On the Retrieval of Volcanic Sulfur Dioxide Emissions from GOME Backscatter Measurements

We focus on the retrieval of volcanic sulfur dioxide (SO₂) emissions from an analysis of atmospheric UV backscatter spectra obtained by the Global Ozone Monitoring Experiment (GOME) spectrometer on board the ESA European Remote Sensing Satellite (ERS-2). Here, the last major eruptions of Mt. Etna on Sicily (Italy) in July/August 2001 and October/November 2002 provided an excellent opportunity to study the retrieval of SO₂ columnar amounts from ground-based, LIDAR and satellite measurements. Our study shows that the bulk of emitted SO₂ was confined in the troposphere, mainly between 700 hPa and 400 hPa which is confirmed by trajectory analysis, by LIDAR observations and AVHRR observations. The area of influence of Mt. Etna eruptions ranges from the Western Saharan Desert to Greece and the near east states and even down to the basin of Tschad, Africa. Our analysis revealed that information about the plume height of volcanic eruptions and aerosol parameters is necessary for a reliable quantitative retrieval of SO₂ from space-borne sensor data at periods perturbed by volcanic eruptions.     

Accelerated plate motion and rates of volcanicity as controls on Archean climates

Although vulcanicity is seen as a possible mechanism of climatic change, under present rates of eruptions it is difficult to envisage volcanic activity acting independently of other factors in causing significant and lasting global climate changes. This note considers the global plate-tectonic regime which may have prevailed during the Archean, and which, as a consequence, should have resulted in rates of volcanic eruptions significantly higher than at present. From this would follow atmospheric CO₂ levels significantly higher than those which prevail today. In this note we attempt to establish a link between the Archean global plate-tectonic regime and the high atmospheric CO₂ levels which are thought to have existed at that time.     

Modified HNO3 seasonality in volcanic layers of a polar ice core: Snow-pack effect or photochemical perturbation?

Using the chemical composition of snow and ice of a central Greenland ice core, we have investigated changes in atmospheric HNO₃ chemistry following the large volcanic eruptions of Laki (1783), Tambora (1815) and Katmai (1912). The concentration of several cations and anions, including SO ₄ ^2– and NO ₃ ^– , were measured using ion chromatography. We found that following those eruptions, the ratio of the concentration of NO ₃ ^– deposited during winter to that deposited during summer was significantly higher than during nonvolcanic periods. Although we cannot rule out that this pattern originates from snow pack effects, we propose that increased concentrations of volcanic H₂SO₄ particles in the stratosphere may have favored condensation and removal of HNO₃ from the stratosphere during Arctic winter. In addition, this pattern might have been enhanced by slower formation of HNO₃ during summer, caused by direct consumption of OH through oxidation of volcanic SO₂.     

A review of global stratospheric aerosol: Measurements, importance, life cycle, and local stratospheric aerosol

Stratospheric aerosol, noted after large volcanic eruptions since at least the late 1800s, were first measured in the late 1950s, with the modern continuous record beginning in the 1970s. Stratospheric aerosol, both volcanic and non-volcanic are sulfuric acid droplets with radii (concentrations) on the order of 0.1–0.5 µm (0.5–0.005 cm^− 3), increasing by factors of 2–4 (10–10³) after large volcanic eruptions. The source of the sulfur for the aerosol is either through direct injection from sulfur-rich volcanic eruptions, or from tropical injection of tropospheric air containing OCS, SO₂, and sulfate particles. The life cycle of non-volcanic stratospheric aerosol, consisting of photo-dissociation and oxidation of sulfur source gases, nucleation/condensation in the tropics, transport pole-ward and downward in the global planetary wave driven tropical pump, leads to a quasi steady state relative maximum in particle number concentration at around 20 km in the mid latitudes. Stratospheric aerosol have significant impacts on the Earth's radiation balance for several years following volcanic eruptions. Away from large eruptions, the direct radiation impact is small and well characterized; however, these particles also may play a role in the nucleation of near tropopause cirrus, and thus indirectly affect radiation. Stratospheric aerosol play a larger role in the chemical, particularly ozone, balance of the stratosphere. In the mid latitudes they interact with both nitrous oxides and chlorine reservoirs, thus indirectly affecting ozone. In the polar regions they provide condensation sites for polar stratospheric clouds which then provide the surfaces necessary to convert inactive to active chlorine leading to polar ozone loss. Until the mid 1990s the modern record has been dominated by three large sulfur-rich eruptions: Fuego (1974), El Chichón (1982) and Pinatubo (1991), thus definitive conclusions concerning the trend of non-volcanic stratospheric aerosol could only recently be made. Although anthropogenic emissions of SO₂ have changed somewhat over the past 30 years, the measurements during volcanically quiescent periods indicate no long term trend in non-volcanic stratospheric aerosol.     

