Periodicities of the Solar Wind, Global Electron Power, and Other Indices in 2005 in HSS Barbara A. Emery (NCAR), Ian G. Richardson (GSFC), David S. Evans (NOAA), and Frederick J. Rich (LL/MIT) MURI, October 2008, Boulder CO

ABSTRACT We assess the periodicities of the hourly solar wind velocity (Vsw) and the hourly average global electron auroral power (Pe) with Lomb- Scargle analyses in Other indices such as the 10.7 cm solar flux, total IMF B magnitude (Bt), Kan-Lee merging electric field (Ekl), Kp and Dst are also analyzed. Pe exhibits solar rotational periodicities similar to those for Vsw, where the 9-day periodicity is particularly strong in This 9-day periodicity is also present in Kp, Dst, Bt, Ekl, in neutral densities ~400 km, and in infrared cooling by [NO] and [CO2] between km, but is not found in solar UV radiation or the 10.7 cm solar flux. The periodicities are particularly clear and strong for hours during high-speed solar wind streams (HSS 42%), compared to hours of transients (20%) or slow-speed wind (38%). The periodicities during transients are of large magnitude and chaotic.

Estimates of the electron hemispheric power (HPe) into the auroral regions from particle detectors on NOAA and DMSP satellites were inter-calibrated over 29 years and 24 satellites.

The electron hemispheric power (HPe) is found in both hemispheres on an hourly basis. The sum of the Northern and Southern hemispheres is the global power (Pe). Uncalibrated HpeCalibrated Hpe

Good correspondence between HPe and HPt from POLAR NH Images

Best cross-correlation of HPe with Kp and ap

HPe and HPi functions of Bz and Vsw

9-d periodicity in Vsw from 3 coronal holes ~120 o apart in solar longitude. Not seen in sunspot area, or related to active regions or to Dst. From Temmer et al. (Solar Phys., 241, )

9-d periodicity of HSS also found in Kp and the neutral thermosphere (density at 400 km and infrared cooling by [NO] and [CO 2 ] between km), but not in 10.7 cm solar flux. From Thayer et al., (JGR, 2008) and Mlynczak et al., GRL, 2008)

Solar Rotational Periodicities in Vsw and Pe 9-d max in 2005

Longer Periods in Vsw and Pe

Hourly Vsw and Pe in 2005

Lomb Periodicities

The fraction of time that is spent in each kind of solar wind structure from hourly average Vsw. 2005

Vsw and Pe in Solar Structures

10.7 cm Flux and Pe Solar Structure Periodicities

Vsw and Dsw Solar Structure Periodicities

IMF Bt and Kan-Lee Merging E Field Solar Structure Periodicities

Kp and Dst Solar Structure Periodicities

CONCLUSIONS Solar rotational 27, 13.5, 9, and 7-day periodicities are usually present in the hourly or daily total Vsw and Pe, with larger magnitudes in descending (D) and minimum (N) SC phases. Longer periodicities (>100 days) are not as well correlated between Vsw and Pe. The 9-day periodicities in Vsw and Pe seen in 2005 are also present in IMF Bt, Kan-Lee merging electric field, Kp, Dst, the neutral thermospheric density and infrared [NO] and [CO 2 ] cooling. The cleanest and often the strongest 9-day periodicities are during HSS hours.

References Emery et al. (2008), Seasonal, Kp, solar wind, and solar flux variations in long-term single-pass satellite estimates of electron and ion aurora hemispheric power, J. Geophys. Res., 113, A06311, doi: /2007JA Emery, Richardson, Evans, and Rich (2008), Solar wind structure sources and periodicities of global electron hemispheric power over three solar cycles, J. Atmos. Terr. Phys., HSS Special Issue, accepted Aug ( Mlynczak et al. (2008), Solar-terrestrial coupling evidenced by periodic behavior in geomagnetic indexes and the infrared energy budget of the thermosphere, Geophys. Res. Lett., 35, L05808, doi: /2007GL Temmer et al. (2007), Periodic appearance of coronal holes and the related variation of solar wind parameters, Solar Phys., 241, Thayer et al. (2008), Thermospheric density oscillations due to periodic solar wind high speed streams, J. Geophys. Res., 113, A06307, doi: /2008JA