4.4. 'LANDSAT TM' Tab Pane

'LANDSAT TM' Tab Pane

Figure 4.7. 'LANDSAT TM' Tab Pane


This tab pane (Figure 4.7) consists of four subpanels.

4.4.1. 'Atmospheric Parameters' Subpanel

  • 'Ozone content (cm atm):' : A text field to enter the ozone content value to be used by the AE correction algorithm. The default is 0.32 cm atm, the valid interval is [0.01, 1.0].
  • 'Surface pressure (hPa):' : A text field to enter the surface pressure value to be used by the AE correction algorithm. The default is 1013.0 hPa, the valid interval is [300.0, 1060.0].
  • 'Surface TM apparent temperature (K):' : A text field to enter the ozone content value to be used by the AE correction algorithm. The default is 300 K, the valid interval is [200.0, 320.0].

4.4.2. 'Cloud Flag Settings' Subpanel

  • With the checkboxes in this subpanel, the user can select subsequent tests (see alsoSection 3.2.2) to finally define a cloud flag:
    • Brightness test ('passed' if TM3 < BT)
    • NDVI test ('passed' if NDVI < NDVIT_CLOUD, with NDVI = (TM4 - TM3)/(TM4 + TM3))
    • NDSI test ('passed' if NDSI < NDSIT, with NDSI = (TM2 - TM5)/(TM2 + TM5))
    • Temperature test ('passed' if TM6 < TM6T_CLOUD)
    If all selected tests are passed, the given pixel is considered and flagged as 'cloudy'.
  • With the textfields in this subpanel, the user can specify distinct thresholds for the tests above:
    • Brightness threshold BT: The default is 0.3, the valid interval is [0.0, 1.0]
    • NDVI threshold NDVIT_CLOUD: The default is 0.2, the valid interval is [0.0, 1.0]
    • NDSI threshold NDSIT: The default is 3.0, the valid interval is [0.0, 10.0]
    • Temperature threshold TM6T_CLOUD: The default is 300.0, the valid interval is [200.0, 320.0]

4.4.3. 'Land Flag Settings' Subpanel

  • With the checkboxes in this subpanel, the user can select subsequent tests (see alsoSection 3.2.2) to finally define a land flag:
    • NDVI test ('passed' if NDVI < NDVIT_LAND, with NDVI = (TM4 - TM3)/(TM4 + TM3))
    • Temperature test ('passed' if TM6 > TM6T (summer), TM6 < TM6T (winter))
    If all selected tests are passed, the given pixel is considered and flagged as 'land'.
  • With the textfields in this subpanel, the user can specify distinct thresholds for the tests above:
    • NDVI threshold NDVIT_LAND: The default is 0.2, the valid interval is [0.0, 1.0]
    • Temperature threshold TM6T_LAND: The default is 300.0, the valid interval is [200.0, 320.0]
  • 'Season': With this radio button group (toggle button), the user can specify if he wants to apply the 'winter' or the 'summer' criterion in the temperature test above.

4.4.4. 'Advanced Options' Subpanel

  • 'AE correction grid resolution': With this radio button group (toggle button), the user can specify if the LANDSAT TM AE correction shall be performed with a 300m (MERIS FR) or a 1200m (MERIS RR) resolution.
  • 'Output product type': With this radio button group (toggle button), the user can specify what kind of output he wants to write into the target product:
    • 'Full AE corrected product': The AE corrected product with all radiance bands.
    • 'Flag bands only': Only the flag bands are comoputed and written to the output product. This option has the advantage that the user can adjust the cloud/land test thresholds in several runs towards 'optimal' cloud/land masks without computing the AE correction. This may save computation time significantly since the AE correction needs to be performed only once in a final run with the 'full' product being written.
    • 'Geometry product only (input downscaled to AE correction grid)': The output product will be the same as the input product, but downscaled from the original TM resolution (30m) to the AE correction grid resolution as selected above. This option has the advantage that processing time can be saved for the 'Flag bands only' step described before, since this product (a 'Geometry' product following the ATBD notation) needs to be computed only once and can then re-used as input for different AE correction runs with varying user options (such as test thresholds as outlined above). In principle it is possible to perform a 'full' AE correction run from a Geometry product as well, but in this case, of course, the AE corrected product cannot be upscaled to the TM resolution since the information from the original product is missing.