Tuesday, July 26, 2011

New paper finds solar influence on El Niño and La Niña cycles

A paper published online today in the journal Geophysical Research Letters finds a "robust" effect of solar activity on the ocean oscillations of El Niño and La Niña, which in turn have profound effects upon global climate. The paper finds a lagged response with El Niño-like conditions following solar maxima a "couple of years later." The IPCC dismisses the role of the Sun on climate by only considering small changes in total solar irradiance, ignoring large changes in solar UV (which is capable of penetrating the ocean surface to cause heating unlike IR from 'greenhouse gases'), and ignoring secondary effects (e.g. the cosmic ray theory of Svensmark et al). This paper adds yet another secondary effect of solar activity on climate not considered by the IPCC.


On the robustness of the solar cycle signal in the Pacific region

Key Points:
Solar signal in the tropical Pacific largely depends on the period chosen
North Pacific shows robust SLP (sea level pressure) response to solar forcing
Vertically extended AO-GCM reproduces main features of observed solar response

S. Bal et al

The potential role of the stratosphere for the 11-year solar cycle signal in the Pacific region is investigated by idealized simulations using a coupled atmosphere-ocean general circulation model. The model includes a detailed representation of the stratosphere and accounts for changes in stratospheric heating rates from prescribed time dependent variations of ozone and spectrally high resolved solar irradiance. Three transient simulations are performed spanning 21 solar cycles each. The simulations use slightly different ozone perturbations representing uncertainties of solar induced ozone variations. The model reproduces the main features of the 20th century observed solar response. A persistent mean sea level pressure response to solar forcing is found for the eastern North Pacific extending over North America. Moreover, there is evidence for a La Niña-like response assigned to solar maximum conditions with below normal SSTs in the equatorial eastern Pacific, reduced equatorial precipitation, enhanced off-equatorial precipitation and an El Niño-like response a couple of years later, thus confirming the response to solar forcing at the surface seen in earlier studies. The amplitude of the solar signal in the Pacific region depends to a great extent on the choice of the centennial period averaged.

No comments:

Post a Comment