Crop Yield Forecasting

The 1:1,000,000 soil map of Europe is combined with a more detailed soil map that was
available only for the agricultural zone in the northern part of Morocco. Moreover, the soil’s
hydraulic properties were estimated for the spatial units in the Moroccan soil map.
The land cover mask derived from the GlobCover 26 project is also employed. From this map,
the classes relating to arable land are derived, to calculate the percentage of arable land per
CGSM grid.
The administrative regions for Morocco, consisting of four levels, are taken into consideration;
these levels are district, province, agro-zone and entire country.
2.1.4. Meteorological data
In the CGMS-MAROC, the data collected on a daily basis through the network of 40
meteorological stations (see Figure B3.3, Annex B3.1) are used in two ways: as indicators
for weather monitoring and as inputs for the WOFOST crop growth model. The weather
monitoring component constitutes the core of the CGMS-MAROC at Level 1. This component
consists of the following steps:
• Acquisition, quality checking and processing of raw daily meteorological station data
from the DMN network;
• Computing and estimating the actual vapour pressure;
• Estimating global radiation according to the hierarchical technique (applying the
Ångström 27 and Hargreaves 28 formulas);
• Calculation of advanced parameters: reference evapotranspiration according to the
Penman-Monteith 29 formula, evaporation of water surface and evaporation of wet
bare soil; and
• Spatial interpolation to the regular Moroccan climatic grid.
Daily historical meteorological data from 1987 to 2012 are part of the climatogical database
managed by DMN, and are checked for quality and consistency. Historical time series
and current data are all inserted into a single database, which includes the parameters of
minimum and maximum temperature, rainfall, cloud cover and sunshine duration, daily mean
vapour pressure and daily global radiation at surface (as per Table 3.5 below).
26
ESA GlobCover portal: http://due.esrin.esa.int/page_globcover.php
27
The Ångström formula is R_g=R_a*(A_a+B_a*(n/L)), where R_g is the global radiation, R_a is the Angot radiation, n
represents the bright sunshine hours per day, L is the astronomical day length, and A_a and B_a are the regression
coefficients that depend on the geographical location. The Angot radiation is the amount of extraterrestrial radiation; for
its calculation, see Supit et al. (1994).
28
The Hargreaves formula is R_g=R_a*A_h*√((T_max-T_min ) )+B_h, where A_h and B_h are the regression coefficients
that depend on the geographical location.
29
The Penman-Monteith equation may be viewed at: http://www.fao.org/docrep/x0490e/x0490e06.htm
Crop Yield Forecasting: Methodological and Institutional Aspects 91