Can we link the processes that produce geomagnetic storm effects?
Can we identify long-term variations of solar luminosity and resultant impacts on global change?
To what extent is the geospace system modulated by solar activity on different time scales, and how does this modulation interact with forcing from the lower atmosphere?
Can we reconcile various apparent responses of the middle and lower atmosphere to solar activity, in relation to anthropogenic influences, and can we estimate future changes?
The Four Themes under CAWSES
Theme 1: Solar Influence on Climate
Interpretation of past climate change during the Holocene
Particles and minor constituents in the upper atmosphere: solar-terrestrial influences and their role in climate
Theme 4: Space Climatology
Total solar irradiance variability
Upper atmosphere trends
Radiation belt climatology
Long-term cosmic ray variability
Long-term trends in geomagnetic activity
Historical aurora data
Capacity Building & Education
CAWSES will hold meetings and provide specialized training courses for scientists from developing nations and help with computational and data resources
Develop material to educate the public about solar-terrestrial science, its impact on technology & the global environment
Perspectives on CAWSES
The chair’s view:
CAWSES is an ambitious program that builds on and leverages the broad SCOSTEP programs STEP and S-RAMP and more specialized Post-STEP programs.
CAWSES is particularly timely.
Successful implementation of CAWSES will provide an integrated scientific framework for solar-terrestrial research in the future, and provide an informed basis for guiding later programs under different solar conditions and changing anthropogenic influences and as made necessary by new human institutions and technological advances.
Theme 3 Working Groups
WG 3.1: Dynamical coupling (planetary waves, gravity waves, tides, turbulence) and its role in the energy and momentum budget of the middle atmosphere,
WG 3.2: Coupling via photochemical effects on particles and minor constituents in the upper atmosphere: solar/terrestrial influences and their role in climate, and
WG 3.3: Coupling by electrodynamics including ionospheric/magnetospheric processes.
Theme 4 Working Groups (1 of 2)
WG 4.1 Solar Irradiance Variability: possible secular trend of observed total solar irradiance (TSI) and the short-term variability of TSI and the spectral solar irradiance (SSI), time-dependent spectra for SSI (IR to EUV) which can be used in climate models, time series for PSI and proxies such as MgII index for general use, extend proxies for irradiance variability for the last 1000 years, define a climatology of CMEs and solar wind as far as they influence the Earth's environment on time scales longer than the 27-day rotational period of the Sun.
WG4. 2 Heliosphere Near Earth: geomagnetic field and interplanetary magnetic field and its variability during the last 1000 years, cosmic rays with their relation to solar activity and variability during the last 1000 years, historical aurora data as support for the long-term variation of solar activity.
Theme 4 Working Groups (2 of 2)
WG4. 3 Radiation Belt Climatology: evolution of radiation belts, radiation belts and geomagnetic field interrelationship (see also WG4. 2)
WG4. 4, Ionospheric and Upper-Atmosphere Variability (with established IAGA/ICMA liason): ionospheric F-layer height and density variations, thermospheric density variations, mesospheric issues as noctilucent clouds, temperature minimum, composition, etc. (the geomagnetic record is essential and is provided by WG4. 2)
A further WG for the coordination between Theme 3 and 4 is being established with the main objective to look at trends, so it is simply called ‘TRENDS’.
Solar Forcing on Climate at High Latitudes (1 of 6)
Climate time scales for the upper atmosphere are associated with time scales much larger than geomagnetic disturbances (longer time scales than solar rotation);
Solar Forcing in the upper atmosphere also needs to be distinguished between direct response of solar forcing and delayed solar forcing in the complex Earth-lower atmosphere system being propagated upwards, and/or due to anthropogenic effects;
These areas of solar forcing on climate are treated in Themes 3 and 4 which, in fact, are not independent. Theme 3 will attempt to understand the relative role of the second bullet, while Theme 4 will attempt to understand the direct solar forcing in the upper atmosphere and its effects on upper atmosphere climate.
Solar Forcing on Climate at High Latitudes (2 of 6)
At high latitudes the Earth experiences distinct seasonal modulation of the solar forcing. In contrast to the equator, where solar forcing is a well behaved day-night 24 hour phenomena, the high latitude concept of a solar day varies from zero minutes to weeks during a year;
For the forcing of the atmospheric composition at high latitudes (e.g. Ozone) the variability of the irradiance, especially in the UV plays an important role;
The high latitude solar forcing associated with the solar wind-magnetosphere interaction, has a further dependence on the intrinsic magnetic field (connection to cosmogenic isotopes).
