Project

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Spatial and Temporal Scales of Linkages in the Atmospheric Water Cycle (Waterscales)

Applicant Sodemann Harald
Number 143436
Funding scheme Project funding (Div. I-III)
Research institution Institut für Atmosphäre und Klima ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Meteorology
Start/End 01.04.2013 - 31.05.2016
Approved amount 160'647.00
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All Disciplines (2)

Discipline
Meteorology
Climatology. Atmospherical Chemistry, Aeronomy

Keywords (6)

Atmospheric dynamics; Precipitation recycling; Climate system; Water vapor transport; Weather systems; Atmospheric water cycle

Lay Summary (German)

Lead
Der atmosphärische Teil des globalen Wasserkreislaufs verbindet die Wasserreservoire untereinander. Wasserdampf verdunstet von den Meeren und vom Land, wird durch die Atmosphäre transportiert, kondensiert in Wolken und kehrt als Niederschlag zur Erdoberfläche zurück. Variabilität ist ein Schlüsselmerkmal des atmosphärischen Wasserkreislaufs. Niederschlagsextreme und Trockenheit können schwerwiegende Konsequenzen für die Bevölkerung und Infrastruktur zur Folge haben.
Lay summary

Übergeordnetes Ziel dieses Forschungsprojektes ist es, mittels einer neuartigen Analyse der Verbindungen zwischen Verdunstungsquellen, atmosphärischem Transport und Niederschlagsprozessen zu einem besseren Verständnis globaler Niederschlagsvariabilität beizutragen. Das erste Ziel der Arbeit besteht darin, einen globalen Überblick über die charakteristischen räumlichen und zeitlichen Skalen der Kopplungsprozesse des atmosphärischen Wasserkreislaufs zu gewinnen. Mittels zweier komplexer Analyseverfahren wird dann in Fallstudien auf Schlüsselregionen des globalen Wasserkreislaufs eingegangen. Das daraus für das aktuelle Klima erhaltene Prozessverständnis für den atmosphärischen Wassertransport soll schliesslich auf eine Simulation des zukünftigen Klimas übertragen werden.

Die Ergebnisse unserer Arbeit werden dazu beitragen, extreme Wetterereignisse im heutigen Klima besser zu verstehen und damit möglicherweise besser vorherzusagen. Weiterhin wird die Arbeit wichtige Informationen liefern für die Rekonstruktion früherer Klimavariabilität aus Klimaarchiven. Schliesslich wird unsere Fähigkeit, zukünftige Änderungen im Wasserkreislauf im Rahmen des Klimawandels zu prognostizieren, auf einer solideren Grundlage aufbauen können.

Direct link to Lay Summary Last update: 23.01.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Abrupt ice-age shifts in southern westerly winds and Antarctic climate forced from the north
Buizert Christo, Sigl Michael, Severi Mirko, Markle Bradley R., Wettstein Justin J., McConnell Joseph R., Pedro Joel B., Sodemann Harald, Goto-Azuma Kumiko, Kawamura Kenji, Fujita Shuji, Motoyama Hideaki, Hirabayashi Motohiro, Uemura Ryu, Stenni Barbara, Parrenin Frédéric, He Feng, Fudge T. J., Steig Eric J. (2018), Abrupt ice-age shifts in southern westerly winds and Antarctic climate forced from the north, in Nature, 563(7733), 681-685.
A revised picture of the atmospheric moisture residence time
Läderach Alexander, Sodemann Harald (2016), A revised picture of the atmospheric moisture residence time, in Geophysical Research Letters, 43(2), 924-933.

Collaboration

Group / person Country
Types of collaboration
HyMEX consortium France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
University of Bergen Norway (Europe)
- in-depth/constructive exchanges on approaches, methods or results
University of Oxford Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results

Abstract

The atmospheric branch of the global water cycle is an important link between the major reservoirs, such as ocean, land, and ice sheets. Water vapour evaporates from the world oceans and land surfaces, is transported through the atmosphere governed by atmospheric dynamics, until it condenses and returns as precipitation to the surface. Variability is a key characteristic of the atmospheric water cycle. Extremes in precipitation variability, such as flooding and drought periods can have severe consequences for human societies. It is the aim of this project to contribute to a better understanding of the processes governing precipitation variability on a global scale through a novel analysis of the linkages between evaporation sources, atmospheric transport, and precipitation processes. One way to characterise the connection between precipitation and the water vapour sources are variables of temporal and spatial scale, such as atmospheric residence time and water vapour transport distance. Previous research has indicated that most of the water vapour converted to precipitation by weather systems had already been present in the atmosphere beforehand. It has however not been studied in detail which processes had lead to the evaporation of that moisture in the first place, over which radius water vapour is typically advected into different weather systems, and which life time of the atmospheric water vapour this implies. While on a global mean an atmospheric life time of water vapour of about 10 days can be derived, several recent studies specifically highlight that substantial variability can exist, ranging between less than two days for mid-latitude heavy precipitation events to about two weeks in polar regions. In order to advance the basic understanding of the atmospheric water cycle, this project proposes to provide a first climatology of the characteristic spatial and temporal scales of linkages in the tropospheric water cycle using the ECMWF ERA-Interim reanalysis data set. To this end, two complementary methods developed by the applicant will be used in the proposed PhD project. The first method is a Lagrangian diagnostic to identify the moisture sources and transport pathways of atmospheric water vapour. This is currently the most advanced method of its kind, and will yield global information on the spatial and temporal scales linking the atmospheric water cycle. Explicitly displaying this information globally will allow to delineate regions by characteristic processes, identify transition regions, and their seasonal and inter-annual variability. Second, a regional numerical weather prediction model equipped with a secondary water cycle for the advection of water vapour tracers will be used to better understand the detailed dynamical and physical processes responsible for setting the identified temporal and spatial scales of water vapour transport in regions identified by the first method. By adapting the Lagrangian diagnostic to output from climate model simulations, it will be possible to assess the representation of the derived water cycle characteristics in climate models, and to build hypotheses on how the simulated water cycle responds to climatic changes. The results from the proposed project will help to guide future research on extremes in the present-day atmospheric water cycle, be relevant for interpreting records of past climate variability, and contribute to a better understanding of our abilities to project changes of the hydrological cycle in a future climate.
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