The effects of large-scale atmospheric fields on the cypress pollen season in Tuscany (Central Italy)

This research was performed for the purpose of analysing the relationships between large-scale meteorological information, in particular the North Atlantic Oscillation (NAO) index and the Sea Surface Temperature (SST), and the timing and magnitude of the Cupressaceae pollen season in the Pistoia district of Central Italy. The results demonstrated that in specific periods of the year, the NAO index, by partially determining the distribution of the main meteorological variables over the study area, is negatively correlated with the start and the end, as well as the peak day of pollen concentration. Pollen data were also correlated with the SST of the North Atlantic Ocean east of the Azores for the September–December period of the previous year, which is significant for exploring possibilities in terms of predicting the timing and magnitude of the cypress pollen season. The analysis of such meteorological variables and indices could be used to improve the existing forecasting systems of the phenology of the cypress pollen season. Moreover, the possibility of using meteorological information freely available on internet could cut costs and reduce spatial and temporal representativeness limitations relating to weather monitoring in loco.     

Linkages between common wheat yields and climate in Morocco (1982–2008)

In Morocco, wheat production shows a high inter-annual variability due to uncertain rainfall. In view of the importance of this resource to the country’s economy, it is important to gain a better understanding of the natural large-scale climate oscillation governing this variability. In this study, we analyzed de-trended (1) time series of common wheat yields (1983–2008) from 11 agricultural provinces that account for 80 % of national wheat production; (2) monthly rainfall and 10-day temperature from ten meteorological stations; (3) 10-day normalized difference vegetation index (NDVI) from the AVHRR sensor; (4) monthly atmospheric climate indices [North Atlantic Oscillation (NAO) and Scandinavian Pattern (SCA)] and monthly 500 hPa geopotentials fields; and (5) monthly sea surface temperature (SST) fields and indices (NIÑO3, Tropical North Atlantic and Tropical South Atlantic). The relationship between rainfall and temperature during tillering in early winter and grain filling in early spring and wheat yields already observed at the plot scale was also found to be significant at the provincial scale. The linkages between wheat yields and large scale climate have been analyzed for the first time over Morocco. In agreement with previous studies, results show a complex and competing influence of different climate phenomena. The NAO is found to be significantly related to yields during the early stage of wheat growth in December, whereas the SCA correlates with yields later in the season, in January and February. Interesting lagged correlations with higher lead time are also highlighted, with the leading modes of SST variability in the equatorial Atlantic during October (the “Atlantic Niño” mode) and in the North Atlantic (the “Atlantic tripole” mode) in February. Our conclusion is that regional climate indices and variables represent valuable information with which to increase lead time and skill regarding wheat yield predictions in Morocco.     

华北冬小麦降水亏缺变化特征及气候影响因素分析

为了探究气候变化背景下作物降水亏缺变化规律和影响因素,该文基于华北地区1971－1980年和2001－2010年气象数据和冬小麦生育期资料,研究了冬小麦生育期内降水亏缺变化特点,利用构建的敏感度分析模型探讨了降水亏缺量对主要气候要素的敏感性特征,主要结论：2001－2010年华北中部地区冬小麦全生育期内干旱加重,降水亏缺面积略有增加;播种—返青期内降水亏缺程度自江苏徐州—河南许昌一线往北都有所加剧,返青—拔节期内降水亏缺程度缓解,拔节—抽穗期内降水亏缺程度加重,仅在山西中部太原地区降水略有盈余,抽穗—成熟期内降水亏缺有所缓解;冬小麦拔节—抽穗期降水亏缺量对日照时数高度正向敏感站点最多,主要分布在河北北部地区和安徽省,其次是风速,对温度和降水的高度正向敏感站点最少。该文为制定灌溉定额,农业水资源管理和缓解水资源供需矛盾提供科学依据。     

Combined Effects of the North Atlantic Oscillation and the Arctic Oscillation on Sea Surface Temperature in the Alborán Sea

