TITLE:	Phenocamera RGB image collection from Abisko Observatory, north-western Sweden.
SITES STATION:	Abisko Scientific Research Station
TIME PERIOD:	20220630 - 20220818 
TIME RESOLUTION:	DAILY
TIME ZONE:	UTC+1
SAMPLING POINT:	Abisko Scientific Research Station, on rooftop of Building H at 4.5m, Phenocam 01 :  platform_id=P_RTBH_1
LATITUDE:	68.353729
LONGITUDE:	18.816522
ALTITUDE:	381 m.a.s.l

FILE RETRIEVED FROM:	https://data.fieldsites.se Link to metadata landing page is available in separate file in the downloaded zip.

DATA POLICY:	SITES data is licensed under a Creative Commons Attribution 4.0 international license (http://creativecommons.org/licenses/by/4.0/).

PARAMETERS & UNITS:	Digital Numbers (DN)

DESCRIPTION:	Collection of quality filtered phenocamera RGB images every half an hour from 10:00 to 14:30 UTC+1. The phenocamera pointed to Mount Nuolja. The ecosystems in the images are subalpine birch forest (Betula pubescens var. czerepan) and alpine shrubland (mainly Salix spp., Empetrum nigrum, and Vaccinium vitis–idaea) in the upper slope of Mount Nuolja.

SENSOR DESCRIPTION:	Data acquired with Nikon D300s RGB phenology camera, with wide field of view (FOV) angle of 60 degrees. Images stored in JPG format.

DATA ACQUISITION:	
The original photos were acquired with phenology camera mounted on the rooftop of the observation house, at a height of 4.5 m above ground, looking west (270 degrees) and an off-nadir angle of 59 degrees. The phenocamera acquired images from 10:00 to 14:30 every half an hour. The phenocamera operates between April and November.
The area surveyed by the phenocamera projects a footprint on the ground, the centroid of which is approximately defined by the following coordinate (LAT (DD.ddddd), LON (DD.ddddd), WGS84): 68.353921, 18.789888.

The centroid of each ROI used to extract the mean values of RGB channel, and corresponding GCC-RCC is approximately defined by the following coordinate (LAT (DD.ddddd), LON (DD.ddddd), WGS84):
ROI_1: 68.354065, 18.811611
ROI_2: 68.354247, 18.790801
ROI_3: 68.344180, 18.752320

The field of view for the ROIs can be seen in the image name `SITES_ROIS_<station_name>_<platform_id>_*.jpg`. 


PROCESSING METHODS:	Data processing level 2 Green Chromatic Coordinates  (GCC) Composite Image Mean Values, daily

REFERENCES:	
    Richardson, A. D., Braswell, B. H., Hollinger, D. Y., Jenkins, J. P., & Ollinger, S. V. (2009). Near surface remote sensing of spatial and temporal variation in canopy phenology. Ecological Applications, 19(6), 1417-1428.
    Richardson, A. D., Hufkens, K., Milliman, T., Aubrecht, D. M., Chen, M., Gray, J. M., & Frolking, S. (2018). Tracking vegetation phenology across diverse North American biomes using PhenoCam imagery. Scientific data, 5(1), 1-24.
    

