# # Program information file # PROGRAM_ID 2022A045 PROGRAM_TITLE Search for variation of minor species in Venus' Atmosphere PROGRAM_INV1 Nicholas Mehrle PROGRAM_INV2 Kaitlin Rasmussen PROGRAM_INV3 Sara Seager PROGRAM_INV4 Janusz Petkowski PROGRAM_INV5 PROGRAM_SCICAT major planets / satellites PROGRAM_ABSTRACT_BEG Temporal variation in Venus' cloud top SO2 abundance over timescales of ~10 years is a well documented phenomenon [Vandaele et al. 2017]. It has been suggested the SO2 abundance variation is driven by episodic events such as volcanism or other dynamical instabilities. Using iSHELL K3 band data from 2020, we have detected evidence for temporal variation of HF, with an anomalous abundance a few times higher than previous measurements. We now propose to observe Venus at high spectral resolution in the L/M band to search for similar variation of HCl and OCS abundances. Previous measurements of these species by Krasnopolsky 2010a and Krasnopolsky 2010b respectively, both from IRTF/CSHELL, will be used for comparison. Variation in these species would support the hypothesis that dynamical processes drive the observed change in HF abundance, while lack thereof would suggest fluorine chemistry is responsible. Outside of any potential temporal variation, further constraining the abundance and spatial variation of these species is important for informing models of Venus' chlorine and sulfur photochemistry above the clouds. We propose to observe Venus at 4 spatial locations - North/South pole and equatorial region on the dayside, and equatorial region on the nightside in both the L and M bands to accomplish these goals. High spectral resolution will allow us to distinguish features from Venus' atmosphere with solar and telluric lines. 8 hours of time spread over 2-3 nights on iSHELL with a spectral resolution of ~80,000 will allow for an SNR of ~550, which is more than sufficient to constrain these abundances. PROGRAM_ABSTRACT_END