Measurements Of Climate Variables Research Articles

Does Climate Variability Influence Internal Migration Flows in Senegal? An Empirical Analysis

This paper aims to estimate the total effect of climate variability on interregional migration flows in Senegal. We match regional climate data at origin, represented by normalised rainfall and normalised temperatures (maximum and minimum), with regional migration flow data from Senegal’s Agence Nationale de la Statistique et de la Démographie (ANSD) censuses to construct a panel database covering the five-yearly internal migration waves of 1976, 1988, 2001 and 2013. Using a gravity equation model where migration flows are explained by measures of climatic variability at origin, controlled for geographical, socioeconomic and demographic factors traditionally identified in the literature. Our results show that only negative precipitation anomalies at the origin area act as a push factor and accelerate emigration. In the predominantly agricultural regions, rainfall deficits appear, alongside traditional socioeconomic variables, as an additional significant factor shaping mobility across the country.

Population Density of European Hare Predicts Risk of Tularemia Infection, Czech Republic, 2006-2022.

Background: Over 200 different animal species are susceptible to infection by tularemia, highly infectious disease caused by Francisella tularensis. Hares (Lepus sp.) and small rodents, such as common vole (Microtus arvalis), have been acknowledged as the most significant sources of human tularemia infection in most European countries. Our objective was to verify ability of these species in predicting incidence of human tularemia in a Central European country, the Czech Republic. Materials and Methods: We used 17 years of data on densities of European hare (Lepus europaeus) and common vole, and climate variability to test effects of these factors on temporal dynamics of tularemia incidence. The data were obtained from annual reports available from online e-repositories. Results: The analysis showed that 33% of the yearly variation in human tularemia incidence was explained solely by the abundance of European hare in the Czech Republic during 2007-2022. Density of common vole and North Atlantic Oscillation index, a measure of climate variability, did not significantly explain tularemia incidence. While hare population declined severely during 1993-2022, we did not detect any clear accompanied decrease in the prevalence of tularemia in humans and hares. Conclusion: Contrary to expectations, only hares proved capable in predicting yearly dynamics in human tularemia incidence in the Czech Republic. We call for continued monitoring of infection rates in hares and advocate the use of hunter estimates of hare abundance as a cheap and effective means of predicting the risk of tularemia.

Is it feasible to estimate radiosonde biases from interlaced measurements?

Abstract. Upper-air measurements of essential climate variables (ECVs), such as temperature, are crucial for climate monitoring and climate change detection. Because of the internal variability of the climate system, many decades of measurements are typically required to robustly detect any trend in the climate data record. It is imperative for the records to be temporally homogeneous over many decades to confidently estimate any trend. Historically, records of upper-air measurements were primarily made for short-term weather forecasts and as such are seldom suitable for studying long-term climate change as they lack the required continuity and homogeneity. Recognizing this, the Global Climate Observing System (GCOS) Reference Upper-Air Network (GRUAN) has been established to provide reference-quality measurements of climate variables, such as temperature, pressure, and humidity, together with well-characterized and traceable estimates of the measurement uncertainty. To ensure that GRUAN data products are suitable to detect climate change, a scientifically robust instrument replacement strategy must always be adopted whenever there is a change in instrumentation. By fully characterizing any systematic differences between the old and new measurement system a temporally homogeneous data series can be created. One strategy is to operate both the old and new instruments in tandem for some overlap period to characterize any inter-instrument biases. However, this strategy can be prohibitively expensive at measurement sites operated by national weather services or research institutes. An alternative strategy that has been proposed is to alternate between the old and new instruments, so-called interlacing, and then statistically derive the systematic biases between the two instruments. Here we investigate the feasibility of such an approach specifically for radiosondes, i.e. flying the old and new instruments on alternating days. Synthetic data sets are used to explore the applicability of this statistical approach to radiosonde change management.

