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Viewing 15 posts - 1 through 15 (of 21 total)
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  • in reply to: ENVISAT RA2 waveform shape using BRAT #15837

    brat
    Keymaster

    Hi Deepa,

    1. Yes, you will need SGDR to get the Waveforms as they are not included in all the Envisat products.

    In the following link, https://earth.esa.int/pub/ESA_DOC/ENVISAT/RA2-MWR/PH_light_1rev4_ESA.pdf , you have information describing the parameters in the SGDR file.

    In page 143 (150 of the pdf) you can see the waveform details.
    2. You can get SGDR data by requesting access through the ESA EO-SSO https://earth.esa.int/web/guest/-/ra-2-sensor-data-record-1471

    3. Sigma0 is the backscatter estimate calculated from the AGC and the power level of the radar echo. The signal path attenuation, as calculated from the in-flight calibration records, is applied. To compute an accurate Sigma0, geophysical corrections such as liquid water and water vapour attenuation must be applied. The return echoes power is just the power received by the radar, without any geophysical correction.

    Kind Regards,

    Albert, BRAT Team

  • in reply to: River water level #15833

    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

  • in reply to: ENVISAT RA2 waveform shape using BRAT #15832

    brat
    Keymaster

    You can find the information about the RA2 product format in the following url: https://earth.esa.int/pub/ESA_DOC/ENVISAT/RA2-MWR/PH_light_1rev4_ESA.pdf

    For plotting the waveforms you can follow slides56-60 of the following training presentation: https://drive.google.com/file/d/0B2-IGHnWA7ceZURrSTF4OHplVnM/view

    Regards,

    Albert – Brat Team

  • in reply to: River water level #15827

    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

  • in reply to: find Saral ssh using brat #15360

    brat
    Keymaster

    Dear Marjan,

    Yes, there is not a specific expression for SSH in SARAL, so you can use the default one.

    All the formulas are stored in a file in your machine called formulas.ini. In the same folder you can find the aliases.xml that links similar variables from different missions with the same tag.

    In the formulas.ini you can see that the SSH formula is just using the alias for the ssh written as “%{ssh}”. In the aliases.xml file you can see for the SARAL case you can see that the ssh is %{sla} + %{mean_sea_surface}, so in the end ssha + mss_dtu13 .

    My advice is that you don’t use the ssh formula to compute the water level for a lake. The SSHA is probably using the range computed with the ocean retracker, and the Mean Sea Surface model DTU 13 is not probably the best over land.

    You can compute the water level for the lake by using a variation of the WSH_Inland_Waters formula
    %{altitude} – %{range} – %{iono_corr} – %{dry_tropo_corr} – %{wet_tropo_corr}

    For SARAL you have to write
    alt – range – model_wet_tropo_corr – model_dry_tropo_corr

    As the wet and dry tropospheric corrections are at 1Hz you should use “alt” and “range” that are also at 1Hz. Also, the variable in your axis should have the same dimensions, so put “lat” and “lon” variables and don’t use “lat_40Hz” or “lon_40Hz”. If your lake is too small you will need to go to 40Hz measurements making the retrievals a bit more tricky as the corrections are not provided at 40Hz.

    Additionally, you can consider using the PEACHI products based on the SARAL mission. They are product oriented to get better results over inland waters. You can get them from the ODES service

    Also, take into account that the orbit for SARAL is drifting since July 2016 so the revisit time over your lake will change.

    Depending on the size of the lake the measurements will be contaminated and special processing will be needed. You can check if your lake is listed in one of the services providing water levels from altimetry.

    Services
    Rivers and Lakes (ESA)
    Hydroweb (LEGOS)
    Global Reservoir and Lake Monitoring (US Dept. of Agriculture)
    DAHITI project

    Development projects
    CRUCIAL project
    SHAPE project

    Let us know if you have any other issue,

    Regards,

    Albert, BRAT Team

    • This reply was modified 2 years, 2 months ago by  brat.
  • in reply to: Viewing multiple plots in one view #15357

    brat
    Keymaster

    Hello Shamsa,

    The process is described in slides 30 to 32 in the training presentation.
    – You should create both fields in the same operation
    – Make sure that the button to “split plots” is not activated. It is located just above the “execute” button.
    – They should have the same units. For SLA and SSH, you shouldn’t have this problem

    Let see if these tips help you.

