ИСТИНА

The South-Pacific Convergence Zone (SPCZ) is the chief part of atmospheric circulation in tropical Pacific, and undergoes unprecedented displacements during the El-Nino - Southern Oscillation (ENSO) cycle. The SPCZ is shifting from the center of Pacific during the warm phase of ENSO to the eastern Australian coast during the cold phase. The areas of active tropical cyclogenesis genetically coupled with this zone undergo respective displacements. At the SPCZ converge two macro-scale currents of an opposite directions: easterly trade winds and equatorial westerly winds. This macro-scale convergence shift strongly to the east and lead to formation at the center of Pacific an extensive band of ascending movements during the warm ENSO phase (El-Nino) in the SPCZ system. Over Indonesia and Northern Australia, on the contrary, emerges the macro-scale divergence zone. Therefore, the water vapor is carrying, on the one hand, to Pacific, towards South America and, on the other hand, to Indian, towards Eastern Africa. This activation of SPCZ in the central Pacific is caused by intensive development of tropical cyclogenesis, involving rich tropical rains in uncharacteristic region. The well-known disastrous fires and droughts in Indonesia and Northern Australia during El-Nino are apparently the consequence of macro-scale divergence zone, mentioned above. During the cold ENSO Phase (La-Nina) the macro-scale atmospheric tropic circulation pattern changes considerably. The water vapor transport in these conditions to Indonesia and Northern Australia region as at trade winds circulation system from Pacific, so and at equatorial westerly winds system from Indian. This situation leads to generation of powerful South-Pacific Convergence Zone. This SPCZ during La-Nina is at most shifted to northeastern Australian coast at the expense of vigorous Pacific trade winds. This displacement of SPCZ to the Australian summer monsoon zone is namely one of reasons of abrupt activity of tropical cyclogenesis in this monsoon region. This activity is corresponding with a rich precipitation, storm winds and frequently dramatic floods. The striking example of these events is the most famous recent La-Nina 2010/11 accompanied with the destructive flood and, particularly, with the most vigorous tropical cyclone in Australian history, “Yasi”.