 |
| Titel |
The influence of spatially and temporally high-resolution wind forcing on the power input to near-inertial waves in the ocean |
| VerfasserIn |
Antonija Rimac, Jin-Song von Storch, Carsten Eden |
| Konferenz |
EGU General Assembly 2013
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250079936
|
|
|
|
|
|
| Zusammenfassung |
| The estimated power required to sustain global general circulation in the ocean is
about 2 TW. This power is supplied with wind stress and tides. Energy spectrum
shows pronounced maxima at near-inertial frequency. Near-inertial waves excited by
high-frequency winds represent an important source for deep ocean mixing since
they can propagate into the deep ocean and dissipate far away from the generation
sites.
The energy input by winds to near-inertial waves has been studied mostly using
slab ocean models and wind stress forcing with coarse temporal resolution (e.g.
6-hourly). Slab ocean models lack the ability to reproduce fundamental aspects of
kinetic energy balance and systematically overestimate the wind work. Also, slab
ocean models do not account the energy used for the mixed layer deepening or the
energy radiating downward into the deep ocean. Coarse temporal resolution of
the wind forcing strongly underestimates the near-inertial energy. To overcome
this difficulty we use an eddy permitting ocean model with high-frequency wind
forcing.
We establish the following model setup: We use the Max Planck Institute Ocean Model
(MPIOM) on a tripolar grid with 45 km horizontal resolution and 40 vertical levels. We run
the model with wind forcings that vary in horizontal and temporal resolution. We use
high-resolution (1-hourly with 35 km horizontal resolution) and low-resolution winds
(6-hourly with 250 km horizontal resolution). We address the following questions: Is the
kinetic energy of near-inertial waves enhanced when high-resolution wind forcings are used?
If so, is this due to higher level of overall wind variability or higher spatial or temporal
resolution of wind forcing? How large is the power of near-inertial waves generated by
winds?
Our results show that near-inertial waves are enhanced and the near-inertial
kinetic energy is two times higher (in the storm track regions 3.5 times higher) when
high-resolution winds are used. Filtering high-resolution winds in space and time, the
near-inertial kinetic energy reduces. The reduction is faster when a temporal filter is used
suggesting that the high-frequency wind forcing is more efficient in generating
near-inertial wave energy than the small-scale wind forcing. Using low-resolution wind
forcing the wind generated power to near-inertial waves is 0.55 TW. When we use
high-resolution wind forcing the result is 1.6 TW meaning that the result increases by 300%. |
|
|
|
|
|