32 D. Rijks, M.W. Baradas Agricultural and Forest Meteorology 103 2000 27–42
decision making processes. Among the subjects that command more and more attention by these clients is
the use of meteorological information to promote the efficiency of the use of water and energy, the reduction
of pollution and the conservation of the environment. Some further examples are:
•
Weather forecasts following food situation assess- ments made with real-time data, to help determine
the food security outlook; •
Information for the monitoring, and possible fore- cast, of floods and droughts and for the alleviation
of their effects; •
Monitoring of desertification, avoidance of over- grazing, salinization, wind- and water-erosion;
• Information for wildlife conservation and manage-
ment. 3.4. Methods, techniques, software packages for
specific applications For clients that wish to operate their own daily in-
formation service, agrometeorological services may be asked to provide tested software packages or parts
thereof, such as those for the calculation of the water balance, for the monitoring and control of some pests
and diseases, or for crop growth monitoring. Another much-demanded product is a reference data bank for
comparing actual data with the mean, with those of the last year or those of any other period.
4. Some products that an agrometeorological service can offer
4.1. Products available Meteorological services offer a series of products,
ranging from basic data observed at a worldwide homogeneous network of stations, using a com-
mon methodology, through elementary-derived data, composite-derived data, to meteorological forecasts
and client-specific products. A characteristic of many of these products is that they are often rather el-
ementary, but usually quality-controlled, and that they can serve in the way they are made available,
often without further transformation or adaptation. Meteorological Services can also offer a number of
well-proven methods, techniques, software packages and expertise in data analysis and product develop-
ment see Section 3.4. Finally, meteorological ser- vices are often a partner of the agricultural services
in the development, description and use of the rela- tions between meteorological regimes and agricultural
phenomena.
4.2. Basic data The products offered include those obtained from
INFOCLIMA, an inventory of available meteorologi- cal and associated data, and CLICOM, a widely used
harmonised system for meteorological data manage- ment.
Past basic data can be obtained from CLICOM or another national data bank, and when necessary ba-
sic data can be delivered to clients fairly easily and soon after the moment of observation through the GTS
Global Telcommunication System. Other basic data are obtained from automatic stations or interpreted
from remotely sensed observations, either for their point value, their areal extent, or both.
The basic meteorological data most often used in agrometeorology are observations of rainfall, sun-
shine, solar radiation, temperature of the air, and sometimes of the soil and rarely of the water near its
surface, humidity, and wind speed and direction.
These basic data are derived from point observa- tions, but not always without certain omissions in the
time series. Packages are available that provide sub- stitute values for missing observations e.g. Meteo-
consult, 1991, other packages can provide area-wide estimates based on consideration of a number of
point-values e.g. van der Voet et al., 1993, and oth- ers again provide values of one missing parameter
by deduction from observations of other parameters Rijks et al., 1998, and especially the annexes 1–14 by
Augter, Choisnel, Gommes, Hough, Keane, LeMeur, Mata Reis, Oliveira, Parker, Seguin and Wendling.
Other basic data concern the observations on the occurrence of hail, lightning and other difficult-to-
quantify phenomena that may nevertheless have an impact on agriculture or forestry.
4.3. Derived data Among the packages available, tested, user-friendly
and rather widely used for transforming these ba-
D. Rijks, M.W. Baradas Agricultural and Forest Meteorology 103 2000 27–42 33
sic, hourly, three-hourly or daily observations, into ‘values’ of parameters that are more commonly
used in agrometeorology, is the INSTAT INteractive STATistics package, developed by Stern and Knock
1998 at the University of Reading. It can give totals and means over various timespans e.g. the maximum
and minimum values of temperature, humidity, wind speed, sunshine hours, solar radiation and rainfall,
calculated over the timespan desired by the client. It can also give distributions, extreme values, prob-
abilities of occurrence at certain thresholds, and of combinations of values of different parameters such
as low humidity and high windspeed, etc..
Much used among these derived data are the values of rainfall distribution and probability, the probabil-
ity of the beginning and the end of the rains, the probability of receipt of quantified rainfall amounts
in a specified period, or of rain after a moment dur- ing the season when a certain amount has already
been received. Further parameters are the values of potential evapotranspiration, stress degree days,
and duration of canopy wetness and curves for the amount-intensity-duration of rainfall.
Many derived parameters rely on inputs from dis- ciplines other than meteorology, such as soil science,
plantcrop physiology or agronomy. Among these, the water balance is perhaps the most frequently calcu-
lated. Other examples are: •
the probability of obtaining the optimal length of the growing season for a crop with specified growth
characteristics; •
the risk of the occurrence of drought or dry spells at the beginning, in the middle or at the end of the
season; •
the optimal timing for certain agricultural opera- tions; and
• the assessment of the need to have available alter-
native options, such as the choice of other varieties or crops.
