Nili Harnik, Professeur invité du mois de septembre 2016

Nili Harnik, Professeur invité du mois de septembre 2016

The atmospheric patterns of wind, pressure, and temperature, and their temporal variations, influence our daily lives through the changes in weather, and on seasonal and longer time scales, through changes in climate conditions. The global circulation of the atmosphere, which consists of a few different regions, is one of the main features determining the climate zones on Earth. Understanding the circulation of the atmosphere, and the ability to simulate it numerically and predict the weather, have advanced greatly in the past half century or so. The vast growth of data from these efforts has strengthened our need for a fundamental physical understanding of this circulation, in particular, it is important to understand its natural variability, in relation to the response to external forcing and man made changes.

Research in my group centers on developing an understanding of the main atmospheric wind and temperature patterns, their natural variations and response to different forms of forcing, on daily, seasonal, annual and longer time scales. Recent and ongoing projects include:

The large scale circulation of the troposphere:

  • How the mutual interactions between the Hadley circulation, the zonal jet streams and mid latitude waves shapes the global circulation.
  • How the different dynamical regimes affect the dominant wave modes, the characteristics of internal variability, and the distribution of extreme events.

Extreme weather and climate:

  • The role of warm core outflow in the dynamics of Hurricanes
  • Circumglobal teleconnection patterns and extreme North American cold spells.
  • The effect of temperature advection on surface temperature skewness and extremes distribution

The large scale circulation of the stratosphere:

  • The interaction of planetary scale Rossby waves with the polar jets in the stratosphere, in particular downward reflection vs absorption, how it is affected by external factors and how it affects internal variability in the stratosphere and troposphere.
  • The interaction between planetary waves, the QBO, radiation and ozone

Waves and instabilities in geophysical flows:

  • The fundamental processes which shape geophysical fluid flows, like shear flow instabilities, nonlinear equilibration of waves with the mean flow, interaction of waves and turbulence, jet formation and sharpening.