A COMPARISON OF SUNSPOT
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A COMPARISON OF SUNSPOT POSITION MEASURMENTS FROM DIFFERENT DATA SETS. Ivana Poljan č i ć Physics Department U niversity of Rijeka , C roatia [email protected] IHY-ISWI Regional Meeting Heliophysical phenomena and Earth's environment. 7-13 September 2009, Šibenik, Croatia.

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Ivana poljan i physics department u niversity of rijeka c roatia ipoljancic phy uniri hr

A COMPARISON OF SUNSPOT

POSITION MEASURMENTS

FROM DIFFERENT

DATA SETS

IvanaPoljančić

Physics Department

University of Rijeka, Croatia

[email protected]

IHY-ISWI Regional Meeting

Heliophysical phenomena

and Earth's environment

7-13 September 2009, Šibenik, Croatia


Ivana poljan i physics department u niversity of rijeka c roatia ipoljancic phy uniri hr

...with

R. Brajsa1, D. Ruzdjak1,

D. Hrzina2, R. Jurdana-Sepić3,

H. Wöhl4, W. Otruba5

1Hvar Observatory, Faculty of Geodesy, University of Zagreb

2Zagreb Astronomical Observatory, Croatia

3Department of Physics, University of Rijeka, Croatia

4Kiepenheuer-Institut für Sonnenphysik,

Freiburg, Germany

5Solar Observatory Kanzelhöhe,

Austria

7-13 September 2009, Šibenik, Croatia

IHY-ISWI Regional Meeting

Heliophysical phenomena

and Earth's environment


Ivana poljan i physics department u niversity of rijeka c roatia ipoljancic phy uniri hr

Solar differential rotation - Scientific context

  • one of the fundamental properties of the Sun as the star

  • observational constraint on theoretical models of the rotating convection zone

  • MHD dinamo -> solar magnetic activity

  • Results for the time period 1874 – 1976:

    • dependence of solar rotation on time (Brajša et al. 2006)

    • relationship between the solar rotation and activity (Brajša et al. 2007)

  • -> to extend 1977 - present

IHY-ISWI Regional Meeting, Šibenik, 2009 - A comparison of sunspot position measurments from different data sets


Ivana poljan i physics department u niversity of rijeka c roatia ipoljancic phy uniri hr

Motivation and aims

1. Greenwich Photoheliographic results (GPR)

  • ->1874 – 1976

  • 2. Solar Optical Observing Network (SOON),

  • United States Air Force (USAF),

  • National Oceanic and Atmospheric Administration

  • (NOAA)

  • -> 1977 - present

  • data in almost the same format

  • the aim is to check the precision of the second data set and compare it with the first one

IHY-ISWI Regional Meeting, Šibenik, 2009 - A comparison of sunspot position measurments from different data sets


Ivana poljan i physics department u niversity of rijeka c roatia ipoljancic phy uniri hr

Data sets

  • Positions of sunspot groups :

    • GPR

    • SOON/USAF/NOAA

  • A comparison with other data sets: Kanzelhöhe data, drawings (1947 – present)

  • To identify sunspot groups we also used:

    • Debrecen Photoheliographic Data (1977 - present)

  • IHY-ISWI Regional Meeting, Šibenik, 2009 - A comparison of sunspot position measurments from different data sets


    Ivana poljan i physics department u niversity of rijeka c roatia ipoljancic phy uniri hr

    Data selection for test

    • 1972: GPR & Kanzelhöhe

    • 1993: SOON/USAF/NOAA& Kanzelhöhe

    • aproximately the same phases of different solar cycles

    • mostly isolated single H and J sunspot groups (Zürich types)

    IHY-ISWI Regional Meeting, Šibenik, 2009 - A comparison of sunspot position measurments from different data sets


    Ivana poljan i physics department u niversity of rijeka c roatia ipoljancic phy uniri hr

    Methods

    • determining positions and angular velocities of selected sunspot groups from the digitized Solar Observatory Kanzelhöhe drawings

    • comparing the determined Kanzelhöhe sunspot group coordinates and angular velocities with those from GPR (1972) and SOON/USAF/NOAA (1993)

    • Sungrabber: a special software for determination of tracer’s positions in full disk solar images

    IHY-ISWI Regional Meeting, Šibenik, 2009 - A comparison of sunspot position measurments from different data sets


    Ivana poljan i physics department u niversity of rijeka c roatia ipoljancic phy uniri hr

    Sungrabber

    Kanzelhöhe drawing (25th Jan. 1993)

    • images in the several graphical formats (jpg, gif, bmp...)

