Four cases are presented in which the relative humidity (RH) shows consistent increase by more than 50% in the upper troposphere (200-250 hPa) over tropics at the eastward side of the potential vorticity (PV) intrusion region. The increase in RH is observed irrespective of whether the PV intrusions are accompanied by deep convection or not and is suggested to be due to poleward advection induced by the PV intrusions.

Imposed momentum from mesospheric breaking gravity waves (GWs) is conserved by a balance between vertical divergence of GW momentum flux and Coriolis acceleration of the mean meridional wind. We present the first experimental verification of the momentum balance from the Saura MF radar at 69°N. For contributions from GWs only this balance is fulfilled between 70 and 100km during summer when GWs dominate the mesospheric dynamics, but it does not exist in winter due to planetary wave impacts.

The Indian summer monsoon rainfall climatology during the monsoon onset phase in different climate zones is simulated using the regional model ARW for the decade 2000-2009, using NNRP global reanalysis. Comparisons with IMD & NNRP rainfall show that the model could simulate the onset phase in terms of progression and distribution of rainfall in most zones (except over the northeast) with good correlations and low error metrics, and improves the onset time by 1-3 days in zones 4 and 7 over NNRP.

We present multi-instrument measurements and multi-technique analysis of polar cap patches observed early during the recovery phase of the major magnetic storm of November 20 2003. During this event, the Qaanaaq imager observed variable airglow brightness of the patches between 20:33 and 20:43UT, probably associated with a large-scale gravity wave. Our numerical results indicate that variations in the airglow intensity up to 265R can be produced by a constant 70m/s downward vertical wind.

Magnetic reconnection is a ubiquitous process that drives global-scale dynamics in plasmas. For reconnection to proceed, both ion and electrons must be unfrozen in a localized diffusion region. By analyzing in situ measurements, we show that the non-gyrotropic ion pressure is mainly responsible for breaking the ion frozen-in condition in reconnection. The reported non-gyrotropic ion pressure tensor can specify the reconnection electric field that controls how quickly reconnection proceeds.

In this work we perform numerical simulations of convective gravity waves, using the WRF model. We first run an idealized and highly resolved case. Then, we compare realistic simulations (model top at 68km) with lidar measurements of gravity wave potential energy (Ep) over southern France. Vertical structures of simulated potential energy profiles are found to be in good agreement with those measured by lidar. On the other hand, the magnitude of simulated wave energy is clearly underestimated.

Multi-year observations of gravity wave momentum fluxes have been analyzed at three different sites using meteor radar data. This is a first, as no such experimental results on the latitudinal dependence of these parameters at low latitudes had been derived with ground-based instruments in the MLT region before. Until now similar studies had been carried out with satellites and circulation models. Therefore this thematic can be lead to a valuable scientific contribution.

The latitudinal structure of the nightside outer magnetosphere of Saturn was studied by using Cassini CAPS plasma measurements. It was found that the plasma density and the azimuthal velocity decrease simultaneously as the spacecraft moves away from the magnetic equator. The magnetosphere exhibits an “onion shell like” structure: the inner regions spin rapidly corotating with the planet, but moving outward and/or further away from the equatorial plane one can encounter slower and slower shells.