Increased Stratospheric Hydrogen Chloride in the El Chichón Cloud

Abstract

Spectroscopic observations of the total column amount of hydrogen chloride above an altitude of 12 kilometers in the latitude range 20 degrees to 40 degrees N have been made both before and 3 to 6 months after the eruptions of El Chichón Volcano in March and April 1982. In the region of the cloud of volcanic aerosols, the hydrogen chloride total column after the eruptions increased by approximately 40 percent, even after allowance is made for the global secular increase in hydrogen chloride of 5 percent per year. The column amounts of hydrogen fluoride show no such increase.

Assessment of the record of the 1982 El Chichón eruption as preserved in Greenland snow

“…In addition to the sulfur component, several other products of importance to our study were released during the E1 Chich6n eruption. Mankin and Coffey [1984] reported increased HC1 levels in the stratosphere over northern midlatitudes for several months following the eruption. Using this information, they suggested a total stratospheric loading of 0.04 x 106 Mt HC1 from the eruption itself, a 40% increase over preeruption lev- •Value in parentheses is la.…”

Long‐term trends of inorganic chlorine from ground‐based infrared solar spectra: Past increases and evidence for stabilization

“…Secondary sources of stratospheric HCl are the decomposition of CH 3 Cl (methyl chloride) released from marine algae [e.g., Cicerone, 1981] and the burning of vegetation [e.g., Penkett et al, 1980]. Direct injection of HCl from powerful volcanic eruptions is an infrequent source of stratospheric chlorine [Mankin and Coffey, 1984;Mankin et al, 1992;Coffey, 1996].…”

Chlorofluorocarbons and Ozone

“…Based on measurements made after the eruption of El Chichon in 1982, Mankin andCoffey (1984) estimated an injection of about 40 million kg of chlorine or about 6% of the chlorine content of the CFC used in 1986. Since volcanic eruptions that inject material directly into the stratosphere are relatively infrequent, the chlorine they inject decays with a time constant of 1-2 years, and El Chichon was one of the larger volcanic eruptions of the past several decades, it is unlikely that volcanoes are a major source of stratospheric chlorine.…”

“…First, the eruption may deposit chemically active material, such as water vapor and chlorine compounds, into the stratosphere. An increase in stratospheric HCl of approximately 40% was observed in the stratospheric plume created by the eruption of El Chichon, for example (Mankin and Coffey, 1984). Second, SOz from the volcano which reaches the stratosphere will be oxidized to HzS04, which can then enhance the formation of the stratospheric sulfate aerosol layer.…”