Solar wind connection to regional climate

Lead Research Organisation: NERC British Antarctic Survey
Department Name: Science Programmes

Abstract

Lu et al. (2008) have shown that there is a robust relationship between solar wind dynamic pressure and the winds and temperatures in the northern polar winter stratosphere and troposphere. These wind and temperature variations are indicative of the Northern Annular Mode of climate oscillation which largely determines the predominant winter weather pattern across Europe. The signature of solar wind dynamic pressure in the lower atmosphere data is stronger and statistically more robust than those associated with either the QBO or the 11-yr solar cycle, and the timescales suggest that the most likely link is a dynamical one. Clilverd et al. (2006) predicted that solar cycle number 24, which is just beginning, would be unusually low. This has since been circumstantially supported by recent observations which show that the current solar minimum is the lowest for 200 years, that the onset of cycle 24 has been delayed, and that the solar wind dynamic pressure is ~20% lower than the previous cycle, the weakest it has been during the era of in-situ spacecraft measurements. Taken together this evidence that we are currently entering an era of low solar wind dynamic pressure, and the evidence that solar wind dynamic pressure is related to the NAM imply that, between 2012 and 2017 (the next solar maximum), we are likely to see drier winter weather with fewer storms in the UK and Scandinavia together with wetter weather in Southern Europe. However, while the statistical evidence for a relationship between the solar wind dynamic pressure and the NAM is very strong (>99%), a physical connection is not understood. The aim of the proposed research is to substantiate whether a physical connection exists by exploring, using both observations and models, just how the solar wind dynamic pressure can connect to the stratosphere in the polar regions, and hence how it can be strongly correlated with the Northern Annular Mode.

Publications

10 25 50
 
Description Solar Wind Connection to Regional Climate The project is investigating the apparent link between the solar wind and regional climate - particularly with reference to the effect of the solar wind on the Northern Annular Mode (NAM) of atmospheric oscillation in the stratosphere and hence an effect on European winter climate. So far the research has shown that a dynamically consistent pattern in the mean flow and waves descends over a period of some 45 days in response to stronger than normal positive solar wind dynamic pressure (SWDP). This implies that stratospheric anomalies affect the tropospheric circulation and that a top-down mechanism therefore plays a role in the solar wind signature. We also find an equatorward shift of Rossby wave breaking near the tropopause in late winter and a pattern of wave breaking which suggests that it is associated with a positive NAM; we have previously shown the positive NAM to be associated with positive SWDP anomalies. We have also shown that during enhanced geomagnetic activity, induced by solar wind variabiity, the polar vortex becomes stronger in late winter and more planetary waves are refracted equatorward; this has a clearer signature under high solar irradiance.
We have shown that during periods of precipitation there is a measurable change in the mesospheric winds at high latitudes, which have the possibility to effect chemical transport. In the southern hemisphere large geomagnetic storms can generate precipitation from the inner edge of the outer radiation belt to latitudes that have not yet been considered as important. The consequences of this change in chemistry is yet to be explored
Exploitation Route Papers have been published with Key findings that can be accessed by the peer community. Outreach items are being prepared that will be made available to stake-holders.
Sectors Environment

 
Description In order to accurately measure the changes to regional climate induced by human activity we first need to quantify the background variations occurring due to natural processes. There is recent statistical evidence that some of these background variations may be driven by the continually varying solar wind - a stream of ionised particles blowing away from the Sun and encompassing Earth in its path. We have compared solar wind observations taken in outer space with measurements from within the bottom 40km of Earth's atmosphere. We have found that when the pressure of the solar wind increases, patterns of large scale wave activity move down through the atmosphere in the northern hemisphere winter taking about 45 days to pass from the upper stratosphere to the surface. The pattern itself can change in a complex way dependent upon the phase of the solar cycle, and the air circulation in the stratosphere over the Arctic. This work is a step toward quantifying how much climate has been, and will be, be altered by solar activity. Beneficiaries: Climate science peer community
Sector Environment
Impact Types Cultural

 
Description EGU 2014 conference (Austria) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presentation on: "The Impact of solar wind co-rotating interaction regions on the dynamics of the neutral middle atmosphere"
Presented at the European Geosciences Union General Assembly in Vienna, Austria (27 April - 02 May 2014).
The work was seen by many colleagues in my field (~100) plus many from related fields. Feedback indicated a strong interest in following this work to identify whether the results were repeatable for other observations sites.
Year(s) Of Engagement Activity 2014
URL http://www.egu2014.eu/
 
Description EGU_2015_conference 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Poster presentation on "The radiation belt slot region: A source of energetic electron precipitation in the southern hemisphere polar vortex".
Presented at the 2015 European Geosciences Union General Assembly in Vienna, Austria (12 - 17 April 2015)
Purpose: to communicate a new result to the wider community, feedback suggested interest from colleagues on pursuing this area of investigation.
Year(s) Of Engagement Activity 2015
URL http://www.egu2015.eu/
 
Description NAM-MIST conference 2015 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact A presentation at the Joint National Astronomy Meeting/ Magnetosphere-Ionosphere-Solar Terrestrial meeting at Llandudno, UK, (http://nam2015.org/). Originally a talk: "The radiation belt slot region: A source of energetic electron precipitation in the southern hemisphere polar vortex" but invited to give an introduction on "high Energy particles in the Atmosphere".
The talk stimulated some interesting debate on the causes of the results and a school teacher who attended expressed a strong interest in pursuing a possible collaboration to provide ground station data taking for their cube-sat project.
Year(s) Of Engagement Activity 2015
URL http://nam2015.org/
 
Description SuperDARN workshop 2015 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Presentation of the expanded study of: "The impact of solar wind co-rotating interaction regions on the dynamics of the neutral middle atmosphere" presented at the International SuperDARN workshop, 2015, held in Leicester, UK (1-5 June). The purpose was to share the results of the study with colleagues associated withe the instruments used to generate the data. Generated useful discussion on the steps to improve statistics and highlighted aspects to concentrate on.
Year(s) Of Engagement Activity 2015
URL http://www2.le.ac.uk/departments/physics/research/rspp/sd/superdarn-2015/sd2015