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Fig. 5.11
MIZEX TKE production and dissipation estimates. Arrows indicate samples with sim-
ilar friction velocity before and after crossing the thermal front. Asterisk at time 191.125 is the
expected neutral value of
P
s
(Adapted from McPhee 1994. With permission American Meteoro-
logical Society)
5.3 The Statically Unstable IOBL
Forthesamereasonsthatitisdifficulttoeasilymeasureconditionswithrapidmelt-
ingandstabilizingbuoyancyflux,thestaticallyunstableIOBLthatpersistswhenice
isfreezingrapidlyhasbeenlittlestudied.Byfarthemostambitiousprojectaimedat
examiningtheimpactoffreezingonboundarylayerdynamicswastheLeadExper-
iment(LeadEx)inMarchandApril1992.ThestrategyforLeadExwastoestablish
a base camp over the deep Canadian Basin north of Alaska, then wait for leads to
open nearby. Once a suitable lead opened, two helicopters would transport equip-
mentandshelterstotheleadedgeasrapidlyaspossibleinordertomeasureasmany
characteristicsofthefreezingprocessanditsimpactonbothatmosphereandocean
dynamics as possible. With temperatures typical of the Arctic in March and early
April,leadsdonotgenerallyremainopenforlong,so speedwasimportant.
A scientific party comprising considerable collective experience was assembled
under the leadership of Chief Scientist Jamie Morison, the base camp was estab-
lished,andwewaited,andwaited.Formanyofuswhohadexperiencedthebreakup
of several ice stations (e.g., AIDJEX Big Bear and FRAM I) over the years, it
seemed high irony that when we were looking and hoping for leads, Nature would