Surface ozone distributions and variations from 1973–1984: Measurements at the NOAA Geophysical Monitoring for Climatic Change Baseline Observatories

Abstract

Surface ozone data are presented from up to 12 years of continuous measurements at Point Barrow, Alaska; Mauna Loa, Hawaii; American Samoa, South Pacific; and South Pole, Antarctica. Annual cycle characteristics of the data are described relative to atmospheric mixing and transport processes that give rise to the observed annual ozone distributions. Both positive and negative long‐term trends are exhibited by the data. From examination of trends in the seasonal and monthly data, it is concluded that the cause of the trends is most likely a fluctuation over the years in the stratospheric‐tropospheric exchange and tropospheric circulation processes that distribute ozone within the troposphere, coupled with tropospheric circulation disturbances such as those associated with the El Niño/Southern Oscillation events of 1976 and 1982–1983. Because the positive ozone trend at Barrow occurs during summer months, photochemical ozone production in increasingly polluted Arctic air cannot be ruled out. Ozonesonde data are used to show that the surface ozone observations at Mauna Loa observatory in the downslope wind regimes, and at South Pole, are representative of ozone measurements in the free troposphere, and that the ozone trends observed at Point Barrow and Samoa are likely representative of the lower free troposphere even though the measurements are made in air modified within the boundary layer.

Observation of halogen species in the Amundsen Gulf, Arctic, by active long-path differential optical absorption spectroscopy

“…Similarly, ozone depletion events (ODEs) in the polar boundary layer, arising after sunrise, were discovered in the 1980s (1,2,3). These events were found to be related to high concentrations of filterable bromine.…”

MAX‐DOAS measurements of BrO and NO2 in the marine boundary layer

“…[2] The importance of halogen chemistry for the tropospheric ozone budget is known since the investigation of sudden ozone depletion in the polar boundary layer (BL) after polar sunrise [Oltmanns and Komhyr, 1986;Bottenheim et al, 1986]. Barrie et al [1988] reported high filterable bromine concentrations during these events, suggesting that Br species are involved in the destruction of ozone.…”

The wind field around Mauna Loa derived from surface and balloon observations

“…The Dasibi was periodically calibrated by a traveling secondary standard Dasibi photometer that was itself calibrated to a standard ultraviolet ozone meter maintained by the U.S. National Bureau of Standards [Oltmans and Komhyr, 1986]. An ozone source was used to make weekly calibration checks.…”

“…Ozone mixing ratio was measured at MLO using a Dasibi ultraviolet photometer from a sampling height of 13 m AGL [Oltmans, 1981;Oltmans and Komhyr, 1986;Oltmans and Levy, 1994]. The Dasibi was periodically calibrated by a traveling secondary standard Dasibi photometer that was itself calibrated to a standard ultraviolet ozone meter maintained by the U.S. National Bureau of Standards [Oltmans and Komhyr, 1986].…”