Solar x-ray flux data.

The TIROS/NOAA satellite series, also known as POES, is designed to meet the National Oceanic and Atmospheric Administration's need for operational, remote sensing products for numerical weather and space environment forecasts. The TIROS designation represents the experimental classification of a new instrument configuration while NOAA represents the operational classification. For January 1979 through present, the National Centers for Environmental Information (formerly National Geophysical Data Center) archive data from the POES Space Environment Monitor instrument. Subcomponents of the SEM include: HEPAD (High Energy Proton and Alpha Detector), MEPAD (Medium Energy) and TED (Total Energy) data from TIROS and NOAA satellites. The satellites are in sun-synchronous orbits at 850 kilometers altitude, an orbital period of 102 minutes and an inclination of 99 degrees. The orbital plane is tilted toward the sun in the Northern Hemisphere. Usually, two satellites are operational at all times.NOAA's Polar Orbiting Environmental Satellites (POES) (formerly known as TIROS for Television and InfraRed Observation Satellite) carry a suite of instruments that detect and monitor the influx of energetic ions and electrons into the atmosphere and the particle radiation environment at the altitude of the satellite. Both phenomena vary as a result of solar and geomagnetic activity. Beginning with the NOAA-15 satellite, an upgraded version of the Space Environment Monitor (SEM-2) is being flown. A number of SEM-2 instruments have been procured and it is anticipated that the SEM-2 instruments will be included on the NOAA/POES satellites until superceded by the NPOESS satellite program sometime after 2010.Because the SEM-2 instruments differ significantly from the earlier SEM-1, there has been a complete revision to the data processing and archiving process. A number of improvements have also been included. Among these are incorporating up-to-date satellite orbit information and magnetic field models in the calculation of various magnetic coordinates, and improved data quality control. The Total Energy Detector (TED) is designed to measure the energy flux carried by auroral particles, both positively charged ions (assumed here to be protons) and electrons, into the polar atmosphere. The magnitude and spatial extent of this energy flux are good measures of both the level of auroral activity and the atmospheric response to that energy input. The Medium Energy Proton and Electron Detector (MEPED) includes a set of solid-state energetic particle detectors that monitor the intensities of protons and electrons over a range extending from 30 keV to more than 200 MeV. Particles having those energies include the radiation belt (Van Allen belt) populations, the particles in energetic solar particle events (solar proton events), and the low energy portion of the galactic cosmic ray population. Enhanced fluxes of these particles entering the atmosphere can produce significant and widespread degradation in short-wave radio propagation; in extreme cases even radio blackouts. The energetic particles also contribute to astronaut radiation exposure, especially on high inclination orbit missions during energetic solar particle events.

The Space Environment Monitor (SEM) instruments onboard GOES 13-15 have four Energetic Particle Sensors, which include SEM/HEPAD (High Energy Proton and Alpha Particles Detector), SEM/EPEAD (Energetic Proton, Electron and Alpha Detector), SEM/MAGED (Magnetospheric Electron Detector), and SEM/MAGPD (Magnetospheric Proton Detector). These sensors measure proton, alpha-particle, and electron fluxes at geosynchronous orbit. The v1 processing includes operational data from GOES 13-15. The v2 processing includes data processed from GOES 14 ‘storage mode’ observations to fill gaps in the operational period of record. Note: Longitudinal variations in magnetospheric particle fluxes make the GOES-East and GOES-West particle data not representative in general of the fluxes present at the storage location (105 degrees West). At this location, GOES 14 is magnetically conjugate to a region of Canada west of Hudson Bay that is well instrumented with magnetometers and all-sky auroral imagers. This data collection includes Level-1b and L2 SEM-HEPAD/EPEAD/MAGED/MAGPD data from GOES 14. The data were produced from ‘storage mode’ observations acquired from May 23, 2013 to November 30, 2017. The data include the following science-quality enhancements: more accurate time stamps, a saturation flag for MAGED and MAGPD data, and the removal of several artificial data spikes. The data were produced by NOAA’s National Centers for Environmental Information (NCEI) and archived by NOAA's Comprehensive Large Array-Data Stewardship System (CLASS).

The National Oceanic and Atmospheric Administration (NOAA) monitors the geospace and solar environments using a variety of space weather sensors aboard its fleet of operational satellites.

