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UID:3680f34905dad16c7b33681792c83d7b
DTSTAMP:20260917T205616Z
SUMMARY:SPC Seminar – Space – Dr. Maria Smirnova (Weizmann Institute of
  Science)
DESCRIPTION:Title: The Revival of Radio Occultations: Investigating the Atm
 ospheres of Jupiter and Saturn\nSpeaker: Dr. Maria Smirnova (Weizmann Inst
 itute of Science)\nAbstract:\nRadio occultation (RO) is a uniquely powerfu
 l technique for probing giant planet atmospheres. As a spacecraft radio si
 gnal passes behind the planetary limb\, it is refracted by the atmosphere\
 , and the measured changes in the signal can be inverted to retrieve high-
 vertical-resolution profiles of refractivity\, density\, pressure\, and te
 mperature from the upper troposphere into the stratosphere. At rapidly rot
 ating and strongly oblate planets\, these measurements require dedicated r
 ay-tracing inversions that account for planetary shape\, gravity\, winds\,
  and the full radio-path geometry.\nAt Jupiter\, NASA’s Juno mission has
  produced the first new atmospheric radio occultations since Voyager. Sinc
 e 2023\, we have retrieved more than 50 temperature-pressure profiles span
 ning low\, mid\, and polar latitudes\, with measurements reaching depths o
 f about 0.6 bar. This growing dataset is now allowing us to compare Jupite
 r’s thermal structure across various dynamical regimes. Recent observati
 ons probe the cold northern polar stratospheric vortex and regions close t
 o the polar cyclones\, while lower-latitude profiles reveal variations in 
 atmospheric stability and vertical structure. Together\, these measurement
 s provide new constraints on coupling between the stratosphere and upper t
 roposphere\, as well as on vertical mixing\, waves\, and large-scale dynam
 ics. Comparison with TEXES and Cassini’s CIRS observations places the Ju
 no profiles within a broader picture of Jupiter’s spatial and temporal t
 hermal variability.\nAt Saturn\, we are revisiting the extensive but still
  largely underexplored Cassini radio occultation archive\, comprising more
  than 75 atmospheric RO measurements collected over the mission’s 13-yea
 r tour. These observations span a wide range of latitudes and the transiti
 on from northern winter toward northern summer\, providing a unique record
  of Saturn’s atmosphere over more than a decade of seasonal change. By p
 rocessing these observations within a common framework\, we are constructi
 ng a mission-long view of Saturn’s upper troposphere and lower stratosph
 ere. The dataset allows us to investigate temperature variability near the
  1-bar level\, changes in vertical thermal structure with latitude and sea
 son\, and dynamical variability in the stratosphere\, including Saturn’s
  stratospheric oscillation.\nTogether\, Juno and Cassini show that radio o
 ccultations are more than individual vertical profiles: they provide ancho
 rs for the thermal structure of giant planet atmospheres. Their high verti
 cal resolution allows us to probe layers where infrared retrievals can be 
 limited by vertical smoothing and temperature–composition degeneracies. 
 Accompanied by other ground- and space-based observations\, they provide a
 n independent reference for tracing atmospheric structure across altitude\
 , latitude\, season\, and dynamical regime. This revival of giant planet r
 adio occultations is opening a new window on atmospheric dynamics\, season
 al evolution\, and vertical coupling\, with ESA’s JUICE extending this r
 ecord in the future.
URL:https://www.imperial.ac.uk/events/213453/spc-seminar-space-dr-maria-smi
 rnova-weizmann-institute-of-science/
DTSTART;TZID=Europe/London:20260925T140000
DTEND;TZID=Europe/London:20260925T150000
LOCATION:Lecture Theatre 2\, Blackett Building\, South Kensington Campus\, 
 Imperial College London\, London\, SW7 2AZ\, United Kingdom
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