scholarly journals Transport of Antarctic stratospheric strongly dehydrated air into the troposphere observed during the HALO-ESMVal campaign 2012

2015 ◽  
Vol 15 (16) ◽  
pp. 9143-9158 ◽  
Author(s):  
C. Rolf ◽  
A. Afchine ◽  
H. Bozem ◽  
B. Buchholz ◽  
V. Ebert ◽  
...  

Abstract. Dehydration in the Antarctic winter stratosphere is a well-known phenomenon that is annually observed by satellites and occasionally observed by balloon-borne measurements. However, in situ measurements of dehydrated air masses in the Antarctic vortex are very rare. Here, we present detailed observations with the in situ and GLORIA remote sensing instrument payload aboard the German aircraft HALO. Strongly dehydrated air masses down to 1.6 ppmv of water vapor were observed as far north as 47° S in an altitude between 12 and 13 km in the lowermost stratosphere. The dehydration can be traced back to individual ice formation events above the Antarctic Peninsula and Plateau, where ice crystals sedimented out and water vapor was irreversibly removed. Within these dehydrated stratospheric air masses, filaments of moister air reaching down to the tropopause are detected with the high-resolution limb sounder, GLORIA. Furthermore, dehydrated air masses are observed with GLORIA in the Antarctic lowermost stratosphere down to 7 km. With the help of a backward trajectory analysis, a midlatitude origin of the moist filaments in the vortex can be identified, while the dry air masses down to 7 km have stratospheric origins. Antarctic stratosphere–troposphere exchange (STE) and transport of dehydrated air masses into the troposphere are investigated. Further, it is shown that the exchange process can be attributed to several successive Rossby wave events in combination with an isentropic exchange of air masses across the thermal tropopause. The transport into the troposphere is caused by air masses that are detached from the potential vorticity (PV) structure by Rossby wave breaking events and subsequently transported diabatically across the dynamical tropopause. Once transported to the troposphere, air masses with stratospheric origin can reach near-surface levels within several days.

2015 ◽  
Vol 15 (6) ◽  
pp. 7895-7932 ◽  
Author(s):  
C. Rolf ◽  
A. Afchine ◽  
H. Bozem ◽  
B. Buchholz ◽  
V. Ebert ◽  
...  

Abstract. Dehydration in the Antarctic winter stratosphere is a well-known phenomenon that is occasionally observed by balloon-borne and satellite measurements. However, in-situ measurements of dehydration in the Antarctic vortex are very rare. Here, we present detailed observations with the in-situ and GLORIA remote sensing instrument payload aboard the new German aircraft HALO. Strongly dehydrated air masses down to 1.6 ppmv of water vapor were observed as far north as 47° S and between 12 and 13 km in altitude, which has never been observed by satellites. The dehydration can be traced back to individual ice formation events, where ice crystals sedimented out and water vapor was irreversibly removed. Within these dehydrated stratospheric air masses, filaments of moister air reaching down to the tropopause are detected with the high resolution limb sounder, GLORIA. Furthermore, dehydrated air masses are observed with GLORIA in the Antarctic troposphere down to 7 km. With the help of a backward trajectory analysis, a tropospheric origin of the moist filaments in the vortex can be identified, while the dry air masses in the troposphere have stratospheric origins. The transport pathways of Antarctic stratosphere/troposphere exchange are investigated and the irrelevant role of the Antarctic thermal tropopause as a transport barrier is confirmed. Further, it is shown that the exchange process can be attributed to several successive Rossby wave events in combination with an isentropic interchange of air masses across the weak tropopause and subsequent subsidence due to radiative cooling. Once transported to the troposphere, air masses with stratospheric origin are able to reach near-surface levels within 1–2 months.


2005 ◽  
Vol 5 (5) ◽  
pp. 10301-10337
Author(s):  
A. Carré ◽  
F. Ravetta ◽  
J.-P. Cammas ◽  
P. Mascart ◽  
J. Duron ◽  
...  

Abstract. This study documents several processes of stratosphere-troposphere transport (STT) in the subtropical region. A case study of the interaction between a Rossby Wave breaking over the Canary Islands and a subtropical vortex core situated further south is analysed with ozone airborne measurements (in-situ and Lidar). The investigation is conducted using a Reverse Domain Filling technique to reconstruct high-resolution potential vorticity fields with a Lagrangian approach and with simulations of a mesoscale model. Results show irreversible STT associated with tropopause folding, Rossby Wave Breaking and the filamentation of the subtropical vortex core.


