Date post: | 14-Apr-2017 |
Category: |
Environment |
Upload: | david-fratantoni |
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monsoon-modulated ring generation in the eastern gulf of aden
david m. fratantoniwoods hole oceanographic institution
acknowledgements: amy bower, bill johns, hartmut peters deb glickson, heather furey
summer
the western indian ocean is governed by the monsoons
düing (1970)
ncep reanalysis: fratantoni et al. (2006)
wind speed is bold
the western indian ocean is dominated by eddies and pirates
United Nations Institute for Training and Research Operational Satellite Applications Programme (UNOSAT)
red sea outflow experiment (redsox)
amy bower & dave fratantoni (whoi)bill johns and hartmut peters (miami)
satellite ocean color and altimetry
aviso ssh
seawifs chlorophyll
things to notice:
‣ blue colors indicate relatively lifeless oceanic water
‣ a variety of eddies translate into the gulf of aden from the east
‣ there is a general pattern of alternately rotating eddies in the gulf
‣ ring formation appears to occur in oct/nov and (less clearly) in apr/may
ring characteristics from frontal tracings and altimetry
diameter 250 km
radius of max velocity 80-100 km
azimuthal speed 30-50+ cm/s
translation speed 5-8 cm/s
observed lifetime 5 months
core watermass origin 5° S
H1: ring generation occurs during episodes of maximal flow through socotra passage
what do we know?
discrete translating rings composed of near-equatorial indian ocean water are generated in the eastern gulf of aden in boreal autumn and spring
H2: maximal flow coincides with the fully-established monsoon circulation
need: measurements of socotra passage flow
extended time-series of socotra passage flow
H1: YES ring generation occurs during episodes of maximal flow through socotra passage
17 years of socotra passage flow variability: annual cycle
socotra passage velocity anomaly is bold
max flow
17 years of socotra passage flow variability: annual cycle
socotra passage velocity anomaly is bold
monsoon transitions
max flowmax wind
H2: NO maximal flow through socotra passage coincides with the monsoon transitions
conclusions
next: new field measurements? numerical experiments?
discrete translating rings composed of indian ocean water are generated in the eastern gulf of aden in boreal autumn and spring
maximal flow coincides with the transitions between monsoons
ring generation occurs during episodes of maximal flow through socotra passage
rings with near-equatorial watermass properties appear to form as the “steady” monsoon circulation regimes collapse