BACKGROUND
Scientists monitor the structure of the solar corona, the outer most regions of the Sun's atmosphere, using radio waves -- the surface of the Sun is 6,000 degrees Kelvin, while the high corona can reach several million degrees Kelvin. Solar radio emissions at different frequencies allow us to observe radiation from different heights in the atmosphere. The lower the frequency, the higher the height of origin. The frequency, like the electron density, decreases uniformly outwards: 245 MHz originates high in the corona, while 15,400 MHz originates in the low corona. The 5 MHz emission corresponds to about 10 solar radii height. For a detailed review, see McLean and Labrum (1985)SOLAR RADIOPHYSICS.
Radio bursts are associated with solar flares. The delay at Earth of the different radio frequencies during burst events is due to the outward movement of the source. Bursts can have temperatures of 10xE12 degrees Kelvin. Large bursts last 10 to 20 minutes on average. Longer radio noise storms of persistent and variable high levels of radiation originate in sunspot groups, areas of large, intense magnetic fields. These storms are strongly circularly polarized due to the intense magnetic fields.
The microwave wavelength 2800 MHz daily radio flux correlates highly with the daily sunspot number and the two databases are used interchangeably. The 2800 MHz, or 10.7 cm, responds to the same conditions that produce changes in the visible and X-ray wavelengths. Schmahl and Kundu (1995) find that the solar radio fluxes in the spectral range 1000-9400 MHz correlate well with the total solar irradiance. The intermediate frequencies (at 2800 and 3750 MHz) are produced mainly by free-free gyroresonance emission from sunspot structures, while 1000 and 9400 MHz flux are produced mainly by free-free processes from structures associated with plages. They can distinguish plage-associated emission from spot-associated emission in the time series of microwave flux, both contributing opposing effects on the total solar irradiance.
For great movies of solar radio events and more information about Solar and Stellar Radio Astronomy, please visit the website of Dr. Stephen White. His PowerPoint talk The Radio Sun is also available.
Solar radio tables that appear in the monthly report Solar-Geophysical Data (SGD) are available in PDF format.
1. Solar Radio Bursts Event Listings from a worldwide network of stations -- Descriptive Text (text)
- Solar radio burst data format (text) -- print before viewing data
- SOLAR RADIO BURST Listings by year:
2a. Solar Radio 10.7 cm Daily Flux (text) (2800 MHz) noon values from Ottawa/Penticton
- Observed 10.7 cm Solar Radio Fluxes
- Observed 10.7 cm Daily Fluxes by year:
Adjusted Solar Radio 10.7 cm Daily Flux (text) (2800 MHz) noon values from Ottawa/Penticton
- Adjusted to 1 Astronomical Unit (AU) 10.7 cm daily solar radio fluxes
- Adjusted to 1 AU Daily Fluxes by year:
2b. Solar Radio Daily Solar Radio Flux (text) noon values from USAF stations Learmonth, Palehua, Sagamore Hill, and San Vito
- Learmonth, Australia data
- Palehua, Hawaii, USA data
- Sagamore Hill, Massachusetts, USA data (see descriptive text)
- San Vito, Italy data
3. International Astronomical Union (IAU) Quarterly Bulletin on Solar Activity (QBSA) daily solar radio noon flux values
-- from 55 stations, for the time period 1949-1986 (722 station-years, 16.6 Mbytes)
- Descriptive text, including file format, data problems, station list, and years and frequencies covered by each station.
