Fast transport from Southeast Asia boundary layer sources to Northern Europe: rapid uplift in typhoons and eastward eddy shedding of the Asian monsoon anticyclone

During the TACTS aircraft campaign enhanced tropospheric trace gases such as CO, CH 4 , and H 2 O and reduced stratospheric O 3 were measured in situ in the lowermost stratosphere over Northern Europe on 26 September 2012. The measurements indicate that these air masses di ﬀ er from the stratospheric background. The calculation 5 of 40 day backward trajectories with the trajectory module of the CLaMS model shows that these air masses are a ﬀ ected by the Asian monsoon anticyclone. Some air masses originate from the boundary layer in Southeast Asia/West Paciﬁc and are rapidly lifted (1–2 days) within a typhoon. Afterwards they are injected directly into the anticyclonic circulation of the Asian monsoon. The subsequent long-range transport (8–14 days) 10 of enhanced water vapour and pollutants to the lowermost stratosphere in Northern Europe is driven by eastward transport of tropospheric air from the Asian monsoon anticyclone caused by an eddy shedding event. We ﬁnd that the combination of rapid uplift by a typhoon and eastward eddy shedding from the Asian monsoon anticyclone is an additional fast transport pathway that, in this study, carries boundary emissions 15 from Southeast Asia/West Paciﬁc within approximately 5 weeks to the lowermost stratosphere in Northern Europe.

barrier from the surrounding air. Vice versa stratospheric trace gases such as O 3 (Randel and Park, 2006;Liu et al., 2009;Konopka et al., 2010) show low concentrations in the anticyclone. However, the impact of different boundary layer sources on the chemical composition of the air in the Asian monsoon anticyclone (e.g., Li et al., 2005;Park et al., 2009;Chen et al., 2012;Bergman et al., 2013) and the mechanisms for transport 5 into the lowermost stratosphere (Dethof et al., 1999;Park et al., 2009;Randel et al., 2010;Bourassa et al., 2012) are subject of current debate.
Trajectory calculations suggest air mass contributions in the Asian monsoon anticyclone from boundary sources originating in India/Southeast Asia (including the Bay of Bengal) and the Tibetan Plateau (Chen et al., 2012;Bergman et al., 2013). Chen et al. 10 (2012) found the main contribution to air at tropopause height from the tropical Western Pacific region and the South China Seas, while Bergman et al. (2013) found that contributions from the Tibetan Plateau are most important at 100 hPa. In the Asian monsoon, findings by Chen et al. (2012) indicate that timescales of transport from the boundary layer to the tropopause region by deep convection overshooting are about 1-2 days, 15 while several weeks by large scale ascent. Further, there is evidence that emissions on the eastern side of the anticyclone (northeast India and southwest China) are lifted upward and trapped in the Asian monsoon anticyclone (Li et al., 2005).
There is evidence that the mean upward transport at the eastern/southeastern side of the Asian monsoon anticyclone is a gateway of tropospheric air to the stratosphere 20 by direct convective injection (Rosenlof et al., 1997;Park et al., 2007Park et al., , 2008Chen et al., 2012). However, the impact of this effect on the composition of the stratosphere has not been isolated from the influence of the transport in the deep tropics, entrained into the upward Brewer-Dobson circulation (Gettelman et al., 2004;Bannister et al., 2004), which is the primary transport pathway of air from the troposphere to the stratosphere 25 (Holton et al., 1995).
One of the possible pathways for long-range transport of air masses from the Asian monsoon anticyclone to the extratropical lowermost stratosphere are smaller anticyclones breaking off a few times each summer from the main anticyclone characterised  (Hsu and Plumb, 2001;Popovic and Plumb, 2001;Garny and Randel, 2013). This process is referred to as "eddy shedding". Westward transport of monsoon air masses by eddy shedding from the Asian monsoon anticyclone seems to be a common phenomenon, in contrast to eastward migrating anticyclones that occur less frequently (Popovic and Plumb, 2001;Garny and Randel, 2013). Garny and Randel 5 (2013) found that westward propagation often appear after periods of strong convective forcing. Hsu and Plumb (2001) inferred from shallow-water calculations that in case the anticyclone is sufficiently large asymmetric, the elongated anticyclone becomes unstable and westward eddy shedding occurred. In contrast, eastward eddy shedding is ascribed to the interaction of the monsoon anticyclone with an eastward moving mid-10 latitude synoptic-scale tropospheric cyclone (Dethof et al., 1999). Eddy shedding events have the potential to carry air with enhanced tropospheric trace gases such as water vapour or pollutants from the Asian monsoon anticyclone to mid and high latitudes of the Northern Hemisphere (Dethof et al., 1999;Garny and Randel, 2013). These air masses can be transported into the extratropical lower strato- 15 sphere where they are eventually mixed irreversibly with the surrounding stratospheric air (Dethof et al., 1999;Garny and Randel, 2013) and thus affect the chemical and radiative balance of the extra-tropical UTLS.
