What is Space Weather? THE ACTIVE SUN

Transcription

1 Aardvark Roost AOC Space Weather in Southern Africa Hannes Coetzee 1

2 What is Space Weather? THE ACTIVE SUN 2

3 The Violant Sun 3

4 What is Space Weather? Solar eruptive events (solar flares, coronal Mass Space weather describes the conditions in space ejections (CMEs)) are the main drivers of space that affect Earth and its technological systems. weather generation propagation interaction Space weather is a consequence of the behaviour sun interplanetary space of the sun, the nature of Earth's magnetic field and atmosphere, and our shock location waves in the solar system. magnetosphere/earth solar eruptive events expelled plasma & magnetic fields accelerated particles potentially geoeffective agents after Scherer et. al 2004 radio emission 4

5 The Earth s Space Environment This schematic diagram shows the sun, solar wind, and Earth s magnetosphere, the environment in which space weather is generated. 5

6 Sun-Earth Space Environment 6

7 Space Weather Effects 7

8 Communication and Navigation 8

9 Solar Event From SUN to Hermanus Magnetic Observatory 22 Nov Nov Nov 2001 : SOHO observation of CME on Sun 24 Nov 2001 : Major Magnetic Storm on Earth Observations by Hermanus Magnetic Observatory 9

10 Coronal Mass Ejection (CME) UT : F = 143 nt H = -270 nt D = -70 min. Z = -231 nt 10

11 CME effect on HF Radio Comms fof2, [M MHz] April Day Number fof2 [MHz] GRAHAMSTOWN 11

12 Geomagnetically Induced Currents GIC occur at the end of the space weather chain. GICs are driven by electric fields produced by variations in the Earth's magnetic field that occur during ggeomagnetic g storms. GICs flowing in power transformers produce extra magnetic flux which cause transformer failures. Intense GIC levels can cause collapse of power systems. 12

13 Characterizing the Ionosphere South African Ionosonde Network (22.4ºS, 30.9ºE ) Madimbo Louisvale (28.5ºS,21.2ºE) 21 2ºE) Installed June 2008 Hermanus (34.4ºS, 19.2ºE) N(h) profiles from 1996 Grahamstown (33.3ºS, 26.5ºE) 13

14 Real Time Ionospheric Information Grahamstown 33.3 S, 26.5 E Madimbo 22.4 S, 30.9 E Hermanus 34.4 S, 19.2 E Louisvale 28.5 S, 21.2 E 14

15 Frequency Predictions Cape Town Pretoria March

16 Modelling the Ionosphere IRI International Reference Ionosphere -- global model -- updated annually -- covers all upper atmosphere parameters National SA Model -- South African Ionospheric model -- Bottomside ionosphere -- neural network based Global fof2, hmf2 and M3000F2 Models -- neural network based -- initially trained with data from 50 worldwide stations -- developed as PhD project in South Africa -- current version includes 135 global stations 16

17 Real-Time Ionospheric Map 17

18 Total Electron Content (GPS) integral of electron density N along cylindrical column centred on ray path s, between receiver R and satellite S through the ionosphere. TEC corresponds to total number of free electrons- included in cylindrical column with sectional area 1m 2. 1 TEC Unit = electrons per square meter 18

19 Total electron Content (TEC) Hourly GNSS-derived Ionospheric Total electron Content maps over Southern Africa for 3 March :00 01:00 02:00 03:00 04:00 05:00 06:00 07:00 08:00 09:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00 Hermanus Magnetic Observatory South Africa TEC Units (x10 16 e -.m -2 ) 19

20 Space Weather Instruments at SANEA-IV HF radar Aurora cameras Riometers Magnetometers Neutron Monitors VLF-receiver GPS receiver for geodecy Seismometer Meteorology 20

21 Summary Technology and Communications are growing at a rapid rate Space Weather is going to have a serious impact, especially during high solar activity Northern hemisphere models and predictions not always valid for southern hemisphere There is a very definite need to continue researching Southern African Space Weather h h 21

22 Summary Thank You 22