csi 769-001/phys 590-001 solar atmosphere fall 2004 lecture 14 dec. 08, 2004 sun-earth connection...

CSI 769-001/PHYS 590-001 Solar Atmosphere Fall 2004 Lecture 14 Dec. 08, 2004

Sun-Earth Connection and

Space Weather

Today’s solar wind

Solar Wind

•Solar wind is a continuous outflow of solar particles, largely due to the thermal expansion of high temperature corona (~ 1MK).

•Due to the high thermal conductivity of coronal plasma, the solar atmosphere maintains high temperature even at large heliospheric distance, e.g., ~200,000 K at 1 AU.

•Because of this extended temperature distribution, the solar atmosphere maintains a finite thermal pressure even at large distance.

•Since the thermal pressure of the solar atmosphere can not be balanced by the external pressure (at large distance), the heliosphere can not be in a hydrostatic equilibrium; it expands.

Solar Wind (cont’d)

•The typical solar wind speed is about 400 km/s, which is consistent with Parker’s standard solar wind model that is based on hydrodynamic equations (see textbook section 10.1.2 at P.313)

According to the model, wind speed of 400 km/s when base temperature of 1 MK


•However, observations also show fast solar wind of speed 800 km/s

•Fast solar wind is found to be from coronal holes (and CMEs)

•Why coronal hole yields fast solar wind is still a mystery!

•It is not consistent with Parker’s standard thermal expansion model, because coronal hole has a cooler temperature and therefore a smaller expansion velocity according to the model

•There must be non-thermal energy deposition in solar wind in coronal hole regions


•Solar wind speed distribution with heliospheric latitude•Slow speed (400 km/s) in low latitude (e.g., < 20 degree)•Fast speed (800 km/s) in high latitude (e.g,, > 20 degree)

Interplanetary Magnetic Field (IMF)

The basic configuration: Parker Spiral

Interplanetary magnetic field in the ecliptic plan

Interplanetary Magnetic Field (cont’d)Magnetic Field in the inner corona (< 2 Rs) is mainly closed loops

Interplanetary Magnetic Field (cont’d)Magnetic Field in the outer corona (> 2 Rs, but < 10 Rs) is radial

Interplanetary Magnetic Field (cont’d)Magnetic Field in the interplanetary space is spiral

Interplanetary Magnetic Field (cont’d)

•The spiral interplanetary magnetic field is caused by a combination effect of solar rotation and outward transport of magnetic field embedded with the spherical solar wind flow.

•Because of high electric conductivity, magnetic field is frozen-in with plasma in the corona and in the heliosphere. Solar magnetic field is carried away by solar wind flow due to frozen-in effect

•Solar wind flow is largely spherical along the radial direction

•Interplanetary space is a high β regime, the thermal pressure dominates the magnetic pressure; in other words, solar wind flow carries magnetic field with it.


•Well connected magnetic field from the Earth back to the solar surface at about west 57 degree

•For a typical solar wind of 400 km/s, it takes 104 hours or 4.3 days to reach the Earth

•During the same period, the Sun has rotated 57 degree (using a 27-day rotation period)


•Where is magnetically-well-connected solar region?


•The implications of magnetically-well-connected solar region.

• Impulsive SEP events, that are accelerated in flare regions, originate from a narrow region in western hemisphere, because particles move along the spiral field.

•When a coronal hole is present in the low latitude, fast solar wind shows in geo-space.

Interplanetary Coronal Mass Ejection (ICME)

•The counterpart of solar CME in interplanetary space.

•They are often caused by halo CMEs that are most likely to intercept the Earth’s orbit.

•Solar wind signature of ICME•Shock interface•Enhanced solar wind speed•Enhanced magnetic field•Magnetic cloud•Enhanced plasma density•Reduced proton temperature

ICME (cont’d)

•Solar wind signature of ICME

Space Weather in Geospace

•Earth Magnetic Field


•Van Allen Belt: trapped energetic particles


•Magnetosphere


•The impact of ICME on magnetosphere


•A geo-effective ICME usually has a sustained strong southern magnetic field

•Southern magnetic field is able to reconnect with the Earth magnetic field that is northern at the interface

•Reconnection at the magnetopause allow the reducing of magnetic shield of the Earth’s magnetosphere. As a result, solar wind energy and particles are dumped into the magnetosphere, causing geomagnetic storms

Space Weather in Geospace•Ionosphere

Space Weather Effects

•Solar EM Radiation•Due to solar flares•No warning time•Lasting short (tens of minutes)•Scaled by NOAA GOES Soft X-ray magnitude•Affect Ionosphere

