English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

. We have performed backward trajectory calculations andsimulations with the three-dimensional Chemical Lagrangian Model of theStratosphere (CLaMS) for two succeeding monsoon seasons using artificialtracers of air mass origin. With these tracers we trace back the origin ofyoung air masses (age &lt;6 months) at the top of the Asian monsoonanticyclone and of air masses within the tropical pipe(6 months &lt; age &lt;18 months) during summer 2008. The occurrence ofyoung air masses (&lt;6 months) at the top of the Asian monsoon anticyclone upto ∼460 K is in agreement with satellitemeasurements of chlorodifluoromethane (HCFC-22) by the MichelsonInterferometer for Passive Atmospheric Sounding (MIPAS) instrument. HCFC-22can be considered as a regional tracer for continental eastern Asia and theMiddle East as it is mainly emitted inthis region. Our findings show that the transport of air masses fromboundary layer sources in the region of the Asian monsoon into the tropicalpipe occurs in three distinct steps. First, very fast uplift in “aconvective range” transports air masses up to 360 K potentialtemperature within a few days. Second, air masses are uplifted fromabout 360 K up to 460 K within “an upward spiralling range” within afew months. The large-scale upward spiral extends from northern Africato the western Pacific. The air masses are transported upwards bydiabatic heating with a rate of up to 1–1.5 K per day, implyingstrong vertical transport above the Asian monsoon anticyclone. Third,transport of air masses occurs within the tropical pipe up to 550 Kassociated with the large-scale Brewer–Dobson circulation within∼1 year. In the upward spiralling range, air masses are uplifted by diabaticheating across the (lapse rate) tropopause, which does not act as atransport barrier, in contrast to the extratropical tropopause.Further, in the upward spiralling range air masses from inside theAsian monsoon anticyclone are mixed with air masses convectivelyuplifted outside the core of the Asian monsoon anticyclone in thetropical adjacent regions. Moreover, the vertical transport of airmasses from the Asian monsoon anticyclone into the tropical pipe isweak in terms of transported air masses compared to the transport fromthe monsoon anticyclone into the northern extratropical lowerstratosphere. Air masses from the Asian monsoon anticyclone(India/China) contribute a minor fraction to the composition of airwithin the tropical pipe at 550 K (6 %), and the major fractions arefrom Southeast Asia (16 %) and the tropical Pacific (15 %).

Lagrangian simulations of the transport of young air masses to the top of the Asian monsoon anticyclone and into the tropical pipe