Orli Lachmy's homepage

I am an Atmospheric Scientist at the Department of Natural Sciences in the Open University of Israel. I am interested in the dynamics of the general circulation of the atmosphere.

The atmospheric circulation is both fascinating in its complex behavior and affecting our everyday life. The distribution of climate zones results from the configuration of Earth's atmospheric circulation. The variability of the circulation controls the variability of the regional climate. The response of the circulation to increased greenhouse gas emissions is expected to affect the distribution of precipitation and extreme weather events.

Atmosphere dynamics research has done a huge step forward in the past few decades, with increased computational power. The challenge facing our field is to utilize numerical models to improve our understanding, on one hand, and to implement our theoretical knowledge to improve model reliability, on the other hand.

My research focuses on improving our theoretical understanding of the interactions between the zonal mean flow and eddies, and their affect on internal climate variability. Together with Prof. Nili Harnik, we have constructed a new idealized numerical model, which includes only the basic components needed to capture the qualitative nature of the circulation cells, the jet stream, the midlatitude eddies and all their mutual interactions. We used this model to explain the mechanisms maintaining the different flow regimes of the jet stream. Our work showed that stabilization of baroclinic eddies at low latitudes by the beta effect enables the maintenance of the subtropical jet regime, and that increased wave energy can lead to a transition from a subtropical to a merged jet regime. A further increase in the wave energy can lead to a transition to a turbulent eddy-driven jet regime.

In a collaborative work with Prof. Tiffany Shaw from the University of Chicago we used the Eliassen and Palm relation to connect the response of the eddy-driven jet and storm track to climate change. Our work showed that the latitude of the eddy-driven jet can be estimated given the eddy potential energy flux and the Doppler shifted phase speed, according to the Eliassen and Palm relation. This provides a new path for connecting the storm track and eddy-driven jet. Our work suggests that the climatological zonal-mean zonal flow plays an important role in the response of the eddy-driven jet to climate change.


    2017-present: Lecturer at the Department of Natural Sciences, the Open University of Israel.

    2015-2017: Postdoc at the Department of Geophysical Sciences, University of Chicago.

    2015: PhD in Atmospheric Sciences. Tel-Aviv University, Israel. 
Supervisor: Prof. Nili Harnik.
Title: "Atmospheric extratropical wave-mean flow interactions maintaining the different flow regimes of the jet stream"

    2008: M.Sc in Atmospheric Sciences. Tel-Aviv University, Israel.
Supervisor: Prof. Nili Harnik
Title: "A wave amplitude transition in a quasi-geostrophic wave-mean flow interaction system"

    2004: B.Sc. in Physics. The Hebrew University, Jerusalem, Israel.


    2012: Scholarship for promoting women in science, Israel Ministry of Science and Technology.

    2009: The Rector and President scholarship for excellent research students, Tel-Aviv University.


Lachmy, O. and T. Shaw, 2017: "Connecting the energy and momentum flux response to climate change using the Eliassen and Palm relation", submitted.

Lachmy, O. and N. Harnik, 2016: "Wave and jet maintenance in different flow regimes", Journal of the Atmospheric Sciences, 73, 2456-2484.  

Harnik, N., C. L. Garfinkel and O. Lachmy, 2016: "The influence of the jet stream regime on extreme weather events", Dynamics and Predictability of Large-Scale, High-Impact Weather and Climate Events 2, 79. Ed. Li, J., R. Swinbank, H. Volkert and R. Grotjahn. Cambridge University Press.

Lachmy, O. and N. Harnik, 2014: "The transition to a subtropical jet regime and its maintenance", Journal of the Atmospheric Sciences, 71, 1389-1409.

Lachmy, O. and N. Harnik, 2009: "A wave amplitude transition in a quasi-linear model with radiative forcing and surface drag", Journal of the Atmospheric Sciences, 66, 3479-3490.

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