MEaSURing Ocean Surface Wind Vectors

MEaSUREs creates a comprehensive record of ocean surface winds in order to improve weather forecasting. This false-color image is based on measurements taken by scatterometer SeaWinds in 1999. more about MEaSUREs

scroll for more

About this MEaSUREs-Funded Project

Ocean surface winds are one of the key components of the Earth system. By using Scatterometer observations, we can understand the effect of ocean surface winds on ocean circulation and on the air-sea interactions that fuel weather systems.

Understanding these interactions is critical for improving weather forecasting — from isolated storms to organized squalls, and from hurricanes to seasonal and intraseasonal phenomena such as El Niño and monsoon rains. Indeed, operational meteorologists have grown accustomed to make their forecast of hurricane formation and evolution based on scatterometer wind estimates.

learn more

Scatterometry

Scatterometers bounce pulses of microwave energy off the ocean surface. The returned energy gives us information on the size and orientation of waves, which change depending on wind speed and direction. Scatterometer data helps us monitor surface wind around the world’s oceans.

Scatterometer missions can be broadly classified in two categories, defined by the electromagnetic frequency used and the scanning strategy. Different frequencies have different sensitivities to atmospheric parameters like rain, and to ocean surface parameters like sea surface temperature and wind speed.

C-band Push-Broom Instruments (5.25 GHz)

The observing geometry provides better accuracy across the measurement swath, but at the expense of a large gap in coverage. C-band instruments provide better retrievals in rain than Ku-band instruments because of the lower impact of rain at these lower frequencies.
C-band

C-band Scan Characteristics

Employed by EUMETSAT. Three fan-beam antennae in a single or dual swath configuration transmit high radar frequency pulses and receive backscattered energy from the ocean surface. One example of this type of scatterometer is ASCAT.
Ku-band

Ku-band Scan Characteristics

Employed by NASA and the Indian Space Research Organization (ISRO). The antenna spins and emits two continuous beams of high radar frequency pulses. The antenna receives backscattered energy from the ocean surface. One example of this type of scatterometer is RapidScat.
Ku-band Conically-Scanning Pencil Beam Instruments (~13.4 GHz)

The scanning strategy provides wind estimates over a much larger swath but with lower accuracy near the center of the swath. These instruments provide very accurate winds in rain-free conditions and in some rainy conditions, but are negatively impacted in stronger rain events.

Meet the Scatterometers

Scatterometer Infographic Launched between 1999 and 2016, these NASA, NOAA, ISRO and ESA scatterometers create a full, continuous picture of ocean surface winds that help improve weather forecasting.

Data Products

Surface wind speed and direction

The size and orientation of waves changes depending on wind speed and direction, giving us a way to monitor the surface wind vector around the world's oceans using satellite scatterometer observations of the wind-modulate ocean surface.
Derivitives: curl and divergence of the wind

Divergence and convergence (negative divergence) describe whether there is an outflow from a region (divergence) or inflow into the region (convergence). The tropical atmospheric circulation is largely driven by the near-surface convergence of momentum and moisture that on some scales can be estimated from the scatterometer-derived wind convergence.
Surface wind stress magnitude and direction

Wind stress is the drag force exerted on the ocean surface by adjacent (near-surface) layer of moving air. Wind stress is the most important forcing on the upper ocean circulating, driving the surface currents.
Derivatives: curl and divergence of the wind stress

The curl of the wind stress is very important in deep ocean circulation, a primary driver of the upper-ocean circulation and has been shown to modulate the air-sea coupling in regions of strong fronts in sea surface temperature.

Data Portals

Through use of consistent records, MEaSUREs expands understanding of the Earth system by linking multiple satellites into a constellation and by facilitating use of data in developing comprehensive Earth system models.

Worldwide Ocean Wind (WOW) Portal

Dedicated to the visualization and online analysis of the ocean surface winds as observed by a number of scatterometers since 2014. The WOW portal will be augmented to include the entire data record of scatterometer winds, stress sand spatial derivatives, starting in 1999.