same period), when used with synthetic rainfall data based on climate-change scenarios, enables changes in future annual groundwater-level minima to be modelled. The method is illustrated at three sites on the Chalk, Permo-Triassic sandstone and Jurassic limestone aquifers.     

The use of simplified weather data to estimate thermal loads of non-residential buildings

This paper presents a methodology to analyse the thermal loads of non-residential buildings based on simplified weather data, which are available for 206 Brazilian locations. These data include monthly average of maximum and minimum temperatures, atmospheric pressure, cloud cover and relative humidity. For each month, two typical days are used to estimate the cooling and heating loads. The Transfer Function Method was used to run load calculations and the validation was evaluated according to ASHRAE Standard 140. The methodology showed good results for cases with low mass envelope but revealed limitation to represent thermal inertia influence on the annual cooling and heating loads.     

Local climate assessment: a meso-scale analysis of long period rainfall in a rural dry sub-humid district from India

The present study investigates the temporal variability in monthly, seasonal and annual rainfall over a drought prone district in India. Long period rainfall data, from 1950 to 2012, were investigated over the district by analysis of anomalies and application of both parametric and non-parametric statistical tests. Decline in annual rainfall is evident in the study area with highest number of below mean rainfall years observed in the recent decade (2000–2009). Only 25% of the annual rainy days span across pre-monsoon, post-monsoon and winter season, reinforcing the high dependence of local communities on monsoonal rainfall for effective crop growth. Against this, a decreasing trend in monsoonal rainfall is noticed over the years. In conclusion, the present paper argues for district level rainfall studies which will provide local stakeholders with the necessary information for better planning and management of rainfall dependent development sectors, thus resulting in reduced overall socio-economic upheaval of rural communities.     

Assessing the spatio-temporal climate variability in semi-arid Karamoja sub-region in north-eastern Uganda

Semi-arid areas show climatic variability on a spatio-temporal scale. There are few studies on the long-term trends and intensity of this variability from East Africa. We used National Ocean and Atmospheric Administration re-analysis climate data (1979–2009) in this study. Rainfall exhibited a non-significant long-term trend. The climate of the area is variable (coefficient of variation-CV?>35.0%) with spatio-temporal oddities in rainfall and temperature. A rise in minimum (0.9?°C), maximum (1.6?°C) and mean (1.3?°C) temperature occurred between 1979 and 2009. There were more months with climate variability indices below the threshold (<1.0) from 1979 to 1994 than between 1995 and 2009, with wetness intensity increasingly common after 2000, leading to the observed reduction in the recurrence of multi-year drought events. More extreme wet events (rainfall variability index?>2.6) were experienced between 2004 and 2009 than between 1984 and 2003. We consider that the use of spatio-temporal climatic information for timely adjustment to extreme climate variability events is essential in semi-arid areas.     

Contributions of meteorology to the phenology of cyanobacterial blooms: implications for future climate change

Cyanobacterial blooms are often a result of eutrophication. Recently, however, their expansion has also been found to be associated with changes in climate. To elucidate the effects of climatic variables on the expansion of cyanobacterial blooms in Taihu, China, we analyzed the relationships between climatic variables and bloom events which were retrieved by satellite images. We then assessed the contribution of each climate variable to the phenology of blooms using multiple regression models. Our study demonstrates that retrieving ecological information from satellite images is meritorious for large-scale and long-term ecological research in freshwater ecosystems. Our results show that the phenological changes of blooms at an inter-annual scale are strongly linked to climate in Taihu during the past 23 yr. Cyanobacterial blooms occur earlier and last longer with the increase of temperature, sunshine hours, and global radiation and the decrease of wind speed. Furthermore, the duration increases when the daily averages of maximum, mean, and minimum temperature each exceed 20.3 °C, 16.7 °C, and 13.7 °C, respectively. Among these factors, sunshine hours and wind speed are the primary contributors to the onset of the blooms, explaining 84.6% of their variability over the past 23 yr. These factors are also good predictors of the variability in the duration of annual blooms and determined 58.9% of the variability in this parameter. Our results indicate that when nutrients are in sufficiently high quantities to sustain the formation of cyanobacterial blooms, climatic variables become crucial in predicting cyanobacterial bloom events. Climate changes should be considered when we evaluate how much the amount of nutrients should be reduced in Taihu for lake management.     

