Search

Deep convection within the Asian summer monsoon (ASM) transports surface level air into the upper troposphere-lower stratosphere (UTLS). This work aims to understand the distribution of NO

TROPOMI, on-board the Sentinel-5 Precursor satellite is a nadir-viewing spectrometer measuring reflected sunlight in the ultraviolet, visible, near-infrared, and shortwave infrared spectral range. From these spectra several important air quality and climate-related atmospheric constituents are retrieved at an unprecedented high spatial resolution, including nitrogen dioxide (NO(2)). We present the first retrievals of TROPOMI NO(2) over the Canadian Oil Sands, contrasting them with observations from the OMI satellite instrument, and demonstrate its ability to resolve individual plumes and highlight its potential for deriving emissions from individual mining facilities. Further, the first TROPOMI NO(2) validation is presented, consisting of aircraft and surface in-situ NO(2) observations, as well as ground-based remote-sensing measurements between March and May 2018. Our comparisons show that the TROPOMI NO(2) vertical column densities are highly correlated with the aircraft and surface in-situ NO(2) observations, and the ground-based remote-sensing measurements with a low bias (15–30 %) over the Canadian Oil Sands. PLAIN LANGUAGE SUMMARY: Nitrogen dioxide (NO(2)) is a pollutant that is linked to respiratory health issues and has negative environmental impacts such as soil and water acidification. Near the surface the most significant sources of NO(2) are fossil fuel combustion and biomass burning. With a recently launched satellite instrument (TROPOspheric Monitoring Instrument; TROPOMI) NO(2) can be measured with an unprecedented combination of accuracy, spatial coverage, and resolution. This work presents the first TROPOMI NO(2) measurements near the Canadian Oil Sands and shows that these measurements have an outstanding ability to detect NO(2) on a very high horizontal resolution that is unprecedented for satellite NO(2) observations. Further, these satellite measurements are in excellent agreement with aircraft and ground-based measurements.

The variability of stratospheric aerosol loading between 1985 and 2010 is explored with measurements from SAGE II, CALIPSO, GOMOS/ENVISAT, and OSIRIS/Odin space-based instruments. We find that, following the 1991 eruption of Mount Pinatubo, stratospheric aerosol levels increased by as much as two orders of magnitude and only reached "background levels" between 1998 and 2002. From 2002 onwards, a systematic increase has been reported by a number of investigators. Recently, the trend, based on ground-based lidar measurements, has been tentatively attributed to an increase of SO2 entering the stratosphere associated with coal burning in Southeast Asia. However, we demonstrate with these satellite measurements that the observed trend is mainly driven by a series of moderate but increasingly intense volcanic eruptions primarily at tropical latitudes. These events injected sulfur directly to altitudes between 18 and 20 km. The resulting aerosol particles are slowly lofted into the middle stratosphere by the Brewer-Dobson circulation and are eventually transported to higher latitudes.

[1] For the first time OSIRIS has derived and analyzed mesopause region temperatures at the summer poles. Temperatures have been derived from observations of O2 A-band emission spectra, with a typical estimated accuracy of better than ±3 K at altitudes near 90 km. The current results show that OSIRIS temperatures near the mesopause are usually ∼10 K colder than CO2 temperature results from the SABER instrument on board the TIMED satellite, however the difference between OSIRIS temperatures and SOFIE ice temperatures agrees well with previous model results, and OSIRIS temperatures are consistent with potassium lidar derived atmospheric temperatures. Between 2003–2010, the retrieved OSIRIS polar summer mesopause temperatures are often below 120 K, and on 16 January 2008, at 80°S and 223°E, a temperature of 91 ± 6 K was retrieved at an altitude of 92 km.

[1] One of the largest solar proton events in the past thirty years took place on October 28, 2003 and had a significant impact on the Earth's middle atmosphere. The incoming protons produce significant amounts of HOx constituents in the mesosphere and upper stratosphere that lead to ozone depletion. For 11 hours during the solar proton event the OSIRIS instrument on Odin measured high spatial resolution profiles of the oxygen infrared atmospheric band at 1.26 microns which under sunlit conditions can be used as a direct proxy for ozone. Ozone depletion is observed across the southern polar cap for the duration of the observations and extends to latitudes as far north as 45°S. OSIRIS observed significant ozone depletion between 50 and 80 km with a maximum value of 75% around 65 km. The actual maximum depletion could have been even greater as observations ceased while the depletion was still increasing.