SOUZA, I. A.; SOUZA, Ioneide Alves de.
Resumen:
The objective of this study is to verify the importance of climatic variability
produced by the tropical Pacific and Atlantic Ocean temperature anomalies, over
the fluctuations in the aridity indices and consequently in the desertification
processes in the State of Rio Grande do Norte. Monthly precipitation totals of 57
stations, which are spacially distributed over the State of Rio Grande do Norte,
and the mean monthly values of air temperature and insolation of six stations were
used in this study. The air temperatures were estimated, for those stations which
did not possess the observed temperature data, for those years of occurrence of
the events of El Nino, La Nina, Positive South Atlantic Dipole and Negative South
Atlantic Dipole. The aridity indices were calculated for each of the above events
and the results of these indices were compared. It is observed that in the years of
El Nino and Negative South Atlantic Dipole, there was a decrease in the annual
precipitation totals throughout the State and an increase in values of insolation, air
temperature and evapotranspiration. Consequently, there is a rise in the aridity
indices, which resulted in the predominance of arid and semi-arid climatic regions
practically throughout the State. In the years of occurrence of La Nina and Positive
South Atlantic Dipole there was an increase in the annual precipitation totals
throughout the State and a decrease in the values of insolation, air temperature
and evapotranspiration. As a consequence of this, there is a decrease in the
aridity index, which resulted in the predominance of sub-humid and humid regions
throughout the State. Thus reducing the areas affected by the processes of semidesertification.
This interannual fluctuation is reflected in the degree of aridity
contributing to the advancement or recession of the desertification processes in
the State. Besides these climatic fluctuations, practically all the predominant soils
in that State are not fertile, principally, deficient in mineral, plant and organic
nutrientes, and as a result they are vulnerable to desertification. Practically, the
whole State of Rio Grande do Norte is susceptible to the conditions of
desertification.