Agung Eruption Research Articles

Dip in the atmospheric CO2 level during the mid‐1960's

Removal of the southern oscillation effect from the CO2 records at Mauna Loa, Hawaii, and the South Pole reveals corresponding decreases following the Agung eruption in 1963. The period of the decreases roughly corresponds to the period of reduced solar transmittance, as measured at Mauna Loa. It is suggested that the decrease in CO2 level is due to reduced sea surface temperatures, for which there is some direct evidence. The temperature anomaly required to produce the CO2 level dip is calculated on the basis of several simple models and found to be close to that observed.

Umkehr vertical ozone profile errors caused by the presence of stratospheric aerosols

The unusually large increase in stratospheric aerosol concentration resulting from the eruption of Agung in 1963 is shown to produce fictitious anomalies in the record of vertical ozone profiles determined from Umkehr observations at Aspendale, Australia. The anomalies are of sufficient magnitude that an empirical haze error to the profiles can be extracted from a comparison between seasonal averages of ozone profiles observed shortly after the Agung event and ozone profiles observed during periods of volcanic quiescence. Haze errors to the ozone profiles are also theoretically calculated for various models of vertical profiles of aerosols, ranging from relatively large concentrations of tropospheric aerosols to large concentrations located exclusively in the stratosphere. It is shown that the theoretically determined haze errors are essentially of the same character as those determined empirically. Haze error corrections are applied to a long‐term Umkehr record of north temperate upper stratospheric ozone concentration following Agung. The results imply that the anomalously low ozone concentrations in the upper stratosphere, noted after the eruption of Agung and Fuego in 1974, may not be real.

Possible effects of volcanic eruptions on stratospheric minor constituent chemistry

Although stratosphere penetrating volcanic eruptions have been infrequent during the last half century, periods have existed in the last several hundred years when such eruptions were significantly more frequent. Several mechanisms exist for these injections to affect stratospheric minor constitutent chemistry, both on the long-term average and for short-term perturbations. These mechanisms are reviewed and, because of the sensitivity of current models of stratospheric ozone to chlorine perturbations, quantitative estimates are made of chlorine injection rates. It is found that, if chlorine makes up as much as 0.5 to 1% of the gases released and if the total gases released are about the same magnitude as the fine ash, then a major stratosphere penetrating eruption could deplete the ozone column by several percent. The estimate for the Agung eruption of 1963 is just under 1% an amount not excluded by the ozone record but complicated by the peak in atmospheric nuclear explosions at about the same time. The long-term contribution to stratospheric CIX by volcanic eruptions is estimated as ∼0.1 ppbv for the period 1900–60 and ∼1 ppbv for the much more volcanically active period 1780–1840. All of the estimates are subject to large uncertainties, perhaps a factor of 2 or 3 on the high side and a factor of 10 or more on the low side.

Volcanically Related Secular Trends in Atmospheric Transmission at Mauna Loa Observatory, Hawaii

Twenty years of atmospheric transmission data from Mauna Loa Observatory show secular decreases at irregular intervals. In addition, a regular annual variation is present during unperturbed as well as perturbed periods. These variations in transmission can be measured to a few tenths of a percent from the data record. Transient decreases in transmission are strongly correlated with explosive volcanic eruptions that inject effluent into the stratosphere. Recovery from these ejections takes as much as 8 years and the recovery curve is linear. Observations in 1977 at Mauna Loa show that, for the first time since the Mount Agung eruption in 1963, the atmospheric transmission of direct-incidence solar irradiation at Mauna Loa returned to values measured in 1958 to 1962.

Estimate of Global Temperature Variations in the 100–30 mb Layer between 1958 and 1977

Based on a network of 42 radiosonde stations distributed around the world, the (smoothed) global temperature within the 100–30 mb layer was indicated to be colder in the spring of 1977 than at any time since initiation of the record in 1958, a result mainly of very cold temperatures in the tropics (east wind phase of the quasi-biennial oscillation). This cold followed by about six months the record-cold global temperature observed for the surface–100 mb layer. The highest global temperature of record in the 100–30 mb layer was observed after the eruption of Mt. Agung in 1963, the phase of the quasi-biennial oscillation in the tropics being such as to augment any stratospheric warming induced by Agung. Since the Agung eruption, there is indicated to have been slightly greater global cooling in the 100–30 mb layer than in the surface–100 mb layer. However, this result derives solely from uncertain Southern Hemisphere data and cannot be cited as evidence of a carbon dioxide influence on atmospheric temperature because in the Northern Hemisphere, if anything, an opposite tendency has been observed. The quasi-biennial oscillation of temperature in the low tropical stratosphere extends, with much reduced amplitude, into the north-temperate-latitude stratosphere with a lag time of about two months. There is evidence of tropospheric temperature variations in north extratropics which follow the three-year oscillations in the tropics by about six months (of obvious importance for seasonal foreshadowing in northern latitudes), as well as evidence that temperature variations in the low tropical stratosphere follow the variations in the tropical troposphere by about nine months. However, a longer data record is required to clarify the relation between El Nin˜o occurrences, or the Southern Oscillation, and the quasi-biennial oscillation of the tropical stratosphere.

