AC-sea-ice Interaction Cases
Case 1: THINICE Cyclone #3 Growth Phase
Period: 16-21 August 2022
This August 2022 AC, which was observed as
"Cyclone #3" during the ONR THINICE field campaign,
formed east of Greenland over open water on 15 August.
It was accompanied by features considered typical of ACs,
such as lower-tropospheric fronts,
a low-level jet (LLJ),
upper-level forcing,
and a cold-core structure.
The AC strengthened until reaching its peak intensity on
August 18, when the AC had tracked toward the sea-ice edge in the
Fram Strait between Greenland and Svalbard. From its peak intensity,
the AC then advanced poleward through the Fram Strait, moving nearly
parallel with but slightly toward the marginal ice zone (MIZ) as it weakened.
By 20 August, the AC center had clearly moved over the sea ice,
where its intensity moderated.
Case 1 focuses on the period when this AC intensified as it moved toward the
sea-ice edge, as well as when the AC moved through the Fram Strait and
decayed. This case is selected to examine an archetypal AC that
intensified as it approached sea ice, and then continued to track
close to or over the MIZ after its intensification. The hypothesis is that
the AC's approach toward sea ice may have played a role in its intensification.
Further, there is the question of whether the AC's continued proximity to
the sea ice after peak intensity is important to its evolution. This question
will be addressed more directly in Case 2, as well.
Case 2: THINICE Cyclone #3 Mature Phase
Period: 21-27 August 2022
This August 2022 AC is the same as that examined in Case 1.
After 21 August, the AC stalled over a large swath of marginal ice
poleward of Franz Josef Land. The AC decayed until 25 August, when it
redeveloped over the MIZ and began to reintensify. The AC moved off of
the sea ice and into the Barents and Kara Seas on 26 August, before
decaying once again until its dissipation east of Novaya Zemlya on 27 August.
Case 2 focuses on the period when this AC stalled over the MIZ, decayed,
and then redeveloped over the MIZ before finally dissipating off of
the sea ice. The hypothesis is that
the AC's multi-day period over the MIZ may have played a role in its decay,
as well as its redevelopment on 25 August. Aside from highlighting different
phases of this AC's life cycle, Case 2 differs from Case 1 in that the AC
during the Case 2 period interacts with a considerably expansive area of marginal ice.
If this AC's evolution is sensitive to physical processes specific to the MIZ,
then one might expect that Case 2 simulations will show more sensitivity to
model specifications of the sea-ice field and neighboring ocean.
ERA-MSK
ERA-M15
ERA-M80
GHR
GHR-UP
GHR-OCN
Case 3: Great Arctic Cyclone Growth Phase
Period: 04-10 August 2012
This 2012 AC has been regarded in literature and media as the
"Great Arctic Cyclone." This AC was an anomalously large, deep,
and long-lived AC that spent over five days over sea ice after
reaching its peak intensity on 6 August. Similar to Case 1, this AC reached
its peak intensity as it advanced toward the sea ice. However,
the origin of the AC is quite different, as it formed inland on 2 August
near the coast Siberia. The AC moved off land and into the East Siberian Sea
on 4 August, intensifying as it moved over the ocean continued toward the
sea ice.
Case 3 focuses on the period when this historic AC moved off land,
intensified to peak intensity as it moved toward sea ice, and then
remained over the sea ice whilst decaying. The
evolutionary path of this AC may seem similar to that outlined in Case 1.
However, this AC was anomalous in many measures of its
size and strength. Relative to the archetypal AC examined in Cases 1 and 2,
whether the evolution of this AC is more or less sensitive
to model specifications of the sea-ice field and neighboring ocean
is a motivating research question.
ERA-MSK
ERA-M15
ERA-M80
ERA
ERA-UP
GHR
GHR-UP
GHR-OCN