Severe and extensive denitrification in the 1999–2000 Arctic winter stratosphere

Popp, Peter; Northway, M. J.; Holecek, J. C.; Gao, R. S.; Fahey, D. W.; Elkins, James W.; Hurst, D. F.; Romashkin, P. A.; Toon, G. C.; Sen, B.; Schauffler, S.; Salawitch, R. J.; Webster, Christopher R.; Herman, R. L.; Jost, H.; Bui, T. P.; Newman, Paul A.; Lait, Leslie R.

doi:10.1029/2001gl013132

Cited by 78 publications

(115 citation statements)

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“…Since the MarkIV instrument measures most NO y species, here we compare the observed denitrification (NO y -NO * y ) with the model denitrification (NO y -passive NO y ) for each of the runs -M1, M2, E1, E2. Figure 6 shows that significant denitrification was observed by the MarkIV (black line) between ∼520 and ∼600 K. The observed denitrification does not tend to zero above 650 K because the NO * y (N 2 O) relation from Popp et al (2001) begins to break down for the low N 2 O concentrations at these altitudes. The two different model denitrification schemes predict two different shaped denitrification profiles.…”

Section: • E) On 16 December 2002 Figures 5cmentioning

confidence: 92%

“…To determine an observed denitrification from the MIPAS-E measurements we use the MIPAS-E N 2 O and the relation of Popp et al (2001) (derived for the 1999/2000 winter) to infer the deviation of HNO 3 from the expected NO y value in the absence of any denitrification (referred to as NO * y ). The modelled denitrification from DLAPSE is usually calculated as the difference between the nitric acid (or NO y ) concentration in a DLAPSE run and the corresponding passive run where the denitrification in the model has been switched off.…”

Section: Determining and Comparing Observed Mipas-e And Modelled Dlapmentioning

confidence: 99%

“…Fahey et al, 1990;Sugita et al, 1998;Kondo et al, 2000;Santee et al, 2000). In situ NO y observations from the NASA ER-2 during the cold Arctic winter of 1999/2000 revealed denitrification of an unprecedented magnitude (Popp et al, 2001). In addition to extensive denitrification, ER-2 flights in January and February 2000 revealed the presence of very large nitric acid trihydrate (NAT) particles (up to 20 µm diameter) with very low concentrations Published by Copernicus GmbH on behalf of the European Geosciences Union.…”

Section: Introductionmentioning

confidence: 99%

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Testing our understanding of Arctic denitrification using MIPAS-E satellite measurements in winter 2002/2003

et al. 2006

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Abstract. Observations of gas-phase HNO 3 and N 2 O in the polar stratosphere from the Michelson Interferometer for Passive Atmospheric Sounding aboard the ENVISAT satellite (MIPAS-E) were made during the cold Arctic winter of 2002/2003. Vortex temperatures were unusually low in early winter and remained favourable for polar stratospheric cloud formation and denitrification until mid-January. MIPAS-E observations provide the first dataset with sufficient coverage of the polar vortex in mid-winter which enables a reasonable estimate of the timing of onset and spatial distribution of denitrification of the Arctic lower stratosphere to be performed. We use the observations from MIPAS-E to test the evolution of denitrification in the DLAPSE (Denitrification by Lagrangian Particle Sedimentation) microphysical denitrification model coupled to the SLIMCAT chemical transport model. In addition, the predicted denitrification from a simple equilibrium nitric acid trihydrate-based scheme is also compared with MIPAS-E. Modelled denitrification is compared with in-vortex NO y and N 2 O observations from the balloon-borne MarkIV interferometer in mid-December. Denitrification was clearly observed by MIPAS-E in midDecember 2002 and reached 80% in the core of the vortex by early January 2003. The DLAPSE model is broadly able to capture both the timing of onset and the spatial distribution of the observed denitrification. A simple thermodynamic equilibrium scheme is able to reproduce the observed denitrification in the core of the vortex but overestimates denitrification closer to the vortex edge. This study also suggests that the onset of denitrification in simple thermodynamic schemes may be earlier than in the MIPAS-E observations.

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Section: • E) On 16 December 2002 Figures 5cmentioning

confidence: 92%

Section: Determining and Comparing Observed Mipas-e And Modelled Dlapmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Testing our understanding of Arctic denitrification using MIPAS-E satellite measurements in winter 2002/2003

et al. 2006

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“…Extensive denitrification was observed in 1999/2000 by both in situ (Popp et al, 2001) and remote (Santee et al, 2000;Kleinböhl et al, 2002) instruments. Large nitric acidcontaining particles (10 to 20 µm diameter) at low number concentrations (between 10 −5 and 10 −3 cm −3 ) were measured by the NOAA NO y instrument aboard the NASA ER-2 aircraft in the 1999/2000 winter Arctic vortex and have generally been inferred to be NAT (Fahey et al, 2001;Northway et al, 2002a).…”

Section: Introductionmentioning

confidence: 99%

“…tions? There are observations of denitrification in each of the cold winters 1994/5 (Sugita et al, 1998;Waibel et al, 1999/6 (Hintsa et al, 1998Dessler et al, 1999), 1996/7 (Kondo et al, 2000Irie et al, 2001) and 1999/2000 (Santee et al, 2000;Popp et al, 2001;Kleinböhl et al, 2002). See also Santee et al (1999) for MLS measurements of denitrification between 1991 and 1998.…”

