Geoscience Reference
In-Depth Information
Table 2.
Annual total precipitation (mm) in Regions 1 and 2 from 1998 to 2004.
2004
1998
1999
2000
2001
2002
2003
(Jan.-Sep.)
Region 1
82.0
80.9
54.4
44.8
58.7
58.5
35.8
Region 2
435.5
285.5
275.4
265.1
289.0
374.4
312.7
(a) Region 1
0.08
0.06
0.04
0.02
0.00
-0.02
21 Year average
Monthly VI
-0.04
-0.06
-0.08
1998
1999
2000
2001
YEAR
(b) Region 2
0.5
0.4
0.3
0.2
0.1
21 Year average
Monthly VI
0.0
-0.1
1998
1999
2000
2001
YEAR
Fig. 3. The time series of monthly mean AVHRR Vegetation index ( ) averaged in
(a) Region 1 and (b) Region 2 with the averaged value for the period of 1998-2001 (
).
in both Regions, especially in 2001 when the precipitation was a minimum.
Since the data are available up to September 2001 only, the vegetation
index during the vegetation recovery period of 2003 and 2004 is not shown
in Fig. 3.
The above analysis clearly indicates that surface conditions in the Asian
dust source regions have changed significantly after 2002, especially in the
northeastern part of China, where the grassland is regenerating thereby
reducing raised dust. To consider this in the ADAM model, the emission
reduction factor in the ADAM model has been modified for the grasslands
that are located to the east of 105
◦
E and to the north of 40
◦
N.
