Large increase of NO₂ in the north polar mesosphere in January–February 2004: Evidence of a dynamical origin from GOMOS/ENVISAT and SABER/TIMED data

Abstract

[1] Odd nitrogen species play an important role in the stratospheric ozone balance through catalytic ozone destruction. A layer of strongly enhanced NO 2 was detected in the north polar mesosphere by the GOMOS/ ENVISAT stellar spectrometer in mid-January 2004. Large NO 2 enhancements in the polar winter mesosphere have been previously reported by several authors and have been attributed to NO production by solar proton or by energetic electron precipitations. The simultaneous occurrence of an intense mesospheric warming observed by the SABER/ TIMED instrument indicates that a strong air descent occurred in the polar region, transporting a large quantity of NO from the upper mesosphere-lower thermosphere to the lower mesosphere. The proposed mechanism may have a significant contribution to the budget of polar stratospheric ozone. Citation: Hauchecorne, A., J

N2O production by high energy auroral electron precipitation

“…The temperature anomaly pattern is similar to that inferred from SABER temperatures by Hauchecorne et al [2007] (see their Figure 3). This feature is associated with enhanced diabatic downwelling that develops towards the end of the major sudden warming event as the stratospheric westerlies recover and easterly gravity wave drag increases in the mesosphere.…”

“…A part of this disagreement could possibly be due to the absence of other branches of reaction (1) in this model run, which would reduce the amount of N 2 O produced by a factor of two. But another significant factor is that NO 2 (Figure 8, top) forms in large quantities in the model about 8 km higher than in observations by GOMOS (see the altitude versus time distribution of NO 2 at 80°N shown in Figure 1 of Hauchecorne et al [2007]). This is due to the large amounts of O 3 produced in the region above 70 km (Figure 8, bottom) and the warmer temperatures.…”

“…Typical N 2 O mixing ratios are less than 0.5 ppbv above 50 km in the wintertime polar region due to descent of N 2 O depleted air from above. The NO x anomaly started its descent in the upper mesosphere around mid January [Hauchecorne et al, 2007] and appears to be associated with the occurrence of an exceptional major sudden stratospheric warming starting in late December 2003 [Manney et al, 2005]. In 2006, the ACE-FTS observed another NO x anomaly descending below 60 km with N 2 O values of 2 to 3 ppbv in the same air mass.…”

“…In the winter time, during the long polar night and under suitable dynamical conditions significant amounts of NO x may be transported down to the lower mesosphere and upper stratosphere [e.g., Solomon et al, 1982;Randall et al, 2005;Hauchecorne et al, 2007]. If the latter occurs then the auroral NO x can impact the ozone budget in the stratosphere [e.g., Rozanov et al, 2005].…”

Global ozone monitoring by occultation of stars: an overview of GOMOS measurements on ENVISAT

“…-The TOM is sometimes fully destroyed by two types of events: by sudden stratospheric warmings, followed by a strong downward transport of upper mesospheric air rich in NO, another scavenger of ozone (through NO 2 ), as discussed, for example, by Hauchecorne et al (2007) for the January 2004 event, and by energetic particles precipitation such as Solar Proton events (SPE), as discussed in Seppälä et al (2006) for the January 2005 SPE event.…”