Influence of spatial distribution of the gravity wave activity on the middle atmospheric circulation and transport.

Petr Šácha* and Friederike Lilienthal, Petr Pisoft, Christoph Jacobi
Charles University in Prague, Faculty of Mathematics and Physics, Department of Atmospheric Physics

Using the GPS RO density profiles, we have recently (Sacha et al., 2015) pointed out a localized area of enhanced GW activity and breaking in the lower stratosphere of the Eastern Asia/North-western Pacific region.

With a mechanistic model for the middle atmosphere (MUAM) we performed experimental runs to study an effect of such a localized breaking region on the large-scale circulation and transport. Our results demonstrate an important role of a spatial distribution of the GW activity (geometry of the problem) for the formation of PW. We show that PW created by such a localized forcing can have consequences for the polar vortex stability and the stratosphere-troposphere exchange in the tropical region of South-East Asia. By comparing the patterns of the 3D residual circulation computed from the experimental runs with the realistic tracer distributions (N2O, CO, H2O, O3) observed by satellites, we identify the role of the GW hotspots in longitudinal variability of the BDC (e.g. enhanced downwelling branch in the EANP region).

Finally, we discuss consequences of our research for the traditional 2D BDC concept, highlighting the uncertainty in its response to a climate change stemming from the uncertainty of future evolution of spatio-temporal distribution of the GW activity.

Also, as a supplement for this theoretical study and in connection to findings of Sacha et al (2014) and (2015), we have made a robust comparison of GW spectra gained from density and dry temperature GPS RO data helping us to quantify contributions of nonhydrostatic GW and noise to the spectral differences.


Šácha, P., Foelsche, U., and Pišoft, P.: Analysis of internal gravity waves with GPS RO density profiles, Atmos. Meas. Tech., 7, 4123-4132, doi:10.5194/amt-7-4123-2014, 2014.

Sacha, P., Kuchar, A., Jacobi, C., and Pisoft, P.: Enhanced internal gravity wave activity and breaking over the Northeastern Pacific/Eastern Asian region, Atmos. Chem. Phys. Discuss., 15, 18285-18325, doi:10.5194/acpd-15-18285-2015, 2015.


*email: petr.sacha@mff.cuni.cz
*Preference: Oral