Solar Forcing on Climate at High Latitudes (3 of 6)
A number of asymmetries at the Earth come into play independent of the variability of the Sun:
Because the magnetic field is not a "centered dipole" the northern and southern hemisphere are forced differently;
Because the summer-winter seasons are six months apart, northern summer and southern summer observations can never be synchronized, hence, comparisons are fraught with difficulty;
It is well known that the high latitude plasma environments in the northern and southern hemispheres are different.;
Somewhat less well known is that the thermosphere in the northern and southern hemisphere are also different. One explanation, and it has been modelled, is that this difference in the upper atmospheric gas is due to solar forcing via the ionospheric (plasma) coupling to the thermosphere (CAWSES Theme 4). Other explanations, perhaps not as mature, involve the lower atmosphere and the sea-land north-south difference which in turn leads to another difference in solar forcing via the lower atmosphere (CAWSES Theme 3).
Solar Forcing on Climate at High Latitudes (4 of 6)
Important problems are with calibrating solar input or normalizing solar variability to understand how effective solar forcing is;
The solar wind coupling to the geospace depends on orientation of solar wind magnetic field to magnetopause magnetic field directions. At the present time equinoxes are more efficient than solstices;
The deposition of energy from the magnetosphere to the upper atmosphere depends on ionospheric conductivities. We don't know if we have a "voltage" or "current" generator, hence efficiency of deposition is unclear;
Solar wind solar forcing is episodical, peaking e.g. during geomagnetic storms. Hence even climate (long term) studies need to consider how to integrate these weather inputs into the longer term (long-term CME statistics);
During the Maunder Minimum can we deduce that because geomagnetic storms were probably less frequent and less energetic, the upper atmosphere was climatically different? Would such a difference have been independent of the anthropogenic or lower atmosphere solar forcing climatology effects?
Solar Forcing on Climate at High Latitudes (5 of 6)
Studying solar forcing on climate at high latitudes is about as challenging as one can ask for variability independent of solar changes;
The conjugate differences imply that any study must be done over many seasons to obtain true north or south climate trends after integrating over weather, hence years;
This immediately begins to beat with the solar 11 year cycle. Hence, the study needs to be over a century and we are quickly back to limited data sets as well as the anthropogenic effects.
Solar Forcing on Climate at High Latitudes (6 of 6)
The variability of the mesospheric temperature minimum (minimum temperature at an altitude near 90 km) could be an issue. It is well known to be coldest in the summer, but the physics involves complicated transport processes on almost global scales;
The understanding of the various energy sources and their contribution as a function of season is not easily separated from understanding the entire global atmosphere;
CAWSES Theme 4 will have to address solution approaches that are different in different regions. As an example the ionosphere has well separated north and south high latitudes, but are connected by closed field lines globally. In contrast the atmosphere below has strong coupling via global atmospheric dynamics. Concepts like eddy diffusion are the "black boxes" that buffer our various CAWSES regions in still quite unclear ways.
Conclusions
Besides the CAWSES working groups will do great science, publish papers, etc. CAWSES Theme 4 plans to create a "quality controlled and homogenized" climate data base with data from each of the separate regions and phenomena that represent CAWSES Sun-Earth climatology.
This data base would be all on "one CD" and to whatever extent possible be "uninterpreted" that is, as raw as possible.
Additional analyzed data products would also be included as appropriate.
Addresses and Contacts
Claus Fröhlich, Physikalisch Meteorologisches Observatorium Davos, World Radiation Center, CH-7260 Davos Dorf, Switzerland; cfrohlich@pmodwrc.ch
Jan Sojka, Center for Atmospheric and Space Sciences, Utah State University, Logan, UT 84322-4405, USA; fasojka@sojka.cass.usu.edu
CAWSES: Center for Space Physics, Boston University, BOSTON, MA 02215, USA; http://www.bu.edu/cawses with Sanada Basu,Chair, sbasu@cawses.bu.edu and Pallamraju Duggirala, Scientific Coordinator: raju@cawses.bu.edu
SCOSTEP: NOAA-NGDC, Boulder, CO 80305-3328, USA; http://www.noaa.gov/stp/SCOSTEP/scostep.html with Marvin Geller, President: Marvin.Geller@sunysb.edu and Joe Allen, Scientific Secretary: Joe.H.Allen@noaa.gov
