N2O and O3 relationship in the lowermost stratosphere: A diagnostic for mixing processes as represented by a three‐dimensional chemistry‐transport model

Bregman, Ahron; Lelieveld, Jos; Broek, M. van den; Siegmund, P.; Fischer, H.; Bujok, O.

doi:10.1029/2000jd900035

Cited by 31 publications

(35 citation statements)

References 53 publications

(33 reference statements)

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“…In particular, we are interested in the N 2 O-O 3 correlation in the LMS that has been also used in former studies for transport diagnostics in this region (e.g. Bregman et al, 2000;Hegglin et al, 2006;Hegglin and Shepherd, 2007). Figure 4 shows a schematic of the N 2 O-O 3 correlations in the lower stratosphere.…”

Section: Midlatitude N 2 O-o 3 Correlationsmentioning

confidence: 99%

“…In the discussion that follows, we will use the term Brewer-Dobson circulation (BDC) for the overall chemical tracer transport circulation of the stratosphere reflecting its discovery by Brewer (1949) and Dobson (1956) in order to explain the observed water vapour and ozone distribution in the stratosphere. The Brewer-Dobson circulation includes therefore net mass transport and two-way mixing.…”

Section: Introductionmentioning

confidence: 99%

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On the structural changes in the Brewer-Dobson circulation after 2000

et al. 2011

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Abstract. In this paper we present evidence that the observed increase in tropical upwelling after the year 2000 may be attributed to a change in the Brewer-Dobson circulation pattern. For this purpose, we use the concept of transit times derived from residual circulation trajectories and different in-situ measurements of ozone and nitrous dioxide. Observations from the Canadian midlatitude ozone profile record, probability density functions of in-situ N 2 O observations and a shift of the N 2 O-O 3 correlation slopes, taken together, indicate that the increased upwelling in the tropics after the year 2000 appears to have triggered an intensification of tracer transport from the tropics into the extratropics in the lower stratosphere below about 500 K. This finding is corroborated by the fact that transit times along the shallow branch of the residual circulation into the LMS have decreased for the same time period (1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003). On a longer time scale , the transit time of the shallow residual circulation branch show a steady decrease of about −1 month/decade over the last 30 yr, while the transit times of the deep branch remain unchanged. This highlights that changes in the upwelling across the tropical tropopause are not sufficient as an indicator for changes in the entire BrewerDobson circulation.

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Section: Midlatitude N 2 O-o 3 Correlationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

On the structural changes in the Brewer-Dobson circulation after 2000

et al. 2011

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“…Since this shape is shared by different long-lived species, scatter plots of two such tracers form linear correlations. Tracer-tracer correlations since then have been demonstrated to serve as valuable tools for the study of transport processes in the stratosphere and for the validation of CTMs (Bregman et al, 2000) or GCMs (Sankey and Shepherd, 2003). The use of a chemical framework removes much of the variability found in tracer time series which are caused by advection of air masses (because different long-lived tracers are advected similarly).…”

Section: Tracer-tracer Correlationsmentioning

confidence: 99%

Measurements of NO, NOy, N2O, and O3 during SPURT: implications for transport and chemistry in the lowermost stratosphere

et al. 2006

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Abstract. We present measurements of NO, NO y , O 3 , and N 2 O within the lowermost stratosphere (LMS) over Europe obtained during the SPURT project. The measurements cover all seasons between November 2001 and July 2003. They span a broad band of latitudes from 30 • N to 75 • N and a potential temperature range from 290 to 380 K. The measurements represent a comprehensive data set of these tracers and reveal atmospheric transport processes that influence tracer distributions in the LMS. Median mixing ratios of stratospheric tracers in equivalent latitude-potential temperature coordinates show a clear seasonal cycle related to the Brewer-Dobson circulation, with highest values in spring and lowest values in autumn. Vertical tracer profiles show strong gradients at the extratropical tropopause, suggesting that vertical (cross-isentropic) mixing is reduced above the tropopause. Pronounced meridional gradients in the tracer mixing ratios are found on potential temperature surfaces in the LMS. This suggests strongly reduced mixing along isentropes. Concurrent large gradients in static stability in the vertical direction, and of PV in the meridional direction, suggest the presence of a mixing barrier. Seasonal cycles were found in the correlation slopes O 3 / N 2 O and NO y / N 2 O well above the tropopause. Absolute slope values are smallest in spring indicating chemically aged stratospheric air originating from high altitudes and latitudes. Larger values were measured in summer and autumn suggesting that a substantial fraction of air takes a "short-cut" from the tropical tropopause region into the extratropical LMS. The seasonal change in the composition of the LMS has direct implications for the ozone chemistry in this reCorrespondence to: M. I. Hegglin (michaela@atmosp.physics.utoronto.ca) gion. Comparisons of measured NO with the critical NO value at which net ozone production changes from negative to positive, imply ozone production up to 20 K above the local tropopause in spring, up to 30 K in summer, and up to 40 K in autumn. Above these heights, and in winter, net ozone production is negative.

