CO2 dilution in the lower atmosphere from temperature and wind speed profiles

Temperature and wind speed profiles obtained from 3?years of radio acoustic sounding system sodar measurements at a rural site in the northern Spanish plateau were fitted to polynomial functions. Depending on the extrema of these fits, several groups of profiles were considered. Daily evolution of temperature profiles corresponded to the lower boundary layer evolution. However, wind speed profiles revealed a frequent low-level jet during the whole day. CO₂ surface concentrations were analysed, and surface CO₂ dilution was also considered by selection of thin canopies with variable depth, resulting in dilution rates of 7 and 18?ppm when the layer increased 100?m for the 95th percentile and temperature and wind speed profiles, respectively.     

Extreme climatic events in the Amazon basin

During 2009 the Amazon basin was hit by a heavy flooding with a magnitude and duration few times observed in several decades. Torrential rain in northern and eastern Amazonia during the austral summer of 2008–2009 swelled the Amazon River and its tributaries. By July 2009, water levels of the Rio Negro, a major Amazon tributary, reached at Manaus harbor a new record, the highest mark of the last 107?years. During the 2008–2009 hydrological year, the rainy season on northern and northwestern Amazonia started prematurely, and was followed by a longer-than-normal rainy season. An anomalously southward migration of the ITCZ during May–June 2009, due to the warmer than normal surface waters in the tropical South Atlantic, was responsible for abundant rainfall in large regions of eastern Amazonia and Northeast Brazil from May to July 2009. We also compared the flood of 2009 with other major events recorded in 1989 and 1999. The hydrological consequences of this pattern were earlier than normal floods in Amazon northern tributaries, which peak discharges at their confluences with the main stem almost coincided with the peaks of southern tributaries. Since the time displacement of the contribution to the main stem of northern and southern Amazon tributaries is fundamental for damping flood waves in the main stem, the simultaneous combinations of peak discharges of tributaries resulted in an extreme flood.     

A seasonal study of the atmospheric dynamics over the Iberian Peninsula based on circulation types

A seasonal analysis of the atmospheric circulation over the Iberian Peninsula (IP) based on circulation types (CTs) obtained from sea level pressure and 500-hPa geopotential height is presented. The study covers the period of 1958–2008, when a high variability and important changes in winter and spring precipitation and temperature have been reported. Frequency, persistence, and the most probable transitions of the circulation types are analyzed. Among the clustering methods available in the literature, two of the most reliable classification methods have been tested, K-means and simulated annealing and diversified randomization. A comparison of both methods over the IP is presented for winter (DJF). The quality of the circulation types obtained through both methods as well as the better stability achieved by K-means suggest this method as more appropriated for our target area. Twelve CTs were obtained for each season and were analyzed. The patterns obtained were regrouped in five general situations: anticyclonic, cyclonic, zonal, summertime, and hybrid-mixed. The analysis of frequencies of these situations offers a similar characterization of the atmospheric circulation that others previously obtained by subjective methods. The analysis of the trends in frequency and persistence for each CT shows few significant trends, mainly in winter and spring with a general decrease of the cyclonic patterns and an increase of the anticyclonic situations. This can be related to the negative precipitation trends reported by other authors. Regarding the persistence, an interesting result is that there is a high interannual variability of the persistence in autumn and spring, when patterns can persist longer than in other seasons. An analysis of the most probable transitions between the CTs has been performed, revealing the existence of cyclic sequences in all seasons. These sequences are related to the high frequency of certain patterns such as the anticyclonic situations in winter. Finally, a clear seasonal dependence of the transitions between cyclonic situations associated with extratropical disturbances was found. This dependence suggests that the transitions of low-pressure systems towards the south of the IP are more likely in spring and autumn than in winter.     

Recent trends in mean maximum and minimum air temperatures over Spain (1961–2006)

This study analyzes the mean maximum and minimum temperature trends on a monthly, seasonal, and annual timescale by applying various statistical tools to data from 476 Spanish weather stations during the period between 1961 and 2006. The magnitude of the trends was derived from the slopes of the regression lines using the least squares method, and the nonparametric Mann–Kendall test was used to determine the statistical significance of the trends. Temperature significantly increased in over 60% of the country in March, June, spring, and summer in the case of maximum temperatures and in March, May, June, August, spring, and summer for minimum temperatures. At the annual resolution, temperatures significantly increased in over 90% of Spain with a rise of around 0.3°C/decade. The maximum temperature increased at a higher rate than the minimum temperature from midsummer to early winter as well as in winter, spring, and summer and also on an annual basis.     