In this paper, we show that fast transport from boundary emissions from Southeast Asia has the potential to affect the chemical composition of the lowermost stratosphere 20 over Northern Europe. We focus on the question how transport pathways and time scales from surface emissions from Southeast Asia are influenced by the Asian monsoon circulation and its interaction with tropospheric weather systems.
We use in situ measurements obtained during the TACTS (Transport and Composition in the Upper Troposphere and Lowermost Stratosphere) aircraft campaign Introduction meteorological data sets and are therefore useful for investigating of the origin of air masses, in particular in the region of the Asian monsoon anticyclone (Dethof et al., 1999;Chen et al., 2012;Bergman et al., 2013). The paper is organised as follows: Sect. 2 describes the measurements and Sect. 3 the trajectory calculations. In Sect. 4, the interaction of tropospheric weather systems, in particular of typhoons, with the 5 Asian monsoon anticyclone and the resulting impact on the behaviour of the backward trajectories is discussed. A short summary and conclusion are given in Sect. 5. -The measurements of CO and CH 4 during TACTS/ESMVal were made with the TRIHOP instrument, which is an updated version of the three-channel tunable diode laser instrument for atmospheric research (TRISTAR), which has been used during the SPURT 1 project (Hoor et al., 2004;Engel et al., 2006). TRIHOP achieves a precision of 0.9 ppbv for CO and 5 ppbv for CH 4 , respectively, for 1.5 s 5 integration time. We estimate the reproducibility during the flights was 2.3 ppbv for CO and 15 ppbv for CH 4 , respectively, without any corrections applied.
-The water measurements on board the HALO aircraft were obtained by the Fast In-situ Stratospheric Hygrometer (FISH) which is based on the Lyman-α photofragment fluorescence technique. Instrument and calibration procedure are 10 described in Zöger et al. (1999). The FISH inlet is mounted forward-facing thus measuring total water, i.e. the sum of gas-phase water and water in ice particles. The procedure to correct the data for oversampling of ice particles in the forwardfacing inlet is discussed in Schiller et al. (2008).  Fig. 2, the time period from 09:05 UTC to 10:17 UTC with enhanced tropospheric trace gases and reduced ozone, respectively, is shaded in grey. Strong gradients are found in tracer measurements (at the beginning and the end of this time period) at the same level of potential temperature indicating that air masses were sampled with strongly different origin compared to the background air 5 probed in this part of the flight. The region showing the enhanced tropospheric trace gases is referred to as "region of interest". The region of interest is located at the northwestern flank of the flight path over the Atlantic Ocean as shown in Fig. 1 (shown as white line in the flightpath). The potential vorticity (PV) at 375 K potential temperature indicates that in the region of interest and in the hexagon lower values of PV (7.3-10 8.0 PVU, yellow in Fig. 1) occur than in the stratospheric background, corroborating that these air masses have a different origin, that is more tropospheric, compared to the background. This is also evident in the Fig. 2, where within the flight part shortly before the dive (≈ 13:00 UTC) conducted within the hexagon enhanced CO, CH 4 , and H 2 O and reduced O 3 was measured simultaneously. Between 08:05 UTC and 08:23 UTC 15 a tropospheric signal is also evident in the observations (see Fig. 2) measured over the British Isles ( Fig. 1). However, in the region of interest the measured signatures are most pronounced and therefore we focus here on that part of the flight.