2021 ◽  
Author(s):  
Lukas Krasauskas ◽  
Jörn Ungermann ◽  
Peter Preusse ◽  
Felix Friedl-Vallon ◽  
Andreas Zahn ◽  
...  

<p>We present measurements of ozone, water vapour and nitric acid in the upper troposphere/lower stratosphere (UTLS) over North Atlantic and Europe. The measurements were acquired with the Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) during the Wave Driven Isentropic Exchange (WISE) campaign in October 2017. GLORIA is an airborne limb imager capable of acquiring both 2-D data sets (curtains along the flight path) and, when the carrier aircraft is flying around the observed air mass, spatially highly resolved 3-D tomographic data. We show a case study of a Rossby wave (RW) breaking event observed during two subsequent flights two days apart. RW breaking is known to steepen tracer gradients and facilitate stratosphere-troposphere exchange (STE). Our measurements reveal complex spatial structures in stratospheric tracers (ozone and nitric acid) with multiple vertically stacked filaments. Backward trajectory analysis is used to demonstrate that these features are related to several previous Rossby wave breaking events and that the small-scale structure of the UTLS in the Rossby wave breaking region, which is otherwise very hard to observe, can be understood as stirring and mixing of air masses of tropospheric and stratospheric origin. It is also shown that a strong nitric acid enhancement observed just above the tropopause is likely a result of NO<sub>x</sub> production by lightning activity. The measurements showed signatures of enhanced mixing between stratospheric and tropospheric air near the polar jet with some transport of water vapour into the stratosphere. Some of the air masses seen in 3-D data were encountered again two days later, stretched to very thin filament (horizontal thickness down to 30 km at some altitudes) rich in stratospheric tracers. This repeated measurement allowed us to directly observe and analyse the progress of mixing processes in a thin filament over two days. Our results provide direct insight into small-scale dynamics of the UTLS in the Rossby wave breaking region, witch is of great importance to understanding STE and poleward transport in the UTLS.</p>


2017 ◽  
Vol 30 (9) ◽  
pp. 3381-3399 ◽  
Author(s):  
Huancui Hu ◽  
Francina Dominguez ◽  
Zhuo Wang ◽  
David A. Lavers ◽  
Gan Zhang ◽  
...  

Atmospheric rivers (ARs) have significant hydrometeorological impacts on the U.S. West Coast. This study presents the connection between the characteristics of large-scale Rossby wave breaking (RWB) over the eastern North Pacific and the regional-scale hydrological impacts associated with landfalling ARs on the U.S. West Coast (36°–49°N). ARs associated with RWB account for two-thirds of the landfalling AR events and >70% of total AR-precipitation in the winter season. The two regimes of RWB—anticyclonic wave breaking (AWB) and cyclonic wave breaking (CWB)—are associated with different directions of the vertically integrated water vapor transport (IVT). AWB-ARs impinge in a more westerly direction on the coast whereas CWB-ARs impinge in a more southwesterly direction. Most of the landfalling ARs along the northwestern coast of the United States (states of Washington and Oregon) are AWB-ARs. Because of their westerly impinging angles when compared to CWB-ARs, AWB-ARs arrive more orthogonally to the western Cascades and more efficiently transform water vapor into precipitation through orographic lift than CWB-ARs. Consequently, AWB-ARs are associated with the most extreme streamflows in the region. Along the southwest coast of the United States (California), the southwesterly impinging angles of CWB-ARs are more orthogonal to the local topography. Furthermore, the southwest coast CWB-ARs have more intense IVT. Consequently, CWB-ARs are associated with the most intense precipitation. As a result, most of the extreme streamflows in southwest coastal basins are associated with CWB-ARs. In summary, depending on the associated RWB type, ARs impinge on the local topography at a different angle and have a different spatial signature of precipitation and streamflow.


2021 ◽  
Vol 21 (13) ◽  
pp. 10249-10272
Author(s):  
Lukas Krasauskas ◽  
Jörn Ungermann ◽  
Peter Preusse ◽  
Felix Friedl-Vallon ◽  
Andreas Zahn ◽  
...  