Evolution and modulation of tropical heating from the last glacial maximum through the twenty-first century

Twentieth century observations show that during the last 50?years the sea-surface temperature (SST) of the tropical oceans has increased by ~0.5°C and the area of SST >26.5 and 28°C (arbitrarily referred to as the oceanic warm pool: OWP) by 15 and 50% respectively in association with an increase in green house gas concentrations, with non-understood natural variability or a combination of both. Based on CMIP3 projections the OWP is projected to double during twenty-first century in a moderate CO₂ forcing scenario (IPCC A1B scenario). However, during the observational period the area of positive atmospheric heating (referred to as the dynamic warm pool, DWP), has remained constant. The threshold SST (T _H ), which demarks the region of net heating and cooling, has increased from 26.6°C in the 1950s to 27.1°C in the last decade and it is projected to increase to ~28.5°C by 2100. Based on climate model simulations, the area of the DWP is projected to remain constant during the twenty-first century. Analysis of the paleoclimate model intercomparison project (PMIP I and II) simulations for the Last Glacial maximum and the Mid-Holocene periods show a very similar behaviour, with a larger OWP in periods of elevated tropical SST, and an almost constant DWP associated with a varying T _H . The constancy of the DWP area, despite shifts in the background SST, is shown to be the result of a near exact matching between increases in the integrated convective heating within the DWP and the integrated radiative cooling outside the DWP as SST changes. Although the area of the DWP remains constant, the total tropical atmospheric heating is a strong function of the SST. For example the net heating has increased by about 10% from 1950 to 2000 and it is projected to increase by a further 20% by 2100. Such changes must be compensated by a more vigorous atmospheric circulation, with growth in convective heating within the warm pool, and an increase of subsiding air and stability outside the convective warm pool and an increase of vertical shear at the DWP boundaries. This finding is contrary to some conclusions from other studies but in accord with others. We discuss the similarities and differences at length.     

Interannual to decadal variations of precipitation and daily maximum and daily minimum temperatures in southern Brazil

The interannual to decadal variability of precipitation and daily maximum and daily minimum temperature (TMAX and TMIN) in southern Brazil for the 1913–2006 period is investigated using indices for these variables. Relations of these indices and the sea surface temperature (SST) variability in the eastern equatorial Pacific (Niño 3.4 index) and southwestern subtropical Atlantic (SSA index) are also investigated. Analyses are based on the Morlet wavelet transform. The interannual precipitation variability during the 1913–2006 period is mostly due to the high variances that occurred in specific sub-periods. The TMAX and TMIN indices also show significant interannual variability. The coherency and phase difference analyses of the precipitation index and the SST indices show higher coherency with the Niño 3.4 than with the SSA index. On the other hand, examining the coherencies and phase difference between the temperature indices and the SST indices, weaker coherencies with the Niño 3.4 index than with the SSA index are noted. These differences are discussed in the context of previous results. The new results here, with possible application for climate monitoring tasks, refer to the spectral differences between TMIN and TMAX.     

The meteorological framework and the cultural memory of three severe winter-storms in early eighteenth-century Europe

Three violent eighteenth-century storms that ravaged the North Sea area (1703), western central Europe (1739) and Portugal (1739) are investigated from the point of view of their meteorological setting, their socio-economic impact, and whether and by what means they secured an enduring place in the cultural memory. The evidence draws on individual narrative sources such as chronicles and poems, and institutional sources such as ship’s logbooks and state-organised ‘windthrow’ inventories of tree loss. Each of the three storms had socio-economic impacts that could be described as ‘war-like’ in the damage caused to buildings and the destruction of forests. The “Great Storm” of December 1703 jeopardized English naval supremacy in the War of the Spanish Succession by sinking a number of Royal Navy ships and taking the life of more than 8000 seamen. In January 1739 two similarly destructive storms swept over mainland Europe. The cultural memory of the three events here considered was however strikingly different. The sequence of storms in January 1739 though being the most protracted of the last centuries, and well-chroniceled, did not persist in the collective memories of those in France, Switzerland and elsewhere who experienced them. Likewise, the “Great Storm” was quickly forgotten on the continent, whereas its memory remained deeply rooted in England through the writings of Defoe (1704). In Portugal the 1739 storm won a lasting place in the country’s cultural memory owing to two poems that it inspired. Furthermore, it was recorded in the Kingdom’s official newspaper, in the astronomical prognoses and in written records of the Old Regime’s cultural elite.     

