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
Abstract
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, midtropospheric 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.
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
Vorticity Area Index Decreases with Forbush Decreases and Jz Decreases
Blocking Affects Circulation
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.
Superposed epoch variations of GCR flux, Ap index, and 500 hPa northern
hemisphere Vorticity Area Index, with key days onsets of Forbush decreases
(and Jz decreases), November through March (Tinsley and Deen, 1991)
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
Variations in Magnetic Latitude and Altitude of
Solar and Terrestrial Inputs and resulting Jz .
Does the Enhanced Vorticity Lead to Increased Blocking ?
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).
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”.
1.E-09
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.
(4b) A = 15 μm, RH = 100%
RtCoeff, RH = 100%, A = 15μm, Q = 0e, q = 0e
RtCoeff, RH = 100%, A = 15μm, Q = 100e, q = 5e
1.E-10
RtCoeff, RH = 100%, A = 15μm, Q = 100e, q = 10e
Analytic, RH = 100%, A = 15μm, Q = 0e, q = 0e
Collision rate coefficient
1.E-11
Elecroanti-scavenging
1.E-12
Low
Electro-scavenging
High
1.E-13
High
Low
1.E-14
1.E-15
0.001
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.
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.
Refereences
Following a High Jz Day
0.01
0.1
Particle radius
1
10
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).
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).
SOLAR MODULATION OF BLOCKING IMPACTS ON THE NEARSURFACE (2-m) TEMPERATURE DISTRIBUTION 1955-1999
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.
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.
Variation of squared vorticity (in s-2 )in region 50°5-70°N, 0°-40°W,
with SEP events, from Veretenenko and Thejll, (2004)
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 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.
Barriopedro, D., R. Garcia-Herrera and R. Huth, Solar modulation of the
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aerosols the missing link between tropospheric vorticity and Earth transits of
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storm tracks in the North Atlantic ,Geophys. Res. Lett., 15, 409-412, 1988.
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115, D23211, 2010.
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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.
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.
Acknowledgements
(b) An increase in cyclone frequency At GCR maximum This work was begun in 1987 with the encouragement of the late Dr. Ron
(solar min.) in the Western North Atlantic cyclogenesis
Taylor, Program director for Meteorology at the National Science Foundation.
region (Labitzke and van Loon 1989).
NSF has provided continuing support, most recently with grants
ATM0855351 and ATM0836171.
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).