[Q] Distance in GEDI01_B Browse Image Plot

[hyoklee]

I have a question about the GEDI01_B browse image plot (e.g., [1]).

Does the HDF5 source file contain a dataset for the "Distance Along Track (km)"?
If not, was the distance (x-axis in plot) computed from lat/lon?
If so, what's the formula for calculating the distance from lat/lon?

[1] https://data.lpdaac.earthdatacloud.nasa.gov/lp-prod-public/GEDI02_A.002/GEDI02_A_2025190223019_O37238_01_T09057_02_004_02_V002/GEDI02_A_2025190223019_O37238_01_T09057_02_004_02_V002.1.png

[LP DAAC - jwilson]

@hyoklee We have forwarded your request to our science team for further guidance.
Thank you,
LP DAAC User Services

[LP DAAC - jwilson]

@hyoklee The GEDI team was forwarded your question. Please find their response below.

I have a question about the GEDI01_B browse image plot.

Does the HDF5 source file contain a dataset for the "Distance Along Track (km)"? (Im 99% positive this does not exist in the dataset)
If not, was the distance (x-axis in plot) computed from lat/lon?
If so, what's the formula for calculating the distance from lat/lon?

The answer is yes; the distance was calculated from lat/lon. The calculation takes advantage of the function geodesic () from Python package geopy. Below is the calculation:

for i in range(1, x_size):

p1 = (lat_lowest,lon_lowest)

p2 = (lat_lowest[i-1], lon_lowest[i-1])

x_dist = geodesic( p1, p2 ).km

x_dist = np.cumsum(x_dist)

It calculates the distance between every pair of neighboring points then calculates the cumulative sum at each point as the distance.

Please let us know if you have any other questions.
Science Team