24 Jun 2024
 | 24 Jun 2024
Status: this preprint is open for discussion and under review for Weather and Climate Dynamics (WCD).

Moisture transport axes: a unifying definition for monsoon air streams, atmospheric rivers, and warm moist intrusions

Clemens Spensberger, Kjersti Konstali, and Thomas Spengler

Abstract. The water vapor transport in the extratropics is mainly organized in narrow elongated filaments. These filaments are referred to with a variety of names depending on the contexts, for example atmospheric river, warm moist intrusion, warm conveyor belt, and feeder air stream. Despite the various names, these features share essential properties, such as their narrow elongated structure. Here, we propose an algorithm that detects these various lines of moisture transport in instantaneous maps of the vertically integrated water vapor transport. The detection algorithm extracts well-defined maxima in the water vapor transport and connects them to lines that we refer to as moisture transport axes. By only requiring a well-defined maximum in the vapor transport, we avoid imposing a threshold in the absolute magnitude of this transport or the total column water vapor. Consequently, the algorithm is able to pick up moisture transport axes at all latitudes without requiring region-specific tuning or normalization. We demonstrate that the algorithm can detect both atmospheric rivers and warm moist intrusions, but also prominent monsoon air streams as well as low-level jets with moisture transport. Atmospheric rivers sometimes consist of several distinct moisture transport axes, indicating the merging of several moisture filaments into one atmospheric river. We showcase the synoptic situations and precipitation patterns associated with the occurrence of the identified moisture transport axes in example regions in the low, mid, and high latitudes.

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Clemens Spensberger, Kjersti Konstali, and Thomas Spengler

Status: open (until 05 Aug 2024)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-1709', Franziska Aemisegger, 26 Jun 2024 reply
  • RC2: 'Comment on egusphere-2024-1709', Anonymous Referee #2, 15 Jul 2024 reply
Clemens Spensberger, Kjersti Konstali, and Thomas Spengler
Clemens Spensberger, Kjersti Konstali, and Thomas Spengler


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Short summary
The transport of moisture from warmer and moister towards colder and drier regions mainly occurs in brief and narrow. In the mid-latitudes, such bursts are generally referred to as atmospheric rivers, in the Arctic they are often referred to as warm moist intrusions. We introduce a new definition to identify such bursts which is based primarily on their elongated structure. With this more general definition, we show that bursts in moisture transport occur frequently across all climate zones.