This website hosts a dataset of EUV synoptic maps based on SOHO/EIT and SDO/AIA full-disk images, and synoptic maps of coronal holes based on the EUV maps.

All the synoptic maps are constructed by concatenating 13.3° wide central meridian strips from full disk solar images first mapped into heliographic coordinates. Using the same strip width for both instruments reduces the differences between the maps that may result from different image resolution or different image sampling frequency.

If you decide to use these maps for research we kindly ask you to acknowledge this data source and provide a proper reference to the papers listed below in each section. For more information about these data you can contact:

Amr Hamada (amr.hamada@oulu.fi)

or

Timo Asikainen (timo.asikainen@oulu.fi).

Here you can find synoptic EUV maps based on SOHO/EIT and SDO/AIA full disk images. They are all offered in resolution of 3600 × 1440 pixels, covering all latitudes from −90° to +90° and longitudes from 0° to 360°. Note that there may be gaps at high latitudes due to seasonally varying visibility and sometimes larger missing longitudinal strips due to missing data.

The data values in the FITS data files depict linear pixel intensity. The PNG images show logarithmic pixel intensity. The maps are given for four different wavelengths in both linear and sine latitude.

Detailed description about the construction of these synoptic maps can be found in:

Hamada, A., Asikainen, T., Mursula, K., New Homogeneous Dataset of Solar EUV synoptic maps from SOHO/EIT and SDO/AIA. Sol. Phys., 295, 2, 2019

Instrument | Wavelength | Sine-lat / latitude | Coverage (Carrington rotations and Years) | PNG files | FITS files |
---|---|---|---|---|---|

SOHO/EIT | 171 Å | Sin(lat) | CR1906-CR2211 (Years 1996-2018) | PNG | FITS |

SOHO/EIT | 195 Å | Sin(lat) | CR1906-CR2211 (Years 1996-2018) | PNG | FITS |

SOHO/EIT | 284 Å | Sin(lat) | CR1906-CR2211 (Years 1996-2018) | PNG | FITS |

SOHO/EIT | 304 Å | Sin(lat) | CR1906-CR2211 (Years 1996-2018) | PNG | FITS |

SOHO/EIT | 171 Å | Latitude | CR1906-CR2211 (Years 1996-2018) | PNG | FITS |

SOHO/EIT | 195 Å | Latitude | CR1906-CR2211 (Years 1996-2018) | PNG | FITS |

SOHO/EIT | 284 Å | Latitude | CR1906-CR2211 (Years 1996-2018) | PNG | FITS |

SOHO/EIT | 304 Å | Latitude | CR1906-CR2211 (Years 1996-2018) | PNG | FITS |

SDO/AIA | 171 Å | Sin(lat) | CR2097-CR2234 (Years 2010-2020) | PNG | FITS |

SDO/AIA | 193 Å | Sin(lat) | CR2097-CR2234 (Years 2010-2020) | PNG | FITS |

SDO/AIA | 211 Å | Sin(lat) | CR2097-CR2234 (Years 2010-2020) | PNG | FITS |

SDO/AIA | 304 Å | Sin(lat) | CR2097-CR2234 (Years 2010-2020) | PNG | FITS |

SDO/AIA | 171 Å | Latitude | CR2097-CR2234 (Years 2010-2020) | PNG | FITS |

SDO/AIA | 193 Å | Latitude | CR2097-CR2234 (Years 2010-2020) | PNG | FITS |

SDO/AIA | 211 Å | Latitude | CR2097-CR2234 (Years 2010-2020) | PNG | FITS |

SDO/AIA | 304 Å | Latitude | CR2097-CR2234 (Years 2010-2020) | PNG | FITS |

Here you can find SOHO/EIT and SDO/AIA synoptic EUV maps, which have been standardized and homogenized to the same standard intensity level. These maps are based on the linear scale maps listed above and have the same resolution and coverage as those maps. The homogenization procedure transforms the histograms of standardized logarithmic pixel intensity in EIT synoptic maps to corresponding AIA level.

It should be noted that these maps indeed depict **standardized logarithmic pixel intensities**,
and are mainly intended for identification of various features, e.g., coronal holes, on the solar disk.

*These maps are not suitable to study the temporal behaviour of absolute EUV intensities.*

The data values in the FITS data files depict linear pixel intensity. The PNG images show logarithmic pixel intensity. The maps are given for four different wavelengths in both linear and sine latitude. The homogenized maps are offered in Sine-latitude.