Consideration of some of these may give rise to
alerts, warnings or alarms Keane et al., 1998. Special mention should be made of the practical
uses of the water balance information in the planning, implementation, monitoring and forecasting aspects of
agriculture. It is an essential tool in planning virtually all components of agricultural, lifestock and forestry
production systems, including the manner of use of the other inputs, land-use, genetic material, energy in
all its forms, management and economic and social as- pects and results. As regards implementation, it is used
in scheduling soil preparation, sowing, weeding, thin- ning, ridging, fertilizer and pest and disease control
measures, harvesting and drying. Efficiency of irriga- tion is fully dependent on the knowledge of the water
balance and the outlook for its evolution. The water balance is one of the most ‘decisive’ components in a
crop monitoring and yield forecasting system. Water balance information is used in the management of the
food and water supply for livestock, animal health protection, and the transhumance. It is an essential
tool in watershed and forestry management.
4.4. Agrometeorological surveys and characterization
A number of such surveys has been completed in the 1960s and 1970s, mostly by the joint efforts of
FAO, Unesco, WMO and later UNEP. These surveys were general assessments used for understanding the
agrometeorology of regions where agricultural devel- opment was foreseen. They still retain this general
value, but for practical planning purposes they were later complemented by agrometeorological classifica-
tions FAO, 1978 or characterizations Rijks, 1994, and they can be further refined using computer-based,
remote sensing assisted, analyses, and such as those possible with the INSTAT package.
4.5. Forecasts There are two types of forecasts used in agromete-
orological applications Rijks, 1978: •
purely meteorological forecasts of expected weather and its consequences on agriculture; and
• forecasts of the agrometeorological and agricultural
consequences of observed weather. They are very often used in conjunction.
Forecasts of the first type are obtained from the fore-
cast unit of the meteorological service. Its interpreta- tion is normally the work of an agrometeorologist,
or better, of a pluridisciplinary agro-meteorological group. In some cases, such as the Agromet on-line
individual advisory products in Germany Dommer- muth, 1999, these forecasts are regularly updated and
contain specific agrometeorological prognosis data, and even advisories on hail derived from remotely
34 D. Rijks, M.W. Baradas Agricultural and Forest Meteorology 103 2000 27–42
sensed data. Das 1999 mentions a growing interest in the issue of seasonal forecasts. Currently most skill in
seasonal forecasting is achieved in the tropics and sub- tropics and is especially high in El Nino years Ogallo
et al., 2000. In France, farmers can obtain forecasts that help them to practice ‘precision farming’ Perar-
naud and Hamelin, 1999.
Forecasts of the second type emanate usually from an interdisciplinary team, including a meteorologist,
an agronomist, a lifestock husbandry specialist, a plantanimal health officer, a communications spe-
cialist, a representative of the research community and perhaps others.
The forecast product delivered to the clients may consist of information for scheduling day-to-day agri-
cultural operations Baradas, 1982, 1984, 1985 often after consideration of the ongoing agricultural season,
in the light of known results of earlier research. It can also serve to formulate alerts, warnings and alarms on
a technical, social or economic level. Plant protection services e.g. for desert locust control and crop mon-
itoring and yield forecast teams provide further exam- ples of interdisciplinary cooperation to use forecasts.
4.6. Remotely-sensed data Among the meteorological products of remotely-
sensed data are: •
the assessments of components of the radiation regime with or without reference to the underlying
surfaces; •
the surface temperature and by deduction some estimate of the air temperature near the surface;
• wind and airmass movement;
• estimates of the time and areal extent of the occur-
rence of rainfall, drought, flooding, and of frosts. Such information is rarely provided as a finished
product to the clients. Often it is used to complement the purely meteorological products, or delivered in
combination with other remotely-sensed products, such as information on soil wetness, land or vege-
tation cover NDVI, likely presence of pests andor diseases, estimates of the areal coverage of irrigated
or flood-retreat crops, incidence of bush fires, etc. By the nature of their capacity to indicate the probable
areal extent of a condition, and of the still very rapid evolution of the parameters that can be measured
or derived, remotely-sensed data and their derived products will be a growing resource for the supply of
agrometeorological products to clients.
4.7. Results of research Most agrometeorological research is done in an in-
terdisciplinary context. Results can be made available to users in all concerned disciplines. Agrometeorolog-
ical services can take an active role in this dissimi- nation and in the promotion of the use of these re-
sults. Some examples are the results of studies of the relationships of water shortage on crop performance,
pest and disease incidence on crops and animals, rela- tions between meteorology and the ‘performance’ of
the agro-environment.
5. How to approach the client