Abstract. This paper presents measurements of ozone, water vapour and nitric acid (HNO3) in the upper troposphere/lower stratosphere (UTLS) over North Atlantic and Europe. The measurements were acquired with the Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) during the Wave Driven Isentropic Exchange (WISE) campaign in October 2017. GLORIA is an airborne limb imager capable of acquiring both 2-D data sets (curtains along the flight path) and, when the carrier aircraft is flying around the observed air mass, spatially highly resolved 3-D tomographic data. Here, we present a case study of a Rossby wave (RW) breaking event observed during two subsequent flights 2 d apart. RW breaking is known to steepen tracer gradients and facilitate stratosphere–troposphere exchange (STE). Our measurements reveal complex spatial structures in stratospheric tracers (ozone and nitric acid) with multiple vertically stacked filaments. Backward-trajectory analysis is used to demonstrate that these features are related to several previous Rossby wave breaking events and that the small-scale structure of the UTLS in the Rossby wave breaking region, which is otherwise very hard to observe, can be understood as stirring and mixing of air masses of tropospheric and stratospheric origin. It is also shown that a strong nitric acid enhancement observed just above the tropopause is likely a result of NOx production by lightning activity. The measurements showed signatures of enhanced mixing between stratospheric and tropospheric air near the polar jet with some transport of water vapour into the stratosphere. Some of the air masses seen in 3-D data were encountered again 2 d later, stretched to very thin filament (horizontal thickness down to 30 km at some altitudes) rich in stratospheric tracers. This repeated measurement allowed us to directly observe and analyse the progress of mixing processes in a thin filament over 2 d. Our results provide direct insight into small-scale dynamics of the UTLS in the Rossby wave breaking region, which is of great importance to understanding STE and poleward transport in the UTLS.


2013 ◽  
Vol 70 (9) ◽  
pp. 2982-3001 ◽  
Author(s):  
Alvaro de la Cámara ◽  
Carlos R. Mechoso ◽  
Ana M. Mancho ◽  
Encarna Serrano ◽  
Kayo Ide

Abstract The trajectories in the lower stratosphere of isopycnic balloons released from Antarctica by Vorcore and Concordiasi field campaigns during the southern springs of 2005 and 2010 showed events of latitudinal transport inside the stratospheric polar vortex, both away from and toward the poleward flank of the polar-night jet. The present paper applies trajectory-based diagnostic techniques to examine mechanisms at work during such events. Reverse domain-filling calculations of potential vorticity (PV) fields from the ECMWF Interim Re-Analysis (ERA-Interim) dataset during the events show irreversible filamentation of the PV fields in the inner side of the polar-night jet, which is a signature of planetary (Rossby) wave breaking. Balloon motions during the events are fairly consistent with the PV filaments. Events of both large (~15° of arc length) and small (~5° of arc length) balloon displacements from the vortex edge are associated, respectively, with deep and shallow penetration into the core of the elongated PV contours. Additionally, the Lagrangian descriptor M is applied to study the configuration of Lagrangian structures during the events. Breaking Rossby waves inside the vortex lead to the presence of hyperbolic points. The geometric configuration of the invariant manifolds associated with the hyperbolic trajectories helps to understand the apparent chaotic behavior of balloons' motions and to identify and analyze balloon transport events not captured by reverse domain-filling calculations. The Antarctic polar vortex edge is an effective barrier to air parcel crossings. Rossby wave breaking inside the vortex, however, can contribute to tracer mixing inside the vortex and to occasional air crossings of the edge.


2018 ◽  
Vol 146 (3) ◽  
pp. 695-712 ◽  
Author(s):  
Gan Zhang ◽  
Zhuo Wang

This study investigates the life cycle of anticyclonic Rossby wave breaking during the extended warm season (July–October) over the North Atlantic basin. It was found that upper-tropospheric breaking waves are coupled with lower-level perturbations and can be traced back to a wave train that extends from the North Pacific. The overturning of potential vorticity (PV) contours during wave breaking is associated with the rapid development of an upper-level ridge, which occurs along the east coast of North America and over a warm and moist airstream. The ridge development is investigated using the PV budget analysis and trajectory analysis. The PV budget analysis suggests that the horizontal advection of PV by the perturbed flow dictates the movement and the later decay of the ridge. The ridge amplification, opposed by the horizontal advection of PV, is driven by the vertical advection and the diabatic production of PV, both of which are connected to diabatic heating. The vital role of diabatic heating in the ridge amplification is corroborated by the trajectory analysis. The analysis suggests that diabatic heating reduces the static stability near the tropopause and contributes to the ridge-related negative PV anomalies. The role of diabatic heating in anticyclonic and cyclonic wave breaking in other regions is also discussed. The findings suggest that moist diabatic processes, which were often excluded from the earlier studies of wave breaking, are crucial for Rossby wave breaking during the warm season. The updated understanding of wave breaking may benefit weather forecasting and climate predictions.


