Identification

Title

The longitudinal evolution of equatorial coronal holes

Abstract

In 2011, three satellites-the Solar-Terrestrial RElations Observatory A B, and the Solar Dynamics Observatory (SDO)-were in a unique spatial alignment that allowed a 360 degrees view of the Sun. This alignment lasted until 2014, the peak of solar cycle 24. Using extreme ultraviolet images and Hovmoller diagrams, we studied the lifetimes and propagation characteristics of coronal holes (CHs) in longitude over several solar rotations. Our initial results show at least three distinct populations of "low-latitude" or "equatorial" CHs (below 65 degrees latitude). One population rotates in retrograde direction and coincides with a group of long-lived (over sixty days) CHs in each hemisphere. These are typically located between 30 degrees and 55 degrees, and display velocities of similar to 55. m s(-1) slower than the local differential rotation rate. A second, smaller population of CHs rotate prograde, with velocities between similar to 20 and 45 m s(-1). This population is also long-lived, but observed. +/- 10 degrees from the solar equator. A third population of CHs are short-lived (less than two solar rotations), and they appear over a wide range of latitudes (+/- 65 degrees) and exhibit velocities between -140 and 80 m s(-1). The CH "butterfly diagram" we developed shows a systematic evolution of the longer-lived holes; however, the sample is too short in time to draw conclusions about possible connections to dynamo-related phenomena. An extension of the present work to the 22 years of the combined SOHO-SDO archives is necessary to understand the contribution of CHs to the decadal-scale evolution of the Sun.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d7ht2s1s

codeSpace

Dataset language

eng

Spatial reference system

code identifying the spatial reference system

Classification of spatial data and services

Topic category

geoscientificInformation

Keywords

Keyword set

keyword value

Text

originating controlled vocabulary

title

Resource Type

reference date

date type

publication

effective date

2016-01-01T00:00:00Z

Geographic location

West bounding longitude

East bounding longitude

North bounding latitude

South bounding latitude

Temporal reference

Temporal extent

Begin position

End position

Dataset reference date

date type

publication

effective date

2018-03-01T00:00:00Z

Frequency of update

Quality and validity

Lineage

Conformity

Data format

name of format

version of format

Constraints related to access and use

Constraint set

Use constraints

Limitations on public access

None

Responsible organisations

Responsible party

contact position

OpenSky Support

organisation name

UCAR/NCAR - Library

full postal address

PO Box 3000

Boulder

80307-3000

email address

opensky@ucar.edu

web address

http://opensky.ucar.edu/

name: homepage

responsible party role

pointOfContact

Metadata on metadata

Metadata point of contact