30-year lidar observations of the stratospheric aerosol layer state over Tomsk (Western Siberia, Russia)

Abstract

<p><strong>Abstract.</strong> There are only four lidar stations in the world, which have almost continuously performed observations of the stratospheric aerosol layer (SAL) state for over the last 30 years. The longest time series of the SAL lidar measurements have been accumulated at the Mauna Loa Observatory (Hawaii) since 1973, the NASA Langley Research Center (Hampton, Virginia) since 1974, and Garmisch-Partenkirchen (Germany) since 1976. The fourth lidar station we present started to perform routine observations of the SAL parameters in Tomsk (56.48° N, 85.05° E, Western Siberia, Russia) in 1986. In this paper, we mainly focus on and discuss the stratospheric background period from 2000 to 2005 and the causes of the SAL perturbations over Tomsk in the 2006–2015 period. During the last decade, volcanic aerosol plumes from tropical Mt. Manam, Soufriere Hills, Rabaul, Merapi, Nabro, and Kelut, and extratropical (northern) Mt. Okmok, Kasatochi, Redoubt, Sarychev Peak, Eyjafjallajökull, and Grimsvötn were detected in the stratosphere over Tomsk. When it was possible, we used the NOAA HYSPLIT trajectory model to assign aerosol layers observed over Tomsk to the corresponding volcanic eruptions. The trajectory analysis highlighted some surprising results. For example, in cases of the Okmok, Kasatochi, and Eyjafjallajökull eruptions, the HYSPLIT air-mass backward trajectories, started from altitudes of aerosol layers detected over Tomsk with a lidar, passed over these volcanoes on their eruption days at altitudes higher than the maximum plume altitudes given by the Smithsonian Institution Global Volcanism Program. An explanation of these facts is suggested. The role of both tropical and northern volcanoes eruptions in volcanogenic aerosol loading of the mid-latitude stratosphere is also discussed. In addition to volcanoes, we considered other possible causes of the SAL perturbations over Tomsk, i.e. the polar stratospheric cloud (PSC) events and smoke plumes from strong forest fires. At least two PSC events were detected in 1995 and 2007. We also make an assumption that both the Kelut volcano plume (Indonesia, February 2014) and smoke plumes from massive forest fires occurred in Canada (137 fires in the Northwest Territories, July 2014) and the USA (the Happy Camp Complex fire in California, August–October 2014), with equal probability, could be the cause of the SAL perturbations over Tomsk during the first quarter of 2015.</p>

The Whole Atmosphere Community Climate Model Version 6 (WACCM6)

“…(a) Ny Alesund (78.9°N, 11.9°W) above 10 km (black, Ridley et al, ). (b) Tomsk (56.5°N, 85.0°E) 15–30 km 10‐day averages from Jan 1986 to Dec 2014 (black, Zuev et al, ), and 12–30 km 10‐day averages from Jan 2006 to Dec 2013 (green). (c) Geesthacht (53.4°N, 10.4°E) above the tropopause (black with 1‐ σ error bars, Ansmann et al, ).…”

Radiative and Chemical Response to Interactive Stratospheric Sulfate Aerosols in Fully Coupled CESM1(WACCM)

“…Aerosol optical depth (AOD) measured by lidars at three locations (black circles) are compared to calculated 5 day average AOD above the tropopause in corresponding model columns from our SDVOLC (red dots), FRVOLC (ensemble average, blue dots), and SCVOLC (orange dots) simulations. Observations are (a) integrated backscatter from 15–30 km measured in Tomsk, Siberia (Zuev et al, ), converted to AOD using a lidar ratio of 50; (b) AOD above the tropopause measured in Geestacht, Germany (Ansmann et al, ); and (c) AOD above the tropopause measured in Mauna Loa, Hawaii (Hofmann et al, ; Ridley et al, ).…”

“…Figure a compares to a newly available lidar record from Tomsk, Siberia (Zuev et al, ). While the tropopause altitude is generally 11–13 km, the lidar backscatter was integrated between 15 and 30 km.…”

“…Comparison of SAOD in SCVOLC to FRVOLC shows the impact of the enhanced self-lofting of Pinatubo aerosols when OH depletion is not accounted for. Figure 10a compares to a newly available lidar record from Tomsk, Siberia (Zuev et al, 2016). While the tropopause altitude is generally 11-13 km, the lidar backscatter was integrated between 15 and 30 km.…”

“…We have converted the integrated backscatter to aerosol optical depth (AOD) using a lidar ratio (integrated extinction/backscatter) of 50, which has been found to be appropriate for the stratosphere within 20% (Jäger & Deshler, 2002Ridley et al, 2014). Our calculated AOD is integrated above the tropopause, yielding slightly higher values in SDVOLC over the Pinatubo period than the integrated backscatter, which (Zuev et al, 2016), converted to AOD using a lidar ratio of 50; (b) AOD above the tropopause measured in Geestacht, Germany (Ansmann et al, 1997); and (c) AOD above the tropopause measured in Mauna Loa, Hawaii (Hofmann et al, 2009;Ridley et al, 2014).…”