Microphysics
in Multi-scale Modeling System with Unified Physics
Ming Cai
FSU
Noon, Tuesday March 11, room 2155
Abstract:
We have developed indices measuring the total poleward mass transport
into the upper troposphere and stratosphere above the Arctic and total
equatorward air mass transport out of the lower polar troposphere on a
daily basis using ERA-Interim reanalysis for the period of 1979-2011.
These two indices are very highly positively correlated with little
lead/lag, implying that a stronger poleward warm air mass circulation
in the polar region tends to be compensated by a stronger equatorward
mass transport by the cold air branch below and vice versa. We have
also developed various indices that measure the continental-scale near
surface warmness and coldness in high latitudes and mid-latitudes. It
is shown that a lack of warm air mass flux into polar region is
accompanied by weaker equatorward advancement of cold air near the
surface. And, as a result, the cold air mass is largely imprisoned
within polar circle, responsible for general warmness in mid-latitudes
and below normal temperature in high latitudes. Conversely, a stronger
warm air transport into polar upper atmosphere is accompanied by a
stronger equatorward advancement of cold air near the surface,
resulting in massive cold air outbreaks in mid-latitudes and anomalous
warmth in high latitudes. We have also identified two dominant
geographical patterns of cold air surge associated with strong mass
circulation crossing 60N. One is massive cold air surges over both
North America and Eurasian continents and the other is the dominance of
cold air surges only over one of the two continents with the abnormal
warmness over the other continent in the time periods of 1-10 days
after a stronger mass circulation cross the polar circle. The first
pattern explains the first and forth leading EOFs of winter season
surface temperature anomalies whereas the second mode is related the
second leading EOF modes.