Recent Advances in PhOD
Salinity measurement can improve El Nino forecasts:
AOML scientists have developed a new algorithm for estimating upper-ocean salinity
from other more routinely collected data. Because salinity, as a determinant of density,
influences oceanic currents and evolving sea-surface temperature patterns, this
development offers the promise of improved climate models and better El Niño forecasts.
Better understanding of global El Niño:
Scientists at AOML have done a comprehensive analysis of how the extremes of the El
Niño-Southern Oscillation (ENSO) cycles are tele-communicated to the SST field in the
tropical Atlantic via a tropospheric bridge. It provides essential background for most
studies of the tropical Atlantic SST variability and its relationships with Atlantic regional
climates.
A Unified ENSO Theory:
El Niño-Southern Oscillation is one of the most important climate phenomena on Earth
since it affects weather around the world. Better understanding of ENSO mechanism is
an important step toward finally providing reliable climate prediction for the general
public. The delayed oscillator, the western Pacific oscillator, the recharge-discharge
oscillator, and the advective-reflective oscillator have previously been proposed to
interpret the oscillatory nature of ENSO. Motivated by the existence of these different
ENSO oscillators, scientists at AOML recently developed a unified ENSO theory that
includes the physics of the previous ENSO oscillators. All of the previous ENSO
oscillators are special cases of the unified oscillator. This new theory will help us
understand state-of-the-art coupled ocean-atmosphere GCMs and provide us a guideline
for improving ENSO prediction.
Meridional Overturning Circulation operating at faster rate than previously
estimated:
The oceanic thermohaline circulation (also called the meridional overturning circulation,
MOC) plays a critical role in long-term atmospheric climate variability. The Atlantic
Oceanographic and Meteorological Laboratory and university colleagues have been
monitoring an important component of the MOC, the Deep Western Boundary Current,
and find advective rates of water masses from northern source regions to be considerably
faster that previously estimated. The lower transport times indicate that the MOC is more
robust than previously estimated. These new results will be used to validate the numerical
models being developed to forecast climate change and in studies of the
Intergovernmental Project on Climate Change to evaluate the role of the ocean in
anthropogenic climate variability.
Atlantic Ocean warms in response to climate change:
Decadal variability in surface heat fluxes can most clearly be seen from high
quality hydrographic sections sufficiently accurate enough to measure the small changes
in temperature seen between sections taken during different epochs. The ocean
effectively integrates small changes in surface heat flux that result in small biases in sea
surface temperature, which become subducted and overturned into the deep water.
Repeat hydrographic measurement taken at the same location through time can then be
differenced to get indicators of climate change. OAR laboratories have examined
temperature difference along pressure surfaces between the Ronald H. Brown 1998 and
Discoverer 1957 hydrographic sections. Warming of the water column by as much as 1
degree C with the 300 to 2500 meters depth range is seen suggesting increased surface
heating in the Northern North Atlantic over these decades.
Oceanic measurements help to improve prediction of hurricane sudden
intensification:
Tropical storms need the right atmospheric and ocean conditions to intensify. Several past
hurricane intensification have been linked to the presence of warm ocean features.
AOML scientists use satellite altimetry to monitor the ocean's potential to intensify
hurricanes in the tropical Atlantic, Caribbean Sea and Gulf of Mexico
Multidecadal sea-surface temperature swings may help hurricane prediction:
AOML scientists have identified a multidecadal mode of sea-surface temperature
variability that is correlated to Atlantic hurricane activity - warm North Atlantic is
associated with active conditions for Atlantic hurricanes. This linkage may allow for
prediction of Atlantic hurricane activity on a multidecadal basis.
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