Waves and ocean circulation
-
Hi All,
have just found this project; am very impressed. I am a college student, and am thinking about mapping changes in ocean circulation patterns throughout the past few decades, looking to link to changes in climate; melting sea ice - changes in salinity and speed of gyres, rising temperatures, via satellite-based remote sensing techniques.
There exist some remote sensing methods for application to sensing of ocean dynamics, one that I think is interesting is a technique using along-track interferometric Synthetic Aperture radar SAR (InSAR), which works by taking two images of a scene in rapid succession with a time lag of milliseconds, calibrating for the change in relative motion between the position of the sensor and the earth’s rotation to sense sea surface velocity by analysis of phase differences between images proportional to Doppler shifts of the backscattered microwave signal. Otherwise altimetry, the sensing of sea surface height is also used to calculate geostrophic winds and strength of current.
I was wondering which method is implemented here in the wave animation and forecasting, also the wind. Is it remotely sensed, or interpolated from available sensors, or a different method ?
Best,
David
-
@typhoon-3
In Windy, Waves and Wind are forecast by numerical weather models (NWP from ECMWF, NOAA/NCEP, DWD…). They are not satellite observations.
Currents, for their part, are based on satellite observations .
Click the small circled i to get more information about the data
-
@idefix37 Great, thanks
-
The currents seem to be connected to a forecast model as well
-
In a way you are right. From direct ocean observation by satellite (speed and direction for Currents and sea surface altimetry for Tidal currents) this data is computed to provide 3 days forecast.
Concerning the weather prediction, satellite inputs in the initialization phase are also very important, in addition to ground weather stations, radiosondes, planes, weather buoys, ships… But what I meant is the larger complexity of the weather model to assimilate all this data and compute a 10 days prediction, for example for Wind and Waves. -
The state of the art in ocean forecasting is summarised in this recent WMO bulletin.
-
@idefix37 Thanks for your message. I'm wondering which satellite data based method is used to compute speed and direction of major currents. Is it by inSAR ? I guess it works by taking two images in rapid succession at the same sensor, and then calculating a direction and magnitude vector by first calibrating for the change in relative motion between the position of the sensor and the earth’s rotation to sense sea surface velocity by analysis of phase differences between images proportional to Doppler shifts of the backscattered microwave signal. Do you happen to know which method they use ? It is this method which I find fascinating, however there are others which are of course useful as well.
-
@vsinceac Thanks, will take a look.
-
@typhoon-3
Yes, SAR - synthetic aperture radar - technique is used for ocean currents measurements by ESA/ Copernicus satellites:
https://www.esa.int/Applications/Observing_the_Earth/Satellites_stay_current_on_ocean_currents
https://marine.copernicus.eu/news/new-copernicus-satellite-how-sentinel-6-will-improve-ocean-monitoring.
In Windy, Currents data is provided by Copernicus. -
@idefix37 Great ! Thanks
