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Chase Stoudt
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My last post was in response to Neven.
Toggle Commented Aug 4, 2015 on PIOMAS August 2015 at Arctic Sea Ice
Ya I just pulled up the ECMWF for that system in the Beaufort. My eyeballed values are about 1115 km wide and moving at ~10 meters a second, so really slow and big. Using the Lammert metric the Diameter/ground track speed equals ~31 hours. 3/4 of the local near-inertial period at this latitude is 9.3 hours so it's not even close to make the ice respond inertially, it's all going to be advection like you said with very little to no convergence. I'm not a modeler so I can't speak about Zhang's model results but I agree the 2012 cyclone was definitely powerful enough to make the ice move inertially, thus mixing the upper water column (I could go on here about pumping the pycnocline and what kind of internal waves could have been generated but I won't). That being said, with this current system in the Beaufort you still have broad scale oceanic convergence which can act to deepen the pycnocline and advect warmer water, although I don't know what the extent or magnitude that would transfer through the ice pack.
Toggle Commented Aug 4, 2015 on PIOMAS August 2015 at Arctic Sea Ice
Just adding my two cents about cyclones and sea ice concentration. Work done by Lammert et al. 2009 Observation of cyclone-induced inertial sea-ice oscillation in Fram Strait showed that cyclones had to have a certain size and speed to resonantly force sea ice to move inertially, or in other words inject mechanical energy into the ice pack. I showed in my MS thesis (submitting to GRL soon!) that strong cyclones that resonantly forced sea ice near-inertial motion typically caused convergence of the ice pack. I also found two high pressure systems which resonantly forced the ice pack, but instead of convergence I saw a weak divergence. Zhang et al. 2000 Recent Changes in Arctic Sea Ice: The Interplay between Ice Dynamics and Thermodynamics showed that dynamics can play a role in in an ice-albedo feedback where a diverging ice pack injects thermal energy into the upper ocean and enhances melt. I guess what I'm trying to get at is that a weak cyclone is will cause less convergence (compared with a stronger cyclone) and less compaction so there's slightly more open water to transfer heat from the atmosphere into the ocean. But this process is less efficient than say a high pressure system or lateral advection. I need some time to pull up the numbers, but I'd be really interested in seeing how wide and how fast this cyclone is moving in Beaufort/Chukchi.
Toggle Commented Aug 4, 2015 on PIOMAS August 2015 at Arctic Sea Ice
I just talked to someone who came back from Kotzebue yesterday. They did some CTD casts in the sound and the thermocline temp was 17C! This is only 2.5 weeks after the ice left!
Toggle Commented Jul 7, 2015 on ASI 2015 update 4: massive heat at Arctic Sea Ice
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Jul 7, 2015