GP41A-01
Polar Methane Sulphonic Acid trend associated with solar activity
Solar activity has been proposed as a main contributor to climatic change. Solar variability associated phenomena such as total solar irradiance and cosmic rays could alter the Earth's radiation budget and therefore the climate, the latter through possible modification of the cloud albedo1-4. However, biological processes have also been proposed to change the cloud albedo5. In this work we use wavelet analysis to investigate the relation between polar concentrations of Methane Sulphonic Acid (MSA), a product of seawater algae, and the Total Solar Irradiance (TSI) and the sea surface temperature (SST). Here we found that MSA presents on the 11yrs sunspot cycle a negative correlation with TSI, which would favour a positive feedback for climate, however the non linear relation with the SST also found here, indicates that the MSA is partially contributing to the SST. Our results indicate that the TSI has the possibility to alter the climate indirectly through its effect on biological processes. Quantification of the relationship between the MSA and TSI is a step forward to the knowledge of the mechanisms influencing the climate
GP41A-02
On the Expression of the 41,000 year in the Paleomagnetic Record of the Geomagnetic Field.
Several authors have suggested that there is expression of the obliquity period in the paleomagnetic record, implying a role for precession in driving the dynamo. However, the observation remains controversial. The power at 41,000 years is only weak. Yet, it does appear that (1) excursions and major intensity lows are associated with minima in the obliquity signal during the last 800 kyrs (2) the distribution of the length of events less than 100,000 years peaks at 30 - 40,000 years. i.e. a little shorter than the obliquity cycle (3) reversals preferentially occur when the amplitude of the obliquity signal is low in the past 5 Myrs. (4) reversals occur preferentially within the obliquity cycle close to the point of inflection in the decrease from the maximum value. These observations have been rexamined using additional data, which extend the time scale of the tests. Particular emphasis is placed on the phase relationship of the obliquity cycle and the onset of reversals and excursions. The results are consistent with the earlier suggestion that there is expression of the 41,000yr obliquity cycle in the paleomagnetic record. Thus precession may play a role in driving the dynamo. However, possible relative motion between core and mantle due to changes in surface mass distribution, which are caused by climatic changes, may also occur. Preliminary results indicate that for the last 800 Kyr there is no strong systematic relationship between magnetic intensity lows and the del 18 O record, or ice record.
GP41A-03
Solar Activity, Earth Rotation and Atmospheric Circulation
Earth rotation rate varies on different time-scales - from centuries to days. The seasonal nontidal variations in the Earth rotation rate, or the length of the day (LOD), are believed to be fully explained by large-scale atmospheric motions caused by the temperature differences between the summer and the winter hemispheres. A connection is also supposed between the decadal LOD variations and changes in atmospheric circulation. We demonstrate that the Earth rotation is different in positive and negative solar polarity cycles, therefore even on these time- scales the Earth-atmosphere system is not closed. The correlation between the decadal variations in LOD and atmospheric circulation changes in the beginning of the XX century, moreover it is opposite in the northern and southern hemispheres, so there is no direct relation between the Earth rotation and large-scale atmospheric circulation on decadal time-scales, rather they are both modulated by solar activity. We look for an explanation for the solar activity influences on the Earth rotation and on the atmospheric circulation in the two hemispheres.
GP41A-04
The impact of the October-November 2003 intense solar storm events on the atmospheric circulation in the Pacific Southern Hemisphere Magnetic Anomaly region
Evidences of the solar activity modulation of the Earth's climate have been observed on different time scales. The main solar activity mechanisms to control climate proposed to explain these observations are: (1) the variability of the total solar irradiance causing a change in the total energy input to the earth's atmosphere and consequent warming/cooling; (2) the variability of the solar ultraviolet emission and its effects on the stratospheric ozone and thermal structure; (3) the cosmic rays effects on the cloud coverage; and (4) high energy particle precipitation effects on mesospheric and stratospheric ozone in the auroral and/or southern hemisphere magnetic anomaly regions during solar storm events. It is conceivable that these mechanisms contribute to varying extends on different regions. However, the precise roles of each process during extreme solar events have not yet been investigated. Here we show that the unusual atmospheric circulation conditions over the southern Pacific and Atlantic oceans, and South America on late October and early November 2003 could be related to the large solar storm events, the Halloween events. We observed the development of anti-cyclones in the South Pacific after the onset of the main proton events. We observed also changes in the position and intensity of the Intertropical Convergence Zone and in the South Pacific Convergence zone. This result reveals that effects on the atmospheric conditions, including cloud coverage and radiative flux in the atmosphere, in the southern hemisphere magnetic anomaly region could be observed during extreme solar conditions. Previous studies suggested that the influence of solar activity on climate could be observed on decadal to millennia time scales. Our results demonstrate that the variability of the solar activity could have impact on southern hemisphere weather and climatic conditions. We anticipate our analysis to be a starting point for more sophisticated weather and climatic models. For example, the predictability of El Niño events could be tested, including its worldwide effects, based on space weather processes. Furthermore, the increase of the southern hemisphere temperature could be investigated based on changes of the Earth's magnetic field configuration.
GP41A-05
Long-Term Variations in the Correlations Between Solar Activity, Geomagnetic Activity and Climate - a Link to the Solar Dynamo
Until a few decades ago, the long-term increase in global temperature could be explained to a great extend by the long-term increase in solar activity as measured by the sunspot number, but recently the sunspot number remains nearly constant while global temperature continues increasing. The long-term behavior of the correlation between sunspot number and geomagnetic activity expressed by aa index is very similar. In the 11-year solar cycle, the correlation between aa and sunspot number has been decreasing in the last century, while the lag between their maxima has been increasing. aa can be divided into two components: one due to the solar toroidal field (whose expressions are sunspots and coronal mass ejections, the main source of geomagnetic activity in sunspot maximum), and another due to the solar poloidal field (related to solar coronal holes from which fast solar wind originates, the driver of recurrent geomagnetic activity on the declining and minimum phase of the sunspot cycle). The cyclic transformation of the poloidal field into toroidal field and of this toroidal field into a new poloidal field with the opposite polarity - the solar dynamo, is the basis of solar activity. Here we show that the solar meridional circulation which is a key element in the flux transport dynamo mechanism, has long-term variations determining the long-term variations in solar and geomagnetic activity, and of the correlation between them in the 11-year solar cycle. We study the long-term variations in the poloidal and toroidal components of aa index and demonstrate that the long-term variations in global terrestrial temperature are highly correlated to the long-term variations in the poloidal component of aa, and that using the sunspot number as a measure of solar activity underestimates the role of the Sun in global change.