Agriculture Reference
In-Depth Information
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Table 6.1 Coefficient used for algorithm development for various vegetation indices
Normalized difference vegetation index
Brightness temperature
Pa
rameters
May
June
July
August
May
June
July
August
Raw
0.60
0.22
0.45
0.39
35.3
9.9
31.7
15.4
Smooth
0.39
0.41
0.44
0.45
27.8
28.5
29.3
26.7
Max
0.42
0.44
0.45
0.47
31.0
31.3
31.7
31.1
Min
0.31
0.32
0.34
0.35
27.0
27.5
27.8
26.4
V(T)CI
73
75
91
83
80
74
62
94
VT
77
74
76
88
indicating good vegetation health. In contrast, during drought years, these
in
dices will be
<
40, indicating vegetation stress.
[82],
Monitoring Major Droughts
Line
——
0.3
——
Long
PgEn
U
nited States
The United States is the world largest producer and leading exporter of
agricultural products, including grains. Drought occurs almost every year
somewhere in the nation, affecting agriculture (see chapter 9). Severe
droughts occurred in the United States in 1988, 1989, 1996, and 2000.
The 1988 drought cost around $40 billion in damages to the U.S. economy
in human health, environment, and wildlife. Grain production fell below
domestic consumption probably for the first time in the second half of last
century (Reibsame et al., 1990; Kogan, 1995). AVHRR-based estimates
show that by the end of June 1988, vegetation experienced stress in the
most productive areas of the Great Plains, the U.S. grain basket (figure
6.1). Total world grain production in 1988 dropped by 3% (FAO, 2000).
Drought in 1989 and 1996 began early and by the end of April affected
the primary winter wheat areas. Compared to earlier droughts, the 1988
vegetation stress (black color in figure 6.1) was not seen so early. By July
the 1988 drought turned into a national disaster, affecting vegetation dur-
ing the most critical mid-season period. The crop yield anomalies during
the years of major droughts are well related to vegetation health indices
(Kogan, 1995, 1997, 2000).
[82],
Fo
rmer Soviet Union
If the United States is the largest seller of grains, the former Soviet Union
(FSU) has been and will likely be the largest U.S. grain buyer. Since the
breakup of the USSR in 1991, stagnation in technology-related grain
growth in combination with frequent droughts led to serious grain short-
ages. Therefore, monitoring of the FSU grain production is very important
for U.S. grain growers and traders.
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