Results of backward trajectory calculations
To study the origin of air in the region of interest (highlighted in grey in Fig. 2 (Ploeger et al., 2010). Here, the diabatic approach is applied. This implies using the diabatic heating rate (with contributions from radiative heating including the effects of clouds, latent heat release, mixing and diffusion) as vertical velocity. The transport is simulated with vertical velocities from the diabatic heating rate in the UTLS (< 300 hPa) and using a pressure based hybrid vertical coordinate in the 5 troposphere (> 300 hPa) (Pommrich et al., 2014). 40 day backward trajectories starting at the observation along the flight path (every 10 s) on 26 September 2012 and ending at the origin of the air masses in the past (17 August 2012) are calculated. The potential temperature at the air mass origin (Θ org ) gives information about the vertical transport of the air mass along the trajectory. In , the potential temperature at the air mass origin (Θ org ) is shown as red dots. Most Θ org values lie above or at the same level of potential temperature as during the flight, consistent with the descent of air masses in the lower stratosphere of the Northern Hemisphere. However, in the region of interest some of the air masses originate at much lower levels of potential temperature, namely between 295 K and 15 360 K.
In Fig. 3, two Θ org intervals, 295-320 K (left) and 320-360 K (right), are shown colourcoded by potential temperature (top) and by days reversed from 26 September 2012 (middle). Further, the geographical air mass origin (bottom, red dots in embedded map) and potential temperature vs. time along the 40 day backward trajectories (bottom) 20 colour-coded by latitude are shown.
All air parcels with Θ org below 360 K are affected by air masses originating from the Asian monsoon anticyclone (Fig. 3, top). The air parcels are separated from the Asian monsoon circulation in the region over Japan, East China, and Southeast Siberia approximately 8-14 days before they were sampled during the flight on 26 Septem-Introduction the anticyclone (at ≈ 365 K), then turn over Japan before they become entrained into the Asian monsoon circulation and then move further around the Asian monsoon (left middle). For Θ org between 320 K and 360 K, some of the air masses intrude directly into the anticyclone and move clockwise round the Asian monsoon at the edge of the anticyclonic circulation. Other trajectories perform first a loop over the West Pacific 5 ocean (right middle). Some of the air parcels with Θ org lower than 320 K show a very rapid uplift between 23 and 25 August with a maximum ascent rate of 41 K day −1 (= 523 hPa day −1 ) and originate in Southeast Asia (left bottom). Air parcels with Θ org between 320 K and 360 K are characterised by rapid uplift up to 13 K day −1 (= 139 hPa day −1 ) between 18 and 10 24 August and originate in the West Pacific (northern or western of Philippines) or from northern of India (right bottom). An overview about maximum and mean vertical velocities is given in Table 1.
In the following we discuss also transport pathways of air masses originate in intervals for Θ org between 360-370 K, 370-380 K, and 380-420 K. Related figures are not 15 shown here, but are available as an electronic supplement of this paper.
Most air masses originating at Θ org values between 360 K and 370 K experienced a moderately rapid uplift with mean values of about 2 K day −1 (= 22 hPa day −1 ) roughly in the region of the Asian monsoon anticyclone. Most of these air masses originate in North Africa, South Asia, and in the West Pacific. The trajectories are separated from 20 the anticyclone approximately 8-14 days before the flight on 26 September 2012, and therefore transport air masses from inside the Asian monsoon anticyclone to Northern Europe. At levels above, for Θ org between 370 K and 380 K, the trajectories are affected by both the Asian monsoon anticyclone and the subtropical westerly jet. The moderate 25 uplift along the trajectories is 1 K day −1 (= 16 hPa day −1 ) in the mean. The majority of air masses originate in regions around the Asian monsoon anticyclone and in Central America. In the latter case, the trajectories are most likely affected by the North American monsoon. Most air masses that originate at Θ org between 380 K and 420 K are dominated by the global circulation patterns with a descent of air masses in the Northern Hemisphere lower stratosphere. These trajectories do not circulate around the Asian monsoon anticyclone (except for two trajectories) and the air mass origins are spread out in the entire Northern Hemisphere, excluding regions affected by the Asian monsoon anticy-5 clone such as South Asia or parts of North Africa. Our findings inferred from backward trajectory calculations are summarised in Table 1.
Our trajectory calculations suggest that potential boundary emissions from Southeast Asia and the West Pacific are rapidly uplifted and are transported within approximately 5 weeks to Northern Europe. The air mass origins are not found in surface 10 regions located closed to the core of the Asian monsoon such as North India, South India or East China. This suggests that in our study possible boundary emissions from these regions need a longer time period of upward transport within the Asian monsoon anticyclone to reach the lowermost stratosphere over Northern Europe.
