Ocean winds

Fig: Jan 10, 2000 10m wind vectors and wind curl from QuikScat. Cyclonic curls (red) favor upwelling.

introduction

Steady winds near the surface and their seasonal and longer term fluctuations are a critical driving force for the ocean. The ocean tends to act as a low pass filter to shorter term atmospheric events.

High frequency fluctuations can, however, leave their mark on the ocean . For example, sub-seasonal winds can supply wave and/or turbulent energy to the ocean mixed layer and below. Such processes may not be properly represented in global climate models (e.g. Klinger et al)

Satellites provide a valuable resource for climate modelers by providing information about ocean winds which are otherwise poorly observed.


Satellite and reanalysis wind products

• The passive microwave radiometer, SSM/I has flown on various platforms since 1987 and provides 50km retrievals of windspeed, column water vapor and column liquid water. Wind directions are not reliable.
• A SeaWinds active scatterometer currently flies on the QuikBird satellite (QuikScat). It has been operational since July 1999. This provides reliable wind speed and direction except during rain events and along sea ice margins. Resolution is 0.25 degrees.
• Milliff and Morzel combines QuikScat data and the NRA40 analysis to compensate for rain biases.
  

Here are some comparisons between QuikScat and NRA40 winds.

• NRA Jan 10, 2000 NEPac
• QuikScat Jan 10, 2000, NEPac
  
• NRA March 15, 2000 NAtl
• QuikScat March 15, 2000 NAtl
• NRA July 1, 2000 Weddell Sea
• QuikScat July 1, 2000 Weddell Sea

References

Milliff sensitivity of ocean GCM to scatterometer winds

Wittenberg analysis of tropical Pacific winds

Chin and Milliff

Wikle and Milliff hierarchical bayesian approach to wind modeling

Tim Liu review of progress of scatterometer application

Wikle analysis of TOGA-CORE winds on scales of 1 to 1000 km

Chelton comparison of scatterometer, NCEP and ECMWF

Klinger calculation of friction velocity based on SSM/I

Skyllingstad et al , resonant (inertial) wind-driven forcing in the ocean boundary layer. LES results.

Sanford et al ocean response to hurricanes

D'Asaro energy flux from near-inertial winds to mixed layer oscillations observed

Jim Price internal-inertial wake in response to moving storm

S.P. Xie Gap winds in EPac

Large et al, upper ocean thermal response to autumnal storms in NEPac

Payden et al , tidal and atmospheric forcing in the Gulf of California

Sirven et al, spectrum of wind driven baroclinic fluctuations of the ocean at mid-latitudes

Matt Alford's homepage

David Straub's homepage

Patrice Klein (1981) manuscript on the impact of inertial range atmospheric wind variability on ocean mixed layer dynamics. Horizontal dispersion of near-intertial oscillations in a turbulent mesoscale eddy field. On biological impacts of sub-mesoscale variability.

Internal Wave Action Model

Matt Alford observations of near-inertial gravity waves in the Banda Sea.