火山活动对气候的影响

重大的火山喷发对气候的影响表现为地面温度降低，由于火山喷发存在季节、纬度和强度的差异，因此喷发物的空间分布特征不同，对辐射的影响也不同，降温出现的时间和降温的幅度不一致。中高纬喷发的火山主要影响发生喷发的半球，而中低纬的喷发可影响到全球，且影响时间较长；不同季节的火山喷发后，高纬度的温度响应较低纬明显，夏季的温度响应较冬季明显。有关火山活动对降水的影响目前已有了一些研究，但由于降水序列中火山信号较弱，同时还有ENSO等其他因子的影响，客观地分辨出火山的影响较复杂，目前尚无一致结论。     

The explosive volcanic eruption signal in northern hemisphere continental temperature records

Several catalogs of explosive volcanic eruptions are reviewed and their limitations assessed. A new, homogeneous set of high quality gridded temperature data for continental regions of the northern hemisphere is then examined in relation to the timing of major explosive eruptions. Several of the largest eruptions are associated with significant drops in summer and fall temperatures, whereas pronounced negative anomalies in winter and spring temperatures are generally unrelated to volcanic activity. The effect of explosive eruptions on temperature decreases latitudinally away from the location of the eruption. High latitude eruptions have the greatest impact on high and mid latitudes; low latitude eruptions mainly influence low and mid latitudes. Temperature depressions following major eruptions are very abrupt but short-lived (1 to 3 months) decreasing in magnitude over the course of the subsequent 1 to 3 years. Generally any signal is indistinguishable from noise after 12 months but a small recurrent drop in temperature is evident about 12 to 24 months after the initial anomaly. Considering all known eruptions which injected material into the stratosphere over the last 100 years (except the 5 largest eruptions) a significant temperature depression is observed over the continents only in the month immediately following the eruption. There is no evidence that large eruptions over the last 100 years have had a significant effect on low frequency temperature changes.     

火山活动与我国旱涝、冷暖的关系

本文根据近五百年的火山资料,研究了大火山的喷发与我国旱涝、冷暖的统计关系。发现火山活动对气温的影响比对降水的影响要明显得多。而且在火山喷发后我国有两次降温,分别出现在火山喷发后第8个月和第18个月。第二次降温比第一次降温要强烈得多。1951年以来,我国东北地区夏季低温冷害的发生可能与≥2级的火山喷发有一定联系。     

Uncertainty estimation of the global temperature trends for multiple radiosondes, reanalyses, and CMIP3/IPCC climate model simulations

