1/ Satellite image of Sargassum beds
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The Optical Oceanography Laboratory at the University of South Florida has created a Sargassum Satellite Watch System (SaWS).
This system publishes reprocessed satellite images in an attempt to position and track Sargassum beds. 
These images, free and public, are accessible by clicking on the [SaWS Clickable Map] button on this page: http://optics.marine.usf.edu/projects/saws.html

We reprocess the composite image published by the USF to make a highly compressed image, downloadable and displayable as an overlay in SailGrib WR or Adrena.
The image is published every day and is accessible to everyone on the SailGrib servers at the following address
http://gribserver.sailgrib.com/sat/sargassum_density_most_recent.jpg

The history is available here:
http://gribserver.sailgrib.com/sat/historical

A Gif of the last 30 days is available here :
http://gribserver.sailgrib.com/sat/sargassum_density_most_recent.gif

The latest version of this document is available here:
http://gribserver.sailgrib.com/sat/read_me_first_en.txt

The image is small enough, around 100kb, to be downloaded with an Iridium Go directly into SailGrib WR or with the SailDocs service by email.
recipient: query@saildocs.com
subject [free] e.g. "Sargassum
body: send http://gribserver.sailgrib.com/sat/sargassum_density_most_recent.jpg

We would be grateful if you could share your observations with us upon your return, we will share them with NASA.

2/ Upload to SailGrib WR
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In SailGrib WR, you can easily download and view these images.
To download them: Menu / Get sat image then choose Tropical Atlantic / USF / Sargassum 63W-39W 22N-0N.
The request can be done by direct download or by email.
The map opens and is displayed. Ignore the synchronization and leave the default values.
To open them again: Menu / Open sat image then choose the sat image.

3/ Routing with sargassum banks
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To do a routing with sargassum banks, we define the sargassum zones as slow zones and we degrade the polar in these zones.
After downloading and displaying the sargassum sat image :
- create "slow zones" simply by drawing the outline of the Sargassum beds
- assign a coefficient of efficiency to the polar in these zones, typically between 50% and 80%, which will multiply the boat speed in these zones.
- do the routing

I remind you that with SailGrib WR, you can :
- download and view a multitude of grib files (wind, waves and currents)
- download and view isobaric charts
- download and visualize reworked and highly-compressed satellite images
- make your routings with many options
- follow your navigation with raster nautical charts from GeoGarage (SHOM, UKHO, BSH, NOAA...) or Navionics
- visualize NMEA data and calculate for example your polar efficiency.
- view AIS targets and be alerted in case of danger
- integrate the position files sent by the race direction, calculate the rankings in real and compensated time and analyze your performance from one ranking to the other compared to the competitors.


4/ Use it in Adrena
==========================
It is very easy to add the image to the georeferenced images and then use it as an overlay and create, as in SailGrib, slow zones.
- Go to the Georeferenced Images / Favorites / Create a favorite
- Give a name like "Sargassum", check "A website", enter the image address: http://gribserver.sailgrib.com/sat/sargassum_density_most_recent.jpg then press "Define multiple positions".
- The georeferencing screen opens. Point to a first point, place the red cross in the upper left corner of the screen, for example on the point (20N,60W), enter the coordinates of the point.
  Repeat with 2 other points, e.g. (02N,52W) in the bottom middle and (20N,40W) in the top right. Press the "Validate" button.
- To use it, connect to the Internet and click on the "Sargasso" bookmark, the map will open.
You can download a pdf with more details at http://gribserver.sailgrib.com/sat/image_geeoreferenceee_sur_adrena.pdf

Henri
http://www.sailgrib.fr
henri@sailgrib.com