Weather Glossary

AVERAGE, MAXIMUM AND MINIMUM TEMPERATURE

Lowest, highest and average temperature (C°) recorded during the period considered. 

AVERAGE DAILY TEMPERATURE

Average temperature (⁰C) for the period considered calculated on a daily (24 hour) basis. Weather maps in the MARS Explorer display actual values as well differences with the long term average (LTA) since 1991.

CLIMATIC WATER BALANCE

Difference (mm) between total rainfall and potential evapotranspiration over the period considered, as compared to the long term average (LTA) since 1991. Negative values indicate areas which are drier than usual (i.e. with a smaller surplus or greater deficit than usual). Positive values indicate areas which are wetter (or less dry) than usual (i.e. with a greater surplus or smaller deficit than usual).

MAXIMUM DAILY TEMPERATURE

Highest temperature (⁰C) recorded during the period considered.

MINIMUM DAILY TEMPERATURE

Lowest temperature (⁰C) recorded during the period considered.

NUMBER OF COLD DAYS

Number of days with minimum temperature below a threshold value of 0⁰C during the period considered. Weather maps in the MARS Explorer display actual values as well as differences with the long term average (LTA) since 1991.

NUMBER OF DAYS WITH SIGNIFICANT RAINFALL

Number of days with precipitation above a threshold value of 5 mm during the period considered. Weather maps in the MARS Explorer display actual values as well as differences with the long term average (LTA) since 1991.

NUMBER OF HOT DAYS

Number of days with maximum temperature above a threshold value of 30⁰C during the period considered. Weather maps in the MARS Explorer display actual values as well differences with the long term average (LTA) since 1991.

RAINFALL

Total amount of precipitation (expressed as mm rainfall equivalents) during the period considered. Weather maps in the MARS Explorer display actual values as well differences with the long term average (LTA) since 1991.

TEMPERATURE SUM

Sum of active temperatures over the period considered. Active temperature is defined here as the daily average temperature in excess of a base temperature of 0 ⁰C, as often used for temperate cereals. For example, the temperature sum for a three day period with average temperatures of respectively -5, +5 and 10 ⁰C is 0 + 5 + 10 = 15 ⁰Cd. Weather maps in the MARS Explorer display the temperature sums as actual values as well as % differences with the long term average (LTA) since 1991.

Fruit Glossary

Crop Glossary

CROP DEVELOPMENT STAGE

Advancement of phenological development. On maps, crop development is expressed in descriptive terms (e.g. emergence, tillering, heading, flowering, grain filling, ripening, maturity for cereals). On graphs, crop development is expressed numerically on a range from 0 to 200, where 0 represents emergence, 100 marks the start of yield formation (full anthesis for cereals) and 200 represents the end of yield formation (i.e. physiological maturity).

LONGEST HEAT WAVE AROUND FLOWERING

Duration (d) of the longest period of consecutive days with maximum temperature > 30⁰C during a 31 day period starting 15 days before the calculated date of full flowering (anthesis).

PRECOCITY

Advancement of crop development as compared to the long term average (LTA) since 1991.

RAINFALL AROUND FLOWERING

Total amount of precipitation (mm) during a 31 day period, starting 15 days before the calculated date of full flowering (anthesis). Crop maps in the MARS Explorer display actual values as well % differences with the long term average (LTA) since 1991.

RAINFALL AROUND HARVESTING

Total amount of precipitation (mm) during a 31 day period, starting 15 days before the calculated date of harvest maturity. Crop maps in the MARS Explorer display actual values as well % differences with the long term average (LTA) since 1991.

RAINFALL AROUND SOWING

Total amount of precipitation (mm) during a 31 day period, starting 15 days before the estimated average sowing date.

RELATIVE SOIL MOISTURE

Soil moisture content in relation to plant available water capacity expressed on a scale from 0 (water available to plants) to 100 (soil water content at drained upper limit). Crop maps in the MARS Explorer display actual values as well % differences with the long term average (LTA) since 1991.

Remote Sensing Glossary

fAPAR (smoothed)

fAPAR is the Fraction of Absorbed Photosynthetically Active Radiation of the incoming solar radiation that is absorbed by a crop plant for photosynthetic activity.  It is an important variable in both plant biomass production and plant growth modelling and can be derived from remote sensing observations. fAPAR is defined by the Global Climate Observing System (GCOS) as one of the 50 Essential Climate Variables.

The satellite-derived fAPAR depends, apart from the crop canopy characteristics, on other factors such as atmospheric conditions and the geometry of observations and angular configuration. An interpolation and smoothing procedure is applied to reduce the noise and to assure a better interpretability of the time-series.