CEDAR 2008 Workshop Observations at the Plasmaspheric Boundary Layer with the Mid-latitude SuperDARN radars Mike Ruohoniemi, Ray Greenwald, and Jo Baker Department of Electrical and Computer Engineering Virginia Tech Blacksburg, VA Elsayed Talaat and Rob Barnes The Johns Hopkins University Applied Physics Laboratory Laurel, MD

Mid-Latitude SuperDARN Radar builds – Wallops Island, VA (2005) – Hokkaido, Japan (2006) – Blackstone, VA (2008)

Space Weather: Storm-time Expansion of Ionospheric Electric Fields UT June 12,2005 June 13, 2005 Beam 4 Doppler time series on northerly directed beam shows equatorward expansion of high- latitude convection to  =53 . Velocities in excess of 1600 m/s were observed.

Dusk Sector Subauroral Irregularities Near Plasmapause Boundary Two-Dimensional Image of SAPS and SAID (Scan Duration = 49 seconds) Production mechanism F-region gradient drift inst.

Midnight Sector Subauroral Irregularities Near Plasmapause Boundary  =60   =50  Wallops Island Radar May 5, 2006 ~0400 UT Geomagnetic Coordinates Kp=3

Dawn Sector Subauroral Irregularities Near Plasmapause Boundary

The Quiescent State - Nighttime Continuous scatter throughout nighttime hours Low Doppler velocities except for one brief period Low spectral widths

Examples of Ionospheric Scatter From Plasmasphere Boundary Layer Jan 21, 2006 Beam 4 Jan 22, 2006 Beam 4 Jan 23, 2006 Beam 4 Sept 11, 2005 Beam 1

Sources of Ionospheric Irregularities Mid to high-latitudes – Magnetospheric plasma circulation, horizontal electron- density gradients, Birkeland currents, shear flows, horizontal temperature gradients. – Relevant instability processes. Gradient Drift instability {E and F region} Two-stream instability {E-region} Electrostatic Ion Cyclotron instability {E and F region} Temperature Gradient instability {F region} Kelvin-Helmholtz instability {F region} Others ????

Millstone/Wallops Experiment to Identify Source of Subauroral Irregularities MHO: 34 az, (18/28/48 el) + zenith focused on km Wallops: 16 beam Doppler velocity scan. Millstone Hill is along beam indicated by the arrow.

Wallops HF Radar Measurements Along Viewing Azimuth of Millstone ISR

Millstone Hill Plasma Parameters February –0430 UT Te Zenith 54 inv Te 48 el 55.5 inv Te 28 el 57.0 inv Te 18 el 58.2 inv Log(Ne) Zenith 54 inv Log(Ne) 48 el 55.5 inv Log(Ne) 28 el 57.0 inv Log(Ne) 18 el 58.2 inv

Temperature Gradient Instability is Source of Plasmapause Irregularities Sequence of Events UT: Poleward motion of ocean scatter footprint following sunset UT: Irregularities form in post-sunset ionosphere. Possibly associated with F-region gradient-drift instability as reported previously UT onwards: Temperature gradient reverses and steepens. Backscatter intensifies. Onset of TGI.

Substorm Impacts on the Inner Magnetosphere How do substorms affect inner magnetosphere convection? Do substorms contribute to penetration electric fields? What types of velocity changes occur? What is the local time extent of the effects? What are the time delays? What is their duration?

Magnetic Observations on April 25, 2008 Kp=3 GOES 12 Ottawa St. John

Observations with the mid-latitude SuperDARN radars Dramatic space weather is observed as the expansion of storm- time electric fields to mid-latitudes Under less disturbed conditions strong electric fields are observed in SAPS/SAID events at the equatorward boundary of the oval Unexpected sources of irregularities populate the mid-latitude ionosphere during quiet times – these appear to be associated with the plasmapause The plasmapause electric fields, while comparatively small, exhibit transient behavior Next step – more extended observations at mid-latitudes to address the dynamics of the plasmapause and inner magnetosphere

Mid-Latitude SuperDARN Chain