﻿TITLE: Phenocamera RCC daily average composite images collection from Skogaryd Stordalen, western Sweden.
SITES STATION: Skogaryd Research Catchment
TIME PERIOD: 2018
TIME RESOLUTION: DAILY
TIME ZONE: UTC +1 
LATITUDE: 58.381376
LONGITUDE: 12.146191
ALTITUDE: 80.7 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 a clearcut of a young coniferous forest dominated by spruce trees. The spruce were cut on 2010 and replanted on 2011. In the images, some spruce saplings are visible in year 2015 and only after 2016 a spruce forest can be seen. Since 2013, a secondary species, birch (Betula pendula), is dominating the scene, especially when the leaves are on. A partial clearing of the birch was conducted on 2018. During fall and winter, when the birch drops the leaves, the spruce can be seen in the lower canopy of the forest.

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 a phenology cameras on a observation tower, at a height of 5.9 m above ground, looking south-west (250 degrees from north) and a zenith angle of 60 degrees. 
The phenocamera operates all year long. It starts collecting photos at 5 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 the following coordinates: 58.381278, 12.145964; 58.380055, 12.143313; 58.380081, 12.142461; 58.380296, 12.141789; 58.380789, 12.141731; 58.381056, 12.142774.  

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 + DN blue) (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.








