﻿TITLE: Phenocamera RGB daily average composite image collection from Röbäcksdalen, north-eastern Sweden.
SITES STATION: Röbäcksdalen Field Research Station
TIME PERIOD: 2019-03-19 2019-10-22
TIME RESOLUTION: DAILY
TIME ZONE: UTC +1 
LATITUDE: 63.809446
LONGITUDE: 20.241503
ALTITUDE: 8.5 m.a.s.l.
FILE RETRIVED 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 phenocamera RGB composite images averaged daily from quality-filtered photos from 10 a.m. to 2 p.m.
The phenocamera is pointing to an intensively managed pasture (a mix of Phleum pratense, Festuca pratensis, Trifolium repens) for high-yielding dairy cows, typically renewed every 6-8 year. The occasional year in between renewal of the pasture crop is a year with barley. In 2019 was the fourth year pasture originally seeded in 2015 as a mixture of timothy (Phleum pratense cv Grindstad), meadow fescue (Festuca pratensis, cv Kasper), Kentucky bluegrass (Poa pratensis, cv Sobra) and white clover (Trifolium repens, cv Undrom).  

SENSOR DESCRIPTION:
Data acquired with Mobotix M25 RGB phenology camera, with field of wide view angle (FOV) of 60 degrees. Photos are stored in JPG format. 

DATA ACQUISITION
The original photos were acquired with a phenology camera on a observation tower, at a height of 4 m above ground, looking north-west (305 degrees from north) and a zenith angle of  67 degrees. The phenocamera operates between April and November. It starts collecting photos at 9 a.m. and ends at 3 p.m. and takes one photo every 30 min. 
The area surveyed by the phenocamera projects a footprint on the ground defined by the following coordinates (GCS WGS84, degrees decimal): 63.809206, 20.238749; 63.810195, 20.235780; 63.810908, 20.237758; 63.810690, 20.240983; 63.809398, 20.241539.

PROCESSING METHODS:
Low quality photos were filtered from the original phenology photo collection using thresholds to the spectral signal of the photos (DN), as defined by Richardson et al., 2018. Low quality refers to photos that present sun glare, rain droplets, fog or shadows, or represent low-light or blurry conditions.
For phenology purposes, all photos from 10 a.m. to 2 p.m. were averaged per band (RGB) and pixel, daily. 

REFERENCES 
Richardson, Andrew D., Koen Hufkens, Tom Milliman, Donald M. Aubrecht, Min Chen, Josh M. Gray, Miriam R. Johnston et al. "Tracking vegetation phenology across diverse North American biomes using PhenoCam imagery." Scientific data 5 (2018): 180028.