GLOBAL WARMING AND THE DEMAND FOR WATER

More than a decade has passed since the International Panel on Climatic Change began to study (in depth) the possibility that the global climate was changing. Increasing attention is also being paid to the impact of such changes on society in general, and on the planning and management of water resources. Not least among the water resources planning problems is the estimation of the changes which might occur in public water-supply demands. Such changes are notoriously difficult to evaluate, particularly in the UK where most domestic premises remain un-metered. Elsewhere, econometric models involving climatic parameters as independent variables have had some success, but a recent application of this approach in the UK was unable to identify particular parameters which had a consistent influence over the summer period. This lack of success might be partly caused by the public reaction to summer conditions being a complex function of several parameters, such as duration of sunshine, temperature and rainfall. This complexity has already been recognised by climatologists, who have devised forms of summer indices involving weighted combinations of climatic variables to determine how 'good' or 'bad' a particular period might be perceived by the general public. The use of one such summer index to explain the variations in an index of demand for public water supply in the London supply area has shown that simple and consistent relationships can be derived. Application of these relationships to scenarios of changes in temperature, sunshine duration and rainfall totals for the year 2050 shows an increase of 0.6- 2.9 index points in water-supply demand over the 1950-1990 period average.     

The relationship between potentially erosive storm energy and daily rainfall quantity in England and Wales

Erosive storm energy is the primary driver of soil detachment, and hence a major determinant of transfer of sediment and particulate phosphorus (P) to surface waters. Modelling of sediment and P loss at catchment scale, for example for the development of catchment and national mitigation policies, requires a spatially interpolated estimate of variation in erosion risk. To this end we present a method of estimating total rainfall erosivity, as kinetic energy (KE), for any location in England and Wales, from daily rainfall data or monthly climate data. Analysis of detailed, high-resolution records from eleven contrasting sites showed strong predictive correlations between daily rainfall quantity and associated daily total kinetic energy estimated from hourly rainfall intensities. The coefficients showed systematic seasonal variation, with greatest KE per unit of rainfall in late summer and autumn months. In contrast, no systematic spatial variation was found as a function of location or continentality index. The relationships were integrated with probability distributions of rainfall quantity per rain day derived from spatial climate data (monthly rainfall totals and numbers of rain days). The resulting map captures and quantifies the effects of rainfall quantity and intensity patterns on risk of sediment detachment, and as such provides a critical input layer to catchment-scale models of sediment and P transfer.     

雨量变化对珊瑚岛礁淡水透镜体的影响

为探索雨量变化对珊瑚岛礁淡水透镜体的影响，应用质量守恒、Darcy定律和Ghyben-Herzberg比率，推导了珊瑚岛礁淡水透镜体的数学模型。根据西沙地区1989年-1998年10年的月均降雨量及最高、最低年降雨量，用有限差分法计算了永兴岛淡水透镜体的外型和贮水量的变化。结果表明，永兴岛淡水贮量4月最小，10月最大，相差值为4月贮水量的10．5％，而10年间降雨量最大和最小年淡水透镜体贮量与平水年相比，分别多16．8％乖少7．2％，这一结果可用于制定淡水透镜体的开采战略，实现淡水资源的安全、科学、持续开发利用。     

Modeling the impact of climate variability on diarrhea-associated diseases in Taiwan (1996-2007)

Diarrhea is an important public health problem in Taiwan. Climatic changes and an increase in extreme weather events (extreme heat, drought or rainfalls) have been strongly linked to the incidence of diarrhea-associated disease.This study investigated and quantified the relationship between climate variations and diarrhea-associated morbidity in subtropical Taiwan. Specifically, this study analyzed the local climatic variables and the number of diarrhea-associated infection cases from 1996 to 2007. This study applied a climate variation-guided Poisson regression model to predict the dynamics of diarrhea-associated morbidity. The proposed model allows for climate factors (relative humidity, maximum temperature and the numbers of extreme rainfall), autoregression, long-term trends and seasonality, and a lag-time effect. Results indicated that the maximum temperature and extreme rainfall days were strongly related to diarrhea-associated morbidity. The impact of maximum temperature on diarrhea-associated morbidity appeared primarily among children (0-14 years) and older adults (40-64 years), and had less of an effect on adults (15-39 years). Otherwise, relative humidity and extreme rainfall days significantly contributed to the diarrhea-associated morbidity in adult. This suggested that children and older adults were the most susceptible to diarrhea-associated morbidity caused by climatic variation. Because climatic variation contributed to diarrhea morbidity in Taiwan, it is necessary to develop an early warning system based on the climatic variation information for disease control management.     

