Seminar: Marten Blaauw: The seasonal cycle of Kelvin waves

Četrtek, 18. junij 2015, ob 13:15
Predavalnica F4, 1. nadstropje, FMF, Jadranska 19, Ljubljana

V okviru internega seminarja na katedri za meteorologijo nam bo naš sodelavec Marten Blaauw predstavil svoje raziskovalno delo. Seminar je odprt za vse obiskovalce, potekal pa bo v angleškem jeziku.

Povzetek:

Atmospheric dynamics in the tropical regions are dominated by unbalanced motions in response to convective processes, found to vary on diurnal time scales as well as on (inter)-seasonal time scales (30-60 day Madden-Julian Oscillation, monsoon, ENSO). The Kelvin wave is the gravest wave excited by  convection and it is characterized by eastward and upward propagation away from its convective source. During its upward "journey", a pack of Kelvin waves will experience modulation, dissipation and wave breaking determined by the environment it propagates through.

In this seminar, I will focus on Kelvin wave seasonal cycle in the tropical tropopause layer, a broad region between 100-200 hPa with both tropospheric and stratospheric characteristics. Previous studies show that Kelvin waves play an important role in the stratosphere-troposphere exchange of water vapor and chemical species.

Using 6 years of data from ECMWF operational analyses, the Normal-Mode Function methodology has been applied to filter out the Kelvin waves. Such methodology allows us to study atmospheric modes from a coupled mass and wind perspective. Results for the Kelvin wave seasonal cycle in relation to convection and the ambient atmospheric flow and stability will be presented.