•Solar Particle Radiation •Due to flares and CMEs•Short warning time (< 1 hr)•Lasting long (hours to a few days)•Scaled by particle monitor•Direct impact with electronic and human objects

•Geomagnetic Storm•Due to CMEs•Possibly a few days warning time•Lasting long (days)•Scaled by Kp and Dst index•Effect throughout the geo-space from ground to the entire magnetosphere

Space Weather Effects: NOAA Scale

•Five level scaling•Level 5: Extreme•Level 4: Severe•Level 3: Strong•Level 2: Moderate•Level 1: Minor

•Solar EM Radiation: R1—R5 (Radio Blackouts)

•Solar Particle Radiation: S1—S5 (Solar Radiation Storm)

•Geomagnetic Storm: G1—G5 (Geomagnetic Storms)


•Solar EM Radiation: R5

•HF Radio:Complete HF (high frequency**) radio blackout on the entire sunlit side of the Earth lasting for a number of hours. This results in no HF radio contact with mariners and en route aviators in this sector.

•Navigation: Low-frequency navigation signals used by maritime and general aviation systems experience outages on the sunlit side of the Earth for many hours, causing loss in positioning. Increased satellite navigation errors in positioning for several hours on the sunlit side of Earth, which may spread into the night side.


•Solar Particle Radiation: S5

•Biological: unavoidable high radiation hazard to astronauts on EVA (extra-vehicular activity); high radiation exposure to passengers and crew in commercial jets at high latitudes (approximately 100 chest x-rays) is possible.

•Satellite operations: satellites may be rendered useless, memory impacts can cause loss of control, may cause serious noise in image data, star-trackers may be unable to locate sources; permanent damage to solar panels possible.

•Other systems: complete blackout of HF (high frequency) communications possible through the polar regions, and position errors make navigation operations extremely difficult


•Geomagnetic Storms: G5•Power systems: : widespread voltage control problems and protective system problems can occur, some grid systems may experience complete collapse or blackouts. Transformers may experience damage.

•Spacecraft operations: may experience extensive surface charging, problems with orientation, uplink/downlink and tracking satellites.

•Other systems: pipeline currents can reach hundreds of amps, HF (high frequency) radio propagation may be impossible in many areas for one to two days, satellite navigation may be degraded for days, low-frequency radio navigation can be out for hours, and aurora has been seen as low as Florida and southern Texas (typically 40° geomagnetic lat.)**.

Space Missions for Space WeatherSolar Terrestrial Missions

Operational Developmental Under Study

Ulysses 90

ACRIMSAT 99

Cluster 00

CORONAS-F 01

FAST 96

Geotail 92

GENESIS 01

RHESSI 02

IMAGE 00

Polar 96

SAMPEX 92

SOHO 95

SORCE 03

TRACE 98

WIND 94

ACE 97

Voyager I & II 77

AIM 06

CINDI/CNOFS 04

CORONAS-PHOTON 06

COSMIC 05

EPOP 06

GEC >12MC/DRACO >12

MMS 12Radiation Belt Storm

Probes 12

Picard 06-07SDO 07

Solar-B 06

STEREO 05

Solar Orbiter 11

TWINS 04,05

Interhelioprobe 07-08

Iono-Thermosphere Storm Probes 10

SST 05

RESONANCE ?

TIMED 01

SENTINELS 12-14

RAVENS 07

Solar Probe 12-14

GeospaceHeliosphericSolar

L5 Mission 08

Sich-1 04

Geostorm 09

SWISE 10-12

INTERBALL-PROGNOZ 06-07

THEMIS 06

STORMS 07

ROY/SCHWARM?

Double Star 03/04

Auroral Quartet ?

STEREO Mission

(Trajectories)(Trajectories)

Tools & Services

Science Data Facility

Acquisition & Ingest

Science User Sup

http://spdf.gsfc.nasa.gov/ CDAWLib HelioWeb

Data Environment

Summary

•Introduction•Principles of Spectroscopy, Radiation Transfer •Solar Missions and Instrumentation •Solar Magnetic Field, Solar Cycle, and Solar Dynamo •Lower Solar Atmosphere: Photosphere and Chromosphere •Transition Region and Coronal Loop Dynamics(Midterm) •Coronal Structure•Coronal Plasma Properties, MHD Equations•Ideal MHD, MHD Waves and Coronal Heating•Solar Flare •Solar Flare•Filament Eruption and Coronal Mass Ejection•Coronal Mass Ejection and Solar Energetic Particle (SEP)•Sun-Earth Connection and Space Weather

csi 769-001/phys 590-001 solar atmosphere fall 2004 lecture 14 dec. 08, 2004 sun-earth connection...

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