Section: Introductionmentioning

confidence: 99%

Factors controlling Arctic denitrification in cold winters of the 1990s

et al. 2003

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Abstract. Denitrification of the Arctic winter stratosphere has been calculated using a 3-D microphysical model for the winters 1994/95, 1995/96, 1996/97 and 1999/2000. Denitrification is assumed to occur through the sedimentation of low number concentrations of large nitric acid trihydrate (NAT) particles (as inferred by e.g. Fahey et al., 2001). We examine whether the meteorological conditions that allowed particles to grow to the very large sizes observed in 1999/2000 also occurred in the other cold winters. The results show that winter 1999/2000 had conditions that were optimum for denitrification by large NAT particles, which are a deep concentric NAT area and vortex. Under these conditions, NAT particles can circulate in the NAT-supersaturated air for several days, reaching several micrometres in radius and leading to a high downward flux of nitric acid. The other winters had shorter periods with optimum conditions for denitrification. However, we find that NAT particles could have grown to large sizes in all of these winters and could have caused significant denitrification. We define the quantity "closedflow area" (the fraction of the NAT area in which air parcel trajectories can form closed loops) and show that it is a very useful indicator of possible denitrification. We find that even with a constant NAT nucleation rate throughout the NAT area, the average NAT number concentration and size can vary by up to a factor of 10 in response to this meteorological quantity. These changes in particle properties account for a high degree of variability in denitrification between the different winters. This large meteorologically induced variability in denitrification rate needs to be compared with that which could arise from a variable nucleation rate of NAT particles, which remains an uncertain quantity in models. Sensitivity studies show that although denitrification was likely approaching asymptotic minimum values throughout much of the 1999/2000 vortex, decreases in the volume-averaged nucleation rate would have substantially reduced the denitrification.

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Nitrate deposition to surface snow at Summit, Greenland, following the 9 November 2000 solar proton event

et al. 2014

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This study considers whether spikes in nitrate in snow sampled at Summit, Greenland, from August 2000 to August 2002 are related to solar proton events. After identifying tropospheric sources of nitrate on the basis of correlations with sulfate, ammonium, sodium, and calcium, we use the three-dimensional global Whole Atmosphere Community Climate Model (WACCM) to examine unaccounted for nitrate spikes. Model calculations confirm that solar proton events significantly impact HO x , NO x , and O 3 levels in the mesosphere and stratosphere during the weeks and months following the major 9 November 2000 solar proton event. However, solar proton event (SPE)-enhanced NO y calculated within the atmospheric column is too small to account for the observed nitrate peaks in surface snow. Instead, our WACCM results suggest that nitrate spikes not readily accounted for by measurement correlations are likely of anthropogenic origin. These results, consistent with other recent studies, imply that nitrate spikes in ice cores are not suitable proxies for individual SPEs and motivate the need to identify alternative proxies. IntroductionIdentifying the impact of solar particle storms on the atmosphere remains fundamental in understanding the Sun's influence on Earth's climate [Gray et al., 2010; National Research Council, 2012]. High-energy particles from these solar events increase odd nitrogen and odd hydrogen, catalytically destroying ozone and thereby potentially impacting climate through the chemistry, radiative budget, and dynamics of the upper atmosphere [e.g., Randall et al., 2005;Jackman et al., 2008]. In addition, these space weather events have the potential to disrupt power grids, communications technology, and spacecraft [National Research Council, 2008].Direct observations of solar energetic particle events have only been available since the midtwentieth century. A broader understanding of the potential frequency and intensity of these events requires a more extensive record of historical occurrences, motivating the search for indirect proxy evidence [Schrijver et al., 2012]. There are numerous analytical and predictive studies using nitrate ion (NO 3 À ) variability in polar ice cores as a proxy for solar energetic particle events [e.g., Zeller and Parker, 1981;Dreschhoff and Zeller, 1990;McCracken et al., 2001a;Shea et al., 2006;Kepko et al., 2009]. However, this relationship has been questioned, particularly with regard to the short timescales associated with individual events [e.g., Legrand and Delmas, 1986;Wolff et al., 2008Wolff et al., , 2012. Contemporary progress toward predicting space weather urgently awaits the resolution of whether or not NO 3 À spikes in ice cores can be used to infer past events [e.g., Barnard et al., 2011;Riley, 2012]. [1981] associated nitrate levels with solar activity through the correlation NO 3 À in Antarctic ice cores with cosmogenic carbon isotopes ( 14 C) in tree rings. Statistical correlation studies confirm the covariance between NO 3 À and cosmogenic radionuclides...

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Severe and extensive denitrification in the 1999–2000 Arctic winter stratosphere

Abstract: Abstract.Observations These results show that denitrification in the Arctic lower stratosphere can approach the severity and extent of that previously observed only in the Antarctic.

Cited by 78 publications

References 25 publications

Testing our understanding of Arctic denitrification using MIPAS-E satellite measurements in winter 2002/2003

Testing our understanding of Arctic denitrification using MIPAS-E satellite measurements in winter 2002/2003

Factors controlling Arctic denitrification in cold winters of the 1990s

Nitrate deposition to surface snow at Summit, Greenland, following the 9 November 2000 solar proton event

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