O N THE INFLUENCE OF THE CORONAL HOLE LATITUDE AND POLARITY ON THE GEOMAGNETIC ACTIVITY AND COSMIC RAY VARIATIONS Abunina Maria, IZMIRAN, Russia Abunin Artem, Belov Anatoly, Eroshenko Evgeniya, Gaidash Sergey, Oleneva Victoria, Yanke Victor, IZMIRAN, Russia Kryakunova Olga, Institute of Ionosphere, Kazakhstan I NTRODUCTION Coronal holes is one of two (along with CME) main solar sources of geomagnetic disturbances and transient disturbances of cosmic rays (Forbush decreases) Difficulties for forecasters: speed of solar wind and Bz-component of the IMF polarity and heliolatitude 2 D ATA database on the Forbush effects (IZMIRAN) >6700 events (CR density global survey method for 10 GV rigidity); sources - high-speed solar wind streams from coronal holes; from October 2002 to December 2013; clear coronal holes; coronal hole polarity was known (negative or positive). 299 events were selected: 133 holes with positive polarity and 166 holes with negative 3 4 E XAMPLES OF CORONAL HOLES 1) coronal holes with negative polarity in the northern hemisphere of the Sun (conventionally denoted N-, 71 holes); 2) coronal holes with a positive polarity in the southern part of the solar disk (S+, 60 holes); 3) transequatorial coronal holes irrespective of the polarity (, 148 holes); 4) those holes that are not in any of the above groups (other, 20 coronal holes). 5 F OUR GROUPS Geoefficiency of 4 groups of coronal holes 6 GEOMAGNETIC ACTIVITY Index of geomagnetic activity Ap versus the interplanetary characteristics of high-speed streams 7 GEOMAGNETIC ACTIVITY cc NSC = 0.7 cc other = 0.87 b NSC = 0.67 b other = 8.58 1.17 V 0 = 400 km/s, B 0 = 5 nT, B max the maximum of IMF intensity V max the maximum of solar wind velocity in the disturbance 8 GALACTIC COSMIC RAY MODULATION Galactic cosmic ray modulation by coronal holes. Superposed epoch method. 299 coronal holes. 10 GV Vertical green arrows correspond to the North-South CR anisotropy. Thin lines connect equal points on time scale on the curves of vector anisotropy and CR density in each 6 hours. Moment 0 relates to the beginning of the interaction regions of solar wind streams. 9 Behavior of the CR density (A0) and anisotropy vector in coronal holes with different polarity (superposed epoch) GALACTIC COSMIC RAY MODULATION 166 CH 133 CH M AIN C ONCLUSIONS Transequatorial coronal holes and coronal holes of the northern hemisphere with negative polarity and coronal holes of the southern hemisphere with a positive polarity are more geoeffective than the holes in the same hemisphere, but of opposite polarity. 10 M AIN C ONCLUSIONS Differences in position and polarity of coronal holes have a little effect on the galactic cosmic ray density variations and equatorial component of anisotropy vector. Coronal holes with a negative polarity create an additional North-South component of anisotropy directed to the south, and coronal holes with positive polarity - to the north. 11