Validation of the Aura Microwave Limb Sounder HNO<sub>3</sub> measurements

Santee, M. L.; Lambert, A.; Read, W. G.; Livesey, N. J.; Manney, G. L.; Cofield, R. E.; Cuddy, D.; Daffer, W. H.; Drouin, Brian J.; Froidevaux, L.; Fuller, R. A.; Jarnot, R. F.; Knosp, B.; Perun, V. S.; Snyder, W. Van; Stek, P. C.; Thurstans, R. P.; Wagner, Paul; Waters, J. W.; Connor, B. J.; Urbán, J.; Murtagh, Donal; Ricaud, Philippe; Barret, Brice; Kleinböhl, A.; Kuttippurath, J.; Küllmann, H.; Hobe, Marc von; Toon, G. C.; Stachnik, R. A.

doi:10.1029/2007jd008721

Cited by 113 publications

(119 citation statements)

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“…Aura/MLS and Odin/SMR measurements are very similar as has been shown in recent validation studies (e.g. Santee et al, 2007). However, geographical and temporal sampling as well as the altitude resolution are different and some differences can therefore be expected.…”

Section: Observation Of Denitrification By Odin/smr and Aura/mlssupporting

confidence: 58%

“…MLS is a limb sounding instrument that measures the thermal emission at millimeter and submillimetre wavelengths using seven radiometers to cover five broad spectral regions . Measurements are performed from the surface to 90 km with a global latitude coverage from 82 • S to 82 • N. A detailed assessment of the quality and reliability of the Aura/MLS v2.2 HNO 3 measurements can be found in Santee et al (2007). Here, we use Aura/MLS version v3.3.…”

Section: Aura/mlsmentioning

confidence: 99%

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Denitrification and polar stratospheric cloud formation during the Arctic winter 2009/2010

et al. 2011

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Abstract. The sedimentation of HNO 3 containing Polar Stratospheric Cloud (PSC) particles leads to a permanent removal of HNO 3 and thus to a denitrification of the stratosphere, an effect which plays an important role in stratospheric ozone depletion. The polar vortex in the Arctic winter 2009/2010 was very cold and stable between end of December and end of January. Strong denitrification between 475 to 525 K was observed in the Arctic in mid of January by the Odin Sub Millimetre Radiometer (Odin/SMR). This was the strongest denitrification that had been observed in the entire Odin/SMR measuring period (2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010). Lidar measurements of PSCs were performed in the area of Kiruna, Northern Sweden with the IRF (Institutet för Rymdfysik) lidar and with the Esrange lidar in January 2010. The measurements show that PSCs were present over the area of Kiruna during the entire period of observations. The formation of PSCs during the Arctic winter 2009/2010 is investigated using a microphysical box model. Box model simulations are performed along air parcel trajectories calculated six days backward according to the PSC measurements with the ground-based lidar in the Kiruna area. From the temperature history of the backward trajectories and the box model simulations we find two PSC regions, one over Kiruna according to the measurements made in Kiruna and one north of Scandinavia which is much colder, reaching also temperatures below T ice . Using the box model simulations along backward Correspondence to: F. Khosrawi (farah@misu.su.se) trajectories together with the observations of Odin/SMR, Aura/MLS (Microwave Limb Sounder), CALIPSO (CloudAerosol Lidar and Infrared Pathfinder Satellite Observations) and the ground-based lidar we investigate how and by which type of PSC particles the denitrification that was observed during the Arctic winter 2009/2010 was caused. From our analysis we find that due to an unusually strong synoptic cooling event in mid January, ice particle formation on NAT may be a possible formation mechanism during that particular winter that may have caused the denitrification observed in mid January. In contrast, the denitrification that was observed in the beginning of January could have been caused by the sedimentation of NAT particles that formed on mountain wave ice clouds.

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Section: Observation Of Denitrification By Odin/smr and Aura/mlssupporting

confidence: 58%

Section: Aura/mlsmentioning

confidence: 99%

Denitrification and polar stratospheric cloud formation during the Arctic winter 2009/2010

et al. 2011

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“…The data screening criteria given by Livesey et al (2017) have been applied to the data. A detailed assessment of the quality and reliability of the Aura/MLS v2.2 HNO 3 measurements can be found in Santee et al (2007). The HNO 3 in v4.2 has been significantly improved compared to v2.2.…”

Section: Aura/mlsmentioning

confidence: 99%

Comparison of ECHAM5/MESSy Atmospheric Chemistry (EMAC) simulations of the Arctic winter 2009/2010 and 2010/2011 with Envisat/MIPAS and Aura/MLS observations

