Practical instructions for using Argonautica/ArgoHydro data
Dates
Measurements are provided at the dates available, the most recent available data will be published every Monday.
For satellite measurements on rivers, this availability will depend on how often the satellite passes over the same point, and on the extent of the ground measurements (which can range from a few kilometers for altimeters to several hundred for other techniques). In addition, measurements can be discarded as unreliable. Therefore, there will not be new satellite measurements every week.
Two modes of use
The "real time"
Every Monday, the Argonautica/ArgoHydro site is updated with data potentially up to the day before. It is thus possible to follow the variations of a river or a lake from month to month.
The "archives"
Measurements are provided for as long as they were available at a given point, but also at points that are no longer updated. This allows longer periods to be taken into account, and thus to better understand seasonal cycles or to better define minima and maxima.
Type of information
Satellites: see from afar, see globally
Satellites have the advantage of taking measurements from very high above, and therefore "see" the earth in whole or in large part. Earth observation satellites, apart from some meteorological satellites, are generally "scrolling", i.e. they revolve around the Earth at an altitude that makes the Earth also revolve under them at a different speed. They thus observe the entire surface of the planet (or almost). On the other hand, they only observe the surface: all satellites use electromagnetic waves to observe; of the same nature as light, these waves do not penetrate or penetrate very little into the water.
Plotting the measurements
The measurements can be plotted on graphs, from the downloaded file or by copying and pasting the table of measurements. They can also be located on a map, using the provided longitudes and latitudes.
Figures on the site
A number of figures are provided by Argonautica every week. The figures are available on the site as "thumbnails", so that you can see them all at a glance. By clicking on them, you can enlarge them. You can also download them.