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“…Krol et al, 2004;Krol et al, 2003) and stratosphere (van den Broek et al, 2003). It has been developed by modification of the existing TM3 model, which has also been used for a number of stratospheric chemistry and transport studies Bregman et al, 2000;Bregman et al, 2001). The main improvement is the inclusion of a zooming algorithm and the vertical extension of the model domain up to 0.2 hPa, with a higher vertical resolution.…”

Section: The Tm5 Modelmentioning

confidence: 99%

Implementing growth and sedimentation of NAT particles in a global Eulerian model

2004

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Abstract.Here we present a concise and efficient algorithm to mimic the growth and sedimentation of Nitric Acid Trihydate (NAT) particles in the polar vortex in a state-of-theart 3D chemistry transport model. The particle growth and sedimentation are calculated using the microphysical formulation of Carslaw et al. (2002). Once formed, NAT particles are transported in the model as tracers in the form of sizesegregated quantities or size bins. Two different approaches were adopted for this purpose: one assuming a fixed particle number density ("FixedDens") and the other assuming a discrete set of particle diameter values ("FixedRad"). Simulations were performed for three separate 10-day periods during the 1999-2000 Arctic winter and compared to the results of an existing Lagrangian model study, which uses similar microphysics in a computationally more expensive method for the simulation of NAT particle growth. The resulting particle sizes for both our approaches compare favourably at 430 K with those obtained from this previous model study, and also in-situ observations related to the size of large NAT particles. The particle growth is faster for "FixedDens" resulting in a difference in (de)nitrification by a factor of ∼ 2 for all three simulation periods. Comparisons were made with a standard equilibrium approach and the differences in the redistribution of HNO 3 were found to be substantial. For both approaches the performance of the algorithm is rather insensitive to both the number of size bins and the shape of the size distribution, and show a weak dependence on the prescribed total particle number density during the coldest period. This results in an increase of 7% for the "FixedRad" approach and 17% for the "FixedDens" approach when increasing the total particle number density by a factor of 2.5.Correspondence to: Miranda van den Broek (M. van.den.Broek@sron.nl)

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N₂O and O₃ relationship in the lowermost stratosphere: A diagnostic for mixing processes as represented by a three‐dimensional chemistry‐transport model

Cited by 31 publications

References 53 publications

On the structural changes in the Brewer-Dobson circulation after 2000

On the structural changes in the Brewer-Dobson circulation after 2000

Measurements of NO, NO<sub>y</sub>, N<sub>2</sub>O, and O<sub>3</sub> during SPURT: implications for transport and chemistry in the lowermost stratosphere

Implementing growth and sedimentation of NAT particles in a global Eulerian model

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N2O and O3 relationship in the lowermost stratosphere: A diagnostic for mixing processes as represented by a three‐dimensional chemistry‐transport model

Cited by 31 publications

References 53 publications

On the structural changes in the Brewer-Dobson circulation after 2000

On the structural changes in the Brewer-Dobson circulation after 2000

Measurements of NO, NO&lt;sub&gt;y&lt;/sub&gt;, N&lt;sub&gt;2&lt;/sub&gt;O, and O&lt;sub&gt;3&lt;/sub&gt; during SPURT: implications for transport and chemistry in the lowermost stratosphere

Implementing growth and sedimentation of NAT particles in a global Eulerian model

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N₂O and O₃ relationship in the lowermost stratosphere: A diagnostic for mixing processes as represented by a three‐dimensional chemistry‐transport model

Measurements of NO, NO<sub>y</sub>, N<sub>2</sub>O, and O<sub>3</sub> during SPURT: implications for transport and chemistry in the lowermost stratosphere