Tamara McDunn

Topics in Martian Atmospheric Dynamics

Abstract: The martian atmosphere is a dynamic fluid! In this talk I will discuss two ongoing investigations in  the  exciting  field  of  martian  atmospheric  dynamics.  The  first  topic is polar  warming.  Polar  warming  is  a  temperature  enhancement  over  mid-­‐to-­‐high   latitudes  that  results  in  a  reversed  (poleward)  meridional  temperature  gradient.   Here  I  will  show  observations  of  this  phenomenon  in  the  ~30-­‐90  km  altitude  region   from  the  Mars  Climate  Sounder  (MCS)  instrument  aboard  the  Mars  Reconnaissance   Orbiter.    I  will  also  present  results  of  ongoing  efforts  to  understand  the  drivers  of   this  phenomenon  (including  topography,  dust  loading,  and  gravity  wave  breaking)   using  the  Mars  Weather  Research  and  Forecasting  global  circulation  model.   The second topic  of  this  talk  is  semi-­‐stationary  waves  masquerading  as  stationary   waves.  Stationary  waves  are  a  fundamental  feature  of  the  martian  atmosphere.  They   play  a  crucial  role  in  the  redistribution  of  heat  from  the  equator  to  the  high  latitudes,   significantly  impact  the  atmosphere’s  stability,  and  impart  acceleration  on  the  mean   flow  of  the  middle-­‐to-­‐upper  atmosphere.  Here,  I  will  describe  how  the  traditional   technique  used  to  identify  stationary  waves  from  orbital  data  limited  to  two  local   times  does  not  discriminate  against  a  type  of  wave  here  referred  to  as  “semi-­‐ stationary”  (waves  displaying  near-­‐steady  behavior  on  seasonal  timescales  while   undergoing  significant  variability  on  diurnal  timescales).    Using  MCS  observations,   I’ll  show  that  northern  fall  and  winter  waves  previously  identified  as  stationary  in   fact  behave  in  a  semi-stationary manner and will discuss some possible implications.