Based on three groups of datasets that include radiosondes, reanalyses, and climate model simulations (e.g., Coupled Model Intercomparison Project, CMIP3) from 1979 to 2008, the interannual variability, global temperature trends, and their uncertainty using ensemble spread among intra-group and inter-group datasets have been discussed. The results show that the interannual temperature variability increased from the troposphere to stratosphere, and the maximum occurs around 50?hPa. The CMIP3 climate models have the largest discrepancy in the stratosphere. The intra-group correlations at 500?hPa generally show high similarity within each data group while the inter-group correlations between reanalyses and the CMIP3 climate model simulations indicate lesser similarity. In contrast, the inter-group correlation at 50?hPa is improved except with the Japanese 25-year Reanalysis Project (JRA-25) dataset, and the Twentieth Century Reanalysis (20CR) reanalysis shows a weak cross correlation. The global temperature trends are highly dependent on the individual data sources. Compared to the radiosondes, the reanalyses show a large ensemble spread of trends in the stratosphere, and the CMIP3 climate model simulations have a large ensemble spread in the height of the crossover point where tropospheric warming changes into stratospheric cooling. The largest ensemble spread among the reanalyses in the stratosphere is mainly from the large discrepancy in the JRA-25 reanalysis after 1998 and a relatively weak anomaly in the 20CR before 1986. The largest ensemble spread among the CMIP3 climate models in the troposphere is related to the influence of both volcanic eruptions and El Ni?o/La Ni?a–Southern Oscillation events. The strong anomalies corresponding to the volcanic eruptions of El Chichon in 1982 and Mt Pinatubo in 1991 are clearly identified in the stratosphere. These volcanic eruptions reduced the warming in the troposphere and strengthened the cooling in the stratosphere during the most recent 30?years.     

青海高原太阳辐射时空分布特征

对西宁莫家泉湾和玉树辐射观测站的资料分别进行了订正和插补,对青海省太阳辐射的空间分布、年际变化进行了系统研究。结果表明：青海省年总辐射量高,总的分布趋势西高东低;20世纪70年代是总辐射高值时期,而80年代处于明显的低值时期,80年代末期至90年代初期有所回升,但90年代中期后处于下降状态。70年代的高值期和80年代低值期的出现与该时段青海省云雨状况和全球重大火山喷发事件密切相关,火山喷发是导致80年代总辐射量减少的重要原因。     

Long-term Variability of Integral and Spectral Transparency of the Atmosphere at Mirny Observatory,Antarctica

The aerosol optical depth of the atmosphere obtained from spectral sun photometer measurements and the integral optical depth determined from standard actinometric observations of direct solar radiation are the parameters of the optical state of the atmosphere. The quantitative estimates of the integral transparency and aerosol optical depth of the atmosphere in Antarctica are presented, their long-term variability over the entire period of observations is analyzed. The comparison of obtained data with the estimates for other natural regions and conditions revealed that during the periods without the impact of volcanic eruptions, the levels of atmospheric aerosol turbidity in Antarctica over the recent decades are minimal on the planet and can be considered as global background characteristics.     

Temperature variability in China in an ensemble simulation for the last 1,200?years

Regional temperature anomalies in China during 800?C2005 ad in an ensemble simulation with the atmosphere?Cocean general circulation model ECHAM5/MPIOM subject to anthropogenic and natural forcings are compared to reconstructions. In a mutual assessment of three reconstructed data sets and two ensemble simulations with different solar forcings, a reconstructed data set and a simulated ensemble for weak solar variability are selected for further comparison. Temperature variability in the selected simulated and reconstructed data shows a continuous power spectrum with weak long-term memory. The simulation reveals weak long-term anomaly periods known as the Medieval Warm Period (MWP), the Little Ice Age (LIA), and the Modern Warming (MW) in the three considered regions: Northeast, Southeast, and West China. The ensemble spread yields an uncertainty of ±0.5°C in all regions. The simulated temperature varies nearly synchronously in all three regions, whereas reconstructed data hint to increased decadal variability in the West and centennial variability in the Northeast. Cold periods are found in 1200?C1300 and in 1600?C1900 ad in all regions. The coldest anomalies which are caused by volcanic eruptions in the beginnings of the thirteenth and the nineteenth centuries are only partly consistent with reconstructed data. After 1800, the annual cycle reduces in the Northeast and on the Tibetan plateau, whereas the eastern Pacific shows an enhanced summer?Cwinter contrast.     