Environmental filtering determines patterns of tree species composition in small mountains of Atlantic Central African forests

The determinants of patterns of plant species composition on small mountains are poorly known, especially in Central Africa. We aimed here to identify variation in tree species composition throughout the Ngovayang Massif (southern Cameroon) and determine the relative contributions of environmental factors and spatial autocorrelation in shaping tree species composition. Vegetation surveys were conducted in fifteen 1-ha (100 m × 100 m) permanent plots established along a transect from lowland (200 m) to submontane forests (900 m) in which all trees with a diameter (dbh) ≥ 10 cm were inventoried. Data were investigated using ordination methods (Correspondence Analysis and Canonical Correspondence Analysis). At the local scale, the most important variable in determining tree species composition patterns was slope exposure, followed by distance from the ocean and altitude. Together, these environmental variables explained 28% of floristic variation among plots, and the spatial structure almost disappeared when the effects of these variables were removed. Spatial autocorrelation analysis showed that spatial variables (geographic coordinates of the plots) or geographic distance between plots explained only 1% of the total initial variance. Residual spatial variation not explained by the environmental variables probably reflects the history of vegetation and the effects of other climatic variables that were not included in this study. Floristic variation in the Ngovayang Massif is due to strong environmental heterogeneity. The sensitivity of floristic composition to environmental variables such as slope orientation and altitude suggests that tree species composition may shift with expected climate changes, such as changes in the movement of air masses, increase in mean annual temperatures or increasing severity of the dry season. Our study highlights the need for systematic on-the-ground measurements of climate variables in tropical montane areas in order to better understand the current climate regime and serve as a basis for modelling future changes.

Effect of the climatic environment on ingestive behavior of F1 Holstein x Zebu cows

SUMMARY The objective of this study was to evaluate the ingestive behavior of five different genetic groups of F1 Holstein x Zebu (HxZ) cows during lactation during the summer. The evaluated groups were: Holstein x Gir, Holstein x Nelogir, Holstein x Guzonel, Holstein x Nelore and x Indubrasil. The experiment it occurred place during the summer in the Farm of Agricultural Research Company of Minas Gerais, located in Felixlândia- MG. A completely randomized design with factorial arrangement 5 × 4, five crossings and four periods of observation, with ten repetitions was used. The measurements of climate variables were made using dataloggers and calculated the black globe temperature and humidity index. There was the percentage of animals grazing, rumination, urination, defecation, water intake and salt intake during the day and at night every 30 minutes. The F1 animals used did not affect the grazing behavior due to high BGT values. There was a higher frequency of rumination and idle period in the morning, showing a natural behavior of cattle. Defecation was higher during the day, coinciding with the period of greater movement of animals. Water consumption was greater in the post- milking and the salt consumption in the afternoon. There was a positive statistical correlation between BGT and grazing, and negative correlation between BGT and leisure. Thus, the F1 animals grazing behavior has not changed because of the high BGT values, explaining the adaptability and resilience of five genetic groups, being a viable option for warm climate regions.

Freezing temperatures as a limit to forest recruitment above tropical Andean treelines.

The elevation of altitudinal treelines is generally believed to occur where low mean temperatures during the growing season limit growth and prevent trees from establishing at higher elevations. Accordingly, treelines should move upslope with increasing global temperatures. Contrary to this prediction, tropical treelines have remained stable over the past several decades despite increasing mean temperatures. The observed stability of tropical treelines, coupled with the drastically different temperature profiles between temperate and tropical treelines, suggests that using mean measures of temperature to predict tropical treeline movements during climate change may be overly simplistic. We hypothesize that frost events at tropical treelines may slow climate driven treeline movement by preventing tree recruitment beyond the established forest canopy. To assess this hypothesis, we measured freezing resistance of four canopy-forming treeline species (Weinmannia fagaroides, Polylepis pauta, Clethra cuneata, and Gynoxys nitida) at two life stages (juvenile and adult) and during two seasons (warm-wet and cold-dry). Freezing resistances were then compared to microclimatic data to determine if freezing events in the grassland matrix above treeline are too harsh for these forest species. Freezing resistance varied among species and life stages from -5.7 degrees C for juveniles of P. pauta to -11.1 degrees C for juveniles of W. fagaroides. Over a four-year period, the lowest temperatures recorded at 10 cm above ground level in the grasslands above treeline and at treeline itself were -8.9 degrees C and -6.8 degrees C, respectively. Juveniles maintained freezing resistances similar to adults during the coldest parts of the year and ontogenetic differences in freezing resistance were only present during the warm season when temperatures did not represent a significant threat to active plant tissue. These findings support the hypothesis that rare extreme freezing events at and above tropical treelines can prevent recruitment outside of closed canopy forest for some tree species and may significantly slow treeline advancement despite warming mean temperatures. Predictions of treeline shifts under climate change should be reevaluated to include species-specific' climatic tolerances and measures of climatic variability.