We explored the possible effects of the North Atlantic Oscillation (NAO) and Arctic Oscillation (AO) on interannual sea surface temperature (SST) variations in the Alborán Sea, both separately and combined. The probability of observing mean annual SST values higher than average was related to NAO and AO values of the previous year. The effect of NAO on SST was negative, while that of AO was positive. The pure effects of NAO and AO on SST are obscuring each other, due to the positive correlation between them. When decomposing SST, NAO and AO in seasonal values, we found that variation in mean annual SST and mean winter SST was significantly related to the mean autumn NAO of the previous year, while mean summer SST was related to mean autumn AO of the previous year. The one year delay in the effect of the NAO and AO on the SST could be partially related to the amount of accumulated snow, as we found a significant correlation between the total snow in the North Alborán watershed for a year with the annual average SST of the subsequent year. A positive AO implies a colder atmosphere in the Polar Regions, which could favour occasional cold waves over the Iberian Peninsula which, when coupled with precipitations favoured by a negative NAO, may result in snow precipitation. This snow may be accumulated in the high peaks and melt down in spring-summer of the following year, which consequently increases the runoff of freshwater to the sea, which in turn causes a diminution of sea surface salinity and density, and blocks the local upwelling of colder water, resulting in a higher SST.     

The influence of the North Atlantic Oscillation on the physical, chemical and biological characteristics of four lakes in the English Lake District

1. Thirty‐six years of winter meteorological and limnological measurements from four lakes in the English Lake District are analysed and related to variations in the North Atlantic Oscillation (NAO). Winter weather conditions were strongly influenced by the NAO with mild, wet winters being associated with strongly positive values of the NAO index (NAOI). 2. Lake surface and bottom temperatures were strongly positively correlated with the NAOI, with the highest correlations being recorded in the shallower lakes. 3. Variations in the NAOI also had a significant effect on the winter concentration of nitrate. In all the lakes, there was a significant negative correlation between the NAOI and the detrended winter concentration of nitrate. The key driving variable was the local air temperature, which appeared to limit the quantity of nitrate reaching the lake by increasing the amount assimilated in the surrounding catchment in mild winters. 4. Dissolved reactive phosphorus (DRP) concentrations were not significantly correlated with the NAOI in the two larger basins but significant positive correlations were recorded in the two smaller lakes. The key driving variable was the local rainfall with higher DRP concentrations being recorded after heavy rain in the lakes with a short retention time. 5. The NAOI‐related changes in rainfall also influenced the phytoplankton. In wet winters the concentration of chlorophyll in the two smaller lakes with the shortest retention time was lower and the spring growth of Asterionella formosa was delayed in the smallest lake. 6. These differential responses demonstrate how the large‐scale effects associated with the NAO can be ‘filtered’ by the physical characteristics of a particular site.     

Climate warming decreases the survival of the little auk (Alle alle), a high Arctic avian predator

Delayed maturity, low fecundity, and high adult survival are traits typical for species with a long‐life expectancy. For such species, even a small change in adult survival can strongly affect the population dynamics and viability. We examined the effects of both regional and local climatic variability on adult survival of the little auk, a long‐lived and numerous Arctic seabird species. We conducted a mark‐resighting study for a period of 8 years (2006‐2013) simultaneously at three little auk breeding sites that are influenced by the West Spitsbergen Current, which is the main carrier of warm, Atlantic water into the Arctic. We found that the survival of adult little auks was negatively correlated with both the North Atlantic Oscillation (NAO) index and local summer sea surface temperature (SST), with a time lag of 2 and 1 year, respectively. The effects of NAO and SST were likely mediated through a change in food quality and/or availability: (1) reproduction, growth, and development of Arctic Calanus copepods, the main prey of little auks, are negatively influenced by a reduction in sea ice, reduced ice algal production, and an earlier but shorter lasting spring bloom, all of which result from an increased NAO; (2) a high sea surface temperature shortens the reproductive period of Arctic Calanus, decreasing the number of eggs produced. A synchronous variation in survival rates at the different colonies indicates that climatic forcing was similar throughout the study area. Our findings suggest that a predicted warmer climate in the Arctic will negatively affect the population dynamics of the little auk, a high Arctic avian predator.     

