The calibration pipeline of the level zero images obtained from the Magneto-Optical filters at Two Heights (MOTH II) instrument is presented. MOTH II consists of two 20 cm aperture instruments, each using a Magneto-Optical Filter (MOF): one at 5896 Å (Na D2-line), the other one at 7700 Å (K I-line). MOTH II instruments thus provide full disk line-of-sight Doppler velocity and magnetic field measurements at two heights in the solar atmosphere. The developed MOTH II pipeline employs a set of standard calibration corrections, a correction for signal leakage, due to the non-ideal behavior of the polarizers, and the geometrical registration between the eight images acquired by four CMOS cameras, relative to two components of the signal in two circular polarization states, in each of the two channels. MOTH II data are used to investigate atmospheric dynamics (e.g., internal gravity waves and magneto-acoustic portals) and Space Weather phenomena. Particularly, flare forecasting algorithms, based on the detection of magnetic active regions (ARs) and associated flare probability estimation, are currently under development. The possible matching of MOTH II data with SDO/HMI and SDO/AIA images into a flux rope model, developed in collaboration between Harvard-Smithsonian CfA and MIT Laboratory for Nuclear Science, is being tested.

The solar prolateness (also known as Ovalisation, a french origin name) of the extended dynamical chromosphere is established from measurements performed above 2 Mm heights during the years of solar minimum, using the H$\alpha$, Ca II K and HeII 304 line emissions from both ground-based and space-based observations. Coronal X-EUV emissions usually penetrate deep enough into the chromosphere to completely mask this effect on transition region lines and produce the so-called coronal hole effect. However, cool lines like H$\alpha$ and Ca II lines, do NOT show this Coronal Hole (CH) effect. Coronal lines and HeI (D3; 1083 nm) do show CHs but do not show the prolateness effect. We first briefly review different methods which can potentially be used to measure the prolateness. Further we note the similarity of the geometric behaviour of the prolateness and its variation along the solar cycle compared to the behaviour of the fast solar wind. It suggests the same origin possibly related to the emergence of the small scale network and internetwork magnetic field towards the corona and small scale magnetic reconnections. A simple geometric model was proposed to explain the effect of the prolateness of the solar chromosphere by considering that the specific dynamical part of the solar atmosphere above the 2 Mm level, being a mixture of up and down moving jets of chromospheric matter with the coronal plasma between them, is responsible for the solar prolateness (Filippov and Koutchmy, 2000). We however note that polar regions are also showing different types of activity in the low corona, including small prominence eruptions seen e.g. in H$\alpha$ and linear jets seen in SXR and EUV as well as in W-L (eclipses). Some kind of dynamical dissipation of the newly emerged magnetic field is needed. More systematic measurements should be done to build a more complete, possibly 3D, picture to explain the extended in the horizontal direction lifting effect of a large part of the polar chromosphere.

The propagation of surface and body linear MHD modes in a twisted magnetic flux tube embedded in a magnetically twisted plasma environment is considered. The dispersion relation for surface and body modes is derived assuming constant external twisted field. Analytic approximate solutions to the dispersion equation are found for the long and short wave length cases.

It was found, that in case the twisted component of the magnetic field in the environment of the flux tube is constant the index of Bessel functions $\nu$ in the corresponding dispersion relation is not integer. In the particular case of a homogen magnetic twist the total pressure is found to be constant across the boundary of the flux tube.