BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:HF radar remote sensing of the marginal ice zone and other interes
 ting places - Stuart Anderson\, University of Adelaide
DTSTART:20221101T140000Z
DTEND:20221101T150000Z
UID:TALK187574@talks.cam.ac.uk
CONTACT:Dr. Shenjie Zhou
DESCRIPTION:The proliferation of HF radars\, both skywave and surface wave
 \, has galvanised a search for new environmental observables. Traditionall
 y used for ocean surveillance and mapping of surface currents and wave hei
 ght\, HF ‘over-the-horizon’ radars can now provide data of such resolu
 tion and dynamic range that the echoes from the ocean surface can be inter
 rogated for more subtle geophysical signatures. In some instances\, first 
 generation theory was developed long ago\, in the hope that one day the te
 chnology would render the measurement objective achievable. In others\, ev
 en the first generation theories are only now being developed. \nThe key t
 o implementing this expanded palette of radar missions lies not only with 
 the hardware and signal processing techniques\; it depends overwhelmingly 
 on the availability of high fidelity models of the phenomena of interest\,
  with commensurate attention paid to the external factors that govern sign
 al degradation during propagation\, and to the electromagnetic scattering 
 theories that are used to map from the geophysical state variables to the 
 radar echoes. A related issue is the consideration of specific geographica
 l circumstances\, and how these impact on radar design. There have been se
 veral HF radar deployments that achieved far less than was possible becaus
 e insufficient care was taken to model the operating environment and optim
 ise the radar design accordingly. \nOne particular class of prospective ob
 servables embraces those that characterise ice-covered seas\, such as ice 
 type\, thickness\, growth rate and composition. HF radars have very poor s
 patial resolution when compared with their microwave counterparts but poss
 ess exquisite Doppler sensitivity\; it follows that the path to any practi
 cal ice monitoring and analysis capability lies in the exploitation of the
  ice surface dynamics as it moves in response to forcing by ocean waves th
 at penetrate the ice field. To this end\, we have generalised the HF scatt
 ering theory to incorporate the ice type dependence of the dispersion rela
 tion of propagating waves in the ice zone. Using this theory\, we are able
  to model the radar signatures of arbitrary ice scenarios\, explore the de
 pendence on key parameters\, develop optimum measurement strategies and so
  on. What remains to be completed is the retrieval of the ice parameters f
 rom observations. This nonlinear inverse problem is now being addressed us
 ing a new optimisation technique.\nIn this talk I shall describe these dev
 elopments\, along with other new remote sensing prospects.\n
LOCATION:https://ukri.zoom.us/j/91008981392\;BAS Seminar Room 330b
END:VEVENT
END:VCALENDAR