Monitoring Space Weather with GPS Anthea J. Coster

USES OF GPS NAVIGATION NAVIGATION STEERING GOLF CARTS, ROUTES FOR TAXI CABS STEERING GOLF CARTS, ROUTES FOR TAXI CABS FAA/AIR TRAFFIC CONTROL (WAAS and LAAS) FAA/AIR TRAFFIC CONTROL (WAAS and LAAS) Tracking pigeons! Tracking pigeons! GEODETIC GEODETIC EARTHQUAKE PREDICTION/MONITORING PLATE MOTION EARTHQUAKE PREDICTION/MONITORING PLATE MOTION ICEBERG TRACKING AND OFFSHORE OIL EXPLORATION ICEBERG TRACKING AND OFFSHORE OIL EXPLORATION PRECISE SURVEYING PRECISE SURVEYING EARTH SCIENCE EARTH SCIENCE WATER VAPOR MEASUREMENTS WATER VAPOR MEASUREMENTS IONOSPHERIC MAPPING, STUDIES OF TIDS (TRAVELING IONOSPHERIC DISTURBANCES) IONOSPHERIC MAPPING, STUDIES OF TIDS (TRAVELING IONOSPHERIC DISTURBANCES)

Block II/IIA Block IIR GPS Space Segment  24-satellite (nominal) constellation  Six orbital planes, four satellites per plane - 55 deg inclination  Semi-synchronous, circular orbits (~20,000 km altitude)

Global Positioning System ERROR SOURCES GPS CLOCK ERROR RECEIVER NOISE MULTIPATH TROPOSPHERE IONOSPHERE x,y,z,t

Atmospheric Propagation

Illustration of Atmospheric Effects Elevation Refraction Range Delay

Ionospheric Delay as a Function of Frequency

Types of GPS Processing SPS - Standard Position Service (L1 frequency only) SPS - Standard Position Service (L1 frequency only) pseudorange measurements made by single, simple stand- alone receiver pseudorange measurements made by single, simple stand- alone receiver PPS - Precise Positioning Service (L1 and L2) PPS - Precise Positioning Service (L1 and L2) encrypted P-code (Y-code) available to authorized users encrypted P-code (Y-code) available to authorized users synthesized P-code synthesized P-code (pseudoranges plus (pseudoranges plus L2 carrier available) L2 carrier available) DGPS and RTK – DGPS and RTK – Differential GPS and Real-time kinematic

Map of GPS Sites Scripps Orbit and Permanent Array Center (SOPAC) Distributed networks of sensors yield global physics unattainable with single- point measurements

Global Positioning System: Very Precise Navigation By measuring Delay (path length) to each satellite… N ° E ° Receiver has a simple ionospheric thickness model

Global Positioning System… Affected By Space Weather! Ionospheric density changes - so delay changes (locally). Receiver doesn’t know this… Wrong position… But – we can turn it around and derive Ionospheric information! (Total Electron Content)

Solar Flare of 14 July 2000 Biggest Solar Storm in Nine Years Strikes Earth Est. Planetary Kp (3 Hr.) Begin: 2000 Jul UT es NOAA/SEC Boulder, CO USA

GPS Loss of Lock at Millstone Hill

Florida site TEC Disturbances on 15 July 2000

GPS Total Electron Content Map Illustration of Storm Enhanced Density

A Decade Of Storm Enhanced Density Day 77, 1990 Day 149, 2003 Day 101, 2001 Day 90, 2001

Nov 2003 Space Weather Effects GPS derived maps of Total Electron Content (TEC) in Earth’s Upper Atmosphere >1000 GPS Receivers Global Storm Response Using GPS Data

Apr 2001 Space Weather Effects GPS derived maps of Total Electron Content (TEC) in Earth’s Upper Atmosphere >1000 GPS Receivers Global Storm Response Using GPS Data

Northern Europe and American Sector SED Plumes Northern Europe American Sector

20 Nov :20 UT

High Latitude Mid-Latitude Low Latitude

Storm-time Electric Fields Cross-tail electric fields energize and inject particles into the inner magnetosphere forming the disturbance Ring Current Cross-tail electric fields energize and inject particles into the inner magnetosphere forming the disturbance Ring Current Strong storm-time penetration eastward electric field uplifts equatorial ionosphere Strong storm-time penetration eastward electric field uplifts equatorial ionosphere Enhances the Equatorial anomaly Enhances the Equatorial anomaly Sub-auroral polarization Stream forms – which is an electric field that is radially outward at the equator and poleward at higher latitudes. Where the SAPS field overlaps the region of enhanced electron density in the mid-latitudes Sub-auroral polarization Stream forms – which is an electric field that is radially outward at the equator and poleward at higher latitudes. Where the SAPS field overlaps the region of enhanced electron density in the mid-latitudes Storm-Enhanced Density (SED) Storm-Enhanced Density (SED)

AURORAL OVAL LOW  SAPS E FIELD Ring Current / SAPS/ SED Plume (Sub Auroral Polarization Stream Electric Field) Duskside Region-2 FACs close poleward across low- conductance gap Duskside Region-2 FACs close poleward across low- conductance gap SAPS: Strong poleward Electric Fields are set up across the sub-auroral ionosphere SAPS: Strong poleward Electric Fields are set up across the sub-auroral ionosphere SAPS erodes the cold plasma of the ionosphere and the outer plasmasphere SAPS erodes the cold plasma of the ionosphere and the outer plasmasphere

Figure courtesy of J. Foster

21:00 UT Uplift Downwelling Guiana Key West

Polar Convection E E x B DuskDawn The SAPS electric field produces a westward plasma flow at subauroral latitudes Some plasma travels through dayside cusp into polar regions where it becomes entrained in the polar convection and carried over the pole

Plasmasphere extension of ionosphere and part of the inner magnetosphere. filled with ionospheric plasma from the mid- and low latitudes plasma gas pressure is equalized along the entire field line. plasma co-rotates with the Earth and its motion is dominated by the geomagnetic field. Plasma on magnetic field lines associated with higher latitudes (~ above 60 deg. geomagnetic lat.) is convected to the magnetopause Quiet conditions - plasmapause may extend to ~ 7 Earth radii Disturbed conditions – plasmapause can contract to ~3 or less Earth radii.

Plasmasphere

Plasmaspheric Tails and Storm Enhanced Density

IMAGE Data of Plasmasphere

Conjugacy Examples

Aurora in New Brunswick, Canada 30 October 2003

Aurora as seen in Big Bend, Texas 30 October 2003 SUMMARY Electric Fields generated in the magnetosphere are imposed on the ionosphere during geomagnetic storms and dramatically rearrange ionospheric plasma and “empty out” the plasmasphere Networks of ground-based receivers can contribute to our understanding of these processes We are excited about the developing networks of atmospheric sensors in Africa