Journal Article•
Parameterization of Spatio-temporal Patterns of Volcanic Aerosol Induced Stratospheric Optical Depth and its Climate Radiative Forcing
01 Jan 1999-Atmosfera (Universidad Nacional Autónoma de México. Centro de Ciencias de la Atmósfera)-Vol. 12, Iss: 2, pp 111-133
TL;DR: In this article, a radiation transfer parameterization was proposed to investigate volcanic climate forcing, which takes into account the undisturbed seasonal and latitudinal pattern of radiation uptake as well as the extension of a ray path in a spherical layer.
Abstract: Explosive volcanism is known to have a large impact on climate. Thus, in order to understand past climate variability, volcanic forcing has to be considered. For the most recent explosive volcanic eruptions instrumental data of stratospheric aerosol optical depth are available. For early eruptions only index values with no or only crude spatial and seasonal resolution do exist. To estimate the spatio-temporal patterns of aerosol induced optical depth of the atmosphere due to any known strong volcanic eruption, we introduce a stratospheric aerosol distribution parameterization using recent information about stratospheric transport phenomena as well as date, location, and strength of an eruption. Using this parameterization, observed time series of stratospheric aerosol optical depth can be reproduced with reasonable accuracy. To investigate volcanic climate forcing, we introduce a radiation transfer parameterization which takes into account the undisturbed seasonal and latitudinal pattern of radiation uptake as well as the extension of a ray path in a spherical layer. Thus, spatio-temporal patterns of volcanic climate forcing for any known volcanic eruption can be estimated, too.
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TL;DR: This paper extracted volcanic sulfate signals from each ice core record by applying a high-pass loess filter to the time series and examining peaks that exceed twice the 31-year running median absolute deviation.
Abstract: [1] Understanding natural causes of climate change is vital to evaluate the relative impacts of human pollution and land surface modification on climate. We have investigated one of the most important natural causes of climate change, volcanic eruptions, by using 54 ice core records from both the Arctic and Antarctica. Our recently collected suite of ice core data, more than double the number of cores ever used before, reduces errors inherent in reconstructions based on a single or small number of cores, which enables us to obtain much higher accuracy in both detection of events and quantification of the radiative effects. We extracted volcanic deposition signals from each ice core record by applying a high-pass loess filter to the time series and examining peaks that exceed twice the 31-year running median absolute deviation. We then studied the spatial pattern of volcanic sulfate deposition on Greenland and Antarctica and combined this knowledge with a new understanding of stratospheric transport of volcanic aerosols to produce a forcing data set as a function of month, latitude, and altitude for the past 1500 years. We estimated the uncertainties associated with the choice of volcanic signal extraction criteria, ice core sulfate deposition to stratospheric loading calibration factor, and the season for the eruptions without a recorded month. We forced an energy balance climate model with this new volcanic forcing data set, together with solar and anthropogenic forcing, to simulate the large-scale temperature response. The results agree well with instrumental observations for the past 150 years and with proxy records for the entire period. Through better characterization of the natural causes of climate change, this new data set will lead to improved prediction of anthropogenic impacts on climate. The new data set of stratospheric sulfate injections from volcanic eruptions for the past 1500 years, as a function of latitude, altitude, and month, is available for download in a format suitable for forcing general circulation models of the climate system.
603 citations
01 Jan 2001
324 citations
TL;DR: In this article, the authors used the Community Earth System Model Last Millennium Ensemble (CESM-LME) by examining of ensemble realizations with distinct posteruption ENSO responses.
Abstract: The hydroclimate response to volcanic eruptions depends both on volcanically induced changes to the hydrologic cycle and on teleconnections with the El Nino–Southern Oscillation (ENSO), complicating the interpretation of offsets between proxy reconstructions and model output. Here, these effects are separated, using the Community Earth System Model Last Millennium Ensemble (CESM-LME), by examination of ensemble realizations with distinct posteruption ENSO responses. Hydroclimate anomalies in monsoon Asia and the western United States resemble the El Nino teleconnection pattern after “Tropical” and “Northern” eruptions, even when ENSO-neutral conditions are present. This pattern results from Northern Hemisphere (NH) surface cooling, which shifts the intertropical convergence zone equatorward, intensifies the NH subtropical jet, and suppresses the Southeast Asian monsoon. El Nino events following an eruption can then intensify the ENSO-neutral hydroclimate signature, and El Nino probability is enhan...
152 citations
TL;DR: In this paper, the authors used a state-of-the-art climate model to simulate the last millennium and found that modelled variations of surface temperature in the Northern Hemisphere are coherent with existing reconstructions.
