Filter by category

Filter by first letter

All | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

xxx terms

Agroclimatology

A field in the interdisciplinary science of agrometeorology, in which principles of climatology are applied to agricultural production systems. Its origins relate to the foremost role that climate plays in plant and animal production.

Agroecology

The study of agricultural ecosystems and their components as they function within themselves and in the context of the landscapes that contain them.

Anomaly

Something that deviates from what is standard, normal, or expected. There are different types of anomalies:

Difference from average: This is the actual observation minus the long-term average. Difference from average is useful for quantifying deficits and surpluses in the same units as the original observation. 0 = no difference; positive means above average; negative means below average.
Percent of average: This is the actual observation divided by the long-term average, and multiplied by 100 (to convert to percent). Percent of average is useful for quantifying deficits and surpluses in a relative manner. 100 = same as average; >100 means above average, <100 means below average.
Standardized anomaly: This is the difference from average divided by the standard deviation. Seasonal forecast maps may present the standardized anomaly. The Standardized Precipitation Index (SPI, a commonly used drought measure) uses a standardized anomaly.

Atmospheric Circulation

The flow, or movement, of a fluid (e.g., liquid or gas) in or through a given area or volume.

Climate

Average weather over a long period of time: the composite or generally prevailing weather conditions of a region, throughout the year, averaged over a series of years.

Climate Mode

A description of one aspect of the way Earth’s climate behaves. Identifiable characteristics include variations in temperature, precipitation, and wind speed/direction. An example of a climate mode is the El Niño Southern Oscillation (ENSO).

Climatology

The study of climate, scientifically defined as weather conditions averaged over a long period of time. However, when we say we expect climatology in terms of forecasts, these are not simply average conditions, but include the range of variability in rainfall quantity, spatial distribution, and temporal distribution that are historically possible for a region.

Corn/Maize

Maize is the plant and corn is the kernel or grain, but corn can refer to kernels of different plants, not just maize. In some countries, including North America, maize and corn are used interchangeably, but this is not the case in most parts of the world. In general, we use maize when referring to the crop.

Crop Phrenology

Crop phenology is the study of periodic plant lifecycle events and how these are influenced by seasonal and interannual variations in climate, as well as habitat factors (such as elevation).

Crop Tours

A tool used to assess conditions in designated areas to help gauge the impact on food security and strengthen FEWS NET assumptions about the upcoming seasons.

Dipole

Two opposing patterns in space.

Drought

A drought is a period of below-average precipitation in a given region, resulting in prolonged shortages in the water supply, whether atmospheric, surface water or ground water. This document, however, makes a distinction between a single failed rainy season and consecutive failed rainy seasons; the latter is referred to as a drought.

Dynamical Forecasts

Dynamical models use laws of physics and observed conditions to estimate future conditions.

Ensemble Forecast

An ensemble forecast is either a collection of model runs (using the same model) started from slightly different initial conditions, or a collection of model runs using different models. This tests the strength of forecasts; if ensembles give similar results (a convergence of evidence), then we have confidence in the forecast.

Forecast Skill

Skill is measured by calculating the difference between a model forecast and observed conditions. An acceptable threshold of skill is chosen by a person responsible for running a model. The threshold for skill is subjective. Model runs exceeding the defined threshold of skill are considered to have skill and are therefore reliable for predicting the climate.

Groundnuts

A variety of legumes that produce seeds on the ground. Peanuts are a type of groundnut.

Indian Ocean Dipole (IOD)

An irregular oscillation of sea surface temperatures and related atmospheric circulation in the Indian Ocean.

Inter-Tropical Convergenze Zone (ITCZ)

The point at which air from both hemispheres comes together. When air comes together at the ITCZ, it is forced to rise, which results in clouds and precipitation. The ITCZ moves north and south with the seasons, and is the primary cause of weather/climate and rainfall over the tropics.

Inter-Tropical Front (ITF)

The leading edge of the ITCZ. The rainfall associated with the ITCZ is always equator-ward of the ITF.

Long-cycle Crops

Crops that mature in greater than 90 days, such as sorghum and corn.

Meridional

In meteorology, a flow, average, or functional variation taken in a direction that is parallel to a line of longitude, along a meridian, northerly or southerly.

Monsoon

A thermally driven wind arising from differential heating between a land mass and the adjacent ocean that reverses its direction seasonally.

Oscillation

In meteorology, oscillation is a shift in the position of high and low pressure systems, usually in the same place. These are often described using an index (often a single number that represents the distribution of temperature and pressure over a wide area, usually over the oceans, such as the El Niño-Southern Oscillation, North Atlantic Oscillation, or Pacific Decadal Oscillation).

Agroclimatology Terms