Climate Variability in the Origin Countries as a “Push” Factor on Tourist Arrivals in the Philippines

The objective of this paper is to test the impact of climate variability in origin countries as a “push factor” on tourist arrivals, specifically in the Philippines, and to select a suitable proxy to measure climate variability. This paper uses the Southern Oscillation Index (SOI) constructed by the Australian Bureau of Meteorology. Climate variability is strongly linked to the El Niño Southern Oscillation (ENSO) and this link is used by meteorologists to forecast changes in weather globally. SOI is a widely used indicator of the ENSO and its best known extremes are the El Niño (warm phase) and La Niña (cold phase) effects. The study proves to some extent that there is a significant increase in US tourist arrivals in the Philippines when La Niña-like weather conditions prevail in the USA. More importantly, the SOI proved to be a good measure of climate variability.

A record of Lateglacial/Holocene environmental change from a high‐elevation site in the Intermountain West, USA

AbstractRecords of past vegetation and fire history can be complicated by changes in the depositional environment of a sampling location. However, these changes can alternatively be used as a measure of climate variability. Our study site, ca. 18.0 cal. ka BP record from Little Brooklyn Lake, Wyoming, located near the crest of the Snowy Range, records three moisture states. Initially, the lake was likely a glacier‐fed pond indicated by the presence of Pediastrum algae colonies. Around 13.0 cal. ka BP this pond transitioned to a meadow environment, suggested by the loss of Pediastrum algae colonies and slow sedimentation rates. Meadow conditions were maintained until ca. 5.0 cal. ka BP when Pediastrum algae colony abundance increased,indicating the formation of a shallow lake. From 18.0 to ca. 5.0 cal. ka BP, the pollen record is suggestive of alpine vegetation conditions with relatively high spruce and herbaceous taxa. Low charcoal influx also characterizes the period between 18.0 and 5.0 cal. ka BP. After 5.0 cal. ka BP, the coincidence of the formation of shallow lake and pollen data, indicating a shift to a spruce and fir forest, suggests an increase in effective moisture. Fire remained rare in this basin over the entire record, however, once the lake established sedimentation rates and charcoal influx increased. Copyright © 2013 John Wiley & Sons, Ltd.

Importance of regional climates for plant species distribution patterns in moist Afromontane forest

AbstractQuestionsHow are plant species distribution patterns in tropical montane forest linked to altitude, regional climate and geographic location? Which climatic variables are most important in explaining variations in floristic diversity? What are potential effects of climate change on species diversity?LocationEthiopia.MethodsVegetation surveys were conducted in 180 study plots distributed across five moist montane forest areas in southwest and southeast Ethiopia (1000–2300 m a.s.l.). Temperature and precipitation data, as well as bioclimatic variables, were derived for each study plot from the WorldClim global climate data set. Species and climate data were analysed with direct and indirect ordination techniques and multivariate regression trees (MRT).ResultsEach of the sampled forest areas showed a distinct species composition and was governed by a particular regional temperature and precipitation pattern related to the topographic variability of the Ethiopian highlands. Hence, a general altitudinal cut‐off level for different forest types applicable in all five moist montane forest areas could not be identified. The most important bioclimatic variable in determining species distribution patterns was the amount of precipitation after the dry season (i.e. precipitation in the warmest quarter), followed by minimum temperature in the coldest month. At a lower hierarchical level, temperature and precipitation seasonality were also identified as significant discriminating variables. Generally, in areas with high precipitation during the warmest quarter (≥288 mm) and low minimum temperature in the coldest month (<10.9 °C), the number of Afromontane species was highest and that of Guineo–Congolian species lowest.ConclusionsThe altitudinal effect on species diversity in the Ethiopian moist montane forests is strongly modified by regional differences in precipitation and temperature regime. The predicted increase in temperature for the Ethiopian highlands due to climate change is likely to affect the distribution of the endemic Afromontane species. Furthermore, the study highlights the need for systematic on‐the‐ground measurements of climate variables in tropical montane areas in order to understand the current climate regime and as a basis for modelling future changes.

