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STAR - Global Vegetation Health Products : El Nino

El Nino is one part of a multi-year cycle of the interaction between the ocean and atmosphere. The second part is called La Nina. A typical characteristic of this cycle is emergence of a huge mass of warm water in the central and eastern Pacific during El Nino and cold during La Nina years. These shifts between warm and cold cycles occurs irregularly every three to five years and affects the environment of different areas around the world on a variety of time scales. One of the areas is Southern Africa, where during El Nino years, rainfall reduces considerably leading to drought and severe vegetation stress while in La Nina year the effect is opposite.

El Nino Implications for Land Ecosystems

Typical Vegetation Condition in historical perspective
Focus on South Africa

Vegetation and Temperature Condition Index, Southern Africa,

Dynamics in the Corn Area of the Republic of South Africa

These time series produced from two-year average of VT for each event. The data were received from NOAA-9, NOAA-11 and NOAA-14 polar orbiting spacecraft. The values of VT for stressful conditions are below 35, for fair 36-65, and for favorable above 65.

The typical features of vegetation:

Identical conditions before December
Deterioration of conditions in El Nino and improvement in La Nina years from January.
Severe vegetation stress in El Nino years during the main part of the growing season (January-April)

Vegetation Condition (VT-index), Last Week in January

map and chart Vegetation and Temperature Condition Index, Southern Africa

The typical patterns of vegetation condition are severe drought-related vegetation stress in El Nino and favorable conditions in La Nina years. The most productive agriculturla areas of Botswana, Zimbabwe, Lesotho, Republic of South Africa and Mozambique have severe vegetation stress in El Nino years during the most critical period of the growing season.

Click here to download a sample AVI animation of weekly VT index images from first week in October through the last week in April of the following year. VT Index is an average for the two most recent El Nino and La Nina years.

STAR VCI Pages by Felix Kogan and David Forsyth.
For information, contact Felix.Kogan@noaa.gov

Latest Revision: February 28, 2001