Direct and Indirect Thermospheric Heating Sources for Solar Cycles 21–23 |
| |
Authors: | D J Knipp W K Tobiska B A Emery |
| |
Institution: | (1) Department of Physics, US Air Force Academy, CO 80840, USA;(2) Space Environment Technologies, Pacific Palisades, CA 90272, USA;(3) High Altitude Observatory, NCAR, Boulder, CO 80301, USA |
| |
Abstract: | Solar variability is often cast in terms of radiative emission and the associated long-term climate response; however, growing
societal reliance on technology is creating more interest in day-to-day solar variability. This variability is associated with both solar radiative and solar wind emissions. In this paper we explore
the combined effects of radiative and solar wind fluctuations at Earth. The fluctuations in radiative and geomagnetic power
create an extended interval of solar maximum for the upper atmosphere. We use a trio of empirical models to estimate, over
the last three solar cycles, the relative contributions of solar extreme ultraviolet (UV) power, Joule power, and particle
kinetic power to the Earth’s upper atmosphere energy budget. Daily power values are derived from three source models. The
SOLAR2000 solar irradiance specification model provides estimates of the daily extreme and far UV solar power input. Geomagnetic
power is derived from a combination of satellite-estimated particle precipitation power and an empirical model of Joule power
from hemispherically integrated estimates of high-latitude energy deposition. During the interval 1975 to 2003, the average
daily contributions were: particles – 36 GW, Joule – 95 GW and solar – 464 GW for a total of 595 GW. Solar wind-driven geomagnetic
power provided 22% of the total global upper atmospheric energy. In the top 15 power events, geomagnetic power contributed
two-thirds of the total power budget. In each of these events, Joule power alone exceeded solar power. With rising activity,
Joule power becomes the most variable element of solar upper atmosphere interactions. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|