How does the Sun drive the dynamics of Earth’s thermosphere and ionosphere

Wenbin Wang, Alan Burns, Liying Qian and Stan Solomon

High Altitude ObservatoryNational Center for Atmospheric

ResearchBoulder, USA

Outline

Earth’s thermosphere and ionosphere

Energy and momentum inputs to the thermosphere and ionosphere

Thermospheric response to geomagnetic activity

Simulation of the thermosphere and ionosphere response to a CIR event

The Thermosphere-Ionosphere System

http://en.wikipedia.org/wiki/Ionosphere

Major Species Density Structure of the Atmosphere

Diffusively Separating

Fully Mixed

OO2 N2

Total Density

MSIS empirical model atmosphere

mid-daymid-latitude

5

MSIS/IRI

mid-daymid-latitude

Thermosphere-Ionosphere Variability

Living with a Star Targeted Research and Technology program:“Plasma–Neutral Gas Coupling in the Chromosphere and Ionosphere”

Leake et al., Ionized Plasma and Neutral Gas Coupling in the Sun’s Chromosphere and Earth’s Ionosphere/Thermosphere, Space Sci. Rev., Doi:10.1007/s11214-014-0103-1, in press, 2014.

Chromosphere Thermosphere

Neutral Gas

Plasma

Thermosphere-Ionosphere System: an Externally Driven System

Sun Magnetosphere

ThermosphereIonosphere

Solar WindIMF

Ultravioletand

X-rays

Tides andPlanetary

Waves

Turbulenceand

Convection

Auroral Currents

Energetic Particles

Heliosphere

Lower & MiddleAtmosphere

Knipp et al., Solar Physics, 2004, 224: 495-505

Global Energy Input to the Thermosphere-Ionosphere System

Geomagnetic Forcing on the T-I system

Enhanced Electric Field and Ion Drag Enhanced Auroral Precipitationand Ionospheric Conductivity

Dynamics Explorer Stan Solomon

Joule Heating

Ion Drag

Thermospheric Temperature Response to Geomagnetic Forcing

F107: 190UT:1200DOY: 356HT: ~300km

Quiet

Storm

National Center for Atmospheric Research-Thermosphere ionosphere Electrodynamics Global Circulations Model (TIEGCM)

Neutral Winds in Quiet and Active Conditions

Quiet

Storm

Thayer and Killeen, 1993

Prolss (1981, 2011)

Thermospheric Composition Response to Geomagnetic Forcing

Thermospheric N2 perturbation

TIEGCM

Superposed epoch results of solar wind speed, IMF Bz, Dst, AE and ap indicies for 79 CIR events.

Corotating Interaction Regions (CIRs)

March, 2004 CIR Event

Neutral Temperature: : TIEGCM Simulations

Zonal Winds

O/N2

How is the electron density determined?

Transport: Electric Fields, Neutral Winds and Ambipolar Diffusion

Composition: O/N2 in the F-region

F2 Peak Densities

O/N2

F2 Peak Densities

Summary

1. Earth’s thermosphere and ionosphere system is strongly driven by the energy and momentum input from the Sun.

2. Thermospheric temperature, winds, and composition show global changes during storm events.

3. During a CIR event of 2004, these changes occur over the entire period of the event and do not recover one day after the event.

4. Ionospheric F-region density changes during this CIR event appear to be mostly related to thermospheric composition variations.

2004

Neutral Temperature

Zonal Winds

O/N2

8 min

hours-16 days

SunCMECIR

Magnetosphere

Thermosphere-Ionosphere: An Externally Driven System

EUV and UV

Radiation

Lower and Middle Atmosphere

Thermosphere-Ionosphere

2-10 days

Leake et al., Ionized Plasma and Neutral Gas Coupling in the Sun’s Chromosphere and Earth’s Ionosphere/Thermosphere, Space Sci. Rev., Doi:10.1007/s11214-014-0103-1, 2014.

Conductivity

Chromosphere Thermosphere