Common growth signal and spatial synchrony of the chronologies of tree-rings from pines in the Baltic Sea region over the last nine centuries

The common growth signal and spatial synchrony of nine chronologies of tree rings (Pinus sylvestris L.) from the Baltic Sea region were studied using moving correlations with time windows of 50 and 100 years. Drifts from synchrony to asynchrony and again back to synchrony across several centuries were observed. The chronologies showed higher (or lower) coefficients of correlations and correspondingly gentler (or steeper) declines in spatial synchrony in certain periods. In accordance with research into other ecological phenomena, the origin of the spatial synchrony was found to relate to the intensity of the westerly circulation over the Atlantic and Europe as described by the North Atlantic Oscillation (NAO) index. The tree rings from all of the analysed subregions were found to be wider, identifying faster periods of growth, when there was a positive NAO during the extended winter season from December to March that preceded the period of growth. Previous studies showed that the NAO index can be linked with the growth of tree rings because of factors in the local climate that affect growth, such as temperature and precipitation. Moreover, the spatial synchrony showed multidecadal fluctuations that were correlated with variations of a similar scale in the reconstructed NAO index. However, a high degree of spatial synchrony was observed during the 20^th century in the presence of values of NAO index that were strongly negative. A more detailed view was provided by maps of the correlations in which spatial changes were demonstrated in the growth of pines between the 12^th and the 20^th century. These results could be used as background information in the development of improved proxy-based reconstructions of the NAO index (or other similar meteorological variables), which could also be inferred from tree ring data relating to earlier centuries.     

Relation between climatic factors,diet and reproductive parameters of Little Terns over a decade

We used 10 years of data on clutch size, egg size and diet, and 8 years of data on timing of laying on Little Terns (Sternula albifrons) breeding in Ria Formosa lagoon system, Algarve, Portugal to assess whether diet acts as an important intermediary between climatic conditions and breeding parameters. We used Generalized Linear Models to relate (1) the relative occurrence and size of the main prey species, sand smelts (Atherina spp.), with environmental variables, a large-scale climate variable, the North Atlantic Oscillation (NAO) index, and a local scale variable, the sea-surface temperature (SST), and (2) the respective effects of sand smelts relative occurrence, NAO index and SST on Little Tern breeding parameters. The diet of Little Terns was dominated by sand smelts, with a frequency occurrence of over 60% in all years. The winter SST (February) was negatively associated with the relative occurrence of sand smelts in the diet of Little Terns during the breeding season which, in turn, was positively associated with Little Tern clutch size. Our results suggest that negative NAO conditions in the Atlantic Ocean, often associated with rougher sea conditions (greater vertical mixing, stronger winds and lower SST) were related with earlier breeding, and lower SST in the surroundings of the colony during winter–spring favour the abundance of prey fish for Little Terns as well as their reproductive parameters. Climate patterns at both large and local scales are likely to change in the future, which may have important implications for estuarine seabirds in Southern Europe.     

Lagged effects of North Atlantic Oscillation on spittlebug Philaenus spumarius (Homoptera) abundance and survival

The North Atlantic Oscillation (NAO) is a large‐scale pattern of climate variability that has been shown to have important ecological effects on a wide spectrum of taxa. Studies on terrestrial invertebrates are, however, lacking. We studied climate‐connected causes of changes in population sizes in island populations of the spittlebug Philaenus spumarius (L.) (Homoptera). Three populations living in meadows on small Baltic Sea islands were investigated during the years 1970–2005 in Tvärminne archipelago, southern Finland. A separate analysis was done on the effects of NAO and local climate variables on spittlebug survival in 1969–1978, for which survival data existed for two islands. We studied survival at two stages of the life cycle: growth rate from females to next year's instars (probably mostly related to overwintering egg survival), and survival from third instar stage to adult. The latter is connected to mortality caused by desiccation of plants and spittle masses. Higher winter NAO values were consistently associated with smaller population sizes on all three islands. Local climate variables entering the most parsimonious autoregressive models of population abundance were April and May mean temperature, May precipitation, an index of May humidity, and mean temperature of the coldest month of the previous winter. High winter NAO values had a clear negative effect on late instar survival in 1969–1978. Even May–June humidity and mean temperature of the coldest month were associated with late instar survival. The climate variables studied (including NAO) had no effect on the growth rate from females to next year's instars. NAO probably affected the populations primarily in late spring. Cold and snowy winters contribute to later snow melt and greater spring humidity in the meadows. We show that winter NAO has a considerable lagged effect on April and May temperature; even this second lagged effect contributes to differences in humidity. The lagged effect of the winter NAO to spring temperatures covers a large area in northern Europe and has been relatively stationary for 100 years at least in the Baltic area.     

