Latitudinal extent of the January 2005 solar proton event in the Northern Hemisphere from satellite observations of hydroxyl

Verronen, Pekka T.; Rodger, Craig J.; Clilverd, Mark A.; Pickett, Herbert M.; Turunen, Esa

doi:10.5194/angeo-25-2203-2007

Cited by 30 publications

(36 citation statements)

References 33 publications

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“…These WACCM3 simulations are summarized in Table 1. The ionization rates, when included, were applied uniformly over both polar cap regions (60-90 • N and 60-90 • S geomagnetic latitude) as solar protons are guided by the Earth's magnetic field lines to approximately these areas (McPeters et al, 1981;Jackman et al, 2005a). Verronen et al (2007) show that the geomagnetic boundary can vary with the proton forcing ranging from none to a full affect between about 57 and 64 • N for the January 2005 SPEs time period. Our assumption of a uniform forcing over the entire polar cap may slightly overestimate the affected area.…”

Section: Ho X and No X Productionmentioning

confidence: 99%

Northern Hemisphere atmospheric influence of the solar proton events and ground level enhancement in January 2005

et al. 2011

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Abstract. Solar eruptions in early 2005 led to a substantial barrage of charged particles on the Earth's atmosphere during the 16-21 January period. Proton fluxes were greatly increased during these several days and led to the production of HO x (H, OH, HO 2 ) and NO x (N, NO, NO 2 ), which then caused the destruction of ozone. We focus on the Northern polar region, where satellite measurements and simulations with the Whole Atmosphere Community Climate Model (WACCM3) showed large enhancements in mesospheric HO x and NO x constituents, and associated ozone reductions, due to these solar proton events (SPEs). The WACCM3 simulations show enhanced short-lived OH and HO 2 concentrations throughout the mesosphere in the 60-82.5 • N latitude band due to the SPEs for most days in the 16-21 January 2005 period, somewhat higher in abundance than those observed by the Aura Microwave Limb Sounder (MLS). These HO x enhancements led to huge predicted and MLS-measured ozone decreases of greater than 40 % throughout most of the northern polar mesosphere during the SPE period. increases (< 0.05 ppbv) in the upper stratosphere during this time period. Polar mesospheric enhancements of NO x are computed to be greater than 50 ppbv during the SPE period due to the small loss rates during winter. Computed NO x increases, which were statistically significant at the 95 % level, lasted about a month past the SPEs. The SCISAT-1 Atmospheric Chemistry Experiment Fourier Transform Spectrometer NO x measurements and MI-PAS NO 2 measurements for the polar Northern Hemisphere are in reasonable agreement with these predictions. An extremely large ground level enhancement (GLE) occurred during the SPE period on 20 January 2005. We find that protons of energies 300 to 20 000 MeV, associated with this GLE, led to very small enhanced lower stratospheric odd nitrogen concentrations of less than 0.1 % and ozone decreases of less than 0.01 %.

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Section: Ho X and No X Productionmentioning

confidence: 99%

Northern Hemisphere atmospheric influence of the solar proton events and ground level enhancement in January 2005

et al. 2011

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“…Changes in the concentrations of O 3 , HO x , NO x , HNO 3 and in temperature caused by the SPEs of 17 and 20 January 2005 have been reported in recent studies (e.g., Seppälä et al, 2006;Verronen et al, , 2007Verronen et al, , 2011aKlekociuk et al, 2007;Damiani et al, 2008;Seppälä et al, 2008;Orsolini et al, 2009;Becker and von Savigny, 2010;Jackman et al, 2011). In this paper we study the changes that occurred in a larger set of chlorine species (i.e., HCl, ClO, HOCl and ClONO 2 ) by using MLS and MIPAS data and Whole Atmosphere Community Climate Model (WACCM) version 4 simulations.…”

