1990-2020年阿根廷门多萨流域冰川变化研究

冰川是南美洲阿根廷门多萨流域(33°S)重要的淡水资源,冰川作为气候变化的敏感指示器,对于理解和评估全球和区域气候变化具有重要意义。为了解门多萨流域冰川分布及变化趋势,探讨其对区域水资源和生态系统的影响,为应对气候变化提供科学依据,研究基于1990-2020年Landsat遥感影像,参考RGI冰川编目数据和阿根廷国家冰川清单,通过比值阈值法和人工解译法得到7期冰川边界,研究了门多萨流域冰川面积分布与变化特征。并结合TerraClimate气候数据,揭示了该区域在研究期间的气候变化趋势,探讨了区域气候变化对冰川变化的影响。结果表明:①2020年门多萨流域冰川面积为134.09±11.86 km^(2),1990-2020年冰川总体呈极显著波动下降趋势(p<0.01),面积共减少了86.87±21.30 km^(2)(39.31±10.14%),其中,2010-2020年冰川面积退缩速率最高。②门多萨流域冰川规模>10 km^(2)占比最大,<0.1 km^(2)占比最小,>10 km^(2)规模冰川退缩速度最大;冰川主要分布在南坡,西北坡冰川最少,东南、东北坡冰川退缩速度最大;冰川主要分布在坡度5°~40°之间,50°~55°的冰川退缩速度最大;冰川主要分布在海拔4200~5400 m之间,<4000 m冰川退缩速率最大。③20世纪50年代末以来门多萨地区气温整体呈现极显著的上升趋势(p<0.001),研究区年均最高、最低气温每十年上升0.53、0.29℃。气温持续上升是门多萨流域冰川退缩的长期原因,降水变化是该区域冰川变化的短期原因。本研究为门多萨流域预防冰川变化导致的水资源可用性变化和地质灾害预防提供参考。

2023: Weather and Climate Extremes Hitting the Globe with Emerging Features

Globally,2023 was the warmest observed year on record since at least 1850 and,according to proxy evidence,possibly of the past 100000 years.As in recent years,the record warmth has again been accompanied with yet more extreme weather and climate events throughout the world.Here,we provide an overview of those of 2023,with details and key background causes to help build upon our understanding of the roles of internal climate variability and anthropogenic climate change.We also highlight emerging features associated with some of these extreme events.Hot extremes are occurring earlier in the year,and increasingly simultaneously in differing parts of the world(e.g.,the concurrent hot extremes in the Northern Hemisphere in July 2023).Intense cyclones are exacerbating precipitation extremes(e.g.,the North China flooding in July and the Libya flooding in September).Droughts in some regions(e.g.,California and the Horn of Africa)have transitioned into flood conditions.Climate extremes also show increasing interactions with ecosystems via wildfires(e.g.,those in Hawaii in August and in Canada from spring to autumn 2023)and sandstorms(e.g.,those in Mongolia in April 2023).Finally,we also consider the challenges to research that these emerging characteristics present for the strategy and practice of adaptation.

Understanding and Forecasting Zonda Wind (Andean Foehn) in Argentina: A Review

This paper focuses on the “state of the art” research of the Argentinian zonda wind at the beginning of 2015. Zonda (similar to foehn) is a strong, warm, very dry wind associated with adiabatic compression upon descending the eastern slopes of the Andes Cordillera in western central Argentina. Particularly, hourly surface meteorological information obtained from the Argentine National Weather Service (Servicio Meteorológico Nacional, SMN) from Mendoza Aero (32?50’S, 68?47’W, 704 m ASL) and San Juan Aero (31?34’S, 68?25’W, 598 m ASL) airport meteorological stations was used. The paper contains a history of zonda research mentioning the principal papers since the 1950s, the characteristics of zonda wind (conceptual model, a classic event, intensities categories) and examples of non-classical episodes. Also zonda dynamics, zonda climatology and forecasting problems are considered. A probabilistic method and the model forecast that are running in operative way are commented. Also the climate impact, air quality and damages caused are mentioned. There has been substantial progress in the understanding of this kind of complex wind during the last years, especially since the last decade, accelerated using different models. This paper has highlighted some of these advances by synthesizing some of the major findings. The probabilistic prediction method developed in the 1980s is still very useful to predict zonda in the cities of San Juan and Mendoza. This as well as the new available tools, such as the eta/PRM and GEM models running operatively (continuously) at PRM (Mendoza Regional Meteorology Program), offered the community the possibility to generate an Early Warning System to warn the population particularly in its severe manifestations. The answer to questions regarding time of onset of the event, place where it will occur first, duration, intensity and offset still poses a great challenge for researchers and forecasters in the region.