- Station data:
- ABST Abastumani, Russia (1957-1986)
- AOP Potsdam, Tremsdorf, Germany
- BEIJ Beijing, China
- BERL Heinrich Hertz Institute, Berlin, Germany
- BJU Bjurakan, Moscow
- BOL Bologna, Italy
- BORD Bordeaux, France
- CAN Canberra, Australia
- CAV Cavendish Lab, Cambridge, England
- CIT Chalmers Inst. of Technology, Gothenburg, Sweden
- COR Cornell Univ, Ithica, NY, USA
- CRIM Crimea, Russia
- CUBA Havana, Cuba
- GORK Gorky Univ, Russia
- HARS Oslo, Norway
- HIRA Hiraiso, Japan
- HUAN Huancayo, Peru
- IRKU Irkutsk, Russia
- IRS I.R.S.A.D., D.S.-Bukava, Belgian Congo
- IZMI IZMIRAN, Moscow, Russia
- JOD Jodrell Bank Experiment Station, England
- KIE Kiel, Germany
- KIEV Kiev Univ, Russia
- KISV Kislovodsk, Russia
- KRAK Cracow, Poland (see readme file and additional data -- 94, 95, 96)
- MANI Manila Obs., Philippines
- MAR Marcoussis, France
- MEU Meudon Obs., Paris, France
- NAN Meudon Obs., Nancay Station, France
- NBS National Bureau of Standards, Boulder, Colorado, USA
- NED Nederhorst, Netherlands
- NOBE Nobeyama Solar Radio Obs., Japan
- ONDR Ondrejov Obs., Ondrejov, near Prague, Czech Republic
- OSA Osaka, Japan
- OTTA Ottawa, Canada
- PALE Palehua Solar Obs., Palehua, Hawaii, USA
- PENT Penticton, Canada
- PUL Pulkovo, Russia
- PURP Purple Mountain Obs., Nanjing, China
- RIG Riga, Russia
- SANM San Miguel, Argentina
- SAOP Sao Paulo, Brazil
- SGMR Sagamore Hill Radio Obs., Hamilton, Massachusetts, USA
- SIM Simferopol, Russia
- SIS Simeis, Russia
- SUN Sunspot, New Mexico, USA
- SYDN Sydney, Australia
- TOKO Tokyo Astronomical Obs., Mitaka, Japan
- TORN Torun, Poland
- TRST Trieste, Italy
- TYKW Nagoya Univ, Toyokawa, Japan -- see text
- UCCL Uccle, Humain, Belgium
- USS Ussuruisk, Russia
- VORO Voroshilov, Russia
- YUNN Yunnan Obs., Kunming, China
4. USAF RSTN Radio Solar Telescope Network 1 second Data -- 8 selected frequencies from four worldwide station network -- for data 1980-2000, please check the rstn tape catalog. For earlier data on strip charts, 1977-1984, please check the solar radio charts catalog.
- Descriptive text -- Data User's Guide, written in 1980 -- discusses instrumentation.
- Many of these data and earlier data resided also in the Space Physics Interactive Data Resource (SPIDR) system. SPIDR allows browsing, plotting and downloading of data archives. However, the latest version of SPIDR does not include these data at this time.
- For specifics of the fixed frequency archived data, see also the documentation file written by John Kennewell and Graham Steward, IPS Radio and Space Services, Learmonth Solar Observatory, Australia. The text includes the format of the fixed frequency data and a description of the RSTN3VUE data viewer.
- The RSTN3VUE Data Viewer RSTN3VUE.exe runs on a desktop PC system. Download the executable file and the data files to your desktop PC.
- Daily files:
- Learmonth, Australia -- For data Aug 1980-Apr 2000, contact the data center
- 2000: Dec
- 2001: Jan, Aug, Sep, Oct, Nov Dec
- 2002: Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2003: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2004: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2005: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2006: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2007: Jan,
Feb,
Mar,
Apr,
May,
Jun,
Jul,
Aug,
Sep,
Oct,
Nov,
Dec,
- 2008:
Jan,
- Palehua, Hawaii -- for data May 1980 and Aug 1982-Jan 2000, contact the data center.
- 2000: May
- 2001: Jun, Jul, Aug, Sep, Oct, Nov Dec
- 2002: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec,
- 2003: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec,
- 2004: Jan, Feb, Mar, Apr
- 2005: Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2006: Jan, Feb, Mar, Apr, May, Jun,
- Sagamore Hill, Massachusetts -- for data Oct 1981-Feb 2000, contact the data center.
- 1998: Jun
- 1999: Jun
- 2001: Sep, Oct, Nov Dec
- 2002: Jan, Feb, Mar, Apr, May, Jun, Sep, Oct, Nov, Dec
- 2003: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2004: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2005: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2006: Jan, Feb, Mar, Apr, May, Jun, Jul,
- San Vito, Italy -- For data Sep 1986-Apr 2000, contact the data center.