In this work, we focus on the region of interest (cf. Sect. 2), however also in other 15 parts of the flight enhanced tropospheric signals in tracers and reduced ozone are measured between 08:05 UTC and 08:23 UTC and along the hexagon before the dive. The latter signal is also caused by transport of air masses from lower levels of potential temperature as evident in 40 day backward trajectories (Fig. 3, top). The tropospheric signal between 08:05 UTC and 08:23 UTC is not present in 40 day backward trajecto- 20 ries, but in 50 day backward trajectories to a small extend. The trajectories from lower levels originate in South Asia, Northwest America and over the Atlantic ocean.

Interaction between the Asian monsoon anticyclone and other tropospheric weather systems
To understand the behaviour of the backward trajectories presented in the previous 25 section, the meteorology of the Asian monsoon area will be analysed based on ERA-Interim re-analysis data (Dee et al., 2011). In August 2012, the Asian monsoon anticy- Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | clone was well established over Southern Asia and the Middle East. The Asian monsoon anticyclone is characterised by low PV values, indicating that it consists mainly of air masses of tropospheric origin. To the north the Asian monsoon anticyclone is connected to the subtropical jet, to the south the equatorial westward flow is adjacent. The Asian monsoon anticyclone extends over a height range from 400 hPa or 340 K 5 upward well into the lowermost stratosphere. During August and September 2012 several tropical cyclones had impact on meteorological conditions in the vicinity of the Asian monsoon anticyclone. Further, during September 2012 the subtropical jet over Asia was disturbed by strong Rossby waves triggered by low pressure systems travelling with the Arctic jet. The interaction between 10 these disturbances and the Asian monsoon anticyclone is discussed in the next sections.

Very rapid uplift in tropical cyclones in August 2012
In the northwestern Pacific region, tropical cyclones (typhoons) are observed at all times of the year, with storm activity peaking in late northern summer (e.g., Emanuel, Between 18 and 20 August 2012, the typhoon Tembin (named Igme by the Philippine Atmospheric, Geophysical and Astronomical Services Administration PAGASA) 20 grew from a tropical depression to a category 4 typhoon southeast of Taiwan 2 . Only a few days later the tropical typhoon Bolaven (PAGASA name Julian) formed east of the Philippines and moved northwest towards Taiwan. Bolaven was also classified as ACPD 14,2014 Fast transport from Asian monsoon anticyclone to Europe    Table 1). Bolaven moved northward during the next 4 days until it made landfall in Korea. This motion is also visible in the 40 day backward trajectories for Θ org between 295 K and 310 K. Along the trajectories the air parcels move first cyclonically around the typhoon, before they move northward and enter the outer edge of the anticyclonic flow of the 20 Asian monsoon anticyclone over Korea at ≈ 370 K (see Fig. 3

left middle panel).
In summary, our trajectory calculations show that typhoons in the northern West Pacific have the potential to very rapidly uplift air masses from the sea surface up to altitudes of the Asian monsoon anticyclonic circulation within 1 to 2 days. Balloon measurements of water vapour and ozone in the Asian monsoon anticyclone launched in the Asian monsoon anticyclone (Munchak et al., 2010). These measurements support the results of our trajectory calculations for September 2012 showing that rapid uplift by typhoons in the West Pacific may transport air parcels from the boundary layer directly in the outer edge of the Asian monsoon anticyclone. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | eddy shedding event and occurs a few times each summer (Dethof et al., 1999;Hsu and Plumb, 2001;Popovic and Plumb, 2001) (cf. Sect. 1). Figure 5 shows that both the Asian monsoon anticyclone and the secondary eastward propagating anticyclones are characterised by low PV values, indicating that it consists mainly of air masses of tropospheric origin.

5
The general behaviour of 40 day backward trajectories shown in Fig. 3 can be explained by the temporal evolution of the Asian monsoon anticyclone. Nearly all trajectories below a Θ org of 380 K are affected by the eddy shedding event on 20 September 2012 or by the separation of filaments with low PV values at the northeastern flank of the anticyclone.

