TABLE 1.
Data source | Raw data | Model input variables | Variable name | Pearson correlation |
Grower data | ||||
Yield records from 8 major almond growers in the Central Valley of California. | Planting year Historical yield Cultivar variety and composition |
Age Previous two years’ yield Cultivar percentage |
Age Pre 2Y Yld, Pre 1Y Yld CulP 1, …., CulP 20 |
−0.16* 0.53*, 0.53* −0.27∼0.25 |
Weather data | ||||
CA-BCM data with 270 m spatial resolution for years 1990–20161; | Monthly mean daily maximum temperature (Tmax); Monthly mean daily minimum temperature (Tmin); Monthly accumulative precipitation (PPT) |
Current year monthly Tmax and Tmin from January to June2, and PPT from January to March | Tmin, Tmax, PPT January Tmin, Tmax, PPT February Tmin, Tmax, PPT March Tmin, Tmax April Tmin, Tmax May Tmin, Tmax June |
−0.06*, −0.06, −0.22* −0.17*, 0.17*, −0.27* 0.05*, 0.21*, −0.30* 0.25*, 0.30* 0.17*, 0.12* 0.17*, 0.21* |
Previous year summer mean temperature averaged over July and August | Pre Tmean July–August | 0.36* | ||
Long-term mean seasonal Tmax, Tmin, PPT (averaged over 1990–2009 for each season3). | LT Tmin, Tmax, PPT January–March LT Tmin, Tmax, PPT April–June LT Tmin, Tmax, PPT July–September LT Tmin, Tmax, PPT October–December |
0.26*, 0.50*, −0.58* 0.43*, 0.60*, −0.61* 0.38*, 0.49*, −0.57* −0.31*, 0.51*, −0.58* |
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CIMIS station data for years 2009–2017 | Hourly temperature | Winter chilling portions calculated by the Dynamic Model | ChillP | −0.14* |
Remote sensing imagery | ||||
NAIP aerial imagery from 2016 with 0.6m resolution | NAIP RGB imagery acquired in 2016 | 2016 canopy cover percentage | CCP | 0.20* |
Landsat satellite imagery with 30 m resolution years 2009–2017 | Landsat multispectral imagery every 16 days | Previous year annual maximum NDVI and EVI; Current year June average EVI |
Pre Max NDVI Pre Max EVI June Mean EVI |
0.13* 0.31* 0.35* |
12017 Tmax, Tmin and PPT were collected from the original PRISM data archive. 2Variables used only for mid-season prediction models were shown in Italic. 3The four seasons are separated as (1) January–March, (2) April–June, (3) July–September, (4) October–December. *Represents for p < 0.05.