晋南地区冬小麦生育期气候变化特征及其对产量的影响

明确气候变化特征及其对小麦生产的影响,有助于为农业适应气候变化方案的制定提供理论依据.本研究分析了晋南小麦主产区临汾、运城市1957-2015年降水量、气温、日照时长、潜在蒸散量、干燥度等变化及其对冬小麦生育期及产量的影响.结果 表明:1957-2015年,临汾、运城市全年降水量和冬小麦生育期日照时长均呈下降趋势,冬小...     

Mediterranean climate patterns and wine quality in North and Central Italy

Results show that the year-to-year quality variation of wines produced in North and Central Italy depends on the large-scale climate variability, and that the wine quality improvement in the last four decades is partially due to an increase of temperature and to a decrease of precipitation in West and Central Mediterranean Europe (WME; CME). In addition, wine quality is positively correlated with air temperature throughout the entire active period of the grapevine, weakly negatively correlated with precipitation in spring, and well negatively correlated in summer and fall. The month-to-month composites of the NAO anomaly show that, in years of good quality wine, this anomaly is negative in late spring, oscillates around zero in summer, and is positive in early fall; while, in years of bad quality wine, it is positive in late spring and summer, and negative in early fall, i.e. its polarity has an opposite sign in spring and fall in good versus bad years. The composite seasonal maps show that good wines are produced when the spring jet stream over the Atlantic diverts most of the weather perturbations towards North Europe, still providing a sufficient amount of rainwater to CME; when summer warming induced by southerly winds is balanced by the cooling induced by westerly winds; and when a positive geopotential anomaly over WME shelters CME from fall Atlantic storms. Bad quality wines are produced when the jet stream favors the intrusion of the Atlantic weather perturbations into the Mediterranean. Results suggest that atmospheric pattern persistencies can be used as precursors for wine quality forecast.     

North Atlantic Oscillation influences on radial growth of Pinus pinea on the Italian mid-Tyrrhenian coast

The North Atlantic Oscillation (NAO) is the most important source of winter atmospheric variability in the northern hemisphere. NAO inversely reflects the precipitation regime, which plays a fundamental role in Mediterranean regions, e.g., by recharging the water table. As no attempt has been made thus far to analyze the relationship between NAO variability and tree radial growth in coastal Mediterranean conifers, this paper identifies the monthly, winter, annual, and decadal influence of NAO on tree-ring chronologies of six planted Pinus pinea L. populations distributed along the Tyrrhenian coasts of central Italy. Through multidimensional analyses, we identified tree-ring chronology associations in two main groups. The influence of NAO on the regional chronologies was identified with correlation functions for the comparison period between 1949 and 2003 at both annual and decadal timescales. Results indicate that winter NAO influence on radial tree growth at annual and decadal timescales may depend on geographical location, site characteristics, and the age structure of tree-ring chronologies. These results contribute to a better understanding of the P. pinea coastal forest ecology and provide evidence of large-scale climatic forcings that influence forest Mediterranean ecosystems.     

Winter North Atlantic oscillation effects on the tree rings of the Italian beech (Fagus sylvatica L.)

Climatic signals in beech tree-ring width series from Central Italy have been studied over different periods of time. Prewhitened tree-ring chronologies respond mainly to summer precipitation and they do not correlate in a significant manner with the winter North Atlantic oscillation (NAO) index. In this high-frequency pattern the NAO signs are only found on a small number of rings characterized by being very narrow or wide. By contrast, tree-ring width chronologies in which all the frequency components are conserved were significantly related to the NAO. The significant inverse correlation between actual measurements of ring width and NAO is a consequence of the availability of water in the soil at the beginning of the growing season. In fact, in the Mediterranean area the recharging of soil moisture depends on the amount of winter precipitation, which is inversely correlated with the NAO. Strong signals of winter precipitation and NAO are found in the low-frequency components of tree-ring growth. Received: 18 March 1999 / Revised: 29 February 2000 / Accepted: 1 March 2000     

