Calcium Chromosphere Observed from Mt. Wilson Solar Observatory

browse graphicExample Image from Chromosphere_Calcium_MtWilson series.
The calcium datasets consist of full-disk images of the sun in Calcium (Ca) II K wavelength (393.4 nm). Ca II K imagery reveal magnetic structures of the sun from about 500 to 2000 km above the photosphere that are not evident in white light images. The chromosphere is an extremely dynamic layer of the sun consisting of a mixture of hot ionized plasma and cool gas. The presence of calcium ions in the chromospheric (along with other ions such as helium and hydrogen) lead to the absorption of radiant emission from the sun. The Ca II K absorption lines are extremely sensitive to local magnetic fields wherein the presence of stronger magnetic fields results in less absorption (brighter features) than weaker fields (more absorption = darker features). Unique features of the chromosphere evident in Ca II K are plage, pores, supergranulation cells and the chromospheric network. Also observed in Ca II K are solar features typically discussed in the context of the photosphere, including sunspots and faculae. Sunspots in photospheric observations appear as dark regions due to the cooler temperatures (~3000 oK) of the overlying gas compared to the surrounding solar surface (~5500 oK). Although sunspots are regions of intense solar magnetic activity (i.e. less absorption), the lack of radiant emissions from the underlying photosphere results in chromospheric sunspot regions that remain darker than the surrounding sun. Faculae, on the other hand, are brighter regions in chromospheric observations which result from the concentration of magnetic field lines between solar granules (solar convection cells). Closely associated with faculae are bright areas of chromospheric plage, also referred to as floccule, within solar active regions that are associated with sunspot formation. Solar pores are actually small sunspots that have not yet formed (and may never form) into the standard picture of a dark central umbra surrounded by a somewhat brighter penumbra. Supergranulation cells are large regions of convective horizontal flows (larger than individual granules) wherein solar material and an embedded magnetic field flow radially outward from the center and downward at the outer boundaries causing the web-like appearance of the chromospheric network structure.
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  • Chromosphere_Calcium_MtWilson
gov.noaa.ngdc.stp.solar_imagery:Chromosphere_Calcium_MtWilson
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    Distributor William Denig
    DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce
    (303) 497-6323
    solar.ngdc@noaa.gov
    Dataset Point of Contact William Denig
    DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce
    (303) 497-6323
    solar.ngdc@noaa.gov
    Coverage Description Non-geographic
    Time Period 1915-08-09 to 1984-04-30
    Spatial Bounding Box Coordinates Non-geographic
    Documentation links not available.
    Publication Dates
    • creation: 1915-08-09
    Data Presentation Form Digital document - digital representation of a primarily textual item (can contain illustrations also)
    Dataset Progress Status Complete
    Data Update Frequency
    Supplemental Information
    The NOAA National Centers for Environmental Information (formally NGDC) provides scientific data stewardship of solar-terrestrial datasets
    in compliance with NOAA Administrative Order (NAO 212-15), "Management of Environmental Data and Information", published 04 Nov 10. Scientific
    Data Stewardship includes the Archive, Access, and Assessment (AAA) of operational and related solar and space environmental datasets.
    Purpose Scientific data stewardship of solar-terrestrial datasets in compliance with NOAA Administrative Order (NAO) 212-12, "Management of Environmental and Geospatial Data and Information", dated 04 Nov 10. Scientific Data Stewardship includes the Archive, Access, and Assessment (AAA) of operational and related solar and space environmental datasets.
    Publishers
      Publisher information not available.
    Theme keywords Global Change Master Directory (GCMD) Science Keywords
    • Sun-Earth Interactions > Solar Activity > Solar Active Regions
    • Sun-Earth Interactions > Solar Activity > Solar Imagery
    • Sun-Earth Interactions > Solar Activity > Sunspots
    • Sun-Earth Interactions > Solar Activity > Corona
    • Sun-Earth Interactions > Solar Activity > Solar Synoptic Maps
    Data Center keywords Global Change Master Directory (GCMD) Data Center Keywords
    • DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce
    • DOC/NOAA/NESDIS/NGDC > National Geophysical Data Center, NESDIS, NOAA, U.S. Department of Commerce
    Platform keywords Global Change Master Directory (GCMD) Platform Keywords
    • Solar Observatory Stations
    Instrument keywords Global Change Master Directory (GCMD) Instrument Keywords
    • Solar Telescopes
    Place keywords Global Change Master Directory (GCMD) Location Keywords
    • Space > Solar Region > Chromosphere
    Project keywords Global Change Master Directory (GCMD) Project Keywords
    • NOAA > Space Weather Program
    • WDS > World Data Service for Geophysics, Boulder
    Use Constraints No constraint information available
    Access Constraints
    • Distribution liability: NOAA and NCEI make no warranty, expressed or implied, regarding these data, nor does the fact of distribution constitute such a warranty. NOAA and NCEI cannot assume liability for any damages caused by any errors or omissions in these data. If appropriate, NCEI can only certify that the data it distributes are an authentic copy of the records that were accepted for inclusion in the NCEI archives.
    Fees Fee information not available.
    Acquisition Information (collection)
    Instrument
      Platform
      • Mt. Wilson Solar Observatory
      Last Modified: 2016-12-27
      For questions about the information on this page, please email: Karen.E.Horan@noaa.gov