ICESat-2 elevation data

Due to very sparse coverage (relatively dense along track, but not between tracks), these will not work well as point clouds.

Download ICESat-2 ATL08 elevation data
- Get data for tracks crossing the lake/reservoir, and all the dates available.
Convert CSV to DBF
- Insure you have a map open
- Merge nultiple CSV files from the database menu choice.
- Open database to open Single file for later operations; insure you pick tghe DBF and not the CSV file.
From the DB tool bar: Stats, ICESast-2, ICESat-2 file cleanup. This should happen automatically.
- Gets the geoid, and makes geoid heights for the ground and canopy top
- Extracts the date from the FILE_NAME field
- Reduces the "precision" to centimeter
- Removes three unneeded fields in the database
- If you cannot get the records to show up, close and then reopen the database
Plot, Color code by DB numeric field to see canopy height or the ground level on the map
Plot, field quick filter to rapidly find a single altimeter track. You can move among the track, date, and beam. This affects both the map display, and any profiles plotted.

To track the water levels

With satellite image as base map
- Create an NDVI or NDWI map
With DEM as the base map. This requires that the DEM has been editted so that the lake has a single elevation; not all DEMs have this done.
- Adjust the colors on the map to use the full range, so you can clearly see the flat lake
With the grid from the base map

Check the Edit checkbox on the databbase
Edit, DEM/grid, Add interpolated elevation from DEM/grid. Give it a meaningful name
Filter the database.
- With the DEM, use the field you created, and pick a lower and upper bound just slightly different from the elevation of the lake in the DEM
- With the satellite NDVI or NDWI, use the field you created, and pick a bound that differentiates the water from everything else
Adjust the filter until you have only points in the lake
Report, Export DBF Table which will have just the area of the lake and use this database for further operations

With any basemap. This will work well if you have a big lake and it's easy to get all you satellite tracks in a rectangle with no land.
- Zoom to the area of the lake
- Rectangular region on Map query. You want as large an area as possible to cover as any different tracks as possible, to get the largest number of days
- Report:, Export DBF Table which will have just the area of the lake
Stats, ICESat-2, Lat profiles colors from date
- There will be a popup legend with the dates and their colors
- You can adjust the scaling on the graph by right clicking

	ICESat-2 profiles in the reservoir on the Nile in Sudan. This was filtered using the reservoir elevations in the COP DEM. Compared to the lake below, the reservoir is very narrow, and the water level changed dramatically over the period covered by ICESat-2.
	ICESat-2 profiles on one of the Easst African Rift lakes.. This was not filtered, and many of the points are not in the lake. This uses the same vertical scale as the graph above.
	ICESat-2 profiles on one of the Easst African Rift lakes.. This was not filtered, and many of the points are not in the lake. This uses the a vertical scale to highlight the returns from the lake surface.

Icesat File Problems

With some regularity, some of the ICESat-2 files have columns that do not align (probably when there is no canopy anywhere on the profile). To fix that:

Open the DBF that fails in Excel
Find the offending lines.
Cut and paste them to the right so they line up
Save as a CSV
Import into MICRODEN

Last revised 3/22/2022