Does the Enhanced Vorticity Lead to Increased Blocking ?

1. Abstract Observed Responses of Winter Storm Vorticity to Jz Initial Day; Space Charge and Scavenging through an Air Mass Subsequent Days; Effects on Coagulation and Initial Rain Rate Blocking Affects Circulation Following a High Jz Day Refereences Barriopedro, D., R. Garcia-Herrera and R. Huth, Solar modulation of the Northern Hemisphere winter blocking, J. Geophys. Res., 113, D14118, 2008. Byers, H. R., General Meteorology, McGraw –Hill Book Co., New York, 1959. Chronis, Thermis, Investigating possible links between incoming cosmic ray fluxes and lightning activity over North America, J. Clim., 22, 5748-5754, 2009. Huth, R. J., L. Pokorná, J. Bochníček and P. Hejda, Solar cycle effects on modes of low‐frequency circulation variability, J. Geophys. Res., 111, D22107, 2006. Kirkland, M. W., B. A. Tinsley and J. T. Hoeksema, Are stratospheric aerosols the missing link between tropospheric vorticity and Earth transits of the heliospheric current sheet?, J. Geophys. 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Acknowledgements This work was begun in 1987 with the encouragement of the late Dr. Ron Taylor, Program director for Meteorology at the National Science Foundation. NSF has provided continuing support, most recently with grants ATM0855351 and ATM0836171. Following a Low Jz Day The flow of Jz through layer clouds, sea-salt haze or fog layers near the ocean surface produces space charge, which is transported into the updraft of a developing cyclone or polar low by the Grenet-Vonnegut mechanism. Subsequent to a high Jz day, with reduced initial production of rain, more liquid water is carried above the freezing level and releases more latent heat of freezing, which invigorates the updrafts (Rosenfeld et al., 2008). The strengthened updraft increases the vorticity, accounting for the observed correlation of winter cyclone vorticity with Jz. The extra ice is also consistent with greater average winter lightning for greater GCR flux in 1990-2005, and less lightning following Forbush decreases (Chronis, 2009). The enhanced updraft deposits more water in the tropopause region VAI response to Relativistic Electron Precipitation Charge Modulation of Aerosol Scavenging (CMAS): Causing Changes in Cyclone Vorticity, and European Winter Circulation? Brian A. Tinsley, University of Texas at Dallas, Tinsley@UTDallas.edu The change in 700 hPa winds from solar maximum to solar minimum in late winters (Feb.-March) for the west phase of the QBO, from 1950-1988 radiosonde data. Modified from Fig. 5 of Venne and Dartt (1990). The January average sea-level pressure contours at 1004 hPa (from Byers, 1959) indicate the location of the Aleutian and Icelandic Lows, with two regions of deeper Icelandic Low indicated by the 1000 hPa contour. Variations in Magnetic Latitude and Altitude of Solar and Terrestrial Inputs and resulting Jz. Does the Enhanced Vorticity Lead to Increased Blocking ? Weidenmann et al., (2002) state “As the upstream cyclone develops due to dynamic and thermodynamic forcing processes, the forcing mechanisms contributing to cyclone development and downstream ridging are synergistically enhanced, resulting in anticyclonic vorticity transport into the developing or strengthening blocking event”. “Stronger blocking events are associated with rapidly deepening cyclone events”. Space charge on aerosol particles and droplets increases scavenging of large particles (by image attractive force), but decreases Brownian and Phoretic scavenging of small particles (by Coulomb repulsion). Ten out of 20,000 trajectories. From the Monte-Carlo model of Tinsley (2010). 500 hPa VAI response to solar wind and relativistic electron flux decreases, for high volcanic aerosol winters . Key days: heliospheric current sheet crossings (and Jz decreases), Nov.-March; Kirkland et al,1996. Elecro- anti-scavenging Low Electro-scavenging High A number of inputs to the atmosphere that are modulated by solar activity have as their only common feature the modulation of the ionosphere-earth current density (Jz) in the global electric circuit, and for which there are small, high latitude atmospheric responses in winter storm vorticity, surface pressure, mid-tropospheric temperature, and cloud cover. Similar responses are found to internal atmospheric inputs that modulate Jz. The solar inputs include the cosmic ray flux, relativistic electrons, solar energetic particles, and the solar wind electric field. The atmospheric inputs include the variable current output (~1000 A) of global thunderstorms and highly electrified clouds. The flow of Jz through resistivity gradients in clouds or aerosol layers whenever they are present produces space charge, and this modifies the aerosol scavenging due to Brownian diffusion and phoretic forces (Charge Modulation of Aerosol Scavenging, or CMAS). The result is a narrowing of the size distribution of aerosol particles in the air mass, on a timescale of 1-10 days. On a subsequent day, when a cyclone develops, the resulting narrower droplet size distribution in the updraft reduces coagulation and inhibits the production of rain, so that more liquid water is carried above the freezing level (Rosenfeld mechanism). There the enhanced release of latent heat of freezing invigorates the updraft and increases the cyclone vorticity and lightning, consistent with the observations. Also, there will be more transport of water to the tropopause region. Possible consequences for Rossby wave amplitude are explored, including enhanced blocking and circulation changes at solar minima; especially at extended solar minima, as observed. High Low Comparison of observed blocking duration for high vs low solar activity winters, in Atlantic region. From Huth et al. (2006). See also Lockwood et al (2010). Variation of collision rate coefficients for particles from 0.001m to 2m, with droplets of 15m, with droplet charge 100e and particle charge 0e (Brownian diffusion), or 5e, or 10e. ‘Analytic’ is without intercept effect. Tinsley, (2010). Electro-scavenging removes large and giant CCN, and reduces Brownian and Phoretic loss rates of small CCN, so narrows the size distribution and increases the total CCN concentration. SYNTHESIS OF EVENTS ON THE 11-YEAR SOLAR CYCLE : (a) a modulation of high latitude Jz due to solar modulation of the cosmic ray (GCR) flux. (b) An increase in cyclone frequency At GCR maximum (solar min.) in the Western North Atlantic cyclogenesis region (Labitzke and van Loon 1989). Such intensification of cyclones increases large scale ridging and anticyclonic blocking half a Rossby wave downstream (e.g., Wiedenmann et al., 2002). (c) Storm track changes in the Eastern N. Atlantic follow, as in Tinsley (1988) and Tinsley and Deen, (1991). (d) These involve changes in the 700 hPa wind speeds and directions in the North Atlantic and European regions, (Venne and Dartt, 1990). There is a northward meridional flow in the eastern North Atlantic, and reduction of zonal flow of moist air onto Europe for solar min. (Jz max.). This was also inferred for very cold winters in the Maunder minimum by Luterbacher et al. (2001). SOLAR MODULATION OF BLOCKING IMPACTS ON THE NEAR-SURFACE (2-m) TEMPERATURE DISTRIBUTION 1955-1999 VAI response for high stratospheric volcanic aerosol winters compared with low aerosol winters. Key days prior to 1995 are HCS crossings; from 1996 are relativistic electron flux minima. On a subsequent day the increased CCN concentration and more homogeneous CCN size distributions give clouds with smaller droplets and a more homogeneous droplet size distribution. Variations in altitude and magnetic latitude of parameters affecting Jz, and resulting changes in Jz, for longitude 92.5°E, from South Magnetic Pole in Antarctica through the Indian Ocean, South Asia, the Himalayas, Siberia, and across the Arctic Ocean to North Magnetic Pole. In (a) percentage changes in ion concentration, n, during both solar cycle and during Forbush decreases of GCR. In (b) absolute resistivity changes corresponding to (a) derived from Tinsley and Zhou (2006). In (c) amplitudes of various inputs that modulate Jz are estimated or shown schematically, with relativistic electron flux (REF); solar energetic particles (SEP); solar wind By+, By-, and Bz-; GCG+ and GCG- from global circuit generator variations. In (d) the resulting changes in the latitude distribution of Jz variations (for 92.5°E) are estimated or shown schematically. The effect of the REF is complicated by variations in stratospheric aerosol content, and is omitted. With more smaller droplets, and fewer large ones, the rate of coagulation, necessary for ‘warm cloud’ rain is reduced. Thus the production of rain is reduced in the region below the freezing level.. The climatological (all days) distribution of temperatures for all locations is first computed, and then the percentage of Atlantic blocking days with temperature anomalies in the lower tercile is computed with the blocking days sorted by (a) highest solar activity, and (b) lowest solar activity. The effects of LS blocking gives colder temperatures for most of Europe in which more than 50% of the blocking days are associated with temperature anomalies in the lower tercile. For HS the percentage of blocking only exceeds the expected value (33%) in northern Europe. Shaded areas denote those values exceeding 33%, with a 5% contour interval, and the solid line denotes the threshold for the confidence level of 95%. From Barriopedro et al., 2008. Variation of squared vorticity (in s-2 )in region 50°5-70°N, 0°-40°W, with SEP events, from Veretenenko and Thejll, (2004)