The effects of variation in climatic temperature (1980-2001) on breeding activity and tadpole stage duration in the common toad,Bufo bufo

The effects of variation in climatic temperature on breeding behaviour and tadpole growth were investigated using data collected during a 22-year study of a single population of common toads, Bufo bufo, in southern England. Although the start of the breeding season each year, taken as the day when adult toads first arrived at their breeding pond in large numbers, showed no trend over time (1980-2001) it was highly correlated with climatic temperature. Thus, toads started breeding approximately 50 days earlier in the year following very mild winters (1993: February 2nd) compared with very cold ones (1986: March 23rd). Regression analysis of the relationship between the mean temperature of the 40 days immediately preceding the main arrival of toads at the breeding pond revealed that for every 1 degrees increase (or decrease) the toads arrived 12 days earlier (or later). Although the duration of the tadpole stage was longer when spawning was early, toadlets still emerged from the pond earlier than when spawning was late. The increased length of the tadpole stage, in years when spawning was early, was due to an increase in the proportion of cold days when the minimum ground temperature was at or below 0 degrees C. Thus, the tadpole stage was approximately 6 days longer (or shorter) for every 5% increase (or decrease) in the proportion of cold days the tadpoles were exposed to.     

Temperature dependence of anaerobic TCE-dechlorination in a highly enriched Dehalococcoides-containing culture

Temperature dependence of reductive trichloroethene (TCE) dechlorination was investigated in an enrichment culture (KB-1), using lactate or propionate as electron donors at a temperature interval from 4 to 60 degrees C. Dechlorination was complete to ethene at temperatures between 10 and 30 degrees C (lactate-amended) and between 15 and 30 degrees C (propionate-amended). Dechlorination stalled at cis-1,2-dichloroethene (cDCE) at 4 degrees C (lactate-amended), at and below 10 degrees C (propionate-amended), and at 40 degrees C with both electron donors. No dechlorination of TCE was observed at 50 and 60 degrees C. Concentrations of Dehalococcoides had increased or remained constant after 15 days of incubation at temperatures involving complete dechlorination to ethene. Temperature dependence of dechlorination rates was compared using zero order degradation kinetics and a Monod growth-rate model for multiple electron acceptor usage with competition. Maximum growth rates (mu) and zero order degradation rates were highest for TCE dechlorination at 30 degrees C with lactate as substrate (mu(TCE) of 7.00+/-0.14 days(-1)). In general, maximum growth rates and dechlorination rates of TCE were up to an order of magnitude higher than rates for utilization of cis-dichloroethene (cDCE, mu(c)(DCE) up to 0.17+/-0.02 days(-1)) and vinyl chloride (VC, mu(VC) up to 0.52+/-0.09 days(-1)). Temperature dependence of maximum growth rates and degradation rates of cDCE and VC were similar and highest at 15-30 degrees C, with growth rates on cDCE being lower than on VC. This study demonstrates that bioaugmentation of chlorinated ethene sites may be more efficient at elevated temperatures.     

Rainfall identification and estimation in Guangzhou area used for building energy simulation