    Regards,

    Albert, BRAT Team

  • in reply to: BRAT installation on Ubuntu 16.4 #15306

    brat
    Keymaster

    Hi Shamsa,

    The password should be the one you use to log on the OS.
    When installing and using RADS through BRAT the user should have admin permissions.

    In chapter 3.6 of the user manual ( http://www.altimetry.info/filestorage/brat_user_manual.pdf ) you will find all the information. An example of how to use RADS is found at the beginning of this video tutorial https://www.youtube.com/watch?v=4TXAU6CFaaM

  • in reply to: visualizing merged data in BRAT #15305

    brat
    Keymaster

    Dear Adonis,

    We would need a little bit more information about the merged dataset you are using. The advanced operation seems fine. The error can come also from the filter. You can try the same operation without applying it to ensure that the filter is ok.

    You can send us the dataset and we will check it. brat.helpdesk ( at ) esa.int.

    Regards,

    Albert

  • in reply to: Calculate Significant Wave Hight using BRAT #15293

    brat
    Keymaster

    Hi Abdelhak,

    You can find the SWH in the quick operations tab. You can get what you want if you follow the example of the video https://www.youtube.com/watch?v=8guOICQ1t4I

    but using S3 L2 data and checking SWH in the Quick Operations Menu.

    For plotting the wind speed you can follow the advanced operations and drag the wind speed parameter in the S3 L2 dataset into “data” and the latitude and longitude into “lat” “lon”.

    Kind Regards

    • This reply was modified 2 years, 6 months ago by  brat.
  • in reply to: CryoSat-2 Data Generation #15253

    brat
    Keymaster

    Dear Booker,

    The product type that you mentioned should be able to be read by BRAT. The tool was updated in September 2015 to include CryoSat Baseline C products and some new missions such as Sentinel 3 or Jason-3.

    If you have any problem with it please explain what error or issue are you having.

    There are examples using CryoSat L2 products in the Training section:http://www.altimetry.info/radar-altimetry-tutorial/training-material/

    Kind Regards,

    BRAT Team

  • in reply to: CryoSat-2 Data Generation #15250

    brat
    Keymaster

    Dear Booker,

    Yes, you can use BRAT to digest this CryoSat-2 product type.

    On page 74 of the User manual, http://www.altimetry.info/filestorage/brat_user_manual.pdf, you have the list of CryoSat products that can be read by BRAT.

    Regards,

    BRAT Team

  • in reply to: Associated view supported by Brat editor #15236

    brat
    Keymaster

    Dear Bello,

    Which data are you using and what operation are you executing?
    If you want, you can write an email to brat.helpdesk@esa.int with snapshots of the process you are following.

    Regards,

    BRAT Team

  • in reply to: Missing CAPTCHA at login page #15231

    brat
    Keymaster

    Thanks Lukas,
    The issue was related with the plugin used to generate the CAPTCHA. Now the login page is working again.
    Regards,

    BRAT Team

  • in reply to: Installing RADS service #15230

    brat
    Keymaster

    Dear Laurent Testut,

    As usual with this kind of problem, there are several possible causes.
    First you should check an issue reported in the SUM. Here is the important part:

    “In all systems, please make sure that any TCP traffic from your machine to port 873 on the RADS server
    is not being blocked by a firewall. This is usually not an issue, but it can happen if your system is
    accessing RADS behind a more restrictive network configuration.”

    We asked another user with a similar problem to ping the RADS server, and he detected (and solved) network issues on his side. Maybe this is helpful also in this case: ping corads.tudelft.nl

    Finally, you can also increase the value of the paramater default_timeout_in_seconds, that is, replace the line

    default_timeout_in_seconds=30

    with something like

    default_timeout_in_seconds=90

    in the file C:\Users\ltestut\AppData\Roaming\ESA\RadsService.ini

    The service needs to be restarted after this. But usually 30 seconds are enough, so a timeout means other connection problems. Anyway, it should also be tried as a last chance solution.

    I hope this helps.

    Best regards,

    BRAT Team

    • This reply was modified 2 years, 10 months ago by  brat.
  • in reply to: toolbox shows nothing #13134

    brat
    Keymaster

    Hi Konstantinos,

    In order to see the satellite map, you just need to go to the options and set the map to raster layer instead of vector layer. (example attached)

    It is not a problem to have the map as you have it before. It is just an option of the toolbox.

    Kind Regards,

    BRAT Team

Viewing 15 posts - 1 through 15 (of 21 total)