Volcanic dust influence on glacier mass balance at high latitudes

EXPLOSIVE eruptions, which inject large quantities of volcanic dust into the earth's upper atmosphere, are believed to be important factors in climatic change. Theoretical considerations suggest that the greatest climatic effect of a stratospheric dust veil would be at high latitudes during summer months, when solar radiation passes through the greatest depth of atmosphere and the surface is illuminated continously1. Furthermore, the residence time of volcanic dust is greatest at high latitudes, where it may remain in the upper atmosphere for a decade or more, depending on particle size and initial injection height2. Here we present evidence that the eruption of Mount Agung (8 °S, 115 °E) in March 1963, was responsible for a marked change in the climate of the North American High Arctic and that this change has had a significant impact on glacier mass balance in the region.

Combined use of lidar and numerical diffusion models to estimate the quantity and dispersion of volcanic eruption clouds in the stratosphere: Vulcán Fuego, 1974, and Augustine, 1976

Methods are described for estimating the quantity and dispersion on a global scale of the material injected into the stratosphere by a violent volcanic eruption by using a combination of lidar measurements of stratospheric aerosols and a previously described two-dimensional atmospheric dispersion model with the initial volcanic cloud as the ‘source function’ (Cadle et al., 1976). The technique involves comparing the lidar data with model predictions normalized by using data of various kinds obtained after the Gunung Agung eruption in Bali in 1963. In this paper we show that the estimates for the Fuego eruption of 1974 can be made equally well by comparing model and lidar measurements of peak stratospheric concentrations or the total masses within a range of altitudes in a column above the place where the lidar measurements were made. The lidar data previously reported have been extended to several months following the eruption of Augustine volcano in Alaska during January and February 1976. The results indicate that the Augustine eruption must have injected no more than one fiftieth of the amount of material into the stratosphere that was injected by Agung and confirm the previous finding (Cadle et al., 1976) that Fuego injected one fifth of the amount injected by Agung.

Factors Governing Tropospheric Mean Temperature

Two possible factors, which in addition to Pacific sea surface temperatures might affect the mean temperatures of the tropical troposphere are Atlantic sea surface temperatures and volcanic aerosol. The Mt. Agung eruption in March 1963 produced a decrease of about 0.5 degrees C in the mean temperature of the tropical troposphere. The contribution of the Atlantic is not significant.

The global scale dispersion of the eruption clouds from major volcanic eruptions

A two-dimensional dynamic model developed by Louis and Danielsen to study the global scale transport of tracers applied to the investigation of the global scale dispersion of the eruption clouds of Volcan de Fuego (October 1974), Gunung Agung (March 1973), and Bezymianny (March 1956). The strength and chemical composition of source functions were adjusted so that the concentrations and concentration distributions agreed in general with actual measurements, published and unpublished. The resulting agreement with lidar measurements of the stratospheric aerosols is especially encouraging. The results indicate that the Fuego eruption injected no more than one fifth of the mass of material into the stratosphere that was injected by the Agung eruption. Furthermore, an eruption of the size of that of Agung may inject into the stratosphere much greater amounts of chlorine in the form of hydrogen chloride than presently reaches the stratosphere annually as chlorofluoromethanes. As the model is applied to additional eruptions, the adjustments that must be made to the strength and Chemical composition of the eruption cloud so that the model predictions agree with measurements of atmospheric trace constituents resulting from the eruption will furnish important information concerning the very early stages of the eruption cloud that to date has been very difficult to obtain.

The effect of volcanic eruptions on global turbidity, and an attempt to detect long‐term trends due to man

AbstractFollowing a brief discussion of early radiation measurements and the interpretation of the effects of volcanic eruptions in the light of current knowledge of the stratosphere, recent radiation data from USSR, Japan, USA and Australia are examined. Whilst the effects of the Agung eruption are clearly seen on a global scale, the analysis yields no convincing evidence for a recent world‐wide increase in atmospheric turbidity. The need for extreme measurement accuracy is emphasized in the context of long‐term atmospheric monitoring.