Reasons for eastward eddy shedding and intensification by a super typhoon
Dethof et al. (1999) suggested that mid-latitude synoptic disturbances occasionally interact with the Asian monsoon anticyclone and might pull filaments of tropospheric air from its northern flank. This process is referred to as eastward eddy shedding (Hsu and 15 Plumb, 2001;Popovic and Plumb, 2001). Such a situation occurred in September 2012. The subtropical jet was disturbed by strong Rossby waves triggered by low pressure systems travelling with the Arctic jet. The interaction between these disturbances and the subtropical jet can lead to baroclinic instabilities and eddy shedding (e. g. Orlanski and Sheldon, 1995). 20 Under such circumstances, tropospheric air masses from the the Asian monsoon anticyclone are separated within a secondary anticyclone which is still a tropospheric feature as indicated by low PV values. The transport of air masses into the lowermost stratosphere occurs afterwards. In contrast, tropospheric intrusions transport directly quasi-isentropically air masses from the tropical tropopause layer (TTL) into the extra- 25 tropical lowermost stratosphere where the air masses are mixed irreversibly (e.g., Vogel et al., 2011b). This can be caused by Rossby wave breaking events along the subtropical jet (e.g., Homeyer et al., 2011 Moreover, the eddy shedding event of 20 September 2012 was intensified by interaction between the baroclinic waves and a super typhoon (class 5), leading to a weakening of the Asian monsoon anticyclone in its intensity and coherent horizontal structure. Riemer and Jones (2013) show that the impact of a tropical cyclone on the Rossby wave can be quantified as a source of wave activity for the upper-level wave and is 5 sensitive to the phasing between the tropical cyclone and the wave. The interaction with the tropical cyclone can in general initiate wave breaking and, in case of the Asian monsoon anticyclone, lead to the shedding of secondary anticyclones from the main anticyclone.
On 10 September 2012, the super typhoon Sanba (PAGASA name Karen) formed as a tropical depression east of the Philippines and started moving northward. Three days later the storm system underwent a strong intensification and evolved into the strongest typhoon (class 5) during 2012 in the western Pacific region 4 (see Fig. 5).
It made landfall on 17 September in South Korea and changed into an extratropical cyclone afterwards (see Fig. 5).

15
A trough evolved upstream of the Himalayan plateau on 16 September 2012. This perturbation pushed the circulation of the Asian monsoon anticyclone equatorwards and led to a split of the anticyclone in a western part centred over the Arabian peninsula and an eastern part over northern India. The western part weakened during the following days. At this stage the super typhoon Sanba approached the trough off the 20 coast of South Korea (see Fig. 5). The subsequent interaction between the tropical typhoon and the baroclinic wave led to a strong amplification of the system. The typhoon acted as a source for eddy kinetic energy, leading to a strengthening of the meridional wind. The mid-latitude synoptic disturbances yield eastward eddy shedding strengthened by the super typhoon Sanba (see Fig. 5). 25 In summary, our trajectory calculations show that typhoons in the northern west Pacific have the potential to very rapidly lift air masses from the sea surface to the edge Introduction of the Asian monsoon anticyclone within 1 to 2 days. In combination with the monsoon anticyclone and eastward eddy shedding events, this constitutes a new rapid transport pathway of surface emissions form the West Pacific to Northern Europe. In our study, the minimum transport times from surface to the lowermost stratosphere over Northern Europe are approximately 5 weeks. Moistening of the stratosphere is an im-5 portant driver of climate change, therefore the role of this new rapid transport pathway in moistening of the extratropical lower stratosphere during summer needs further investigation. Moreover, in the last 30 years a poleward migration occurred of the latitude where tropical cyclones achieve their lifetime-maximum intensity (Kossin et al., 2014). If this environmental change continues, more tropical cyclones migrate polwards to the northeastern flank of the Asian monsoon anticyclone. Therefore, the frequency of occurrence of both the direct injections of polluted boundary layer air masses by very rapid uplift in typhoons into the Asian monsoon anticyclone and the strength of eastward eddy shedding events could increase. 15

Conclusions
On 26 September 2012, a filament with enhanced tropospheric trace gases such as CH 4 , CO, and H 2 O and reduced stratospheric O 3 was measured over Northern Europe in the extratropical lowermost stratosphere during a flight on board the German Research Aircraft HALO during the TACTS campaign. Trajectory calculations show that 20 these air masses originate in Southeast Asia and are affected by the Asian monsoon anticyclone. Based on our analysis of these observations and the associated trajectory calculations, we propose a new rapid transport pathway of approximately 5 weeks from the boundary layer sources in Southeast Asia to the location of the measurement in the lowermost stratosphere over Northern Europe. circulating around the Asian monsoon anticyclone (at ≈ 365 K potential temperature). Similar timescales are found for deep convection overshooting in this region (Chen et al., 2012) or in convective transport in the West African tropics (e.g., Fierli et al., 2011). Therefore, our findings confirm evidence from previous studies that at the eastern side of the anticyclone tropospheric air masses are lifted and trapped in the anticy-5 clone (Li et al., 2005) or can be injected by convection into the stratosphere (Rosenlof et al., 1997;Park et al., 2007Park et al., , 2008Chen et al., 2012). Moreover, boundary emissions from the core of Asian monsoon anticyclone are not found in 40 day backward trajectories, suggesting that transport from boundary emissions from India and China through the Asian monsoon anticyclone is slower.