Forecasting Zonda Wind Occurrence with Vertical Sounding Data

Zonda wind is a typical downslope windstorm over the eastern slopes of the Central Andes in Argentina,which produces extremely warm and dry conditions and creates substantial socioeconomic impacts.The aim of this work is to obtain an index for predicting the probability of Zonda wind occurrence.The Principal Component Analysis(PCA)is applied to the vertical sounding data on both sides of the Andes.Through the use of a binary logistic regression,the PCA is applied to discriminate those soundings associated with Zonda wind events from those that are not,and a probabilistic forecasting tool for Zonda occurrence is obtained.This index is able to discriminate between Zonda and non-Zonda events with an effectiveness close to 91%.The best model consists of four variables from each side of the Andes.From an eventbased statistical perspective,the probability of detection of the mixed model is above 97%with a probability of false detection lower than 7%and a missing ratio below 1%.From an alarm-based perspective,models exhibit false alarm rate below 7%,a missing alarm ratio lower than 1.5%and higher than 93%for the correct alarm ratio.The zonal component of the wind on both sides of the Andes and the windward temperature are the key variables in class discrimination.The vertical structure of Zonda wind includes two wind maximums and an unstable lapse rate at midlevels on the lee side and a wind maximum at 700 h Pa accompanied by a relatively stable layer near the mountain top.

How Good Is the Debye Model for Nanocrystals?

The question here is whether the Debye model is suited to evaluate the specific heat of nanocrystals. For this, the simplest possible nanocrystal is considered: a basic cubic structure made of atoms that interact through a harmonic potential. This simple model can be solved exactly. This allows the dispersion relation of the mechanical waves to be determined, so that calculating the exact specific heat turns out to be quite straightforward. Then, the same problem is solved using the Debye approximation. Our findings show that the specific heat of a nanocrystal evaluated exactly is higher than the value found in the thermodynamic limit, that is to say, the specific heat decreases as the nanocrystal size increases. In addition, it becomes clear that the Debye model is a poor approximation for calculating the specific heat of a nanocrystal. Naturally, the Einstein model yields an even worse result. The cause of the discrepancy is found in the role of the nanocrystal surface.

Boltzmann or Gibbs Entropy? <br/>Thermostatistics of Two Models with Few Particles

We study the statistical mechanics of small clusters (N ~ 10 - 100) for two-level systems and harmonic oscillators. Both Boltzmann’s and Gibbs’s definitions of entropy are used. The properties of the studied systems are evaluated numerically but exactly;this means that Stirling’s approximation was not used in the calculation and that the discrete nature of energy was taken into account. Results show that, for the two-level system, using Gibbs entropy prevents temperatures from assuming negative values;however, they reach very high values that are not plausible in physical terms. In the case of harmonic oscillators, there are no significant differences when using either definition of entropy. Both systems show that for N = 100 the exact results evaluated with statistical mechanics coincide with those found in the thermodynamic limit. This suggests that thermodynamics can be applied to systems as small as these.

