Presentation on theme: "Heliophysics Integrated Observatory (HELIO) Issues related to designing a VO for Heliophysics Bob Bentley (UCL-MSSL) 13 June 2007 VOiG Conference, Denver."— Presentation transcript:
Heliophysics Integrated Observatory (HELIO) Issues related to designing a VO for Heliophysics Bob Bentley (UCL-MSSL) 13 June 2007 VOiG Conference, Denver CO, USA
Heliophysics Integrated Observatory (HELIO) 2 Outline Examine some of the items needed to facilitate a virtual observatory for heliophysics Identify deficiencies and suggest solutions Talk evolved as I was preparing it… Started looking at proton events and GLEs because of space weather effects related to aviation Found problems with the metadata
Heliophysics Integrated Observatory (HELIO) 3 Heliophysics Heliophysics explores the Sun-Solar System Connection An extension of the study of space weather (SWx++) Heliophysics sits in the boundary between two communities Astrophysics o An understanding of solar phenomena helps in the understanding of stellar observations Planetary sciences (including Geosciences) o Solar activity can influence the environment on/around the planets The discipline must be aware of the need to support the interests of both communities A virtual observatory that supports Heliophysics must facilitate access to data from a number of communities Solar, heliospheric, magnetospheric and ionospheric physics As such, it is in essence a next generation VxO
Heliophysics Integrated Observatory (HELIO) 4 Heliophysics The communities that constitute heliophysics have evolved independently over decades and even centuries Little or no coordination of how each has evolved Each has very different ways of describing, storing and exploiting the data from their observations The desire to solve science problems that span disciplinary boundaries is driving the need to provide combined access to these data To do this, we need to find ways to: Tie the data together through searches across all the datasets Present any results in a form that does not require a detailed understanding of each discipline This requires the re-evaluation of the capabilities provided within each community and some correctative action
Heliophysics Integrated Observatory (HELIO) 5 Types of metadata To facilitate a VxO for heliophysics we need to examine the metadata that is required. There are many ways these can be described, one is: Search metadata o Metadata used to identify time intervals and sets of data of interest Observational metadata o Metadata used to describes the observations, e.g. FITS headers Storage metadata o Metadata that describes how the data are stored and accessed Administrative metadata o Metadata that allows the system to exploit the available resources The rest of the talk will concentrate on issues related to the first two sets
Heliophysics Integrated Observatory (HELIO) 6 Searches In heliophysics, we are interested in how an event on or near the solar surface can propagate through the heliosphere and affect a planetary environment Searches should identify interesting time intervals based on a combination of event, features, etc. metadata Each community of some from of these data There are concerns about the quality and integrity of the metadata and whether it is adequate to support the searches we would like to undertake
Heliophysics Integrated Observatory (HELIO) 7 Solar search metadata Phenomena occur on or near the solar surface Event data gives time and location of phenomena Feature data provides details of location and size of structures that may be relevant Time information can be expressed in many ways Essentially these are the same, with simple transformations Spatial information can be expressed in terms of: Coordinates in the observing frame – e.g. arcsecs from disc centre Coordinates on the rotating body of the Sun – Carrington coords. The position of the observer was ignored for the most part Helio-seismology is an exception In the bigger picture of heliophysics, also need to include the viewing perspective
Heliophysics Integrated Observatory (HELIO) 8 Other search data Observation of phenomena in the heliosphere and near/on planets are more complex For in-situ observations in the heliosphere Time is when a phenomena affected (passed) the observer Position of the observer relative to the Sun is key to understanding When the in-situ observations are made on/near a planet Position of the observer relative to the planet is also important Relating events that are defined from in-situ data to those on/near the Sun requires an understanding of how events propagate Details of the velocity structure of CMEs and the solar wind are not easy to determine…
Heliophysics Integrated Observatory (HELIO) 9 Simple, but not so simple In principle this all seems fairly obvious, but lets look in detail at some common solar event data On 20 January 2005 there was an X7.1 flare that was intensely geo- effective. The flare was associated with particle event and a CME; it was also observed by ground-level neutron monitors – a GLE. Many superlatives were used to describe the event o "The solar energetic particle event of January 20 2005 has been called, by some measures, the most intense in 15 years..." (Mewaldt et al., 2005) o ”The fastest rising SEP event of current cycle [cycle 23]" (Rawat et al., 2006) o ”The most spectacular [solar event] of the Space Age" (Tylka et al., 2006) o ”The largest GLE [GLE 69] in half a century" (Bartol Research Institute) But event is absent from the NOAA SEC list of "Solar Proton Events Affecting the Earth Environment" When you look at the data and how lists are created, you realize that the lists are deficient in several ways o Humans and SmFCACs can understand what happened, but o it is harder for machines...
Heliophysics Integrated Observatory (HELIO) 10 X7.1 of 20 Jan 2005 The event was one of several from AR 10720 Two other X class flares and several M class flares occurred in previous 3 days; others before this
Heliophysics Integrated Observatory (HELIO) 11 X7.1 of 20 Jan 2005
Heliophysics Integrated Observatory (HELIO) 12 X7.1 of 20 Jan 2005 At the time of the event, the proton levels had not returned to normal after previous events The criteria fails to recognize a new event o NOAA lists event on 16 Jan The X-ray data also suffers from problems The end of an event is defined by when the counts drop to 50% o New events can “interrupt” existing events The shape and true duration of the decay phase are lost o NOAA gives start 0636; end 0726 Not all locations are tagged!! Significant brightenings seen on images not declared as flares
Heliophysics Integrated Observatory (HELIO) 13 Some of the problems That major events can be “missed” is worrying and makes automated searches difficult A search for long duration events would yield spurious results Since the locations of all flares are not known, it is impossible to know if they will be geo-effective Instrument flare lists have gaps – nights, off times, etc. – but the reason for a null result is not included
Heliophysics Integrated Observatory (HELIO) 14 Improving event data Existing flare lists can give a distorted picture what has occurred Such deficiencies make it difficult for non-experts to use them The community “knowledge” is not written down Need to re-evaluate and regenerate the event data in all domains with the idea that the data will be used in a joint search across the domains Ensure events more accurately described Include information that might explain null results
Heliophysics Integrated Observatory (HELIO) 15 Observation metadata Metadata related to observations gives information about how the observation was made, etc. There are often quality issues related to the metadata that is provided – parameters sometimes missing, or wrong In solar data, space-based observations much better described than their ground-based counterparts Researchers often used to deficiencies in the data in their own domain Difficult for machines to handle if it is not quantified properly VxOs can sometimes develop ways of patching the gaps What do we do with this information? How is it shared?
Heliophysics Integrated Observatory (HELIO) 16 Observation metadata In solar physics we have tried to introduce standards SOHO made good start with their keyword document EGSO enhanced concepts with its data model Situation better than it was but adoption still not universal Even some problems within SOHO…
Heliophysics Integrated Observatory (HELIO) 17 Standards Need to extend the use of standards to all domains so that all future data are more compatible with the VxOs The situation has changed with enhancements in technology; providers need to ensure they are more compliant VxO will need to handle problems with the older data; providers cannot be expected to do it Standards need to be developed in collaboration with the community and funding agencies Core part that is required Additional information that may be specific to a domain Other information that the instrument team wants to add In developing standards need to draw on the experience gained within the general VO community and adopt the best ideas available
Heliophysics Integrated Observatory (HELIO) 18 Conclusions Developing a virtual observatory to support heliophysics will not be simple Some of the possible problems have been highlighted To address them, we need to engage the communities in all the domains that constitute heliophysics and develop standards that will facilitate the process
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