Jet streams - their feature and genesis

Mai 21, 2019

Hier gibt es bei EOS von der AGU einen interessanten Beitrag zu dem Einfluss der globalen Erwärmung auf die Jetstreams:

Es handelt sich um die Ergebnisse von Simulationen.

Hier der Text aus EOS:

By 20 May 2019

Midlatitude jet streams, narrow bands of strong upper atmospheric winds, steer high- and low-pressure weather systems and help maintain our planet’s habitable climate. They are closely related to the preferred track of midlatitude low-pressure storm systems known as storm tracks.

The position and intensity of jet streams typically vary in response to processes that affect surface temperature gradients between the equator and the poles. Although many comprehensive climate models predict that Earth’s jet streams will shift poleward as the planet warms, the projected magnitudes of these shifts appear to vary widely depending upon the planet’s response to changes in radiative energy.

Now Tan et al. have developed a series of simulations to test how different approaches to modeling radiation can affect the response of jet streams to global warming. The results indicate that when using a gray radiation scheme, which has been used in many simplified modeling studies, the midlatitude jet stream responds by shifting toward the equator rather than the pole.

The authors conclude that despite the prevalence of the gray radiation scheme, this approach does not adequately capture the circulation response to global warming. Instead, the researchers showed that using a simple, four-band longwave radiation scheme that incorporates the effects of water vapor more effectively replicates circulation responses in full general circulation models.

The results suggest the authors’ model captures the fundamental processes that influence the response of midlatitude circulation to increasing temperatures and demonstrate that this approach can boost our understanding of how jet streams and storm tracks will respond to future warming. (Journal of Advances in Modeling Earth Systems (JAMES),, 2019) - Open Access Paper.


Comprehensive climate models exhibit a large spread in the magnitude of projected poleward eddy-driven jet shift in response to warming. The spread has been connected to the radiative response to warming. To understand how different radiative assumptions alone affect the jet shift in response to warming, we introduce a new clear-sky longwave radiation hierarchy that spans idealized (gray versus four bands; without or with interactive water vapor) through comprehensive (correlated-k) radiation in the same general circulation model. The new hierarchy is used in an aquaplanet configuration to explore the impact of radiation on the jet stream response to warming, independent of mean surface temperature and meridional surface temperature gradient responses. The gray radiation scheme produces a split jet and its eddy-driven jet shifts equatorward as climate warms, whereas the storm track shifts equatorward then poleward. Including four longwave bands leads to a merged jet that shifts slightly poleward with warming, and the storm track shifts monotonically poleward. Including interactive water vapor makes the poleward jet shift comparable to the jet shift with comprehensive radiation and interactive water vapor. These jet and storm track differences are linked to the radiation response of the
stratospheric temperature, the tropopause height, and the meridional gradient of the radiative forcing to warming. Dynamically, the equatorward jet shift with the gray scheme is consistent with reduced wave reflection on the poleward flank of the jet, whereas the poleward jet shift with the other schemes is consistent with increased eddy length scale that favors equatorward wave propagation.

Eine von Google-Translate erstellte Übersetzung des Abstrakts ins Deutsche ist hier:

