﻿TITLE: Phenocamera RGB daily average composite image collection from SAFE-A, southern Sweden.
SITES STATION: Lönnstorp Research Station
TIME PERIOD: 2018-03-21 2018-12-31
TIME RESOLUTION: DAILY
TIME ZONE: UTC +1 
LATITUDE: 55.668516
LONGITUDE: 13.110039
ALTITUDE: 295 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 several plots of experimental arable land, covering three different cropping systems. On the upper side of the scene there is an 8-years organic rotation cropping system with 4 crops. In summer 2018, the crops presents are, from left to right of the image, grass legume ley (harvested in June 25th), Faba bean and Spring wheat (between 2018-04-13 and 2018-08-08), winter wheat/ ley (between 2017-09-28 and 2018-07-25), and spring barley/lupine (between 2018-04-21 and 2018-08-08).
In winter 2018, the crops presents are, from left to right of the image, bare soil, winter oilseed rape (harvested in 2018-08-22), grass legume ley (between 2018-05-09 and 2018-09-05) and winter rye (since 2018-09-10). 
In the foreground there is a perennial intermediate system (Intermediate wheat grass, Medicago sativa) that is disregarded as it can be fully observed in P03.

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 10 m above ground, looking north (12 degrees) and a zenith angle of 80 degrees. On March 10th 2019, there was a change in the camera configuration, in terms of time of acquisition, frequency and photo dimensions. Before that date, the phenocamera collected photos from 6 a.m. to 7 p.m. and took one photo per hour. After that date, the phenocamera was configured to take photos from 9 a.m. to 3 p.m. every 30 min. The phenocamera operates all year long. 
The area surveyed by the phenocamera projects a footprint on the ground defined by the following coordinates (GCS WGS84, degrees decimal): 55.669087, 13.111021; 55.673181, 13.113648; 55.673471, 13.106613; 55.669342, 13.106882; 55.668106, 13.108658.

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.






