ionosphere climate studied by f3 / cosmic constellation c. h. liu academia sinica in collaboration...
TRANSCRIPT
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.
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
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