Detailed description about the construction of these homogenized synoptic maps can be found in:

Hamada, A., Asikainen, T., Mursula, K., New Homogeneous Dataset of Solar EUV synoptic maps from SOHO/EIT and SDO/AIA. Sol. Phys., 295, 2, 2019

Instrument | Wavelength | Sine-lat / latitude | Coverage (Carrington rotations and Years) | PNG files | FITS files |
---|---|---|---|---|---|

SOHO/EIT Standardized/Homogenized | 171 Å | Sin(lat) | CR1906-CR2211 (Years 1996-2018) | PNG | FITS |

SOHO/EIT Standardized/Homogenized | 195 Å | Sin(lat) | CR1906-CR2211 (Years 1996-2018) | PNG | FITS |

SOHO/EIT Standardized/Homogenized | 284 Å | Sin(lat) | CR1906-CR2211 (Years 1996-2018) | PNG | FITS |

SOHO/EIT Standardized/Homogenized | 304 Å | Sin(lat) | CR1906-CR2211 (Years 1996-2018) | PNG | FITS |

SDO/AIA Standardized | 171 Å | Sin(lat) | CR2097-CR2211 (Years 2010-2018) | PNG | FITS |

SDO/AIA Standardized | 193 Å | Sin(lat) | CR2097-CR2211 (Years 2010-2018) | PNG | FITS |

SDO/AIA Standardized | 211 Å | Sin(lat) | CR2097-CR2211 (Years 2010-2018) | PNG | FITS |

SDO/AIA Standardized | 304 Å | Sin(lat) | CR2097-CR2211 (Years 2010-2018) | PNG | FITS |

Here you can find synoptic maps of coronal holes based on the standardized and homogenized SOHO/EIT and SDO/AIA EUV synoptic maps listed above. These maps are constructed using the original automatic detection algorithm developed by:

Hamada, A., Asikainen, T., Virtanen, I. and Mursula,K., Automated Identification of Coronal Holes from Synoptic EUV Maps, Sol. Phys., 293: 71, 2018

This original coronal hole detection algorithm (developed for different set of EUV synoptic maps) was modified slightly when applied to the new homogenized synoptic maps listed above. The construction of these coronal hole maps is detailed in:

Hamada, A., Asikainen, T., and Mursula,K., A uniform series of coronal holes in 1973-2018, Sol. Phys. (2020). (Submitted)

The coronal hole maps offered here have the same resolution of 3600 × 1440 pixels as the EUV maps listed above and cover all latitudes from −90° to +90° and longitudes from 0° to 360°. As in the EUV maps there may be gaps at high latitudes due to seasonally varying visibility and sometimes larger missing longitudinal strips due to missing data.

The data values in the FITS data files indicate the following:

Value | Meaning |
---|---|

0 | Not a coronal hole pixel |

+1 | Coronal hole pixel with dominant positive magnetic polarity (magnetic field outward) |

-1 | Coronal hole pixel with dominant negative magnetic polarity (magnetic field inward) |

NaN | Missing data or lack of visibility to poles |

In the PNG files the *red* color indicates coronal holes with dominant positive magnetic polarity,
while the *blue* color indicates dominant negative magnetic polarity coronal holes.

**Note, that even though coronal hole synoptic maps have been constructed for all four EIT/AIA wavelengths
it has been shown that the EIT/195 Å and AIA/193 Å wavelengths depict coronal holes the best! Structures visible in the maps of other
wavelengths are much less reliable!!**

Instrument | Wavelength | Sine-lat / latitude | Coverage (Carrington rotations and Years) | PNG files | FITS files |
---|---|---|---|---|---|

SOHO/EIT | 171 Å | Sin(lat) | CR1906-CR2211 (Years 1996-2018) | PNG | FITS |

SOHO/EIT | 195 Å | Sin(lat) | CR1906-CR2211 (Years 1996-2018) | PNG | FITS |

SOHO/EIT | 284 Å | Sin(lat) | CR1906-CR2211 (Years 1996-2018) | PNG | FITS |

SOHO/EIT | 304 Å | Sin(lat) | CR1906-CR2211 (Years 1996-2018) | PNG | FITS |

SDO/AIA | 171 Å | Sin(lat) | CR2097-CR2234 (Years 2010-2020) | PNG | FITS |

SDO/AIA | 193 Å | Sin(lat) | CR2097-CR2234 (Years 2010-2020) | PNG | FITS |

SDO/AIA | 211 Å | Sin(lat) | CR2097-CR2234 (Years 2010-2020) | PNG | FITS |

SDO/AIA | 304 Å | Sin(lat) | CR2097-CR2234 (Years 2010-2020) | PNG | FITS |