[pccgrads] Postdoc Candidate Seminar, 9/9 at 2:30: indian ocean stratification throughout madden-julian oscillation

UW PCC uwpcc at u.washington.edu
Wed Sep 2 11:46:02 PDT 2015


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>>>>>> APL Special Seminar: SEG Post-Doc Candidate (AIRS
Dept.) <<<<<<
>>>>>> NOTE: Day and Time <<<<<<

Speaker: Elizabeth Thompson
Department of Atmospheric Science
Colorado State University
Colorado Springs, CO

Title: UPPER INDIAN OCEAN RAIN FRESHENING AND DIURNAL WARMING
STRATIFICATION
THROUGHOUT THE MADDEN-JULIAN OSCILLATION

Time: Wednesday, September 9, 2:30 PM <--------------- NOTE: Day

(Coffee/Tea, Cookies and Conversation at 2:00PM)

Place: APL Hardisty Conference Center

Abstract:

The 2011-2012 Dynamics of the Madden-Julian Oscillation (MJO; DYNAMO) field
campaign produced collocated radar, lidar, ocean, and surface flux datasets
at the R/V Roger Revelle research vessel to study air-sea interactions
related to MJO initiation in the central Indian Ocean. The MJO is a
tropical, equatorial 30-60 day oscillation between calm vs.
disturbed oceanic and atmospheric conditions. These high-resolution data
have been used to comprehensively identify and classify precipitation and
atmospheric cold pool events at the ship, which contribute different amounts
of heat, momentum, and salinity into the upper ocean. This study examines
how the diurnal and intraseasonal sequence of radar-indicated storm
morphology and atmospheric cold pool characteristics affect upper ocean
stability and mixed layer depth. Some storms are capable of producing a
stably-stratified rain freshening layer (RFL) in the upper ocean, which
shoals the mixed layer to the surface. Over 45 observation days, 49 rain
freshening layers are classified and 16 quasi-stratified RFLs are also
found. These are compared to determine which storms, atmospheric conditions,
and upper ocean environments are conducive to RFL formation and persistence.
Results surprisingly indicate that stratiform rain events are much more
likely to produce stratified rain freshening layers because of their larger
area and duration, despite actually having lower rain rates and occurring
less often than purely convective storms. Strong winds in atmospheric cold
pools act to cool the ocean surface and deepen the ocean mixed layer, but
compete with the stabilizing freshwater flux when coincident with rain. RFLs
are also compared to 36 classified diurnal warm layers (DWL) and 4 nearly
stratified diurnal warm layers, which are near-surface stable layers due to
surface heating. Given the diurnal and intraseasonal variability of the net
heat flux as well as storm morphology, occurrence, and rain amount over the
course of Madden Julian-Oscillation propagation in the IndoPacific Warm
Pool, we examine how the integrated effects of these rain freshening and
diurnal warming stratification events contribute to diurnal and
intraseasonal SST behavior. This has implications for how the ocean stores
energy and can provide energy back to the atmosphere during this coupled
climate phenomenon.

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UNIVERSITY STUDENTS, STAFF AND FACULTY WELCOME!

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Enter main (east) entrance to the Henderson Hall, and ask at desk or follow
signs to the Conference Center on the 6th floor.

To request disability accommodations, please contact the Office of the ADA
Coordinator; voice: 543-6450, E-mail: access\@u.washington.edu

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