Lidar observations of volcanic aerosol content in the atmosphere over Tomsk

Lidar observations carried out in Tomsk in August 2008 enabled to register the peaks of the back scattering ratio at the altitudes of 8–16 and 18–22 km. The computation of air masses movement trajectories demonstrated that the peaks at the altitudes of 8–16 km correspond to the aerosol layers formed as a result of volcanic eruptions on the Aleutian Islands in July–August 2008. The original software package along with the daily wind speed BADC data and HYSPLIT software with the six-hour GDAS data were used for computations. The periods from the time of eruptions to the time of observations amounted to one or two weeks and more. The verification of results of these computations for these long periods was made on the basis of the satellite data on the sulfur dioxide distribution in the atmosphere after the eruption of the Kasatochi volcano. The computation method applied enabled to simulate the main distribution characteristics of sulfur dioxide pollution areas in the atmosphere within one or two weeks after the eruption.     

COVID-19 to go? The role of disasters and evacuation in the COVID-19 pandemic

Since the start of the pandemic, some U.S. communities have faced record storms, fires, and floods. Communities have confronted the increased challenge of curbing the spread of COVID-19 amid evacuation orders and short-term displacement that result from hazards. This raises the question of whether disasters, evacuations, and displacements have resulted in above-average infection rates during the COVID-19 pandemic. This study investigates the relationship between disaster intensity, sheltering-in-place, evacuation-related mobility, and contagion following Hurricane Zeta in Southeastern Louisiana and The Wildfires in Napa and Sonoma Counties, California, known as the Glass Fire. We draw on data from the county subdivision level and mapped and aggregated tallies of Facebook user movement from the Facebook Data for Good program’s GeoInsights Portal. We test the effects of disasters, evacuation, and shelter-in-place behaviors on COVID-19 spread using panel data models, matched panel models, and synthetic control experiments. Our findings suggest associations between disaster intensity and higher rates of COVID-19 cases. We also find that while sheltering-in-place led to decreases in the spread of COVID-19, evacuation-related mobility did not result in our hypothesized surge of cases immediately after the disasters. The findings from this study aim to inform policymakers and scholars about how to better respond to disasters during multi-crisis events, such as offering hotel accommodations to evacuees instead of mass shelters and updating intake and accommodation procedures at shelters, such as administration temperature screenings, offering hand sanitizing stations, and providing isolated areas for ill evacuees.     

Variations of Total Nitrogen Oxide Content in the Atmosphere over the North Caucasus

The data are presented on total nitrogen dioxide (NO₂) content in the atmosphere from 1979 to 2009 at the high-mountain scientific station located in the unpolluted area in the North Caucasus at the height of 2070 m above the sea level (43.7° N, 42.7° E). The total content of NO₂ was measured on the basis of attenuation of direct solar radiation over slope pathways after the sunrise and before the sunset. Characteristics features are analyzed of temporal variability of total NO₂ content in the atmosphere related to its diurnal and seasonal variations, 11-year solar activity, volcanic eruptions, quasi-biennial oscillations of tropical circulation, and the El Niño effect.     

平流层火山灰气溶胶层对全球温度影响的敏感性研究

本文的数值实验结果表明:火山喷发主要造成全球性降温，火山所在的纬度和喷发的季节都可以对喷发后全球温度变化的形式产生影响。需要特别注意的是，火山喷发，尤其是北半球高纬春夏季节的喷发，能产生很强的冷夏作用，可能会对全球天气、气候的变化产生深远的影响。     

Assessing model-based and conflict-based uncertainty

Assessment panels need to communicate scientific uncertainty, and often face choices about how to simplify or synthesize it. One important distinction is between uncertainty that has been modeled, and that which derives from disagreement among experts. From an economic decision-making perspective the two are in many ways logically equivalent, yet from psychological and social perspectives they are quite different. An experiment on the communication of climate change uncertainty suggests that the two framings of uncertainty differentially influence people's estimates of likelihood and their motivation to take responsive action. It is recommended that assessment panels pay close attention to the social features of uncertainty, such as conflict between experts.     

