(Last update: 26.09.2012 / GW)
The winter 2009/2010 was characterized by a strong Arctic vortex with extremely cold mid-winter temperatures in the lower stratosphere associated with an intense activation of reactive chlorine compounds (ClOx) from reservoir species. Stratospheric limb emission spectra were recorded during a flight of the balloon version of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS-B) from Kiruna (Sweden) on 24 January 2010 inside the Arctic vortex. Several fast limb sequences of spectra (in time steps of about 10 min.) were measured from nighttime photochemical equilibrium to local noon allowing the retrieval of chlorine- and nitrogen-containing species which change rapidly their concentration around the terminator between night and day. Mixing ratios of species like ClO, NO2, and N2O5 show significant changes around sunrise, which are temporally delayed due to polar stratospheric clouds reducing the direct radiative flux from the sun. ClO variations were derived for the first time from MIPAS-B spectra. Daytime ClO values of up to 1.6 ppbv are visible in a broad chlorine activated layer below 26 km correlated with low values (below 0.1 ppbv) of the chlorine reservoir species ClONO2. Observations are compared and discussed with calculations performed with the 3-dimensional Chemistry Climate Model EMAC (ECHAM5/MESSy Atmospheric Chemistry). Mixing ratios of the species ClO, NO2, and N2O5 are well reproduced by the model during night and noon. However, the onset of ClO production and NO2 loss around the terminator in the model is not consistent with the measurements. The MIPAS-B observations along with Tropospheric Ultraviolet-Visible (TUV) radiation model calculations suggest that polar stratospheric clouds lead to a delayed start followed by a faster increase of the photodissoziation of ClOOCl and NO2 near the morning terminator since stratospheric clouds alter the direct and the diffuse flux of solar radiation. These effects are not considered in the EMAC model simulations which assume a cloudless atmosphere. For details, see Wetzel et al. (2012), Atmos. Chem. Phys., 12, 6581-6592, 2012.
Temporal evolution of chlorine monoxide (ClO) as observed by MIPAS-B on 24 January 2010 above northern Scandinavia. A broad ClO layer with a pronounced ClO maximum of more than 1.6 ppbv is visible. The strong photochemically induced increase in ClO mixing ratios starts only some time after sunrise due to the occurrence of stratospheric clouds.
The new imaging FTS GLORIA accomplished its first two flights sucessfully. For more information, please see KIT press release (177/2011) and SWR media centre. GLORIA and MIPAS-STR flights aboard the GEOPHYSICA aircraft were carried out from Kiruna (Sweden) within the frame of the ESSENCE campaign.
The scientific balloon flight MIPAS-B/TELIS/mini-DOAS embedded in the ENRICHED project was launched by CNES on 31 March 2011 from Esrange (67.9°N, 21.1°E) near Kiruna at 0:46 local time. After a long ascent the balloon reached a maximum altitude of 35.4 km. It was cut at 7:00 local time after about 2:40 min at float and touched down in Russia at 7:40 local time.
Roll-out of the gondola for launch in Esrange/Kiruna.
The ClO dimer cycle plays a dominant role in the catalytic destruction of stratospheric ozone in the springtime polar vortex. ClOOCl observations, obtained in the Arctic vortex above northern Scandinavia on 11 January 2001 by the balloon-borne MIPAS (MIPAS-B), show enhanced values of nearly 1.1 ppbv at 20 km in an activated chlorine layer which are in line with the established polar chlorine chemistry. For details, see Wetzel et al. (2010), Atmos Chem. Phys., 10, 931-945, 2010 and KIT press release (086/2010).
Chlorine species as measured by MIPAS-B on 11 January 2001 above northern Scandinavia inside the polar vortex. Besides ClONO2, ClO, ClOOCl, and ClOx, total inorganic chlorine (Cly*), calculated from a N2O-Cly correlation, are shown, too.
The MIPAS-B gondola was launched successfully at 01:46 local time on 24 January 2010 from Esrange near Kiruna (Sweden). Besides MIPAS, the gondola also carried the TeraHertz Limb Sounder TELIS, operated by DLR / SRON, and a Differential Optical Absorption Spectrometer (mini-DOAS) operated by the University of Heidelberg.
The balloon (right) and the gondola hanging under the launch vehicle (left) just before the launch.
The scientific objective of this flight has been two-fold: One goal has been validation of the space experiments ENVISAT and SMILES. The other goal has been to measure the time-dependent chemistry of chlorine and bromine, and to achieve the closure of chemical families (NOy, Cly, Bry, HOx). The measurements have been performed using remote sensing spectroscopic techniques covering the spectral range from the UV via the IR to the MW. Altogether these techniques allow the measurement of more than 30 atmospheric species.
The vortex situation on 24 January 2010 at 30 hPa (~22 km), the coldest levels.
The balloon trajectory of the MIPAS-B/TELIS/mini-DOAS flight.
The balloon reached the float level of 34 km at around 05:00, heading towards the Baltic sea for several hours before it almost stopped and turned around into Finland. Around 13:00 the valve was opened for a slow descent down to 25 km, then the gondola was cut at 14:40 and safely landed in Finland.
The gondola after touchdown in Finland.
Early morning two days later the gondola was back to Esrange in good shape. All systems could be switched on and were working again.
First evaluation of the flight:
The balloon was launched right into the centre of the cold chlorine-activated vortex. Thanks to the meteorological situation and the timing of the balloon operations enabling more than 12 hours of measurements the following tasks could be achieved:
(1) to measure the time-dependent chemistry of activated chlorine (ClO and ClOOCl) from the night-time equilibrium until day
(2) to measure the almost complete partitioning and budget of the NOy and Cly families
(3) to match the overpasses of the ENVISAT and SMILES satellite observations
(4) to observe the same air masses as the Geophysica aircraft on the same day.
Both MIPAS and TELIS worked well, and the quick-look at the recorded spectra is very promising. Power problems prevented the mini-DOAS to measure well into daytime, unfortunately.
From a quick-look at the spectra we summarize qualitatively:
a) a significant redistribution of HNO3 pointing at denitrification above about 20 km and renitrification below
b) a strong chlorine activation with very little amounts of ClONO2 and enhanced ClO
c) a relatively slow build-up of ClO after sunrise.
Research flights have been conducted between January 17 and February 2, 2010, each dedicated to specific scientific issues, such as PSC microphysics, chlorine activation, kinetics of the ClO dimer, NAT rock formation, de-/renitrification, and ozone loss. A second campaign phase was performed between February 27 and March 10, 2010.
For more information on how measurements are taken with the aircraft version of MIPAS and how the data are analysed, see: http://www.imk-asf.kit.edu/english/534.php
For more information on the RECONCILE field campaign and the related EU project, see: https://www.fp7-reconcile.eu/index.html
Christof Piesch, member of the MIPAS-STR team, pointing at a Polar Stratospheric Cloud (PSC) at the start of the
RECONCILE campaign. Such PSCs form at very cold temperatures of below -85°C at altitudes of about 17 to 28 km.
The Russian Geophysica aircraft, capable to fly up to 20 km altitude, in front of the Arena Arctica, a huge hangar at
Kiruna airport, designed for accommodating big aircraft and equipped with labs for a large number of scientific groups.
The MIPAS aircraft instrument is mounted on top of the aircraft between the wings. During flight the instrument is covered
by a dome. MIPAS-STR is capable of measuring cross sections of atmospheric constituents relevant for ozone and climate
research, such as O3, N2O, CH4, HNO3, ClONO2, and CFCs.