# # Program information file # PROGRAM_ID 2024A046 PROGRAM_TITLE A High Spectral Resolution study of the cross-terminator winds and chemical-dynamical tracers on the lower atmosphere of Venus. PROGRAM_INV1 Pedro Machado PROGRAM_INV2 Daniela Espadinha PROGRAM_INV3 Joao Dias PROGRAM_INV4 Thomas Widemann PROGRAM_INV5 Javier Peralta PROGRAM_SCICAT major planets / satellites PROGRAM_ABSTRACT_BEG Venus' atmospheric circulation is a captivating and intricate system driven by superrotating winds and atmospheric waves. Among the several candidates for speeding up the atmosphere 60 times faster than the surface and distributing the atmospheric momentum, the solar tides and a variety of atmospheric waves are regarded as the most plausible candidates. Ground-based observations contribute in a decisive way to a better understanding of the processes governing the atmosphere dynamics. The dynamics on the cross-terminator region are largely unknown and measurements are required to better constrain modeling. In this framework, we intend to use the Doppler velocimetry technique to map for the first time the wind velocity field across the terminator in the lower atmosphere, with high accuracy, using the iSHELL spectrograph. These measurements will provide new science and enhance our understanding of the dynamical transition between the dayside and nightside in the terminator in the lower atmosphere. Additionally, we intend to explore the link between the chemistry and dynamics in the lower atmosphere, using minor chemical species as dynamical tracers. We will use the H, K and L bands. The slit for bands H and K is 0.375'' by 5'' and for band L is 0.375'' by 15'', with a spectral resolution of R=75 000. These spectral bands probe the absorption bands of several minor species, such as SO2, CO and OCS. PROGRAM_ABSTRACT_END