Vertical profile of peroxyacetyl nitrate (PAN) from MIPAS-STR measurements over Brazil in February 2005 and its contribution to tropical UT NO<sub>y</sub> partitioning

Abstract

Abstract.We report on the retrieval of PAN (CH 3 C(O)OONO 2 ) in the upper tropical troposphere from limb measurements by the remote-sensor MIPAS-STR on board the Russian high altitude research aircraft M55-Geophysica. The measurements were performed close to Araçatuba, Brazil, on 17 February 2005. The retrieval was made in the spectral range 775-820 cm −1 where PAN exhibits its strongest feature but also more than 10 species interfere. Especially trace gases such as CH 3 CCl 3 , CFC-113, CFC-11, and CFC-22, emitting also in spectrally broad not-resolved branches, make the processing of PAN prone to errors. Therefore, the selection of appropriate spectral windows, the separate retrieval of several interfering species and the careful handling of the water vapour profile are part of the study presented.The retrieved profile of PAN has a maximum of about 0.14 ppbv at 10 km altitude, slightly larger than the lowest reported values (<0.1 ppbv) and much lower than the highest reported in the literature (0.65 ppbv). Besides the NO y constituents measured by MIPAS-STR (HNO 3 , ClONO 2 , HO 2 NO 2 , PAN), the in situ instruments aboard the Geophysica provide simultaneous measurements of NO, NO 2 , and the sum NO y . Comparing the sum of in-situ and remotely derived NO+NO 2 +HNO 3 +ClONO 2 +HO 2 NO 2 +PAN with total Correspondence to: M. Höpfner (michael.hoepfner@imk.fzk.de) NO y a deficit of 30-40% (0.2-0.3 ppbv) in the troposphere remains unexplained whereas the values fit well in the stratosphere.

MIPAS IMK/IAA CFC-11 (CCl3F) and CFC-12 (CCl2F2) measurements: accuracy, precision and long-term stability

“…Characteristics of MIPAS-STR, the data processing and uncertainties of the retrieval results are briefly summarized in the following. Further information on MIPAS-STR is found in Keim et al (2008), Woiwode et al (2015) and references therein. MIPAS-STR em-3360 E. Eckert et al: MIPAS IMK/IAA CFC-11 and CFC-12: accuracy, precision and long-term stability ploys four liquid He-cooled detectors/channels in the spectral range between 725 and 2100 cm −1 (13.8 and 4.8µm).…”

Peroxynitric acid (HO&lt;sub&gt;2&lt;/sub&gt;NO&lt;sub&gt;2&lt;/sub&gt;) measurements during the UBWOS 2013 and 2014 studies using iodide ion chemical ionization mass spectrometry

“…Observations of PNA are generally limited in scope with most measurements focusing on polar regions (Slusher et al, 2002(Slusher et al, , 2010Huey et al, 2004), the free troposphere (Murphy et al, 2004;Singh et al, 2006Singh et al, , 2007Keim et al, 2008;Kim et al, 2007), and the stratosphere (Rinsland et al, 1996(Rinsland et al, , 1986Sen et al, 1998). Mean PNA observations from these studies range from tens of pptv in polar surface regions to several hundred pptv in the upper troposphere-lower stratosphere.…”

“…Many of the techniques available measure PNA as a component of NO y using O 3 / NO chemiluminescence (Keim et al, 2008) or total peroxynitrates via thermal decomposition laser induced fluorescence (Murphy et al, 2004). Currently, available instrumentation capable of unambiguous measurement of PNA is limited to remote sensing detection via IR absorption spectroscopy (Rinsland et al, 1986(Rinsland et al, , 1996Sen et al, 1998) or in situ measurement via chemical ionization mass spectrometry using the SiF − 6 ion (Slusher et al, 2002(Slusher et al, , 2001, CF 3 O − (Spencer et al, 2009;Huey et al, 1996), and iodide ion (I − ) (Abida et al, 2011).…”

Synergy between middle infrared and millimeter-wave limb sounding of atmospheric temperature and minor constituents

“…MIPAS-STR is described in more detail in Piesch et al (1996); Keim et al (2008); Woiwode et al (2012) and Woiwode et al (2015). The unapodized spectral sampling of MIPAS-STR is 0.036 cm −1 .…”

“…Observations at tropospheric tangent altitudes are limited in the presence of opaque clouds and increasing density, width and saturation of trace gas signatures. Observations of MIPAS aboard Envisat (Fischer et al, 2008, and references therein) were utilized to study the chemical composition from tropospheric to mesospheric altitudes. Airborne observations by MIPAS-STR (e.g., Piesch et al, 1996;Woiwode et al, 2012, and references therein) and CRISTA-NF (e.g., Ungermann et al, 2012) showed that middle infrared observations allow the resolution of narrow vertical structures in trace gas distributions along flight track with high accuracy under cloud-free conditions.…”