Geomechanical model for a seismically active geothermal field:Insights from the Tinguiririca volcanic-hydrothermal system

In this work,we develop a multidisciplinary approach to investigate a geothermal system located at the volcanic arc of a subduction-related orogen and highlight the interplay between active tectonism.stress field and fluid migration.By using results of field investigations from the Tinguiririca geothermal field in the High Andes of Chile(35°S),empirical analysis,and numerical models of static stress variations,we proposed a geomechanical model for evaluating the distribution of hydrothermal manifestations in a seismically-active region.The present geomechanical model follows four major steps:(1)development of the 3 D structural model of fault pattern;(2)estimation of the in-situ stress field;(3)calculation of the resolved-shear-to-normal-stress ratio(slip tendency)on each fault with varying geomechanical parameters(coefficient of friction,pore pressure and cohesion)as inputs;and(4)estimation of Coulomb static stress changes as a consequence of failure in a nearby fault.Through combination of all these analyses,we characterize in detail both the active deformation in the geothermal field and its relationship with hot fluid migration.

Validation of a Statistical Forecast Model for Zonda Wind in West Argentina Based on the Vertical Atmospheric Structure

Zonda is a strong, warm, very dry wind associated with adiabatic compression upon descending the eastern slopes of the Andes Cordillera in western-central Argentina. This research seeks, first, to validate the skill of a statistical forecast of zonda based on the behavior of the vertical structure of the atmosphere and, second, to describe the climatology of the vertical profile leeward of the Andes. The forecast was built for May-August 1974/1983, and was verified against a series of cases recorded in the Mendoza Aero and San Juan Aero weather stations for May-August 2005/2014. It made use of the Stepwise Discriminant Analysis (SDA) and rawinsonde data from Mendoza Aero as predictors, with the following input variables: surface pressure, temperature, dew point, and the zonal and meridional components of the wind on surface and of the fixed levels up to 200 hPa. The variables selected as predictors by the SDA were: surface pressure, dew point depression at 850 hPa, meridional wind component at 850 hPa, and zonal wind component at 400 hPa. Climatology of the vertical profile of the atmosphere leeward of the Andes was built from daily rawinsonde data from Mendoza Aero for May-August 1974/1983. Zonda markedly influences the atmospheric structure leeward of the Andes in western-central Argentina. Its maximum impact occurs at 850 to 800 hPa, with significant heating and decrease of humidity. Validation of the prediction program considered deterministic and probabilistic forecasts. Contingency tables show that probability of zonda occurrence in the plains is generally overestimated, and false alarm cases are far more frequent than surprise events. The main contribution of this paper is precisely the validation of the prediction model, which ensures forecasters one more tool to improve zonda forecasting;this, in turn, will aid decision-makers when taking steps to ameliorate zonda wind impact.

Palynostratigraphy of the Zorritas Formation, Antofagasta region, Chile： Insights on the Devonian]Carboniferous boundary in western Gondwana

The Middle Member of the Zorritas Formation in the Antofagasta region of northern Chile, yielded terrestrial and marine palynomorph assemblages which span the Devonian/Carboniferous boundary. The assemblages show a clear predominance of terrestrial palynomorphs with 70 miospore species, 18 marine phytoplankton species, two non-marine algae and one chitinozoan species, all coming from 15 productive levels. Palynomorphs are poorly preserved and most of them are reworked. Three palyno- logical associations are recognized based on miospores. These are assigned to the Tournaisian-Visean, Tournaisian and probable latest Famennian. Age assignments are discussed in the frame of the spore zonal schemes established for Euramerica and western Gondwana. The stratigraphical distribution of spores allows the identification of the probable position of the Devonian/Carboniferous boundary within the Zorritas Formation. This system boundary is proposed for the first time in Palaeozoic sedimentary rocks of northern Chile. The presence of Gondwanan typical miospore species indicates affinities with this palaeocontinent even though the Tournaisian and Tournaisian-Viseao miospore associations sup- port the cosmopolitanism already suggested for the early Carboniferous flora. The significant number of reworked palynomorphs together with the sedimentological analysis of the studied sections, suggest that these deposits were severely impacted by the climatic change and major sea level fluctuations. Similar conditions were recorded in coeval western Gondwana basins.