Umfassende Klimamodelle weisen eine große Streuung in der Größenordnung der projizierten, durch Wirbel angetriebenen Strahlstromverschiebung (Jetstream) in polwärts gerichteter Richtung als Reaktion auf die Erwärmung auf. Die Verschiebung wurde mit der Strahlungsreaktion auf Erwärmung in Verbindung gebracht. Um zu verstehen, wie die verschiedenen Strahlungs Annahmen allein die Strahlverschiebung in Reaktion auf der Erwärmung beeinflussen, führen wir eine neue klaren Himmel langwellige Strahlung Hierarchie, die idealisierte umspannt (Grau gegen vier Bands, ohne oder mit interaktivem Wasserdampf) durch umfassende (korrelierte-k) Strahlung im gleichen allgemeinen Zirkulationsmodell (GCM). Die neue Hierarchie wird in einer Aqua Konfiguration verwendet, um die Wirkung der Strahlung auf den Strahlstrom als Reaktion auf Erwärmung, unabhängig von den mittleren Oberflächentemperatur und meridionale Oberfläche Temperaturgradienten Reaktionen zu untersuchen. Das graue Strahlungsschema erzeugt einen geteilten Strahl und sein Wirbelstrahl verschiebt sich bei Erwärmung des Klimas äquatorwärts, wohingegen sich die Sturmspur äquatorwärts und dann polwärts verschiebt. Das Einbeziehen von vier Langwellenbändern führt zu einem zusammengeführten Strahl, der sich mit der Erwärmung leicht in die entgegengesetzte Richtung verschiebt, und die Sturmspur verschiebt sich monoton in die entgegengesetzte Richtung. Durch die Einbeziehung von interaktivem Wasserdampf ist die Poleward-Jet-Verschiebung vergleichbar mit der Jet-Verschiebung durch umfassende Strahlung und interaktiven Wasserdampf. Diese Jet - und Storm - Track - Differenzen hängen mit der Strahlungsantwort des. Zusammenstratosphärische Temperatur, die Tropopausenhöhe und der meridionale Gradient des Strahlungsantriebs zur Erwärmung. Dynamisch ist die äquatorStrahlVerschiebung mit der grauen Regelung mit reduzierter Wellenreflexion an der polwärtigen Flanke des Strahls konsistent, während die polwärtigen Strahlverschiebung mit den anderen Systemen mit erhöhter Wirbellängenskala übereinstimmt, die äquatorWellenAusbreitung begünstigt.

März 11, 2019

Remark: Most of the following text and videos is in English.

I start with the atmospheric strucutre and compositions.

The structure of the Earth atmosphere will be described here:

Amanda Pratt
Am 16.10.2013 veröffentlicht

Our wheather and climate takes place in the lowest part of the atmosphere, the troposphere.

Since years I never understood how the arctic (and antarctic) wheater-belt was formed. In particular I was interested how the polar (arctic and antarctic) etstreams are formed.

There are two global jetstreams on Earth: the tropical jetstream and the polar jetstream.
The tropical one can be simply explained, the polar one not so easy. Therefoer I try to collect some information on the polar jetstream - some videos but also scientific articles and possibly textbooks.

Here is explanation of the first (trpical) and the second (polar) one - it stems from Tracie Schroeder. This video lasts about 20 minutes and gives a simple explanation. What you need to know is some knowledge of thermodynamics (gas dynamics) and of the Coriolis-effect.

Tracie Schroeder published this video in 2014

How Earth's global wind belts form

There is always some confusion about how the winds can be deflected in different directions. It is because the wind gets deflected from the direction it is traveling. Imagine you are walking along that arrow between 30*N and 60*N from the south to the north. The Coriolis will deflect you to the right of that direction, and your resulting direction will be to the east. The same thing if you are walking between 0* and 30* only now you are walking north to south. If you get deflected to the right, your resulting direction is to the east. Also, I keep meaning to go back and edit this, but only the circulation cells between 0* and 30* are called Hadley cells. Between 30* and 60* they are called Ferrell cells, and between 60* and 90* they are the polar cells.

Am 03.04.2014 veröffentlicht

UCI ESS 5 The Atmosphere (Spring 2014) Lecture 01: Composition and Evolution of the Atmosphere View the complete course: Instructor: Julie Ferguson, Ph.D. License: Creative Commons CC-BY-SA More Information: More courses at: Description: The composition and circulation of the atmosphere with a focus on explaining the fundamentals of weather and climate. Topics include solar and terrestrial radiation, clouds, and weather patterns. Recorded April 1, 2014 Required attribution: Ferguson, Julie Earth Science System 5 (UCI OpenCourseWare: University of California, Irvine), [Access date]. License: Creative Commons Attribution-ShareAlike 3.0 United States License (