2016 ◽  
Author(s):  
C. P. Webber ◽  
H. F. Dacre ◽  
W. J. Collins ◽  
G. Masato

Abstract. Coarse particulate matter (PM10) has long been understood to be hazardous to human health with mortality rates increasing as a result of raised ground level concentrations. We explore the influence of synoptic scale meteorology on observed PM10 concentration ([PM10]) using Rossby Wave Breaking (RWB). Meteorological re-analysis data for the winter months (DJF) between January 1999 and December 2008 and observed PM10 data for three urban background UK (Midland) sites, were analysed. Three RWB diagnostics were used to identify RWB that had significant influence on UK Midland PM10. RWB events were classified according to whether the RWB was cyclonic or anticyclonic in its direction of breaking and whether the RWB event was influenced more by poleward or equatorial air masses. We find that there is a strong link between RWB events and UK [PM10]. Significant increases (p 


2020 ◽  
Author(s):  
Lukas Krasauskas ◽  
Jörn Ungermann ◽  
Peter Preusse ◽  
Felix Friedl-Vallon ◽  
Andreas Zahn ◽  
...  

Abstract. This paper presents measurements of ozone, water vapour and nitric acid in the upper troposphere/lower stratosphere (UTLS) over North Atlantic and Europe. The measurements were acquired with the Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) during the Wave Driven Isentropic Exchange (WISE) campaign in October 2017. GLORIA is an airborne limb imager capable of acquiring both 2-D data sets (curtains along the flight path) and, when the carrier aircraft is flying around the observed air mass, spatially highly resolved 3-D tomographic data. Here we present a case study of a Rossby wave (RW) breaking event observed during two subsequent flights two days apart. RW breaking is known to steepen tracer gradients and facilitate stratosphere-troposphere exchange (STE). Our measurements reveal complex spatial structures in stratospheric tracers (ozone and nitric acid) with multiple vertically stacked filaments. Backward trajectory analysis is used to demonstrate that these features are related to several previous Rossby wave breaking events and that the small-scale structure of the UTLS in the Rossby wave breaking region, which is otherwise very hard to observe, can be understood as stirring and mixing of air masses of tropospheric and stratospheric origin. It is also shown that a strong nitric acid enhancement observed just above the tropopause is likely a result of NOx production by lightning activity. The measurements showed signatures of enhanced mixing between stratospheric and tropospheric air near the polar jet with some transport of water vapour into the stratosphere. Some of the air masses seen in 3-D data were encountered again two days later, stretched to very thin filament (horizontal thickness down to 30 km at some altitudes) rich in stratospheric tracers. This repeated measurement allowed us to directly observe and analyse the progress of mixing processes in a thin filament over two days. Our results provide direct insight into small-scale dynamics of the UTLS in the Rossby wave breaking region, witch is of great importance to understanding STE and poleward transport in the UTLS.


2017 ◽  
Vol 17 (2) ◽  
pp. 867-881 ◽  
Author(s):  
Christopher P. Webber ◽  
Helen F. Dacre ◽  
William J. Collins ◽  
Giacomo Masato

Abstract. Coarse particulate matter (PM10) has long been understood to be hazardous to human health, with mortality rates increasing as a result of raised ground level concentrations. We explore the influence of synoptic-scale meteorology on daily mean observed PM10 concentration ([PM10]) using Rossby wave breaking (RWB). Meteorological reanalysis data for the winter months (DJF) between January 1999 and December 2008 and observed PM10 data for three urban background UK (Midland) sites were analysed. Three RWB diagnostics were used to identify RWB that had significant influence on UK Midland PM10. RWB events were classified according to whether the RWB was cyclonic or anticyclonic in its direction of breaking and whether the RWB event was influenced more by poleward or equatorial air masses. We find that there is a strong link between RWB events and UK [PM10]. Significant increases (p  <  0.01) in UK [PM10] were seen 1 day following RWB occurring in spatially constrained northeast Atlantic–European regions. Analysis into episodic PM10 exceedance events shows increased probability of [PM10] exceedance associated with all RWB subsets. The greatest probability of exceeding the UK [PM10] threshold was associated with cyclonic RWB preceded by anticyclonic RWB forming an Ω block synoptic pattern. This mechanism suggests an easterly advection of European PM10 followed by prolonged stagnant conditions within the UK and led to an almost threefold increase in the probability of the UK Midlands exceeding a hazardous [PM10] threshold (0.383), when compared to days where no RWB was detected (0.129).


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