Degradation of water quality in Lough Neagh, Northern Ireland, by diffuse nitrogen flux from a phosphorus‐rich catchment

Annually resolved fossil records of nitrogen (N) inputs (as sedimentary δ15N, N content), aquatic production (δ13C, C content), and algal abundance and gross community composition (pigments, nonsiliceous microfossils) from Lough Neagh, Northern Ireland (NI), were compared with annual records of climatic variability, atmospheric and urban nutrient loading, whole‐catchment nutrient budgets, and limnological monitoring data to identify the unique effects of N on the eutrophication of a phosphorus (P)‐rich lake during ca. 1933‐1995. Cluster analysis revealed two major biostratigraphic zones. Zone I (ca. 1933–1955) was characterized by moderate lake production, as inferred from low concentrations of most fossil pigments and reduced δ15N signatures but elevated δ13C values and chlorophyte microfossil concentrations. In contrast, Zone II (ca. 1955‐1995) exhibited greatly increased contents of 15N, N, C, and algal pigments, combined with strongly reduced δ13C ratios and chlorophyte fossil abundance, a pattern consistent with recent severe eutrophication. Overall, microfossils of diazotrophic cyanobacteria were most abundant during the transition period between zones (ca. 1955‐1964). Regression analysis revealed that past N influx to the lake (as δ15N; r2 = 0.916, p < 0.0001), colonial cyanobacterial abundance(as myxoxanthophyll; r2 = 0.837, p < 0.0001), and total algal standing crops (as b‐carotene; r2 = 0.388, p < 0.0001) were all strongly correlated to agricultural inputs of N to NI farmland, weakly correlated to P inputs to NI farmland (r2 δ15N = 0.503, p < 0.0001; r2cyanobacteria = 0.296, p < 0.0001; r2total algae = 0.046, p < 0.05), and uncorrelated to most measures of climatic variability and atmospheric or urban nutrient inputs. Thus, degradation of water quality during the 20th century resulted from excessive loading of diffuse N to the lake from P‐rich agricultural lands.

Wind-induced dust generation and transport mechanics on a bare agricultural field

Strong atmospheric winds may cause wind erosion and dust emissions on bare, dry, erodible fields. Since these dust emissions may exceed particulate matter limits established by the United States Environmental Protection Agency, information on dust generation and transport mechanics is needed to determine the particulate hazard of dust sources. Measurements of climatic variables and airborne sediment mass and concentration were made during three strong wind events on a bare, fine sandy loam field in west Texas. This study clearly shows that dust flux estimates were very sensitive to dust concentration measurement height. PM 10 flux values estimated between heights of 2 and 5 m were 2–5 times those estimated between heights of 5 and 10 m. Tower placement in relation to the upwind unerodible boundary produced significant differences in dust flux that varied with storm intensity. During the most intense storm event, the PM 10 flux between heights of 2 and 5 m measured at the tower 200 m from the unerodible boundary was almost 2.5 times as that measured at the tower 100 m from the unerodible boundary. Vertical PM 10 dust flux was closely related with horizontal sediment flux only when the winds came from the same direction during the entire duration of horizontal sediment flux measurements.

El Niño influence on streamflow forecasting

Stochastic models are often fitted to historical data in order to produce streamflow scenarios. These scenarios are used as input data for simulation/optimization models that support operational decisions for water resource systems. The streamflow scenarios are sampled from probability distributions conditioned on the available information, such as recent streamflow data. In this paper we introduce a procedure for further conditioning the probability distributions by considering the recent measurements of climatic variables, such as sea temperatures, that are used to describe the occurrence of El Nino. We adopt an auto-regressive model and use the “El Nino information” to refine the parameter estimation process for each time step. The corresponding methodology is tested for the monthly energy time series, “inflowing” to the power plants of Colombia. This is a linear combination of streamflow values for the 18 most important rivers of the country.

