Resolution dependence of cross‐tropopause ozone transport over east Asia

Abstract

[1] Detailed analysis of mesoscale transport of ozone across the tropopause over east Asia during the spring of 2001 is conducted using regional simulations with the University of Wisconsin Nonhydrostatic Modeling System (UWNMS), in situ flight data, and a new two-scale approach to diagnosing this ozone flux. From late February to early April, synoptic activity regularly deformed the tropopause, leading to observations of ozone-rich (concentration exceeding 80 ppbv) stratospheric intrusions and filaments at tropospheric altitudes. Since model resolution is generally not sufficient to capture detailed small-scale mixing processes, an upper bound on the flux is proposed by assuming that there exists a dynamical division by spatial scale, above which the wind conservatively advects large-scale structures, while below it the wind leads to irreversible transport through nonconservative random strain. A formulation for this diagnosis is given and applied to ozone flux across the dynamical tropopause. Simulations were chosen to correspond with DC-8 flight 15 on 26-27 March over east Asia during the Transport and Chemical Evolution Over the Pacific (TRACE-P) campaign. Local and domain-averaged flux values using this method agree with other numerical and observational studies in similar synoptic environments. Sensitivity to numerical resolution, prescribed divisional spatial scale, and potential vorticity (PV) level is investigated. Divergent residual flow in regions of high ozone, and PV gradients tended to maximize flux magnitudes. We estimated the domain-integrated flow of ozone out of the lowermost stratosphere to be about 0.127 Tg/day. Spectral analysis of the wind field lends support for utilization of this dynamical division in this methodology.

A Seasonal Climatology of Rossby Wave Breaking in the 320–2000-K Layer

“…Jets are also preferred regions for STE associated with resolved mesoscale motions (Hitchman et al 2004;Büker et al 2005). Momentum fluxes also maximize in these jets, in both zonal mean climatologies (Peixoto and Oort 1992) and in the storm tracks (Lau 1978).…”

The influence of mid-latitude cyclones on European background surface ozone

“…The stratospheric tracer, which uses a similar atmospheric model to the MERRA-2 reanalysis, provides additional information on air mass origin. While models and reanalyses with coarse horizontal resolution (> 100 km) are able to identify stratospheric intrusions (Roelofs et al, 2003;Lin et al, 2015;Ott et al, 2016), the fine-scale nature of the O 3 filaments is best identified at higher horizontal resolutions (Büker et al, 2005;Lin et al, 2012a;Ott et al, 2016), such as the MACC and MERRA-2 reanalyses and by the stratospheric tracer. However, even high-resolution reanalyses may struggle to represent the complex structure of stratospheric intrusions (e.g., Trickl et al, 2016).…”

“…For western Europe, this is mainly the location of two climatological features: (1) the semi-permanent Icelandic Low between 60 and 65 • N, due in part to the NA storm track (the region known for frequent, strong cyclones) and (2) the semi-permanent Azores High over the Atlantic Ocean near 40 • N. Studies of airflow relative to cyclones' frontal zones have led to three-dimensional (3-D) conceptual models of cyclones with generally three main airstreams: a warm conveyor belt (WCB; Harrold, 1973), a cold conveyor belt (CCB; Carlson, 1980), and the dry intrusion (DI; Browning, 1997). The horizontal and vertical transport of air within these airstreams can play an important role in the redistribution not only of moisture, heat, and momentum but also chemical properties of the air from different source regions (Bethan et al, 1998).…”

Observation of secondary ozone peaks near the tropopause over the Korean peninsula associated with stratosphere‐troposphere exchange

“…Reviews and case studies have been carried out for stratosphere to troposphere exchange (STE) events related to trace gases including the ozone concentration observed by various observation platforms [e.g., Davies and Schuepbach , 1994; Holton et al , 1995; Gouget et al , 1996; Hintsa et al , 1998; Bonasoni et al , 1999; Monks , 2000; Galani et al , 2003; Schaeler et al , 2004; Büker et al , 2005]. Small‐scale turbulent diabatic processes as well as large‐scale adiabatic global circulation can cause STE near the tropopause.…”