et al. 2018

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Abstract. We present model simulations with the atmospheric chemistry-climate model ECHAM5/MESSy Atmospheric Chemistry (EMAC) nudged toward European Centre for Medium-Range Weather Forecasts (ECMWF) ERAInterim reanalyses for the Arctic winters 2009/2010 and 2010/2011. This study is the first to perform an extensive assessment of the performance of the EMAC model for Arctic winters as previous studies have only made limited evaluations of EMAC simulations which also were mainly focused on the Antarctic winter stratosphere. We have chosen the two extreme Arctic winters 2009/2010 and 2010/2011 to evaluate the formation of polar stratospheric clouds (PSCs) and the representation of the chemistry and dynamics of the polar winter stratosphere in EMAC. The EMAC simulations are compared to observations by the Michelson Interferometer for Passive Atmospheric Soundings (Envisat/MIPAS) and the observations from the Aura Microwave Limb Sounder (Aura/MLS). The Arctic winter 2010/2011 was one of the coldest stratospheric winters on record, leading to the strongest depletion of ozone measured in the Arctic. The Arctic winter 2009/2010 was, from the climatological perspective, one of the warmest stratospheric winters on record. However, it was distinguished by an exceptionally cold stratosphere (colder than the climatological mean) from mid-December 2009 to mid-January 2010, leading to prolonged PSC formation and existence. Significant denitrification, the removal of HNO 3 from the stratosphere by sedimentation of HNO 3 -containing polar stratospheric cloud particles, occurred in that winter. In our comparison, we focus on PSC formation and denitrification. The comparisons between EMAC simulations and satellite observations show that model and measurements compare well for these two Arctic winters (differences for HNO 3 generally within ±20 %) and thus that EMAC nudged toward ECMWF ERA-Interim reanalyses is capable of giving a realistic representation of the evolution of PSCs and associated sequestration of gas-phase HNO 3 in the polar winter stratosphere. However, simulated PSC volume densities are smaller than the ones derived from Envisat/MIPAS observations by a factor of 3-7. Further, PSCs in EMAC are not simulated as high up (in altitude) as they are observed. This underestimation of PSC volume density and vertical extension of the PSCs results in an underestimation of the vertical redistribution of HNO 3 due to denitrification/re-nitrification. The differences found here between model simulations and observations stipulate further improvements in the EMAC set-up for simulating PSCs.

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“…The most complete dataset to date has been provided by the Microwave Limb Sounder (MLS) instrument aboard Upper Atmosphere Research Satellite (Santee et al, 2004), albeit not in the upper stratosphere. Since July 2004, the EOS/MLS instrument also makes global observations of HNO 3 that cover the mid and upper stratosphere (Santee et al, 2007). The infrared Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) aboard the ENVISAT satellite has also been measuring HNO 3 since July 2002 (Stiller et al, 2005), but following an interruption in 2004, observations have not been continuous.…”

Section: Introductionmentioning

confidence: 99%

Nitric acid in the stratosphere based on Odin observations from 2001 to 2009 – Part 2: High-altitude polar enhancements

2009

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Abstract. The wintertime abundance of nitric acid (HNO 3 ) in the polar upper stratosphere displays a strong inter-annual variability, and is known to be strongly influenced by energetic particle precipitation (EPP), primarily by protons during solar proton events (SPEs), but also by precipitating auroral or relativistic electrons. We analyse a multi-year record (August 2001 to April 2009) of middle atmospheric HNO 3 measurements by the Sub-Millimeter Radiometer instrument aboard the Odin satellite, with a focus on the polar upper stratosphere. SMR observations show clear evidence of two different types of polar high-altitude HNO 3 enhancements linked to EPP. In the first type, referred to as direct enhancements by analogy with the EPP/NO x direct effect, enhanced HNO 3 mixing ratios are observed for a short period (1 week) after a SPE, upwards of a level typically in the mid-stratosphere. In a second type, referred to as indirect enhancements by analogy with the EPP/NO x indirect effect, the descent of mesospheric air triggers a stronger and longerlasting enhancement. Each of the three major SPEs that occurred during the Northern Hemisphere autumn or winter, in November 2001 and January 2005, are observed to lead to both direct and indirect HNO 3 enhancements. On the other hand, indirect enhancements occur recurrently in winter, are stronger in the Southern Hemisphere, and are influenced by EPP at higher altitudes.

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Validation of the Aura Microwave Limb Sounder HNO₃ measurements

Cited by 113 publications

References 50 publications

Denitrification and polar stratospheric cloud formation during the Arctic winter 2009/2010

Denitrification and polar stratospheric cloud formation during the Arctic winter 2009/2010

Comparison of ECHAM5/MESSy Atmospheric Chemistry (EMAC) simulations of the Arctic winter 2009/2010 and 2010/2011 with Envisat/MIPAS and Aura/MLS observations

Nitric acid in the stratosphere based on Odin observations from 2001 to 2009 – Part 2: High-altitude polar enhancements

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Validation of the Aura Microwave Limb Sounder HNO3 measurements

Cited by 113 publications

References 50 publications

Denitrification and polar stratospheric cloud formation during the Arctic winter 2009/2010

Denitrification and polar stratospheric cloud formation during the Arctic winter 2009/2010

Comparison of ECHAM5/MESSy Atmospheric Chemistry (EMAC) simulations of the Arctic winter 2009/2010 and 2010/2011 with Envisat/MIPAS and Aura/MLS observations

Nitric acid in the stratosphere based on Odin observations from 2001 to 2009 – Part 2: High-altitude polar enhancements

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Validation of the Aura Microwave Limb Sounder HNO₃ measurements