Ozone and NO₂ variations measured during the 1 August 2008 solar eclipse above Eureka, Canada with a UV‐visible spectrometer

Abstract

[1] On 1 August 2008, a solar eclipse of 98% totality passed over the Polar Environment Atmospheric Research Laboratory at Eureka, Canada (80.05°N, 86.42°W), which is run by the Canadian Network for the Detection of Atmospheric Change. During the eclipse, a zenith-sky UV-visible spectrometer measured slant column densities (SCDs) and vertical column densities (VCDs) of ozone up to 82% occultation and NO 2 up to 96% occultation, beyond which low light intensities and changes in the solar spectrum due to limb darkening compromised data quality. Ozone VCDs during the eclipse remained within natural variability, and this study is inconclusive regarding ozone oscillations due to limited temporal resolution and measurement errors toward eclipse maximum. Measured NO 2 SCDs increased and decreased symmetrically around the eclipse maximum. NO 2 SCDs were also calculated using a photochemical box model and a one-dimensional radiative transfer model. The modeled ratio of eclipse day SCDs to the previous day's SCDs was compared to the measurements. They agreed within error bars leading up to maximum occultation, but the model ratio was systematically larger than the measured ratio for the second half of the eclipse, perhaps due to changing cloud conditions throughout the eclipse. The measured NO 2 SCD ratio of 1.84 −0.43 +0.12 at 96% totality is larger than observed in past studies and agrees with modeled ratio of 1.91. Therefore our current understanding of stratospheric photochemistry is sufficient to predict the evolution of NO x chemistry through a solar eclipse.

Validation of ACE and OSIRIS ozone and NO<sub>2</sub> measurements using ground-based instruments at 80° N

“…The PEARL-GBS is an NDACC-certified instrument. It was assembled and permanently installed inside a viewing hatch in the PEARL Ridge Lab in August 2006 and has been taking measurements during the sunlit part of the year since then (Adams et al, 2010;Fraser, 2008;Fraser et al, 2009). The GBSs have similar input optics with a field-of-view of 2 • .…”

Measurements of spectral irradiance during the solar eclipse of 21 August 2017: reassessment of the effect of solar limb darkening and of changes in total ozone

“…Data collected during this campaign can be used for studying processes initiated in the atmosphere by the passing of the Moon's shadow and for validating three-dimensional (3-D) radiative transfer (RT) calculations that simulate the irradiance at Earth's surface during the period of totality (Emde and Mayer, 2007). Similar observations have been used during previous solar eclipses to study wavelength-dependent changes in spectral irradiance (Blumthaler et al, 2006;Kazantzidis et al, 2007), the change in the ratio of diffuse and direct irradiance over the period of the eclipse (Zerefos et al, 2000(Zerefos et al, , 2001), short-term and longer-lasting fluctuations in the total ozone column (TOC; Antón et al, 2010;Kazantzidis et al, 2007;Mateos et al, 2014;Mims and Mims, 1993;Zerefos et al, 2000Zerefos et al, , 2001Zerefos et al, , 2007, variations in the NO 2 column (Adams et al, 2010), and comparison of measurements during totality with 3-D RT model results (Kazantzidis et al, 2007). We revisit some of these issues by focusing on the wavelength dependence of solar limb darkening (LD), ozone observations, and the changing direct and diffuse radiation.…”

“…For example, some observations of changes in the TOC during an eclipse are contradictory. Increasing TOCs were reported for measurements from Dobson spectrophotometers (Bojkov, 1968) and Norsk institutt for luftforskning (NILU) UV multifilter instruments (Antón et al, 2010), while measurements with Brewer spectrophotometers generally decrease as an eclipse progresses . These differences cannot be explained with a real change in TOC but must be an artifact from either measurement or data processing.…”

Vertical and Oblique Ionosphere Sounding During the 21 August 2017 Solar Eclipse

“…Solar eclipses provide the opportunity to observe natural ionosphere plasma processes under unusual but relatively controlled conditions. Types of phenomenon that can be probed during an eclipse include changes in E and F region height and plasma densities (Chen et al, ), winds launched toward the center of totality (Risbeth, ) and waves launched along the eclipse path (Adams et al, ), vertical plasma motions driven by neutral winds (Boitman et al, ) and changes in vertical plasma density profiles (Chen et al, ), D region absorption (Singh et al, ), composition and chemistry changes in the thermosphere (Adams et al, ), and the accuracy of global ionosphere/thermosphere models (Muller‐Wodarg & Aylward, ).…”