4d Hcl Transport In The Martian Atmosphere With Comparisons To Tgo Observations. K. Rajendran, School Of Physical Sciences, The Open University, Milton Keynes, Uk (Kylash.Rajendran@Open.Ac.Uk), S. R. Lewis, P. M. Streeter, J. A. Holmes, School Of Physical Sciences, The Open University, Milton Keynes, Uk, M. R. Patel, School Of Physical Sciences, The Open University, Milton Keynes, Uk, Space Science And Technology Department, Science And Technology Facilities Council, Rutherford Appleton Laboratory, Oxfordshire, Uk. The Recent Discovery Of Hydrogen Chloride (Hcl) In The Martian Atmosphere [1, 2] Has Renewed Interest In The Martian Chlorine Cycle And Its Potential Impact On Martian Atmospheric Chemistry. Here We Present The Results Of A Numerical Modelling Study Of The Transport And Chemical Interactions Of Chlorine Species In The Martian Atmosphere, In Order To Better Constrain The Rates Of Creation And Destruction Of Hcl. Korablev Et Al. [1] Used The Atmospheric Chemistry Suite (Acs) Aboard The Exomars Trace Gas Orbiter (Tgo) And Detected Hcl In The 1–4 Ppbv Range In Both Hemispheres Before And During The Mars Year (My) 34 Global Dust Storm. Subsequent Measurements In My 35 [2] Have Confirmed The Seasonal Nature Of Observed Hcl, With Almost All Detections Occurring During The Dusty Second Half Of The Martian Year (Ls =180 − 360°). Hcl