10
In Fig. 6, selected 40 day backward trajectories representing characteristic pathways with different vertical velocities (cf. Table 1) are shown as function of potential temperature and longitude summarising our results. The figure illustrates different transport pathways of air masses with different origin to the location of the measurement over Northern Europe. The observed air masses in the region of interest are a mixture of air 15 masses with distinct origins in different fractions (cf. Table 1). The combination of very rapid uplift by a typhoon and eastward eddy shedding from the Asian monsoon anticyclone yield fast transport (≈ 5 weeks) from Southeast Asia boundary layer sources to Northern Europe (2 % of all trajectories, red). Some of the 40 day backward trajectories originate in the West Pacific troposphere (3 %, blue) or within the Asian monsoon 20 anticyclone over South Asia/North Africa (12 %, green). Air masses that originate in the UTLS at altitudes between 370 K and 380 K potential temperature are mainly from the edge of the Asian monsoon anticyclone (22 %, yellow). Most air parcels originate at higher altitudes between 380 K and 420 K. These air parcels come from the entire Northern Hemisphere, with the exception of the region of the Asian monsoon anticy-25 clone (61 %, grey).
Further, our calculations show that after the injection into the anticyclonic circulation, the air masses circulate clockwise, in an upward spiral, at the edge of the Asian monsoon anticyclone around the core of the anticyclone and do not enter the core of the anticyclone itself. In addition to the upward transport within the Asian monsoon connecting surface air with enhanced pollution to the lower stratosphere (e.g., Park et al., 2009;Randel et al., 2010;Chen et al., 2012;Bergman et al., 2013), the injection into the outer edge of the anticyclone and subsequent clockwise circulation around the core of the anticyclone is an additional pathway of air mass transport from the Asian mon- Our analysis shows that an eastward eddy shedding event occurred mid of Septem-15 ber 2012. The subtropical jet was disturbed by strong Rossby waves triggered by low pressure systems travelling with the Arctic jet. The interaction between these disturbances and the subtropical jet led to the peeling off of secondary anticyclonic structures from the Asian monsoon anticyclone. In addition, this eddy shedding event was intensified by the interaction with the super typhoon Sanba. 20 The backward trajectories show that the transport time of water vapour and pollutants from the Asian monsoon anticyclone to Northern Europe caused by eddy shedding events and transport along the subtropical jet is about 8-14 days in the case study discussed here. Thereafter, the trajectories travel further northeastwards along the subtropical jet to the Pacific Ocean and finally to Northern Europe. In our study, moisture 25 and pollution are transported very fast within up to 5 weeks from the lower troposphere in Southeast Asia to the lowermost stratosphere over Northern Europe caused by the combination of very rapid uplift by a typhoon and eastward eddy shedding from the Asian monsoon anticyclone. This rapid transport pathway into the lowermost strato-ACPD 14,2014 Fast transport from Asian monsoon anticyclone to Europe sphere is for short-lived substances (e.g. bromine-containing short-lived source gases) of particular importance. Eddy shedding events have the potential for long-range transport of enhanced concentrations of boundary layer sources such as water vapour and pollutants from Southeast Asia to mid and high latitudes of the Northern Hemisphere lowermost stratosphere.  Soc., 556, 1079Soc., 556, -1106Soc., 556, , 1999 Dunkerton, T. J.: Evidence of meridional motion in the summer lower stratosphere adjacent to monsoon regions, J. Geophys. Res., 100, 16675-16688, 1995. 18462 Dvortsov, V. L. and Solomon, S.: Response of the stratospheric temperatures and ozone to past 25 and future increases in stratospheric humidity, J. Geophys. Res., 106, 7505-7514, 2001. 18463 Emanuel, K.: Tropical cyclons, Annu. Rev. Earth Pl. Sc., 3, 75-104, 2003, Gurk, C., Hegglin, M., Hoor, P., Königstedt, R., Krebsbach, M., Maser, R., Parchatka, U., Peter, T., Schell, D., Introduction

