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 km altitude - 30 o of separation in longitude - 72 o 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 Starting at LT, strongest at 14-16LT, subsiding after 22LT Lin et al., JGR, 2007

E×B drifts from empirical model: LT Scherliess and Fejer, JGR, LT: 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 2007 Northern Summer Sep-Oct 2007 Equinox Nov-Dec 2007 Northern 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 (longitudinally) 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

H T – Scale Height More prominent at high-lat h m F2 – F2 layer peak height almost uniform globally N m F2 – F2 layer peak density opposite at high and low latitudes Academia Sinica, Taipei, Taiwan

9-day periodic oscillations in 2008 Day TimeNight Time 350 km

Further Studies Other Multi-day Oscillations in the Ionosphere, Mechanisms, Impacts on Space Climate and Weather