Influence of olive mill waste application on the role of soil as a carbon source or sink

Organic matter (OM) is involved in the enhancement of soil quality since it acts on soil structure, nutrient storage and biological activity. Organic carbon (OC), the dominant element constituent of OM, and related soil properties are probably the most widely acknowledged indicator of soil quality. The typically Mediterranean climate of the South of Spain promotes low yields on crops and low organic carbon in soil. The present work was carried out to evaluate the effect of the application of alperujo, olive oil waste difficult to eliminate, on the fixation or emission of carbon on soil in an olive grove situated in Montoro (Córdoba, Spain). In the study three treatments were considered: 15 kg (A), 7.5 kg (B), 0 kg (C) of alperujo per tree and the implementation of the amendment has been made for three consecutive years. The results confirm the benefits of the amendment on the carbon content organic soil with a fixation with respect to control of 4.8 and 6.1 t ha^???1 for the first year and 8.7 and 6.8 t ha^???1 for the second in treatments A and B, respectively. Of the different climatic agents considered in the study, it was the temperature which had a major influence on the emissions of CO₂ into the atmosphere and the flow of gas presented the highest values in soils treated with the highest dose.     

Relationship between climate change and vegetation distribution in the Mediterranean mountains: Manzanares Head valley, Sierra De Guadarrama (Central Spain)

This work analyzes the consequences of climate change in the distribution of the Mediterranean high-mountain vegetation. A study area was chosen at the Sierra de Guadarrama, in the center of the Iberian Peninsula (1,795 to 2,374 m asl). Climate change was analyzed from the record of 18 variables regarding temperature, rainfall and snowfall over the period 1951–2000. The permanence of snow cover (1996–2004), landforms stability and vegetation distribution in 5 years (1956, 1972, 1984, 1991 and 1998) were all analyzed. The Nival Correlation Level of the different vegetation classes was determined through their spatial and/or temporal relationship with several climatologic variables, snow cover duration and landforms. In order to quantify trends and major change processes, areas and percent changes were calculated, as well as Mean Annual Transformation Indices and Transition Matrices. The findings reveal that in the first part of the study period (up to the first half of the 1970s) the temperature rise in the mid-winter months caused the reduction of some classes of nival vegetation, while others expanded, favored by high rainfall, decrease in both maximum temperatures and summer aridity, and longer snow cover duration. The second part of the study period was characterized by the consolidation of the increase in all thermal variables, along with an important reduction in rainfall volume and snow cover duration. As a result, herbaceous plants, which are highly correlated with a long snow permanence and abundance of melting water, have been replaced by leguminous shrubs which grow away from the influence of snow, and which are steadily becoming denser.     

Objective probabilities about future climate are a matter of opinion

In this paper, the unfeasibility of producing “objective” probabilistic climate change scenarios is discussed. Realizing that the knowledge of “true” probabilities of the different scenarios and temperature changes is unachievable, the objective must be to find the probabilities that are the most consistent with what our state of knowledge and expert judgment are. Therefore, subjective information plays, and should play, a crucial role. A new methodology, based on the Principle of Maximum Entropy, is proposed for constructing probabilistic climate change scenarios when only partial information is available. The objective is to produce relevant information for decision-making according to different agents’ judgment and subjective beliefs. These estimates have desirable properties such as: they are the least biased estimate possible on the available information; maximize the uncertainty (entropy) subject to the partial information that is given; The maximum entropy distribution assigns a positive probability to every event that is not excluded by the given information; no possibility is ignored. The probabilities obtained in this manner are the best predictions possible with the state of knowledge and subjective information that is available. This methodology allows distinguishing between reckless and cautious positions regarding the climate change threat.