homepage Forums Altimetry Forum River water level

This topic contains 5 replies, has 3 voices, and was last updated by  Ahalya 9 months, 2 weeks ago.

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  • #15826 Reply

    Md Bhuyian
    Participant

    Hello,

    I am new to altimeter community.

    I want to find time series of inland water level (i.e. rivers, lakes) from altimeter data using BRAT like this plots (http://www.legos.obs-mip.fr/soa/hydrologie/hydroweb/Page_2.html). I am more interested in defining my own virtual stations. How can I do that?

  • #15827 Reply

    brat
    Keymaster

    Dear Md Bhuyian,

    First, you have to check which satellites cover your area and period of interest. In the portal, you have the list of missions and you can search for the ground tracks of them to see if they pass over your region of interest. Then download the data through the corresponding ftp or synchronise BRAT with RAT by selecting the missions that you want. In the first steps of this video tutorial, you can see how to do it https://www.youtube.com/watch?v=4TXAU6CFaaM& .
    You can use the Water Surface Height “WSH_Inland_Waters” provided in the formulas display. You have an example of the use of formulas in the following link https://www.youtube.com/watch?v=GyC4u6icNZs

    The WSH_Inland_Waters formula is based on the definition from the Pistach product handbook over Inland waters areas, CLS-DOS-NT-10-246 Oct. 4, 2010. You can modify the formula and apply some selection criteria to add more robustness to your computation.

    Depending on the area of interest, you should verify that the altimeter measurements are good. For small rivers or lakes, some altimeters are not able to retrieve good measurements. So another source of water level measurements, from in-situ stations, or external studies will help you in that part.

    For further information about applications related to river and lake, monitoring see: Rivers and Lakes (ESA), Hydroweb (LEGOS), Global Reservoir and Lake Monitoring (US Dept. of Agriculture), CRUCIAL project, DAHITI project and SHAPE project.

    Let us know if you can proceed with your study after the info provided,

    Kind Regards,

    BRAT Team

  • #15828 Reply

    Md Bhuyian
    Participant

    Hello,
    Thanks for the informative response. I am using Jason2 and Jason3 (track 166) over an inland wetland. I am trying to recreate and extend this plot http://www.legos.obs-mip.fr/soa/hydrologie/hydroweb/StationsVirtuelles/Serie_tempo/Gan_j2_166_4_serie_tempo.jpg

    I added the NC file for cycle001 from gdr folder (https://www.nodc.noaa.gov/sog/jason/) to apply the built-in WSH formula. But I have some additional questions:

    (1) the inland wet cell along the path is shown as a large block (approximately 30 km x 30 km). How can I find altimeter points along the track?
    (2) How can I download the data from the plots generated after running the functions?
    (3) What is the difference between WSA and WSH function?

    Thanks

  • #15833 Reply

    brat
    Keymaster

    Hello Md Bhuyian

    1) The 2D plots are subsamples with a step of 1/3 of a degree by default. You can change the sampling rate in the plot. You can change that in the “sampling” menu at the left bottom of the operations tab. The 2D plots are not a good approach for inland water analysis. I recommend you to use 1D plots, just using the latitude or the longitude instead of both.

    2) When you generate the image, there is a bar at the right of the plot. The last button can be used to save the image in view.

    3) WSA and WSH are implemented in the formulas.ini file that you can find in brat/bin/data folder. They have been defined in the Pistach Product handbook. https://www.aviso.altimetry.fr/fileadmin/documents/data/tools/hdbk_Pistach.pdf

    [WSH_Inland_Waters]
    Define=%{altitude} – %{range} – %{iono_corr} – %{dry_tropo_corr} – %{wet_tropo_corr}
    Comment=Water Surface Height as defined in Pistach product handbook over Inland waters areas, CLS-DOS-NT-10-246 Oct. 4, 2010
    Unit=m

    [WSA_Inland_Waters]
    Define=%{WSH_Inland_Waters} – %{mean_sea_surface}- %{solid_tides_corr} – %{pole_tides_corr}
    Comment=Water Surface Altitude as defined in the Pistach product handbook over Inland waters areas, CLS-DOS-NT-10-246 Oct. 4, 2010
    Unit=m

    Regards,

    Albert – Brat Team

  • #15937 Reply

    Ramsha

    I had downloaded the Sentinel 3A data from Open Access HUb and open it on brat 4.2.1 but as I try to use the formula of WSH_Inland_Waters, console display an error “BRAT ERROR: FileException #-7: Error reading variable alt_01”.
    I can understand this but confused how to resolve where to define a variable for such errors.
    Plz respond as soon as possible.

    regards,
    Ramsha

  • #15941 Reply

    Ahalya

    Hello,

    I am using Sentinel 3A data over inland water body. Can you please tell me the exact procedure how to use re tracking algorithms using BRAT. Its urgent . waiting for response

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