Climate Effects on Early Phytoplankton Biomass Over Three Decades Modified by the Morphometry in Connected Lake Basins

A 30-year continuous record of chlorophyll a samples in May from six locations in the Swedish Lake Mälaren was tested for the correlation to air temperature, water temperature, precipitation, discharge, nutrients, yellow substance, dissolved phosphorous load, ice cover and NAO (North Atlantic Oscillation) index. In the deep basins subjected to stratification chlorophyll a concentration correlated with air temperature with equal or shorter delay than it did in the shallow basins. Both precipitation and discharge were significant negatively correlated with chlorophyll a concentration in many of the basins with varying retention times. However, discharge into flushed basins had a more immediate influence on chlorophyll a concentration, and precipitation was earlier correlated with chlorophyll a concentration in basins fed from the smaller and closer situated catchment.     

Sea Surface Temperature Influence on Terrestrial Gross Primary Production along the Southern California Current

Some land and ocean processes are related through connections (and synoptic-scale teleconnections) to the atmosphere. Synoptic-scale atmospheric (El Niño/Southern Oscillation [ENSO], Pacific Decadal Oscillation [PDO], and North Atlantic Oscillation [NAO]) decadal cycles are known to influence the global terrestrial carbon cycle. Potentially, smaller scale land-ocean connections influenced by coastal upwelling (changes in sea surface temperature) may be important for local-to-regional water-limited ecosystems where plants may benefit from air moisture transported from the ocean to terrestrial ecosystems. Here we use satellite-derived observations to test potential connections between changes in sea surface temperature (SST) in regions with strong coastal upwelling and terrestrial gross primary production (GPP) across the Baja California Peninsula. This region is characterized by an arid/semiarid climate along the southern California Current. We found that SST was correlated with the fraction of photosynthetic active radiation (fPAR; as a proxy for GPP) with lags ranging from 0 to 5 months. In contrast ENSO was not as strongly related with fPAR as SST in these coastal ecosystems. Our results show the importance of local-scale changes in SST during upwelling events, to explain the variability in GPP in coastal, water-limited ecosystems. The response of GPP to SST was spatially-dependent: colder SST in the northern areas increased GPP (likely by influencing fog formation), while warmer SST at the southern areas was associated to higher GPP (as SST is in phase with precipitation patterns). Interannual trends in fPAR are also spatially variable along the Baja California Peninsula with increasing secular trends in subtropical regions, decreasing trends in the most arid region, and no trend in the semi-arid regions. These findings suggest that studies and ecosystem process based models should consider the lateral influence of local-scale ocean processes that could influence coastal ecosystem productivity.     

Climate and climatic variability at Lake Myvatn

The climate of the Lake Myvatn region is examined through the use of weather station data, using the years from 1971 to 2000 as a reference period. Variations in mean monthly temperature and precipitation at Reykjahlid (Myvatn) are compared with variations at seven other weather stations in north east Iceland. The area is drier and colder than coastal stations and exhibits a seasonal cycle in temperature that is larger than found at the coast. The temperature is significantly influenced by the number of sunlight hours only during the summer months. During summer, the influence of a sea breeze circulation can be clearly identified.The variability of climate since 1936 is also examined in comparison with the seven other weather stations. It is found that temperature variations at the different stations are highly correlated, but for precipitation the correlation is significant but much weaker.The influence of the large scale atmospheric circulation on temperature and precipitation at Lake Myvatn is also examined. It is found that the air temperature at Lake Myvatn is most sensitive to an east-west dipole in the large scale sea surface pressure field, i.e. to a pattern that is very different from the spatial pattern associated with the North Atlantic Oscillation (NAO). Precipitation at Lake Myvatn is to some degree influenced by the NAO, but generally precipitation is associated with northerly winds and cold temperatures whereas southerly winds at Lake Myvatn are likely to be drier.     