基于白扦树轮蓝光强度的中国华北暖季温度重建

In the past 30 years,observational climate datasets reveal a significant a drying and warming trend over in North China.Understanding of climatic variability over North China and its driving mechanism in a long-term perspective is,however,limited to a few sites only,especially the lack of temperature reconstructions based on latewood density and blue intensity.In this study,we developed a 281-year latewood blue intensity chronology based on 45 cores of Picea meyeri in western North China.Based on the discovery that the warm season(May–August)mean maximum temperature is the main controlling factor affecting the change in blue light reflection intensity,we established a regression model that explained 37%of the variance during the calibration period(1950–2020),allowing to trace the mean maximum temperature up to 1760 CE.From the past 261 years,we identified seven persistent high temperature periods(1760–1773,1778–1796,1805–1814,1869–1880,1889–1934,1984–2000,2004–2020)and three persistent low temperature periods(1815–1868,1935–1963,1969–1983)in North China.Comparisons of a nearby temperature reconstructions and climate gridded data indicate that our reconstruction record a wide range of temperature variations in North China.The analysis of links between large-scale climatic variation and the temperature reconstruction showed that there is a relationship between extremes in the warm season temperature and anomalous SSTs in the equatorial eastern Pacific,and implied that the extremes in the warm season temperature in North China will be intensified under future global warming.

Does climate change alter the nutrient trends of Cedrela fissilis Vell.trees in the southern Brazilian Amazon?

Background The increase in the frequency and intensity of droughts is pointed out as one of the main factors altering biogeochemical cycles in the Amazon basin.An eco-nutritional approach using X-ray fluorescence micro-analysis(μXRF)is proposed to verify the long-and short-term effects of droughts on the growth and xylem nutrient concentrations of Cedrela fissilis Vell.Methods Fourteen radii were selected from a tree-ring width chronology and X-rayed by Itrax Multiscanner.Profiles of ring width,wood density,and concentrations of aluminum(Al),phosphorus(P),sulfur(S),calcium(Ca),potassium(K),manganese(Mn),iron(Fe)and strontium(Sr)together with Al/Ca,Ca/Mn,K/Ca,Sr/Ca and Mn/S ratios were constructed and correlated with precipitation,temperature,the difference between precipitation and potential evapotranspiration(P-PET)and standardized precipitation-evapotranspiration index(SPEI).Results During dry years,C.fissilis showed narrower,less dense rings,lower Al,P,S and Ca,and higher K and Fe concentrations(the opposite was found in wet years).Ring width decreased(together with Al,P,S,K,Ca,Mn,Fe,Sr,Al/Ca,K/Ca and Sr/Ca)and wood density increased(together with Ca/Mn and Mn/S),which was associated with an increase in evapotranspiration and temperature over time,mainly since 1990.Cedrela fissilis showed a tendency to increase its capacity for resistance,and a recovery and resilience in growth over time associated with responses in Al,Ca,P and S.However,it showed a risk in the capacity for recovery of the pre-drought density values,associated with unsatisfactory responses in Al,Ca,K,Fe and P.Conclusions This study is the first attempt to analyze tree-ring nutritional evidences of C.fissilis trees to climate sensitivity and resilience to drought,based on long-term data from seasonal moist tropical forests of the Amazon.Our data suggested that C.fissilis is undergoing alterations in the concentration,use and redistribution of nutrients associated with increasing wood density and decreasing growth over time,due to the increase of drought frequency in the southern Amazon.

树轮记录的自公元1200年以来强火山喷发事件与高亚洲南部河流源区气候水文变化的关联

强火山喷发作为气候变化重要的外强迫因素,其所造成的气候环境效应一直是气候变化研究热点,而其对于流域水循环影响较少受关注。本文利用采自高亚洲南部河流源区麦吊云杉(Picea brachytyla)树轮样本,研制出一个长达885 a的树木年轮标准宽度年表。基于树轮气候响应分析结果,利用线性回归模型重建研究区自公元1200年上年11月至当年2月平均最低气温变化,重建方程方差解释量47.1%。该气温重建序列显示,研究区自公元1200年经历了8个冷期和9个暖期,包含有10个极冷年和23个极暖年。同时,该气温重建序列验证了自公元1200年来27次强火山喷发(VEI≥5)对于青藏高原东南部河流源区气候的影响,包括1257年Samalas和1815年Tambora等强火山喷发事件。该气温重建序列与相关河流径流数据对比结果表明强火山喷发在引起高亚洲南部河流源区气温出现明显下降的同时,也可能会进一步导致水循环减缓,使得高亚洲南部河流径流量出现减少。