In uncomfortably warm areas and seasons of the year, passive cooling effects resulting from natural rainfall evaporation can greatly cut down on building energy consumption. To simulate the passive evaporation cooling effect and evaluate the relevant energy-saving potentials, hourly rainfall data are needed. However, in currently used building energy simulation software, such as DOE, EnergyPlus and DeST, no rainfall information is provided in the climatic database. This paper uses a limited set of monthly and daily rainfall distribution data in Guangzhou area to identify and model monthly, daily and hourly rainfall patterns. For a current weather database used by building energy simulation software, rainy days and rainy hours are distinguished using distance discriminant analysis, which uses measured data samples for rain identification. According to an autocorrelation analysis of rain sequences, a one-order AR model is suitable for monthly rainfall estimation by AIC criterion judgment. Distribution of daily rainfall month-by-month shows a Gamma distribution model agrees well with daily rainfall distribution. Using a Gamma distribution model and monthly total rainfall, daily rainfall is assigned stochastically. Analysis shows distribution patterns of hourly rainfall percentage, both in the rainy season and non-rainy season, coincide well with the Beta distribution. Using a Beta distribution model and daily total rainfall, hourly rainfall is assigned stochastically. A comparison of statistics features of simulated data to that of measured data validates the method.     

Spatio-temporal trends and shift analysis of temperature for Wainganga sub-basin,India

ABSTRACT

The temporal variation in maximum (T_max), mean (T_mean) and minimum (T_min) temperature for 63 years (1951–2013) were analysed over the Wainganga sub-basin, part of the Godawari basin using Mann–Kendall (MK) test and Sen’s Slope Estimator (SSE). The shifting in temperature pattern was analysed using Pettitt’s test, Standard Normal Homogeneity Test (SNHT) and Buishand’s test. Results of the MK test and SSE for monthly temperatures show both upward and downward trends. Seasonal analysis shows the positive trend of all temperatures. It has been found that T_max, T_mean and T_min are rising by 0.5 ºC, 0.37ºC and 0.25ºC, respectively, during the study period. Spatial analysis using inverse distance weighted interpolation method (IDW) shows maximum variation in T_min. The annual mean temperature in the southern parts of the basin shows a significant positive trend.     

Simulating the effects of climate change,economic and urban planning scenarios on urban runoff patterns of a metropolitan region

Urban development and climate change are expected to have significant effects on urban stormwater runoff. In this study, the Dynamic Urban Water Simulation Model (DUWSiM) is applied to Dublin, Ireland, to explore urban runoff patterns under varying urban growth and climate scenarios. Results show that annual urban runoff could decrease by 3.0% from climate change and monthly runoff could increase by 30% in winter and decrease by 28% in summer. Results also indicate that urban growth could increase annual runoff by up to 15%. The combined effect of climatic and land-use change generated runoff may potentially increase annual totals from between 2.9% to 21%. Monthly changes in runoff totals could increase by up to 57%. Accommodating these variations in runoff between the scenarios, flexible decentralised systems such as green roofs and pervious pavements, have a vital role in increasing the adaptability and long term sustainability of water infrastructure.     

Effects of temperature and aerial exposure on the BOD of waste zebra mussels removed from navigational locks

This laboratory study evaluated the effects of temperature and aerial exposure on BOD5 (5-day BOD) of waste zebra mussels of the type generated by maintenance operations on dams and navigational locks. The term waste zebra mussels includes the mussels and their associated debris with the latter including sediment, feces, pseudofeces and other small aquatic organisms. The BOD5 of waste zebra mussel was evaluated after aerial exposure of 3 and 10 days at temperatures of 5, 10, and 20 degrees C. The mean BOD5 values for waste zebra mussels in this study ranged from 18,500 to 30,600 mg O2/l. Factorial ANOVA analysis revealed that both temperature and aerial exposure had a negative effect on waste zebra mussel BOD5 (P<0.05) but there was no significant interaction effect (P = 0.119). Multiple regression analysis predicted that for the range of treatment conditions used in this study each 1 degrees C increase in temperature reduced the waste zebra mussel BOD5 by 284mg O2/l or 0.93% of the maximum mean BOD5. Each I day increase in aerial exposure reduced waste zebra mussel BOD5 by 987 mg O2/l or 3.22% of the maximum mean BOD5. Aerial exposure of waste zebra mussels substantially reduces waste BOD5.     