The ionosphere is that part of the Earth's atmosphere that results mainly from the photo ionization of the upper atmosphere. Traditionally, the following ionospheric regions and their approximate height ranges have been designated: D region (60-90 km); E region (90-150 km); F1 region (150-250 km); and F2 region (above 250 km). Ionosondes utilize the radio wave-reflecting properties of the ionosphere. The product of the speed of light in a vacuum and half the elapsed time between vertical transmission of a single frequency electromagnetic wave and reception of the reflected wave at the transmitting location is defined as the virtual height of that frequency. A sweep-frequency ionogram is a plot of virtual height versus frequency and is recorded as instantaneously as possible. These ionospheric data consist mainly of hourly values for at least one of the following characteristics: foF2, M(3000)F2, hF2, foF1, M(3000)F1, hF, foE, hE, foE2, hE2, foEs, fbEs, hEs, fmI, and fxI. The values are five byte (character) fields. The first three bytes of the field are reserved for a numeric value; the last two bytes are reserved for the qualifying and descriptive letter, if present. There are no decimals encoded in these data. Documentation is included. There are two CD-ROM's worth of data. One contains 1957 - 1975 data; the other contains 1976-1990 data. ASCII data files and a DOS-compatible application is included.

Ionograms are recorded tracings of reflected high frequency radio pulses generated by an ionosonde. Unique relationships exist between the sounding frequency and the ionization densities which can reflect it. As the sounder sweeps from lower to higher frequencies, the signal rises above the noise of commercial radio sources and records the return signal reflected from the different layers of the ionosphere. These echoes form characteristic patterns of "traces" that comprise the ionogram. Radio pulses travel more slowly within the ionosphere than in free space, therefore, the apparent or "virtual" height is recorded instead of a true height. For frequencies approaching the level of maximum plasma frequency in a layer, the virtual height tends to infinity, because the pulse must travel a finite distance at effectively zero speed. The frequencies at which this occurs are called the critical frequencies. Characteristic values of virtual heights (designated as h'E, h'F, and h'F2, etc.) and critical frequencies (designated as foE, foF1, and foF2, etc.) of each layer are scaled, manually or by computer, from these ionograms. Typically, an ionosonde station obtains one ionogram recording every 15 minutes. When the scaling is done manually only the hourly recordings are routinely reduced to numerical data. Modern ionosondes with computer-driven automatic scaling procedures routinely scale all the ionograms recorded. The resulting numerical values, along with the original ionograms and station reports, are archived at five World Data Centers (WDCs) for Ionosphere. The ionosphere is divided into four broad regions called D,E, F, and topside. These regions may be further divided into several regularly occurring layers, such as F1 or F2.D Region: The region between about 75 and 95km above the Earth in which the relatively weak) ionization is mainly responsible for absorption of high-frequency radio waves. E Region: The region between about 95 and 150km above the Earth that marks the height of the regular daytime E layer. Other subdivisions isolating separate layers of irregular occurrence within this region are also labeled with an E prefix, such as the thick layer, E2, and a highly variable thin layer, Sporadic E. Ions in this region are mainly O2+. F Region: The region above about 150km in which the important reflecting layer, F2, is found. Other layers within this region are also described using the prefix F, such as a temperate-latitude regular stratification, F1, and a low-latitude, semi-regular stratification, F1.5. Ions in the lower part of the F layer are mainly NO+ and are predominantly O+ in the upper part. The F layer is the region of primary interest for radio communications.

Energetic particle data from the CXD and BDD instrument on the GPS constellation are available to the space weather research community. The release of these data supports the National Space Weather Action Plan which was recently published by the Executive Office of the President's National Science and Technology Council (NSTC).

The GOES Solar X-ray Imager is integrated into the GOES-12 satellite, whose primary mission is to provide Earth-weather monitoring. The SXI is operated by NOAA's National Environmental Satellite, Data, and Information Service (NESDIS). NOAA's Space Environment Center (SEC) receives the telemetry stream directly from SXI, processes the data, and integrates the observations into their space weather alert and forecast services. The data are sent in real time to NOAA National Centers for Environmental Information (formerly National Geophysical Data Center) where they are immediately made available to the public, and preserved in a secure archive for future research. SXi was launched in with GOES-M on July 23, 2001 Post Launch Test data were available from August - December 2001.SXI officially entered operations in April 2003.

A Sudden Ionospheric Disturbance (SID) is any of several radio propagation anomalies due to ionospheric changes resulting from solar or geophysical events.

Scientists monitor the structure of the solar corona, the outer most regions of the Sun's atmosphere, using radio waves (100’s of MHz to 10’s of GHz). Variations in the radiowave spectrum reveal characteristics of the corona and upper chromosphere in terms of altitude profile for the local plasma temperature, density and magnetic field. Typically, the lower the frequency then the higher the height of origin. The frequency, like the solar electron density, decreases uniformly outwards with 245 MHz originating high in the corona whereas 15,400 MHz originates in the low corona. 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.