Spatial distribution,patterns and source contributions of POPs in the atmosphere of Great Mendoza using the WRF/CALMET/CALPUFF modelling system

Global monitoring of Persistent Organic Pollutants(POPs)has allowed the knowledge of levels and distribution around the world as well as the understanding of its transport through the atmosphere.However,there are still some gaps in this regard,especially in some locations,as the case of Great Mendoza,a medium-sized urban area located in the center-west of Argentina.In this work,the WRF/CALMET/CALPUFF modeling system was used to estimate airborne levels of four families of POPs(PCBs,PBDEs,DDTs and HCB)in the study area.The model was validated from measured data obtained from eleven sites using passive air samplers with polyurethane foam disks(PUFs),subsequently analyzed by GC-ECNI/MS.Considering both sets of data,measured and simulated airborne concentrations,five statistical performance metrics were calculated for each family of POP[Mean bias error,(MBE),Fractional Bias(FB),Normalized Mean Square Error(NMSE),Factor of two(Fa2)and Pearson correlation coefficient(r)].Results exhibited a good agreement between modeled and measured data,showing that WRF/CALMET/CALPUFF modeling system predicts POPs airborne concentrations with reasonable accuracy at a local scale.Model output was used to examine the relative source contribution to ground-level concentrations and to assess the spatial variability of the studied POPs in the study area.Source apportionment showed the prevalence of emissions from open burning of municipal solid waste(ranging from 9%to 90%)on the simulated atmospheric concentrations.HCB presented the lowest mean contribution from this activity(37%)but the highest variability(SD=20%),followed by PCBs(69±9%),and PBDEs(84±4%).The spatial pattern obtained from simulations exhibited that both,lowest and highest levels predicted by the model,occurred in areas where no samples were taken,suggesting that the real gradient in the POPs air concentrations would be much greater than those reflected by measured data.This work highlights the usefulness of the implementation of an atmospheric dispersion model,not only in the study of air quality and exposure levels but also as a tool for the proper design of monitoring networks,taking into account the time and cost that sampling campaigns take,and the conclusions that are intended to be made from the analysis of the obtained data.

Use of wild trout for PBDE assessment in freshwater environments: Review and summary of critical factors

Certain wild animals represent sentinels to address issues related to environmental pollution,since they can provide integrative data on both pollutant exposure and biological effects.Despite their technological benefits,PBDEs are considered a threat to environmental health due to their persistence,toxicity,and capacity to be accumulated.These pollutants have been found geographically widespread in fish,particularly in predator species such as trout.The aim of this work is to critically review the applicability and usefulness of wild trout for assessing PBDEs in freshwater environments.Reviewed reports include data from highly industrialized areas as well as areas from remote regions with relatively low human activity,including European and North American great lakes and freshwater environments in Europe,Greenland,subarctic areas and Patagonia,respectively.A summary of relevant factors were grouped into organism-specific factors(food habits,age,size,lipid content,sex and reproduction,tissue type,mechanism of contaminant uptake and metabolism),and PBDE levels in the surrounding environment(sediment).Five wild trout species[rainbow trout(Oncorhynchus mykiss),brown trout(Salmo trutta),lake trout(Salvelinus namaycush),arctic char(Salvelinus alpinus),and brook trout(Salvelinus fontinalis)],collected worldwide within the 1994 to present time frame,were considered.Multivariate techniques(principal component analysis-PCA)and mapping approach,showed clear differences in geographic distribution patterns of PBDE levels in trout depending on the region studied:wild trout from European and North American great lakes have the highest PBDE loads.This pattern could be due to high industrial activity at these locations.A correlational approach used to explore intraspecific relationships between PBDE levels and morphometry,showed positive relationships only for brown trout.Further,brown trout showed the highest trout-to-sediment ratios,which is suggestive of a relatively greater capacity of this species to accumulate PBDEs in relation to sediment levels.Overall,results suggest that adult wild trout could be useful as a PBDE bioindicator.