Elton Chan

TL;DR: In this article, changes in baseline (here understood as representative of continental to hemispheric scales) tropospheric O3 concentrations that have occurred at northern midlatitudes over the past six decades are quantified from available measurement records with the goal of providing benchmarks to which retrospective model calculations of the global O3 distribution can be compared.

TL;DR: In this article, size distributions of water-soluble inorganic ions, including particulate sulphate (SO42-), nitrate (NO3-), ammonium (NH4+), chloride (Cl-), and base cations (K+, Na+, Mg2+, Ca2+), were measured using a Micro-Orifice Uniform Deposit Impactor (MOUDI) during fourteen short-term field campaigns at eight locations in both polluted and remote regions of eastern and central Canada.

TL;DR: In this article, a shift of the seasonal cycle at northern mid-latitudes has been shown to increase the abundance of tropospheric O3 and the observed peak concentrations now appear earlier in the year than in previous decades.

TL;DR: The recent decline in sea ice cover in the Arctic Ocean could affect the regional radiative forcing via changes in the sea ice-atmosphere exchange of dimethyl sulfide (DMS) and biogenic aerosols formed from its atmospheric oxidation, such as methanesulfonic acid (MSA) as discussed by the authors.

TL;DR: In this article, a statistical method was developed to extract baseline levels of ground level ozone in Canada and the US, and to quantify the temporal changes of baseline ozone levels on annual, seasonal, diurnal and decadal scales for the period 1997 to 2006 based on ground-level observations from 97 non-urban monitoring sites.