Geoscience Reference
In-Depth Information
cance and scale of critical situations in the environment depends on
the state of many NSS components. As a rule, natural disasters are evaluated in the
context of damage to human life and economic activity. However, it is well known
that, on the other hand, natural disasters are an important factor of ecodynamics
from local to global scales. As Lindenmayer et al. (2004) note, for many processes
that determine the ecosystems dynamics, natural disasters are of the key importance
as factors that regulate such processes. Therefore Wright and Erickson (2003)
discussed the problem of taking into account the impact of natural disasters within
the problems of the numerical modeling of the environmental change. Special
attention has been recently paid to forest
The signi
fires which, being an important component
of ecodynamics, are mainly of anthropogenic origin and cause both material
damage and humans
'
death.
fires occurring regularly in various global regions have more and more
become a factor of the ecosystem
Forest
re-
induced emissions of greenhouse gases and aerosols to the atmosphere. According
to available estimates, about 30 % of tropospheric ozone, carbon oxide and carbon
dioxide contained in the atmosphere are determined by the contribution of forest
'
is dynamics, which is manifested through
res can sub-
stantially affect the microphysical and optical characteristics of the cloud cover,
leading to climate change. So, satellite observations over Indonesia have demon-
strated, for instance, that the presence of smoke in the atmosphere due to prolonged
fires. Aerosol emissions to the atmosphere connected with forest
fires has led to precipitation suppression, which has further favored the develop-
ment of
fires. In this context, Ji and Stocker (2003) performed a statistical pro-
cessing of the data of TRMM-satellite measuring rains in the tropics as well as of
TOMS (total ozone mapping spectrometer) data for the period January 1998
-
December 2001 in order to analyze the laws of the annual course, intraseasonal and
interannual variability of the number of forest
fires on a global scale. During this
period, there was a clear annual course of
fires in south-Eastern Asia with a
maximum in March, and in Africa and in North and South America
—
in August. An
analysis of data revealed also the interannual variability of forest
fires in Indonesia
and Central America correlating with the El Ni
ñ
o/Southern Oscillation (ENSO)
cycle in 1998
1999. In 1998, the boreal forests burned out over vast territories of
Russia and North America. Fires covered the territory about 4.8 million ha in boreal
forests of Canada and USA and 2.1 million ha in Russia.
There appears a clear correlation between variability of the atmospheric aerosol
content and the above variations of the frequency and intensity of forest
−
res. An
exception is the region of south-Western Australia where intensive
res recorded
from the TRMM data were not followed by smoke layers formation (from the
TOMS data). With the Australian region excluded, the coef
cient of correlation
between the number of
fires and AI (from the TOMS data) constitutes 0.55. The
statistical analysis of data using the calculated empirical orthogonal function (EOF)
revealed a contrast between the Northern and Southern Hemispheres as well as the
existence of the intercontinental transfer of aerosols originating from
fires in Africa
and America. The data of statistical analysis point to the presence of 25
60-day
intra-seasonal variations superimposed onto the annual change of the number of
−
Search WWH ::
Custom Search