Three-year measurements of ambient and indoor air temperatures in Solar Village-3, Athens,Greece

This paper presents the results of ambient and indoor air temperature measurements in the dwellings of Solar Village-3, Athens. The temperatures were monitored centrally using a Data Acquisition System and the measurements cover a 37 continuous month period, from 1/12/88 to 31/12/91. The main effort in this paper was given to the appropriate elaboration and presentation of indoor air temperature measurements in all buildings of Solar Village-3 for all the evaluation period as well as detailed data for representative dwellings. The elaborated data are average, maximum and minimum daily values for buildings, apartments and rooms, as well as daily variation of half hourly values. The daily average temperatures of each apartment are weighted average of the daily mean temperatures of each room, which in turn is the mean value of 48 measurements/day (every 30 min). Analysis shows that indoor temperatures measured during the evaluation period contributed to prevail thermal comfort conditions in winter as well in summer days. Analysis also shows that buildings of high thermal capacity and proper insulation have no need for air conditioning.     

Sulfidogenic fluidized-bed treatment of metal-containing wastewater at 8 and 65 degrees C temperatures is limited by acetate oxidation

Acetate utilization in sulfidogenic fluidized-bed reactors (FBRs) was investigated for the treatment of iron containing wastewater at low (8 degrees C) and high (65 degrees C) temperatures. The FBRs operated at low and high temperatures were inoculated with cultures of sulfate-reducing bacteria (SRB) originally enriched from arctic and hot mining environments, respectively. Acetate was not utilized as a carbon and electron source for SRB at 8 degrees C. With ethanol, hydrogen sulfide was produced from ethanol to acetate oxidation, which precipitated the iron. Then, several attempts were made to obtain acetate oxidation at 8 degrees C. Inoculation of two different low temperature enrichments and operating the FBR for a long period of time (321 days) did not result in enrichment of acetate oxidizing SRB. Due to the absence of acetate oxidation at 8 degrees C, external alkalinity addition was required to keep the pH neutral. At 65 degrees C, average acetate and sulfate removals were 52+/-12% and 24+/-8% at 670 mg/Ld acetate and 1500 mg/Ld sulfate loadings, respectively. The produced alkalinity from acetate oxidation increased the pH from 6.4 to around 7.5 and electron flow to sulfate reduction averaged 65%. Denaturing gradient gel electrophoresis (DGGE) analysis of 16S rRNA genes showed quite stable SRB community at 8 degrees C, whereas, at 65 degrees C SRB community was dynamic. In the FBRs, Desulfomicrobium apsheronum and Desulfosporosinus sp. at 8 degrees C and Desulfotomaculum sp. at 65 degrees C were detected.     

Seasonal heat flux properties of an extensive green roof in a Midwestern U.S. climate

Green roofs, or vegetated roofs, can reduce heat flux magnitude through a building envelope as a result of insulation provided by the growing medium, shading from the plant canopy, and transpirational cooling provided by the plants. This study quantifies the thermal properties of an inverted 325 m² retro-fitted extensive green roof versus a traditional gravel ballasted inverted roof in a Midwestern U.S. climate characterized by hot, humid summers and cold, snowy winters. In autumn, green roof temperatures were consistently 5 °C lower than corresponding gravel roof temperatures. Even during chilly and moist conditions, the heat flux leaving the building was lower for the green roof than the gravel roof. Temperatures at the top of the insulation layer were more variable for both green roof and gravel roof on winter days with no snow cover than on days with snow cover. Variation in temperatures between roof types in spring was similar to those in autumn. Peak temperature differences between gravel and green roof were larger in summer than other seasons (sometimes by as much as 20 °C). Over the course of a year (September 2005-August 2006), maximum and minimum average monthly temperatures and heat fluxes were consistently more extreme for the gravel roof than the green roof.     

A simple procedure for selection and sizing of indirect passive solar heating systems

Equivalent sol-air temperatures have been defined for four indirect gain passive solar heating concepts, namely, mass wall, water wall, Trombe wall and solarium. Steady state thermal efficiencies have also been defined as a measure of the ability of each system to deliver heat into the living space.

Design curves have been developed which relate the average instantaneous solar radiation incident on the passive element to thermal efficiency for different values of ambient temperature. These curves are useful in selection of an appropriate passive heating concept for a particular location.

It is inferred that a solarium is most effective at very low levels of incident radiation and low ambient temperature. Water walls and Trombe walls are most efficient at higher levels of incident radiation.

A simple procedure has been developed for a first approximation of sizing the selected system using these design curves and a minimum of meteorological information, namely, monthly average of daily global solar radiation, monthly average maximum and minimum ambient temperatures.