﻿TITLE: Phenocamera RCC daily average composite image collection from Skogaryd Central, western Sweden.
SITES STATION: Skogaryd Research Catchment
TIME PERIOD: 2019
TIME RESOLUTION: DAILY
TIME ZONE: UTC +1 
LATITUDE: 58.363596
LONGITUDE: 12.149933
ALTITUDE: 81.5 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: Spectral Vegetation Index (fraction)

DESCRIPTION: 
Collection of phenocamera Red Chromatic Coordinate index (RCC) daily composite images, calculated from daily average RGB composites, from quality-filtered photos between 10 a.m. and 2 p.m.
The phenocamera is pointing to an opening in the mature spruce forest with a few species of grasses and herbaceous plants, among others, wood horsetail (Equisetum sylvaticum), creeping bentgrass (Agrostis stolonifera) and common wood sorrel (Oxalis acetosella), on a floor of glittering wood moss (Hylocomium splendens) with some Polytrichum spp and red-stemmed feathermoss (Pleurozium schreberi).

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

DATA ACQUISITION
The original photos were acquired with phenology cameras on a observation tower, at a height of 3 m above ground, looking to west (270 degrees from north) and a zenith angle of 42 degrees. The phenocamera operates between April and October. It starts collecting photos at 4 a.m. and ends at 8 p.m. and takes one photo every hour.
The area surveyed by the phenocamera projects a footprint on the ground defined by an ellipse with a central coordinate (GCS WGS84, degrees decimal): 58.363552N, 12.149788E. The ellipse has a major diameter of 9 m (in east-west direction) and a minor diameter of 6 m (in north-south direction).  

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. RCC composites were calculated from RGB daily averages.  
RCC is defined as: DNred / (DNred + DNgreen + DNblue) (Richardson et al., 2009)

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.

Richardson, Andrew D., Bobby H. Braswell, David Y. Hollinger, Julian P. Jenkins, and Scott V. Ollinger. "Near‐surface remote sensing of spatial and temporal variation in canopy phenology." Ecological Applications 19, no. 6 (2009): 1417-1428.








