Implications of Recent Solar Output Changes for Space Climate
Geomagnetic activity and solar energetic particle events are caused by quasi-steady and transient aspects of the solar wind. This implies that systematic changes in the solar wind will be reflected in space climate changes. Recently startling and unpredicted changes have taken place in the observed wind. At the time of this writing the average solar wind pressure and magnetic field intensities are the lowest they have been since the space age began. At the vicinity of the Earth the interplanetary magnetic field is 1/3 smaller than it was during any previous interval and the solar wind pressure has decreased by 20 percent. The causes and physics behind these changes are not known. However, although the weak solar wind was not predicted it is not unprecedented. There is convincing evidence that weak solar wind frequently occurred before the space age, for example, around the turn of the last century and during the Maunder Minimum. Here I will discuss the implications of low solar wind intensity states for past and future space climate conditions. .
The Dynamo Basis of Solar Cycle Fluctuations and Forecasting Schemes
Because the sun's magnetic cycle modulates its radiative output as well as the frequency of all its geoeffective eruptive manifestations, forecasting the properties of future cycles remain a very active area of research. In this talk I will first review mechanisms and models for solar cycle fluctuations, and then examine the dynamo basis of precursor schemes relying on measurements or proxies of the sun's surface magnetic field during the minimal activity epoch preceding the onset of a new cycle. In particular, I will show that the precursor value of the surface polar field depends on the type of dynamo mechanism underlying the solar cycle, and on the nature of the processes responsible for the observed fluctuations in cycle amplitude and duration. Implications of these results for model-based cycle forecasting schemes will also be discussed.
High Latitude Methane Sulphonic Acid Variability Associated With Solar Activity
The direct impact of solar activity on climate has been widely studied through Total Solar Irradiance. Biological processes also impact climate and are deeply affected by Total Solar Irradiance. Marine phytoplankton emissions into the atmosphere have been proposed to change cloud albedo through cloud formation. In this work we use wavelet analysis to investigate the decadal relation between high latitude concentrations of methane sulphonic acid, a product of seawater algae, and Total Solar Irradiance. We found that some of the main methane sulphonic acid periodicities coincide with periods of solar activity.
Probability Distribution of Fluxes of Extreme Solar Energetic Particles.
The knowledge of probability distribution of Solar Energetic Particles (SEPs) is required to forecast safety conditions for humans and electronic devices in space. Of particular importance are sporadic high fluxes and fluences of SEPs, which cause electronic parts and solar cells degradation, and pose a hazard to biological systems in space and to air personnel in polar orbit. Since extreme SPEs are rare their study require measurements over long periods of time, thus making them relevant to Space Climate. To determine the rate of occurrence of these extreme SEPs we evaluate the tails of cumulative probability distributions of proton fluxes measured by spacecraft and approximated by a power-law distribution. To find the exponent of the tails of the probability distributions we apply the statistical "Max-Spectrum" method (Stoev, 2006) to 1973-1997 IMP-8 data and the 1987-2008 GOES data, which cover a wide range of proton energies.
Ionospheric measurements at magnetically conjugate points in the polar regions during minimum solar cycle
The paper investigtes the ionospheric responses during 9 minor-to-major storm events occuring between 2005 and 2007 at approximately magnetically conjugate points in the polar regions. The GPS data from Scoresbysund/Ittoqqoormiit station (SCOR) in Greenland (Geo: 70.49šN, 338.05šE; CGM: 71.50šN, 71.43šE) and Syowa station (SYOG) at East Ongle Island, Antarctica (Geo: 69.0šS, 39.58šE, CGM: 66.34šS, 72.23šE) are employed in the analysis. The daily TEC measurements statistics for 2007 were also made at another two conjugate points, the Scott Base, Antarctica (SBA) GC: 77.85°S, 166.76°E; CGM: -79.94 °S, 327.44°E and Resolute Bay, Arctic Canadian (GC: 74.69°N', 265.12°E; CGM: 82.91°N 322.24 °E). The storm-time GPS Total Electron Content (TEC) measurements at the conjugate points show clear occurrence of Storm Enhanced Density (SED) at Sudden Storm Commencement (SSC) at the dark- side hemisphere while no significant effect was seen over the dayside hemisphere. The results also show pronounced TEC enhancement occurrence at the dark-side hemisphere while clear TEC depletion occurrence above the dayside hemisphere. Asymmetry in the TEC occurrence at both hemispheres was clearly seen with opposite responses between summer and winter seasons. The statistics of year TEC measurements show good agreement during quite day periods at both hemisphere with different response during storm periods. The GPS TEC measurements at SCOR, SYOG, RESO and SBA stations were compared with the TEC measurements obtained from NASA TEC JPL data over polar regions and with the ionospheric electron density obtained from the European Incoherent Scatter Scientific Association (EISCAT) over northern high latitude European sector. Keywords: Geomagnetic storm, Conjugacy, Ionosphere, GPS, EISCAT
Modelling of Geomagnetically Induced Current at Subauroral Region and Low Latitudes
During large magnetic storm the geomagnetically induced current has a negative impact on ground conducting technology system. The time derivative of horizontal and northern component of geomagnetic field (dH/dt, dX/dt) is greater than 30nT/min for induced current causing undesirable consequence in power grids. Multiple regression analyses were developed to predict level of geomagnetic disturbance using time derivatives of horizontal geomagnetic field, northern component of time derivatives of geomagnetic field, east and north component of geoelectric field, auroral electrojet and disturbance storm time from 1994- 2007 at low and subauroral latitudes. The statistical test RMSE (Root Mean Square Error) and MBE (Mean Bias Error) were employed to evaluate the accuracy of the geomagnetic disturbance. Different variables have been used to develop different types of models. There are high values of correlation coefficient and coefficient of determination which gives good results and with also low statistical indicator. The equations produced the best correlations at subauroral and low latitudes, the best correlation is obtained with low values of RMSE and MBE