Characteristics of anomalous precipitation events over eastern China during the past five centuries

Characteristics of anomalous precipitation events during the past five centuries in North China (NC) and the middle-lower Yangtze River Valley (MLYRV) were investigated using the data network of dryness/wetness index (DWI) over eastern China. The high occurrence frequency of anomalous precipitation events mainly occurred at periods of high solar forcing, active volcanic eruption, and large anthropogenic forcing (the twentieth century). Coherence and dipole were the two dominant modes in spatial patterns of anomalous precipitation events. Coherent floods dominated the eighteenth and nineteenth centuries, whereas coherent droughts occurred frequently in the seventeenth and twentieth centuries. The dipole patterns of anomalous precipitation events were the most frequent in the twentieth century. NC experienced more floods in the cold periods than warm periods. Both NC and the MLYRV experienced far fewer droughts and more floods in the warm eighteenth century when natural climate forcing dominated, and more droughts in the twentieth century when anthropogenic forcing dominated. Coherent drought was the only spatial pattern of precipitation significantly associated with explosive low-latitude volcanic eruptions. The increased coherent droughts and dipole patterns in the twentieth century support the findings of previous modeling studies that the tropospheric aerosols and human-induced land cover changes play important roles in the changes of summer rainfall over eastern China. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. This paper is a contribution to the AMIP-CMIP Diagnostic Sub-project on General Circulation Model Simulation of the East Asian Climate, coordinated by W.-C. Wang.     

An assessment of the possible effects of volcanic eruptions on North American climate using tree-ring data, 1602 to 1900 A.D.

Seasonal and annual temperature reconstructions derived from western North American semi-arid site tree-ring chronologies are used to examine the possible spatial response of North American climate to volcanic eruptions within the period 1602 to 1900. Low-latitude eruptions appear to give the strongest response. Cooling of the annual average temperatures in the central and eastern United States is reconstructed to follow volcanic eruptions with warming in the western states. The magnitude and spatial extent of the reconstructed cooling and warming varies seasonally. The warming that occurs in the west is strongest and most extensive in winter while the cooling in the east is most marked in summer. These results are based on reconstructed climate records which contain error terms unrelated to climatic factors. The suggested pattern of response to volcanic forcing is, however, supported by four independent temperature/proxy temperature series within the area of the temperature reconstructions. Additional support is provided by three independent series lying outside the area which suggest that the temperature spatial response may extend to the north beyond the area covered by the tree-ring reconstructions.     

Volcanic Dry Fogs, Climate Cooling, and Plague Pandemics in Europe and the Middle East

Dry fogs spawned by large volcanic eruptions cool the climate by partially blocking incident sunlight and perturbing atmospheric circulation patterns. The climatic and epidemiological consequences of seven intense volcanic dry fogs of the past 21 centuries, detected in Europe and the Middle East, are investigated by using historical reports, supplemented by tree-ring data and polar-ice acidity measurements. The signal-to-noise ratio in the historical data is very high. In four cases, the first winter following the eruption was exceptionally cold. The eruptions preceding these frigid first winters are known, or strongly suspected, to have occurred at high northern latitudes. Two of the other dry fogs are linked unambiguously to tropical eruptions, after each of which the first winter was comparatively mild. The following few years tended to be cooler on the average in all six of the instances that can be checked. Famine and disease pandemics ensued, with the epidemics in all cases reaching the Mediterranean area within 1 to 5 years after the eruptions. In at least five cases, the contagion responsible for the mass mortality was probably plague.     

The response of the East Asian summer monsoon to strong tropical volcanic eruptions

A 600-year integration performed with the Bergen Climate Model and National Centers for Environmental Prediction/National Center for Atmospheric Research （NCEP/NCAR） reanalysis data were used to investigate the impact of strong tropical volcanic eruptions on the East Asian summer monsoon （EASM） and EASM rainfall.Both the simulation and NCEP/NCAR reanalysis data show a weakening of the EASM in strong eruption years.The model simulation suggests that North and South China experience droughts and the Yangtze-Huaihe River Valley experiences floods during eruption years.In response to strong tropical volcanic eruptions,the meridional air temperature gradient in the upper troposphere is enhanced,which leads to a southward shift and an increase of the East Asian subtropical westerly jet stream （EASWJ）.At the same time,the land-sea thermal contrast between the Asian land mass and Northwest Pacific Ocean is weakened.The southward shift and increase of the EASWJ and reduction of the land-sea thermal contrast all contribute to a weakening of the EASM and EASM rainfall anomaly.