Abstract: The variability of the climate during the last millennium is partly forced by changes in total solar irradiance (TSI). Nevertheless, the amplitude of these TSI changes is very small so that recent reconstruction data suggest that low frequency variations in the North Atlantic Oscillation (NAO) and in the thermohaline circulation may have amplified, in the North Atlantic sector and mostly in winter, the radiative changes due to TSI variations. In this study we use a state-of-the-art climate model to simulate the last millennium. We find that modelled variations of surface temperature in the Northern Hemisphere are coherent with existing reconstructions. Moreover, in the model, the low frequency variability of this mean hemispheric temperature is found to be correlated at 0.74 with the solar forcing for the period 1001–1860. Then, we focus on the regional climatic fingerprint of solar forcing in winter and find a significant relationship between the low frequency TSI forcing and the NAO with a time lag of more than 40 years for the response of the NAO. Such a lag is larger than the around 20-year lag suggested in other studies. We argue that this lag is due, in the model, to a northward shift of the tropical atmospheric convection in the Pacific Ocean, which is maximum more than four decades after the solar forcing increase. This shift then forces a positive NAO through an atmospheric wave connection related to the jet-stream wave guide. The shift of the tropical convection is due to the persistence of anomalous warm SST forcing the anomalous precipitation, associated with the advection of warm SST by the North Pacific subtropical gyre in a few decades. Finally, we analyse the response of the Atlantic meridional overturning circulation to solar forcing and find that the former is weakened when the latter increases. Changes in wind stress, notably due to the NAO, modify the barotropic streamfunction in the Atlantic 50 years after solar variations. This implies a wind-driven modification of the oceanic circulation in the Atlantic sector in response to changes in solar forcing, in addition to the variations of the thermohaline circulation.
116 citations
Cites methods from "Parameterization of Spatio-temporal..."
...The volcanic aerosols in the stratosphere are transported latitudinally in the model following Grieser and Schönwiese (1999) parametrisation....
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TL;DR: This paper showed that the subset of CMIP5 historical climate simulations that produce bidecadal variability exhibits a robust synchronization, with a maximum in Atlantic Meridional Overturning Circulation (AMOC) 15 years after the 1963 Agung eruption.
Abstract: While bidecadal climate variability has been evidenced in several North Atlantic paleoclimate records, its drivers remain poorly understood Here we show that the subset of CMIP5 historical climate simulations that produce such bidecadal variability exhibits a robust synchronization, with a maximum in Atlantic Meridional Overturning Circulation (AMOC) 15 years after the 1963 Agung eruption The mechanisms at play involve salinity advection from the Arctic and explain the timing of Great Salinity Anomalies observed in the 1970s and the 1990s Simulations, as well as Greenland and Iceland paleoclimate records, indicate that coherent bidecadal cycles were excited following five Agung-like volcanic eruptions of the last millennium Climate simulations and a conceptual model reveal that destructive interference caused by the Pinatubo 1991 eruption may have damped the observed decreasing trend of the AMOC in the 2000s Our results imply a long-lasting climatic impact and predictability following the next Agung-like eruption
103 citations
References
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TL;DR: A composite estimate of the magnitude of past explosive eruptions, referred to as the Volcanic Explosivity Index (VEI), is proposed as a semiquantitative compromise between poor data and the need in various disciplines to evaluate the record of past volcanism as mentioned in this paper.
Abstract: A composite estimate of the magnitude of past explosive eruptions, referred to as the Volcanic Explosivity Index (VEI), is proposed as a semiquantitative compromise between poor data and the need in various disciplines to evaluate the record of past volcanism. The VEI is assigned to more than 8000 historic and prehistoric eruptions. It is shown that the VEI can help detect incompleteness and reporting biases and can help in selecting subsets of the historical record suitable for each study. The VEI is a composite estimate of Walkers (1980) magnitude and/or intensity and/or destructiveness and/or (less frequently) dispersive power, violence, and energy release rate, depending on the data that are available.
1,670 citations
"Parameterization of Spatio-temporal..." refers background in this paper
...…(DV 1) proposed by Lamb (1970, 1977, 1983), the severity index by Mitchell (1970), the volcanic explosivity index (V El) by Simkin et al. (1981) or Newhall and Self (1982), the smithsonian volcanic index (SV 1) by Schonwiese (1988), or Cress and Schonwiese (1992) and the ice core volcanic index…...
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TL;DR: In this paper, the delta-Eddington approximation was used to calculate monochromatic radiative fluxes in an absorbing-scattering atmosphere, by combining a Dirac delta function and a two-term approximation, which overcomes the poor accuracy of the Eddington approximation for highly asymmetric phase functions.