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Chem. Phys., 11, 201-214, doi:10.5194/acp-11-201-2011Phys., 11, 201-214, doi:10.5194/acp-11-201- , 2011. 18478 Forster, P. and Shine, K. P.: Stratospheric water vapour change as possible contributor to observed stratospheric cooling, Geophys. Res. Lett., 26, 3309-3312, doi:10.1029/1999GL010487, 1999 vapor 1992-1997, Q. J. Roy. Meteor. Soc., 124, 169-192, 1998. 18463  , 402, 399-401, doi:10.1038/46521, 1999. 18463 Konopka, P., Grooß, J.-U., Günther, G., Ploeger, F., Pommrich, R., Müller, R., andLivesey, N.: Annual cycle of ozone at and above the tropical tropopause: observations versus simulations 25 with the Chemical Lagrangian Model of the Stratosphere (CLaMS), Atmos. Chem. Phys., 10, 121-132, doi:10.5194/acp-10-121-2010, 2010. 18464, 18465 Konopka, P., Ploeger, F., andMüller, R.: Entropy-based Park, M., Randel, W. J., Gettleman, A., Massie, S. T., and Jiang, J. H.: Transport above the Asian summer monsoon anticyclone inferred from Aura Microwave Limb Sounder tracers, J. Geophys. Res., 112, D16309, doi:10.1029/2006JD008294, 2007ical isolation in the Asian monsoon anticyclone observed in Atmospheric Chemistry Experi-5 ment (ACE-FTS) data, Atmos. Chem. Phys., 8, 757-764, doi:10.5194/acp-8-757-2008, 2008. 18463, 18464, 18478 Park, M., Randel, W. J., Emmons, L. K., andLivesey, N    The part of the flightpath discussed within this paper is highlighted in grey (region of interest) (cf. Sect.2 and see Fig. 1). Trajectories with origins (Θorg) lower than 350 K potential temperature in the region of interest are shown in Fig. 3. The part of the flightpath discussed within this paper is highlighted in grey (region of interest) (cf. Sect. 2 and see Fig. 1). Trajectories with origins (Θ org ) lower than 360 K potential temperature in the region of interest are shown in Fig. 3 Fig. 6. Selected trajectories representing characteristic pathways with different vertical velocities (cf. table 1) as function of potential temperature and longitude for the time period between 17.08.12 and 26.09.12. The air mass positions are plotted every hour (coloured dots). Large distances between the single dots indicated very rapid uplift. The classification of the different vertical velocities is derived for the first ten days of the trajectories (17.08.12 -28.08.12). For simplification longitudes between 60 • W and 20 • E are shown twice. The coloured text gives information about the altitude origin and geographical position origin of the different pathways. The figure illustrates different transport pathways of air masses with different origin to the location of the measurement over Northern Europe. The combination of very rapid uplift by a typhoon and eastward eddy shedding from the Asian monsoon anticyclone yield fast transport (≈ 5 weeks) from Southeast Asia boundary layer sources to Northern Europe (red).  Table 1) as function of potential temperature and longitude for the time period between 17 August and 26 September 2012. The air mass positions are plotted every hour (coloured dots). Large distances between the single dots indicated very rapid uplift. The classification of the different vertical velocities is derived for the first ten days of the trajectories (17-28 August 2012). For simplification longitudes between 60 • W and 20 • E are shown twice. The coloured text gives information about the altitude origin and geographical position origin of the different pathways. The figure illustrates different transport pathways of air masses with different origin to the location of the measurement over Northern Europe. The combination of very rapid uplift by a typhoon and eastward eddy shedding from the Asian monsoon anticyclone yield fast transport (≈ 5 weeks) from Southeast Asia boundary layer sources to Northern Europe (red).