NOAA’s environmental satellites, widely known for their role in weather forecasting,
were recently hailed by countries around the world for providing
early warning of drought. Satellite-based information from NOAA provides drought warnings
four to six weeks earlier than ground-based data, NOAA reported
today.

Returning from a recent meeting of the
World Meteorological Organization,
Felix Kogan, of NOAA’s National Environmental Satellite, Data,
and Information Service, reported
that NOAA’s satellite-based system is the only global system
available that can provide such early warnings. Kogan was one
of 25 world experts from 12 countries who assessed the current
status of drought early warning systems at the WMO meeting in
Lisbon.

"Many countries around the world depend
on data from NOAA’s environmental satellites to provide estimates
of drought onset, dynamics, intensity, and geographic areas affected,"
Kogan said. "NOAA provides images outlining vegetation
stress and makes estimates of the percent of a country affected
by droughts of different severity. In addition, we make comparative
analyses of the time the drought started, and the intensity and
speed at which it develops."

After a relatively quite year in 1999,
the year 2000 has seen a series of extreme droughts. The country
of Georgia, a former republic of the U.S.S.R. and now a member
of the Commonwealth of Independent States, which produces excellent
varieties of grapes for wine-making and produces grains and vegetables,
was hit by an unusually intensive drought. "Considering
the severity of the disaster and a lack of infrastructure, the
government of Georgia
asked NOAA to estimate the drought consequences," Kogan
said.

In addition to Georgia, Northern
America, sub-Sahara
Africa, southeastern and central Asia
were among the regions of the world most seriously affected.
Severe vegetation stress has been persisting since spring around
and south of the Caspian Sea, western India, most of Mongolia,
and adjacent areas of China.
In the Horn of Africa, nearly 15 million people were affected
from unusual drought which resulted in crop failures earlier
this year in Ethiopia. Nearly 60 percent of Kenya was affected
by extreme drought, the largest area since 1991. Afghanistan
and Pakistan had severe vegetation stress due to lack of precipitation
and excessive heat since mid-February. In the United States,
in addition to crop and pasture failures in the southeastern
and central states, drought caused large areas of intensive fires
in the northwest.

Poland and Morocco both requested NOAA’s
help in providing digital data on vegetation health in order
to estimate possible crop losses. During Kogan’s visit to China
in May 2000, officials in the province of Jillin (eastern China)
requested NOAA’s assistance in estimating the areas under drought,
the intensity and duration, which were provided several times
during the growing season. Digital data were also sent to Kazakhstan;
drought estimates were provided to Tajikistan.

"The NOAA/NESDIS drought product became
popular worldwide because of its exceptional quality, real-time
availability, and ease of use," said Kogan. "The success
came after scientists from NOAA cooperated with world researchers
and users in testing and calibrating the product comprehensively
against ground data."

The product is based on the normalized
difference vegetation index (NDVI) developed by NASA in the late
1970s. The NDVI
became a popular tool in many countries for analysis of vegetation
distribution and conditions. As time progressed, and the technology
and the science became more sophisticated, it became evident
that NDVI alone was not sufficient for early drought detection
and assessment of the impacts because ambient temperature played
an important role. Therefore, in the late 1980s NOAA/NESDIS scientists
improved drought detection and monitoring techniques adding thermal
information from the radiances measured by an instrument known
as the AVHRR on NOAA’s polar-orbiting satellites.

"Compared to other techniques, the
new method permitted us to identify drought up to six weeks earlier,
delineate areas more accurately, and provide numerical estimates
of the impacts on environment, agriculture, forestry and human
health. In the past six years, the new method of early drought
detection and watch was used globally to make some important
decisions. In Poland, this method has been used since 1997 for
assessment of drought impacts on crop condition and estimating
crop production. During an intensive 1998 drought in Mexico,
this method was used by the government for making important decisions
on implementing an alternative crop program.

More information on the NOAA/NESDIS drought
product is online at:
http://orbit-net.nesdis.noaa.gov/crad/sat/surf/vci/index.html