基于生态位和模糊数学的冬小麦适宜性评价

为定量评价气象、土壤等要素对作物生长的影响,利用江苏省及周边40个气象站1980—2010年日气象资料,选取影响冬小麦品种生长发育的主要气象(如气温、降水、日照时数等)和土壤(如土壤厚度、有机质和p H值等)生态因子,基于生态位理论和模糊数学的方法,依据冬小麦生长对生态各因子的响应关系建立各生态因子适宜度模型,借助GIS空间插值和空间分析,计算江苏省冬小麦品种的种植适宜度并进行等级划分。结果表明:从单要素看,研究区气温适宜度和日照时数适宜度都由北往南逐渐降低,降水适宜度由南往北逐渐降低;大部分地区土壤厚度和土壤有机质适宜,但大部分地区的p H值适宜度较低;从气候适宜度看,江苏省气候适宜度的范围为0.68—0.81,中北部大部分区域适宜度大于0.73,全省的气候适宜度均适合种植冬小麦,大体上呈现由北往南逐渐减小的变化;从土壤适宜度看,全省中部、南部与西北部大部分区域适宜度大于0.70,适合种植冬小麦。从综合适宜度看,全省大部分地区适宜度为0.50—0.86,适宜于冬小麦生长。综合考虑农业气候资源和土壤资源对江苏省冬小麦品种种植的综合适宜性进行评价,评价结果为充分利用江苏省农业生态资源、指导及科学制定冬小麦品种区域种植规划提供科学依据;按作物品种分生育期多角度的精细化研究方法和建立的各因子的适宜度模型可为今后作物区域适宜性评价提供一种新的思路,对同类研究具有一定的借鉴作用。     

Relationships between airborne fungal spore concentration of <Emphasis Type="Italic">Cladosporium</Emphasis> and the summer climate at two sites in Britain

Cladosporium conidia have been shown to be important aeroallergens in many regions throughout the world, but annual spore concentrations vary considerably between years. Understanding these annual fluctuations may be of value in the clinical management of allergies. This study investigates the number of days in summer when spore concentration exceeds the allergenic threshold in relation to regional temperature and precipitation at two sites in England and Wales over 27 years. Results indicate that number of days in summer when the Cladosporium spores are above the allergenic concentration is positively correlated with regional temperature and negatively correlated with precipitation for both sites over the study period. Further analysis used a winter North Atlantic Oscillation index to explore the potential for long-range forecasting of the aeroallergen. For both spore measurement sites, a positive correlation exists between the winter North Atlantic Oscillation index and the number of days in summer above the allergenic threshold for Cladosporium spore concentration.     

Climate/growth relations and teleconnections for a <Emphasis Type="Italic">Hymenaea courbaril</Emphasis> (Leguminosae) population inhabiting the dry forest on karst

Key message

Both water availability and temperature modulate the growth of Hymenaea courbaril on karst in Central Brazil. There is evidence of teleconnections between South Atlantic SST and tree growth.

Abstract

Tropical dry forests have low annual precipitation and long dry seasons. Water availability, the main restrictive growth factor, becomes more pronounced in the shallow and highly porous soil of karst regions. Understanding how climate regulates tree growth in stressful environments is essential for predicting climate change impacts on trees. The aim of this study was to build a tree-ring chronology of Hymenaea courbaril growing in a karst dry forest and evaluate how local climate and teleconnections modulate its growth. To accomplish this, increment cores of 19 individuals were sampled in Terra Ronca State Park located in Goiás State, Central Brazil. After surface polishing, tree rings were identified, measured, dated, and a tree-ring chronology was built with 17 individuals. The chronology was correlated with local and regional climate data (temperature, precipitation, air humidity). We also tested teleconnections with sea surface temperature (SST) of the Equatorial Pacific and South Atlantic. Results show that air humidity, precipitation amount, and its distribution during the transition period between dry and wet seasons positively regulate this species growth. On the other hand, growth is negatively correlated with temperature during the middle of the previous year’s dry season. Additionally, growth is negatively correlated with SST of the Southern Atlantic, but not with Equatorial Pacific. These relationships between climate and growth indicate that predicted increases in regional temperature and decreases in water availability may limit the growth of H. courbaril in karst dry forests.