The sizes of the stratospheric volcanic particles over south-east Australia after Mt. Agung's eruption in 1963

Assuming an air layer of geometric thickness L, a particle number density N, particles of uniform radius a and density ϱ, the optical depth of the particle layer is τ = πa2 QNL, Q being the extinction efficiency factor. The total mass M of the particles in a vertical air column of unit cross-section is M = (4/3)πa3ρNL. The ratio of the two quantities is M/τ = 4aϱ/3Q. The above ratio is applied to data of τ for the observed 20% reduction in direct solar radiation over south-east Australia about mid-1963, reported by Dyer and Hicks. For M, an estimate given by Deirmendjian is used. It is inferred from the above ratio that a particle radius of a few tenths of one micron leads to a Q value such that the values for the radius and for Q are mutually consistent with the Mie scattering theory. If we assume much smaller radii, we run into contradiction with the latter. We thus conclude that most of the extinction must have been effected by particles of radii of about the same magnitude as the wavelengths where the bulk of the solar radiation energy resides. We estimate that the particle concentration may have been about 5 cm−3 and that absorption by the particles was probably very small.

The sizes of the stratospheric volcanic particles over south‐east Australia after Mt. Agung's eruption in 1963

AbstractAssuming an air layer of geometric thickness L, a particle number density N, particles of uniform radius a and density ϱ, the optical depth of the particle layer is τ = πa2 QNL, Q being the extinction efficiency factor. The total mass M of the particles in a vertical air column of unit cross‐section is M = (4/3)πa3ρNL. The ratio of the two quantities is M/τ = 4aϱ/3Q.The above ratio is applied to data of τ for the observed 20% reduction in direct solar radiation over south‐east Australia about mid‐1963, reported by Dyer and Hicks. For M, an estimate given by Deirmendjian is used. It is inferred from the above ratio that a particle radius of a few tenths of one micron leads to a Q value such that the values for the radius and for Q are mutually consistent with the Mie scattering theory. If we assume much smaller radii, we run into contradiction with the latter. We thus conclude that most of the extinction must have been effected by particles of radii of about the same magnitude as the wavelengths where the bulk of the solar radiation energy resides. We estimate that the particle concentration may have been about 5 cm−3 and that absorption by the particles was probably very small.

A climatic model of solar radiation and temperature change

Mean monthly temperatures for the Northern Hemisphere were determined for the years 1955 through 1968 following the same procedures used by H. C. Willett and J. M. Mitchell, Jr., in their studies of long-term trends. It was found that the downward trend they reported starting in the 1940s continued, though interrupted, into the 1960s. The temperature data when combined with radiation data and other components of the hemispheric energy budget led to the formulation of the response ratio, the relationship between change in incoming solar radiation and change in temperature. When this response ratio was applied to the reported trends in direct solar radiation and to the decrease in direct solar radiation following the eruption of Agung in 1963, a probable cause-effect relationship was suggested.

The stratospheric dust event of October 1971

Since early 1970, color ratios of twilight photometry near Boston, Massachusetts, have indicated the return of stratospheric turbidity to normal conditions. However, rather strongly reddened twilights were recorded on October 1 and 17, 1971, and coarse, irregular striations were observed. From trajectories it may be presumed that the stratospheric dust observed on October 1 originated from a still unreported volcanic eruption along the rim of the northern Pacific Ocean. Later, the dust cloud was found to have moved over the southwestern United States before appearing over Boston again. Enhanced twilights and striations were observed until early 1972, when color ratios became very low, as is common in the spring season. The total stratospheric dust burden of the October event is estimated to have been 0.2 million metric tons, compared with the 2 million metric tons of dust in the northern hemisphere from the Agung eruption on Bali in 1963.

Stratospheric Properties and Bali Dust

NEWELL has drawn attention to an anomalous increase of about 5° C in the stratospheric temperatures in tropical and mid-latitudes in the Southern Hemisphere since 1963. He suggested a causal relationship between this increase and the eruption of Mount Agung in March 1963, which injected large quantities of volcanic material into the stratosphere2. I wish to draw attention to several publications which have shown that at the same time a breakdown occurred in the quasi-biennial oscillation. This should be considered before Newell's conclusion can be accepted.

Atmospheric turbidity after the agung eruption of 1963 and size distribution of the volcanic aerosol

Data on atmospheric transmission related to the stratospheric layer of aerosol from the explosion of the Agung volcano in March 1963 at Bali Island are discussed. In midlatitudes of the southern hemisphere the abnormal aerosol optical thickness at λ500 nm reached a peak of 0.3 during September 1963 but became very small after mid-1965. Some pyrheliometric data require consideration of the λ dependency of attenuation on the volcanic dust to conform to spectral data. Over the northern hemisphere, the decrease of transmission due to Agung aerosol was marginal, and a strong seasonal variation that had been derived from pyrheliometric data seems questionable. Observations of the brightness of the eclipsed moon and analysis of brightness of the umbra are in good agreement with the above data if referred to the proper hemisphere. Indications on the size distribution of the volcanic dust from λ dependence of dust attenuation and sky light observations are discussed.