Holism and Reductionism in Microbial Ecology

Microbial ecology is often regarded as the epitome of ecological reductionism. Although many microbial ecologists adopt reductionist approaches to achieve causal explanation, I feel this is due to the small size of the organisms and systems they work with rather than to any necessary preoccupation with small scale entities or approaches. Further, I believe that the relative proportion of holists and reductionists in microbial ecology does not differ from other disciplines. Microbial ecologists, however, must brave a nebulous episteme when laboratory studies of processes are to be related to field measures of the results of these processes. Two very different aspects of my research, one clearly reductionist (in the sense of small vs large) and the other more holistic, eventually brought me to the same point in understanding how tundra ecosystems function. Here I will discuss how observations and measurements of climate variables and respiration in organic residues, on the one hand, and data on microbial taxa, physiology and biomass on the other, gave me the same insight as to how and to what extent microbes contribute to or relate to system functions such as primary productivity, organic matter turnover and nutrient cycling. These ecosystem perspectives emerged fortuitously from studying some of the parts of the system. My basic questions were: 1) How are the processes which result in CO2 emission from soils influenced by climate? 2) To what degree and how efficiently do microbes use energy and mineral resources in the field? To answer the first question we measured the seasonal climate variables of temperate and moisture and the respiration response of various litters, organic soils and litterbag weight losses (Flanagan and Veum 1974). Using climatic data we attempted to predict microbial activities in decaying tundra substrates and relate them to the turnover of organic matter and plant productivity. This could be considered a more holistic approach because it concentrated on microbial activities (respiration) and ignored microbial taxa. As a result of this work, three simulation models were constructed relating microbial activities quantitatively and unambiguously to the environmental phenomena that govern them. One model (GRESP, Flanagan and Bunnell 1976, Bunnell et al. 1977a) relates the respiratory response of different kinds of litter to changing climatic conditions. The second (DECOMP, Flanagan and Bunnell 1976, Bunnell et al. 1977b) expresses the respiration rate as a function of the quality of the litter. The third (ABISKO II, Bunnell and Scoullar 1975) integrates the effects of changing meteorological condition and litter quality within the ecosystem. These models document relationships between weight loss and microbial activities, as they are influenced by abiotic variables and litter quality and the relationship of the processes of microbial populations to primary production and turnover of organic matter. Although the development of these models are based on research in tundra (Flanagan and Bunnell 1976), their predictive abilities have also been tested for conditions found in taiga forest and moors (Bunnell et al. 1977a, Bunnell and Scoullar 1981). Thus the models represent the inference of causation, involving both smaller and larger scales of organization than that of the measurements and observations that went into the formation of the models. The second question (energy and mineral processing by microbes) was approached in my laboratory from what is commonly perceived as a reductionist approach. I isolated the major species components of the microflora and subjected them to experiments on their growth and respiration, on field substrate (cellulose, hemicellulose, sugars, etc.) and evaluation of their yield and maintenance demands on different substrates at varying temperatures (consistent with field conditions) (Flanagan and Scarborough 1974, Flanagan 1978. Having established yield coefficients and maintenance demands in the laboratory (Flanagan 1978) these numbers were used, together with estimates of the total fungal biomass of the study sites, to compute the amount of organic matter necessary to maintain an average standing crop of microbes. The equation used was that of Marr et al. (1963). The remainder of the annual input from plants or the measure of decay in g m-2 yr-' was used as a numerator to be divided by an average microbial standing crop (denominator) to calculate potential annual microbial turnover (productivity). Using the measured yield coefficient (Y) with the calculated productivity gave an estimate of average CO2 emission from decaying organic matter. The potential number of microbial generations was estimated using the equation of Gray and Williams (1971). This equation includes a term allowing for recycling of dead microbial tissues. The microbial biomass (per square meter) in the tundra system of Alaska was 18.1 g and the yield efficiency (g microbial tissue per g of substrate) was 0.35. Based on an average (litter)

The Response of Spring Wheat Yield to Anomalous Climate Sequences in the United States

Abstract The response of spring wheat yield to anomalous climate sequences in the United States is estimated using monthly mean temperature and total precipitation for the years 1932 to 1971. A particular anomaly sequence, which is characteristic of the entire spring wheat season from pre-planting through harvest, is constructed from a regression of detrended yield on the coefficients of eigenvectors of the climate variables. This anomaly sequence is chosen in such a way that its coefficient is maximally correlated with yield variations. The coefficient of this anomaly sequence is then used to predict yield in the years 1972–75. The time series of eigenvector coefficients and several measures of climatic variability are examined for evidence of climatic change.