Ionosphere Climate Studied by

F3 / COSMIC Constellation

C. H. Liu

Academia Sinica In Collaboration with Tulasi Ram, C.H. Lin and S.Y. Su

The Ionospheric Environment is affected by Solar-Terrestrial Connections from above and Atmospheric Dynamics from below. Understanding of the Variations in this region, the Climate and Weather of the Ionosphere, is Important since a large part of Human Activities in Space occurs in this region.

Academia Sinica, Taipei, Taiwan

COSMIC – Constellation Observing System for Meteorology, Ionosphere and Climate

GPS Occultation eXperiment (GOX)

- ~ 2000 Ne(h) profiles per day

- Spatially uniform

A constellation of six micro satellites

- 800 km altitude - 30o of separation in longitude - 72o inclination

FORMOSAT 3 / COSMIC Has

Global Coverage with Good Height

Resolution Suitable to Study Global

Phenomena

Equatorial Ionosphere Modified

by the Atmospheric Tides

Coupling from Below

9-Day Oscillation in the Ionosphere

A New Solar-Terrestrial

Connection

By Binning the 30 day Ionospheric Soundings (excluding magnetic disturbed days) in Every 2(1)-Hour Interval and Taking Median Value of the Soundings located in the 5 degree by 5 degree grid, a Global Electron Density Map for the 30 day Period Is Constructed with good Height Resolution at a Given Local Time.

Low-Latitude Ionosphere is dominated by the electrodynamics

Courtesy of David Anderson

Equatorial Plasma Fountain & The Equatorial Ionization Anomaly (EIA)

Recent discovered four-peaked longitudinal structure produced by atmospheric tides :First reported by Sagawa et al. [2005] and Immel et al. [2006]

Newly discovered ionospheric feature at low-latitude

•E3 Nonmigrating tide produced by the latent heat excited by tropospheric water vapors• Modulating the E-region dynamo and the plasma fountain

IMAGE FUV observation

E3 non-migrating tide modeled by global scale wave model (GSWM) [Hagan and Forbes, JGR, 2002]

Observe the northern hemisphere only

Recent discovered longitudinal structure produced by atmospheric tides :

FORMOSAT-3/COSMIC electron content observations: 2000~2200 LT

The Four-Peaked Longitudinal structure in EIA is caused by the Eastward Wave Number Three (E 3) Nonmigrating Tide Excited by Latent Heat Release in the Troposphere. E 3 shows Stronger Amplitude in Winds and Temperature at the Four Longitudinal Locations. The Stronger Winds Strengthen the E-Region Dynamo generated daytime Eastward Electric Field which in turn mapped to the F-region Produces a stronger Equatorial Plasma Fountain.

Questions:1. In what altitude does the structure becomes prominent?

2. Does the structure occur in daytime or nighttime only or both?

3. What is the diurnal variation of the structure?

3-D structures at 20:00~22:00 LT

Lin et al., GRL, 2007

Diurnal variations of the wave-4 structure during Sep.-Oct. 2006Starting at 08-10 LT, strongest at 14-16LT, subsiding after 22LT

Lin et al., JGR, 2007

E×B drifts from empirical model:10 16 19 LT

Scherliess and Fejer, JGR, 1999

•10LT:

Four-peaked structure formed.

•16LT:

Four-peaked structure become less prominent.

•19 LT:

Possibly connected to re-appearance of four-peaked structure at 20LT.

Suggesting the E3 tidal effect act as a perturbation component to the regular upward E×B drift.

Jul-Aug 2007Northern Summer

Sep-Oct 2007Equinox

Nov-Dec 2007Northern Winter

A 9-Day Recurring Fast Streams in

Solar Wind due to a Triad of Solar

Coronal Holes distributed roughly

120 degree apart in Longitude Cause

Periodic Variations in Thermosphere

Neutral Density, Temperature and

Ionosphere Ionization Distributions.(Lei et al. 2008a, b, c; Thayer et al. 2008; Crowley et al. 2008)

The daytime (0600 to 1800 LT) electron

density profiles in each day are zonally (l

ongitudinally) averaged into 16 latitudinal

bins from -80 to +80 degrees geographic

latitudes and 40 altitudinal bins from 100

to 500 km

Academia Sinica, Taipei, Taiwan

Daily zonal mean electron density from COSMIC

2007 – 2008 (Solar Minimum)

400 km altitude 9-day period

Academia Sinica, Taipei, Taiwan

Zonally mean Ele. density

Spectral peaks at 27, 13.5, 9, 7 and 5-day periods

Sub-harmonic Solar Rotation

Zonally mean Ele. density

Spectral peaks at 27, 13.5, 9, 7 and 5-day periods

Sub-harmonic Solar Rotation

Zonally mean Ele. density

Spectral peaks at 27, 13.5, 9, 7 and 5-day periods

Sub-harmonic Solar Rotation

A comparison of spectra of Helio-Geophysical Parameters

Absent

Mg-II Index

5 7 9 13 27

HT – Scale Height More prominent at high-lat

hmF2 – F2 layer peak height almost uniform globally

NmF2 – F2 layer peak density

opposite at high and low latitudes

Academia Sinica, Taipei, Taiwan

Academia Sinica, Taipei, Taiwan

Academia Sinica, Taipei, Taiwan

9-day periodic oscillations in 2008

Day Time Night Time350 km

Further Studies

Other Multi-day Oscillations in the

Ionosphere, Mechanisms, Impacts

on Space Climate and Weather