Stratospheric Temperature Change from the Mt. Agung Volcanic Eruption of 1963

The volcanic dust from the Mt. Agung eruption on 17 March 1963 strongly influenced the solar radiation reaching the ground, so much so that surface solar radiation measurements could be used to track the spread of the cloud over the globe. This paper outlines fairly strong circumstantial evidence that the presence of the aerosol caused increases of the stratospheric temperature of approximately 5C.

Modification of Stratospheric Properties by Trace Constituent Changes

IT has been suggested that large quantities of water vapour and other pollutants introduced into the stratosphere by supersonic transporters may change the basic properties of the stratosphere1. But what happens when large changes in trace constituent concentrations occur naturally, for example, after a volcanic eruption ? The stratospheric temperature seems to increase by about 5° C and it remains higher than normal for several years. Some of the evidence for this is given in. Figs. 1 and 2. which are based on daily upper air data from Australia and New Zealand. Monthly temperature means were formed for each month, then mean monthly values computed from data for the period 1958–62 inclusive. Deviations from these long term values were noted, and a three-month running average obtained. Fig. 1 gives the time variations of these deviations at selected stations. A major eruption of Mt Agung, Bali (8° S, 115° E), occurred on March 17, 1963, and there have been reports of other eruptions that year. Temperature at the low latitude stations increased almost immediately and remained higher than normal for over two years. Fig. 2 contains meridional cross-sections of the temperature deviations for particular months based on station data for the longitude region 110° E to 180° E. At the beginning of 1963, temperature was below the five year normal and the time variations had been following the characteristic southern hemisphere biennial pattern2. The eruption interrupted this pattern. The cross-sections bear some resemblance to those for the products of nuclear weapons tests (for example, see the isolines of tungsten 185 radioactivity in ref. 3), as might be expected. The deviation pattern exhibits a maximum at low latitudes in the lower stratosphere and slopes downwards towards the pole, in some cases at a slope greater than that of the potential temperature surfaces. It is difficult to detect the changes, if any, below 300 mbar. While negative values predominate in the examples shown, it was not possible to draw in a −2° C contour. Similarly, at higher latitudes in the stratosphere the effect is uncertain; large deviations from average are more common there. It has been reported2 that the Australian Weather Bureau changed its thermistor mounting at the end of 1962. Maps of temperature for January 1963 and 1964 show that the temperature change is present at other longitudes.

Anisotropic diffusion coefficients and the global spread of volcanic dust

The global spread of volcanic dust from the Mt. Agung eruption of March 17, 1963, is assessed on the basis of the decrement in direct solar radiation. The data suggest the establishment of an equatorial reservoir at height of about 22 km, followed by poleward transport into each hemisphere during winter. The poleward-moving waves of dust appeared to have constant amplitude in any one season, with a poleward progression rate of 40 cm sec−1 between 30° and 90° latitude. Analytic solutions are found for the diffusion coefficients Kyy and Kyz for the following cases: (1) 〈ν〉 = 0, i.e., no mean motion. (2) 〈ν〉 = 20 sin 6ϕ, corresponding to a three-cell pattern for the meridional circulation. (3) Same as (2) but with assumption of also latitude attenuation, in an attempt to allow for a stratospheric source of dust particles from gaseous products of the volcano. The results for Kyy are in general agreement with findings of other workers, but the values of Kyz appear to be too high, particularly in the region 30°–60° latitude. It is speculated that better agreement could be found if the diffusion coefficients were chosen to vary seasonally.

Twilights and Stratospheric Dust Before and After the Agung Eruption

Many absolute measurements of twilight sky radiance were made in six spectral ranges from lambda377 nm to lambda970 nm at 20 degrees elevation in the solar vertical, and mostly from sunset to 6 degrees -10 degrees sun depression (sd) in southern Germany, from fall 1962 to summer 1967, and at Bedford, Massachusetts, during winter 1967-1968. A strong change of twilight radiance, especially a large increase in the amplitude of the red/green color ratio between 4.5 degrees (main purple light) and 1 degrees sd, was observed in January 1964 following the explosive eruption of the Agung volcano in March 1963, but twilights were still abnormal and variable in early 1968. Dust mixing profiles of some typical twilight groups were derived, and the volcanic twilights show, as do other optical and direct soundings of the same period, a strong maximum near 20 km. A strong secondary red/green maximum (visually observed as secondary purple light) developed at sun depressions greater than 6 degrees of the volcanic twilights. This seems to have been caused by multiple scattering and not by mesospheric dust. A few twilight observations in 1964 from Australia indicate considerably more volcanic dust in accordance with transmission data, while no stratospheric dust is indicated in Arctic twilights of spring 1966. In order to verify the persistence of abnormal twilight conditions for more than five years, the dependence on red wavelength of the red/green color ratio is investigated, and some earlier twilight measurements are discussed. This persistence may have to be related to even higher amounts of dust in the tropical stratosphere.