- 2001: Jul
- 2002: Jan, Feb, Mar, Apr, May, Jun,
Jul,
Aug,
Sep, Oct, Nov, Dec
- 2003: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2004: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2005: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2006: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2007: Jan,
Feb,
Mar,
Apr,
May,
Jun,
Jul,
Aug,
Sep,
Oct,
Nov,
Dec,
- 2008:
Jan,
5. Solar Radio Spectral Event Data 1967-present -- event listings from worldwide network
- Descriptive text
- Solar radio spectral data format -- for data 1967-June 1994 -- print before viewing data
- Solar radio spectral data format -- for data July 1994 to present -- print before viewing data
- Solar Radio Spectral Events -- listings by year:
- New format begins with the July 1994 data (see read.me file):
- List of Type II solar radio events:
6. RSTN Solar Radio Spectral Graphical Data from four Stations, with viewing software
- The USAF RSTN (Radio Solar Telescope Network) solar radio spectrograph (SRS) sweeps the frequency range 25 to 180 MHz every 3 seconds. It monitors solar radio emissions originating mainly in the solar corona. It has a low band (25 to 75 MHz) antenna (non-tracking semi-bicone) and a high band (75 to 180 MHz) antenna (tracking log-periodic). Data are sent monthly to NGDC. For specifics of the SRS archived data, see the documentation file written by John Kennewell and Graham Steward, IPS Radio and Space Services, Learmonth Solar Observatory, Australia. The text includes the format of the SRS data, a description of the SRSDisplay data viewer, and a short course in data interpretation. See also the PowerPoint presentation of SRS Data Examples.
- The SRS Data Viewer Srsdisp.exe runs on a desktop PC system. Download the executable file and the data files to your desktop PC.
- There is also an IDL-based viewing software available from SolarSoft, initially developed by Stephen White.
- Daily files:
- Holloman Solar Radio Observatory, New Mexico, USA
- 2000: Aug, Oct, Nov, Dec
- 2001: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2002: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2003: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2004: Jan, Feb, Mar, Apr, May, Jun -- monitoring ceased.
- Learmonth Solar Radio Observatory, Australia
- 2000: Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2001: Jan, Feb, Mar, Apr,
- 2002: Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2003: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2004: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec,
- 2005: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2006: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2007: Jan,
Feb,
Mar,
Apr,
May,
Jun,
Jul,
Aug,
Sep,
Oct,
Nov,
Dec,
- 2008:
Jan,
- Palehua Solar Radio Observatory, Hawaii, USA
- 2001: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2002: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2003: Jan, Feb, Mar, Apr May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2004: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2005: Jan, Feb, Mar, Apr, May, June, Jul, Aug, Sep, Oct, Nov, Dec
- 2006: Jan, Feb, Mar, Apr, May, June, Jul, Aug, Sep,
- Sagamore Hill Solar Radio Observatory, Massachusetts
- 2004: Sep, Nov,
- 2005: Jan,Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2006: Jan, Feb, Mar, Apr, May, Jun,
- San Vito Solar Radio Observatory, Italy
- 2000: Aug, Sep, Oct, Nov, Dec
- 2001: Jan,Feb, Mar, Apr, May Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2002: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2003: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2004: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2005: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2006: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec
- 2007: Jan,
Feb,
Mar,
Apr,
May,
Jun,
Jul,
Aug,
Sep,
Oct,
Nov,
Dec,
- 2008:
Jan,
7. Stanford Daily Maps of Solar 9.1 cm Microwave Emission Jun 1962-Aug 1973
- The distribution of microwave emission over the Sun at a wavelength of 9.1 cm was mapped by the Stanford University Radio Astronomy Institute spectroheliograph nearly every day from June 1962 to August 1973. A total of 3,878 maps exist. These spectroheliograms form a valuable resource for comparison with other solar and terrestrial data. Information on the equipment and data are available in Report UAG-44 Synoptic Maps of Solar 9.1 cm Microwave Emission from June 1962 to August 1973 by Werner Graf and Ron Bracewell, May 1975. The maps were published monthly in the NOAA Solar-Geophysical Data (SGD).
- These digital maps are available on the CD-ROM NGDC-05/1 Solar Variability Affecting Earth. The CD-ROM access software will display the maps with the data color-coded. Each month selected is shown in a loop fashion as the Sun rotates. The user can access these maps by selecting SOLAR in the main menu, then RADIO, then MAPS.
8. East-West Solar Radio Scans from several stations 1957 to present
- East-west solar radio scans give the strip intensity distribution at radio wavelength from one limb of the solar disk, through the center of the disk, to the other limb. When daily drift profiles are compared, they reveal the movement and evolution of active regions near the solar equator.
- NGDC archives several solar radio east-west scan databases, including Fleurs (Australia) 1966-1989, MIT (U.S.) 1983-1987, Nancay (France) 1957 to present, Nederhorst (The Netherlands) 1957-1970, Ottawa (Canada) (1968-1988), and Toyokawa (Japan) 1977-1989. Many of these are published in the monthly publication Solar-Geophysical Data (SGD). Please contact the data center for further information.
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