ICESat-2 Validation Survey for Pastures of the Rio Vermelho Watershed

Full data set for comparison of ICESat-2 100m and 20m segments within areas consistently identified as pasture from 2017-2022. ATL08 v5 was used to sample 40 location in August 2023 of the 2947 measurements taken within 10 orbital passes that occurred between September 2022 and September 2023. An overview of all sampled field plots, planned and obtained, together with the sampling design and schematic of field sampling procedure are included in RioVermelho_AllPlots.pdf.

Field work was conducted between 10/01 and 10/05/2023 including field measurements and drone imagery. The canopy height models produced from RGB drone imagery flown over each plot coincident with field height measurements are provided in Drone_CHM.zip. CHMs that are not part of this dataset are not available due to file corruption and were not used in any subsequent analysis or publications. Photographs were taken at 5 locations along each of the 4 transects at nadir and panoramic. Some photographs are geolocated, but not all (typically, lines A and D are better geolocated). Photographs are divided by transect (in order of West to East) with Transect A (Fotos_Nathalia.zip), Transect B (Fotos_Maria.zip), Transect C (Fotos_WIlton.zip) and Transect D (Fotos_Lucas.zip) included. All field measurements are included in "Alturas_raw.csv" and annotated with which segments are best aligned with ICESat-2 in "Alturas_alinhadas.csv". Plants are separated by growth form into Grasses (P), Shrubs (S) and Trees (T), with their heights measured in meters. Heights less than 2 m were measured with a measuring tape, whereas taller plants' heights are estimated to the nearest meter.

ICESat-2 data for ATL08 version 6 was processed and separated for field sampled areas (atl08_fieldsegs.gpkg).  Raw data from ICESat-2 ATL03 v6 was downloaded and filtered to remove potential noise photons (signal_conf_ph > 2) and those that are flagged as having potential reflection within the instrument (ph_quality > 0). The photons coincident with each field location are separated by their field id and provided in BHRV_ATL03.zip. Polygons were drawn for each segment based on photon locations and corrected to 20 x 11 m and 100 x 11 m to facilitate comparison between all datasets (20m_polygons.gpkg and 100m_polygons.gpkg).

Metrics including mean, median, and maximum height of vegetation as well as % tree cover and % vegetation cover were calculated for each of the four datasets as possible. Summarise_all.R runs summary calculations for 20m and 100m segments and outputs summary statistics by data source. Summary data files are also provided including: Field_*m.csv, Drone_*m.csv, ATL08_*m.csv, ATL03_*m.csv.