    • for different purposes (determination of tracer’s heliographic coordinates in full disk solar images)

    • Hrzina et al., 2007

    • (www.zvjezdarnica.hr/sungrabber)


    Ivana poljan i physics department u niversity of rijeka c roatia ipoljancic phy uniri hr

    Sungrabber

    • Seetings -> Coordinate system, Zero Point, Date and Time


    Ivana poljan i physics department u niversity of rijeka c roatia ipoljancic phy uniri hr

    Sungrabber

    • Input -> Sun’s limb, Daily parallel, New Object


    Ivana poljan i physics department u niversity of rijeka c roatia ipoljancic phy uniri hr

    Sungrabber

    • Input -> New Object; File -> Save


    Ivana poljan i physics department u niversity of rijeka c roatia ipoljancic phy uniri hr

    Sungrabber


    Ivana poljan i physics department u niversity of rijeka c roatia ipoljancic phy uniri hr

    Number of analysed sunspot groups

    IHY-ISWI Regional Meeting, Šibenik, 2009 - A comparison of sunspot position measurments from different data sets


    Ivana poljan i physics department u niversity of rijeka c roatia ipoljancic phy uniri hr

    Results – Single H and J sunspot groups

    (GPR vs. Kanz. & SOON vs. Kanz., heliographic coordinates)

    DL, DB – difference between Kanzelhöhe and other data sets longitude (latitude)

    IHY-ISWI Regional Meeting, Šibenik, 2009 - A comparison of sunspot position measurments from different data sets


    Ivana poljan i physics department u niversity of rijeka c roatia ipoljancic phy uniri hr

    Results – Single H and J sunspot groups

    (GPR vs. Kanz. & SOON vs. Kanz., angular velocities)

    Dw– difference between Kanzelhöhe and other data sets angular velocities

    IHY-ISWI Regional Meeting, Šibenik, 2009 - A comparison of sunspot position measurments from different data sets


    Ivana poljan i physics department u niversity of rijeka c roatia ipoljancic phy uniri hr

    Results – Complex sunspot groups

    (heliographic coordinates & angular velocities)

    Results: Observer 1

    IHY-ISWI Regional Meeting, Šibenik, 2009 - A comparison of sunspot position measurments from different data sets


    Ivana poljan i physics department u niversity of rijeka c roatia ipoljancic phy uniri hr

    Difference between the two observers

    (Average absolute deviation)

    IHY-ISWI Regional Meeting, Šibenik, 2009 - A comparison of sunspot position measurments from different data sets


    Ivana poljan i physics department u niversity of rijeka c roatia ipoljancic phy uniri hr

    Conclusions

    • With the assumption of constant reliability of Kanzelhöhe drawings

    • –> SOON/USAF/NOAA data are somewhat less precise then GPR

    • the precision of the second data set (SOON/USAF/NOAA ) is still suitable for the investigation of long term measurments of solar rotation as a global parameter of the Sun as the star

    • future work:

      • to reduce more data and to include further data sets

      • to apply the residual methods (one D value per year) on SOON/USAF/NOAA

      • temporal variations and relationship with the level of solar activity

    IHY-ISWI Regional Meeting, Šibenik, 2009 - A comparison of sunspot position measurments from different data sets


    Ivana poljan i physics department u niversity of rijeka c roatia ipoljancic phy uniri hr

    Acknowledgements

    This work is sponsored by the Air Force Office of Scientific Research, Air Force Material Command, USAF, Under grant member FA8655-07-1-3093.

    Also, the research leading to the results presented here has partly received funding from European Community’s Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 218816.

    IHY-ISWI Regional Meeting, Šibenik, 2009 - A comparison of sunspot position measurments from different data sets


    Ivana poljan i physics department u niversity of rijeka c roatia ipoljancic phy uniri hr

    Acknowledgements

    Finally, we are thankfull to E. Cliver and N. Gopalswamy for usefull suggestions and discussions.

    Thank you for your attention!

    IHY-ISWI Regional Meeting, Šibenik, 2009 - A comparison of sunspot position measurments from different data sets


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