homepage Forums Altimetry Forum ENVISAT RA2 waveform shape using BRAT

This topic contains 7 replies, has 2 voices, and was last updated by  Deepa 10 months, 2 weeks ago.

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  • #15831 Reply

    Deepa

    Hi, im working with Envisat RA2 Altimetry data – RA2_MWS_2P-SGDR products(v 2.1). Could you please tell me how to get the plot of waveform shapes? that means window bin vs backscatter. how to plot them? I am doing water level extraction of continental water bodies. now i need to analyze waveform for further studies.
    i found those in you documentaries.
    Thanks in advance.

  • #15832 Reply

    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

  • #15834 Reply

    Deepa

    Hi,
    Thank you for the useful reply. but I need to plot waveform as available in http://www.altimetry.info/wp-content/uploads/2015/09/issykkul_GE_J2pass131_wvf_sm.jpg, the plot of gates vs return echo power.

    I have additional questions on this,
    1. which fields of ENVISAT RA2 data represent gate numbers and return echoes?
    2. does RA2_MWS_2P-SGDR data contains this information? otherwise where to download?
    3. what is the difference between return echoes power and sigma0?

    Thanks.

  • #15835 Reply

    Deepa

    Any suggestion on this?

  • #15837 Reply

    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

  • #15838 Reply

    Deepa

    Thank you very much for your informative reply

  • #15839 Reply

    Deepa

    I am having difficulties while visualizing multidimensional data( for eg. Average S-band waveforms(128), Average Ku-band waveforms) with corresponding lat and long.

    could you please tell me, how it can be done?
    Thank you!

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