2. 2 Data Sources
The meteorological data that are necessary to drive CLM5 including
precipitation, air temperature, atmospheric pressure, wind speed,
relative humidity, and incoming solar radiation, were acquired from
three meteorological stations located at different altitudes within the
PHO (Figure 1) as well as two stations located in the orchards S09 and
S10. For the agricultural plain, detailed soil texture and organic
matter information was collected during an extensive soil sampling
campaign. In total, 116 locations were sampled with one sample from the
topsoil (0-50 cm) and a second sample from the subsoil (50-100 cm)
(Figure 2). In addition to the point measurements, the LUCAS topsoil
physical properties for Europe soil map [Ballabio et al. ,
2016] and the European Soil Database (ESDB) derived data product
[Hiederer , 2013] provide soil information for the area at a
resolution of 500x500 and 1000x1000 m, respectively (Table 2). These
data sources were combined to create soil texture (point
measurements+LUCAS) and soil organic carbon (point measurements+ESDB)
maps for model input (Figure 2). In a first step, for the unsampled
regions, data points were extracted from the map products in a sampling
density equal to the average density of the soil sampling locations
(~580x580 m). Next, the extracted points were combined
with the sampled points to a single set of data points (Figure 2). Then,
the points were interpolated to the target resolution of 100x100 m using
ordinary kriging and a spherical variogram model with a radius that
included 30 measurements around an estimation point. Topographic
information was available through the European Digital Elevation Model
(EU-DEM) [Copernicus , 2016], version 1.1 at a spatial
resolution of 25x25 m (Figure 1). Detailed maps of the agricultural
fields and orchards were provided by the Hellenic Payment and Control
Agency for Guidance and Guarantee Community Aid while the land use of
the remaining area was digitized from satellite imagery, using
ArcGIS® software by Esri (Figure 1).
Orchard scale SM data were retrieved from S09 and S10, which were
equipped for extensive monitoring in September 2020 (Figure 1). SM was
monitored via a SoilNet wireless sensor network [Bogena et al. ,
2010; Bogena et al. , 2022] with 12 nodes per orchard. Each node
had six SMT100 SM sensors (Truebner GmbH, Neustadt, Germany) divided
into two separate profiles which were installed at 5, 20, and 50 cm
depth as well as two TEROS21 soil matric potential (SMP) sensors (METER
Group Inc., Pullman, USA) installed at 20 cm depth. Irrigation amounts
were recorded with TW-N flowmeters (TECNIDRO, Genova, Italy), installed
at different irrigation sectors within the orchards. Meteorological data
was collected by the cost-effective but reliable all-in-one Atmos41
weather station (METER Group Inc., Pullman, USA) installed above the
canopy in each orchard [O. Dombrowski et al. , 2021]. A more
detailed description of the instrumentation and setup used to monitor SM
dynamics, irrigation, and meteorological variables is given inBrogi et al. [2023]. Additionally, S10 was equipped with six
SFM-1 sapflow sensors (ICT International Pty Ltd, Armidale, Australia)
to estimate whole-tree transpiration. The sapflow sensors were installed
on the trunk of six trees to represent, as much as possible, the
orchards’ trees in terms of height, perimeter, and vigor covering all
five varieties. The installation and data correction followed the
procedure outlined in Burgess [2018]. Phenology of the three
main apple varieties was monitored using six phenocams (SnapShot Cloud
4G, Dörr GmbH, Germany) installed in S10.
Table 2: Main characteristics of
the different soil data products used for the surface file creation of
the regional case.