Abstract: This paper presents a rapid yet accurate method, the “delta-Eddington” approximation, for calculating monochromatic radiative fluxes in an absorbing-scattering atmosphere. By combining a Dirac delta function and a two-term approximation, it overcomes the poor accuracy of the Eddington approximation for highly asymmetric phase functions. The fraction of scattering into the truncated forward peak is taken proportional to the square of the phase function asymmetry factor, which distinguishes the delta-Eddington approximation from others of similar nature. Comparisons of delta-Eddington albedos, transnmissivities and absorptivities with more exact calculations reveal typical differences of 0–0.022 and maximum differences of 0.15 over wide ranges of optical depth, sun angle, surface albedo, single-scattering albedo and phase function asymmetry. Delta-Eddington fluxes are in error, on the average, by no more than 0.5%0, and at the maximum by no more than 2% of the incident flux. This computationally fa...
1,075 citations
TL;DR: A global stratospheric aerosol database employed for climate simulations is described in this article, where the authors estimate the optical depths from optical extinction data, whose quality increases with time over that period.
Abstract: A global stratospheric aerosol database employed for climate simulations is described. For the period 1883-1990, aerosol optical depths are estimated from optical extinction data, whose quality increases with time over that period. For the period 1850-1882, aerosol optical depths are more crudely estimated from volcanological evidence for the volume of ejecta from major known volcanoes. The data set is available over Internet.
884 citations
"Parameterization of Spatio-temporal..." refers background or result in this paper
...The first one (PI) is given in equation (2) to fit the aerosol transport parameterization to observations given by Sato et al. (1993), Sato (1995), and Stothers (1996). Because the AOD values by Stothers (1996) are valid for the visible speetral range and the AOD values provided by Sato et al. (1993) and Sato (1995) relate to a wavelength of ....
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...The AOD time series, calculated in this paper, is better correlated with the time series proposed by Stothers (1996) than with the time series published by Sato (1995). Apart from the Northern Hemisphere extra-tropics, correlations between the data of Sato (1995) and Stothers (1996) are not as high as data resulting from this paper compared with both of the other series, respectively....
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...The first one (PI) is given in equation (2) to fit the aerosol transport parameterization to observations given by Sato et al. (1993), Sato (1995), and Stothers (1996)....
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...Solid lines: this paperj daehed lines: Stothere (1996); dotted lines: Sato et al. (1993, 1995)....
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...Sato et al. (1993) provide annual mean stratospheric AOD with respect to the wavelength A = ....
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01 Jan 1970-Philosophical transactions - Royal Society. Mathematical, physical and engineering sciences
TL;DR: In this paper, the authors examine aspects of importance, or possible importance, to meteorology, such as the dust veils created in the atmosphere, particle sizes and distribution, heights, fall speeds and atmospheric residence times.
Abstract: After defining the terms commonly used in reporting volcanic eruptions and noting previous approaches to assessment of their magnitudes, this study proceeds to examine aspects of importance, or possible importance, to meteorology―principally the dust veils created in the atmosphere, particle sizes and distribution, heights, fall speeds and atmospheric residence times. Later sections deal with spread of the dust by the atmospheric circulation and the direct effects apparent upon radiation, surface temperature and extent of ice in the polar regions. These effects, as well as various crude measures of the total quantity of solid matter thrown up, are used to arrive at numerical assessments of volcanic eruptions in terms of a dust veil index (d. v. i.). The latitude of origin of the dust (latitude of the volcano) receives some attention, and apparently affects the course of development of the atmospheric circulation over the three or four years following, at least in the case of great eruptions (d. v. i. > 100 over one hemisphere). Effects upon the extent of ice on the polar seas may be of somewhat longer duration, and thereby influence the atmospheric circulation over a longer period of years, since there seems to be some association with the cumulative d.v.i. values when successive great eruptions occur with only few years between. The time distribution of volcanic dust since the last Ice Age, and since a. d. 1500, are indicated in as much detail as the evidence permits. Some associations with changes of climate are suggested, but it is clear that volcanic dust is not the only, and probably not the main, influence in this. The appendices give a chronology of eruptions (including those which it seems possible to dismiss as regards any effect on world weather or climate) and a chronology of d. v. i. values. A third appendix displays by means of graphs the variation of some circulation parameters in January and July in the region of northwest Europe over the years immediately following forty of the greatest eruptions since 1680.
686 citations
"Parameterization of Spatio-temporal..." refers methods in this paper
...These index value time series are the dust veil index (DV 1) proposed by Lamb (1970, 1977, 1983), the severity index by Mitchell (1970), the volcanic explosivity index (V El) by Simkin et al. (1981) or Newhall and Self (1982), the smithsonian volcanic index (SV 1) by Schonwiese (1988), or Cress and…...
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Book•
01 Jan 1976
557 citations
"Parameterization of Spatio-temporal..." refers methods in this paper
...(13) It can be approximated by the formulation given by Paltridge and Platt (1976) ó = .006918 - .399912 cos {) + .070257 sin {) - .006758 cos 2{) + .000907 sin 2{) - .002697 cos 3{) + .001480 sin 3{) (14) with {) = 211"t y ti> = 211" (td - 12h)....
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...It can be approximated by the formulation given by Paltridge and Platt (1976)...
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