Section: A Damiani Et Al: January 2005 Spe On Chlorine Species 4161mentioning

confidence: 99%

Impact of January 2005 solar proton events on chlorine species

et al. 2012

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Abstract. Sudden changes in stratospheric chlorine species in the polar northern atmosphere, caused by the Solar Proton Events (SPEs) of 17 and 20 January 2005, have been investigated and compared with version 4 of the Whole Atmosphere Community Climate Model (WACCM4). We used Aura Microwave Limb Sounder (MLS) measurements to monitor the variability of ClO, HCl, HOCl and Michelson Interferometer for Passive Atmospheric Sounder (MIPAS) on ENVISAT to retrieve ClONO 2 . SPE-induced chlorine activation has been identified. HCl decrease occurred at nearly all the investigated altitudes (i.e., 10-0.5 hPa) with the strongest decrease (of about 0.25 ppbv) on 21 January. HOCl was found to be the main active chlorine species under nighttime conditions (with increases of more than 0.2 ppbv) whereas both HOCl and ClO enhancements (about 0.1 ppbv) have been observed at the polar night terminator. Further, small ClO decreases (of less than 0.1 ppbv) and ClONO 2 enhancements (about 0.2 ppbv) have been observed at higher latitudes (i.e., at nighttime) roughly above 2 hPa.While WACCM4 reproduces most of the SPE-induced variability in the chlorine species fairly well, in some particular regions discrepancies between the modeled and measured temporal evolution of the abundances of chlorine species were found. HOCl changes are modelled very well with respect to both magnitude and geographic distribution. ClO decreases are reproduced at high latitudes, whereas ClO enhancements in the terminator region are underestimated and attributed to background variations. WACCM4 also reproduces the HCl depletion in the mesosphere but it does not show the observed decrease below about 2 hPa. Finally, WACCM4 simulations indicate that the observed ClONO 2 increase is dominated by background variability, although SPE-induced production might contribute by 0.1 ppbv.

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“…In particular, since we can assume the same ionisation rate at the two sites at any time when solar proton precipitation dominates (see e.g. Verronen et al, 2007), the differing χ between the sites provide a very sensitive test of the χ dependence of the ionospheric response. For the same ion production rate at 12:45 UT the model computations reproduce well the difference in the electron density at h≤70 km between EISCAT and PRM ( Fig.…”

Section: Minor Neutral Constituentsmentioning

confidence: 99%

D-region electron density and effective recombination coefficients during twilight – experimental data and modelling during solar proton events

et al. 2009

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Abstract. Accurate measurements of electron density in the lower D-region (below 70 km altitude) are rarely made. This applies both with regard to measurements by ground-based facilities and by sounding rockets, and during both quiet conditions and conditions of energetic electron precipitation. Deep penetration into the atmosphere of high-energy solar proton fluxes (during solar proton events, SPE) produces extra ionisation in the whole D-region, including the lower altitudes, which gives favourable conditions for accurate measurements using ground-based facilities. In this study we show that electron densities measured with two ground-based facilities at almost the same latitude but slightly different longitudes, provide a valuable tool for validation of model computations. The two techniques used are incoherent scatter of radio waves (by the EISCAT 224 MHz radar in Tromsø, Norway, 69.6 • N, 19.3 • E), and partial reflection of radio-waves (by the 2.8 MHz radar near Murmansk, Russia, 69.0 • N, 35.7 • E). Both radars give accurate electron density values during SPE, from heights 57-60 km and upward with the EISCAT radar and between 55-70 km with the partial reflection technique. Near noon, there is little difference in the solar zenith angle between the two locations and both methods give approximately the same values of electron density at the overlapping heights. During twilight, when the difference in solar zenith angles increases, electron density values diverge. When both radars are in night conditions (solar zenith angle >99 • ) electron densities at the overlapping altitudes again become equal. We use the joint measurements to validate model computations of the ionospheric parameters f + , λ, α eff and their variations during solar proton events. These parameters are important characteristics of the lower ionosphere structure which cannot be determined by other methods.

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Latitudinal extent of the January 2005 solar proton event in the Northern Hemisphere from satellite observations of hydroxyl

Cited by 30 publications

References 33 publications

Northern Hemisphere atmospheric influence of the solar proton events and ground level enhancement in January 2005

Northern Hemisphere atmospheric influence of the solar proton events and ground level enhancement in January 2005

Impact of January 2005 solar proton events on chlorine species

D-region electron density and effective recombination coefficients during twilight – experimental data and modelling during solar proton events

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