A52B-01 INVITED
Modeling the Entire Atmosphere, its Variability and its Changes
The HAMMONIA Model has been developed to integrate in a single modeling framework atmospheric dynamical, radiative and chemical processes from the surface to the thermosphere. The model together with observational data are used to investigate the coupling between different atmospheric processes and to simulate possible changes resulting from natural forcing (e.g., solar variability) or from human-induced perturbations (CO2 emissions). Several results obtained by the model will be presented and discussed.
A52B-02 INVITED
Impact of Solar Variability on the Earth's Climate Patterns
We discuss the effect of solar variability on the Earth climate patterns. The climate patterns are naturally excited in the noisy atmosphere-ocean dynamical system as deviations (anomalies) from a global (mean) state. Some of the climate patterns couple the upper and lower atmosphere and are affected by the ocean. An example of this type of climate pattern is the Northern Annular Mode (NAM), a climate anomaly with two basic states corresponding to higher pressure at high latitudes with a band of lower pressure at lower latitudes and the other way round (Thompson & Wallace, 1998; Baldwin & Dunkerton, 1999). Two states of the NAM arise due to the dynamical interaction of planetary waves and zonal mean wind (Limpasuvan & Hartmann, 2001; Ruzmaikin et al., 2006). The NAM accounts for 23% of atmospheric variability at sea level and about 50% of the variability in the stratosphere. Solar variability influences the NAM through the change of the UV flux in upper atmosphere. The influence depends on the phase of the Quasi Biennial Oscillation and time in the winter season (Ruzmaikin & Feynman, 2002). We discuss a possible mechanism by which solar variability can affect the NAM and the climate patterns in general (involving the Rossby-Palmer conjecture, Palmer, 1999). In contrast to the standard linear evaluation of climate sensitivity to an external forcing we outline a non-linear approach to the forcing problem. In particular, we evaluate the distributions of residence times spent in each state of the pattern and show how these distributions depend on external forcing caused by the anthropogenic and solar changes. References: Thompson, D. W. J. & J. M. Wallace, Geophys. Res. Lett., 25, 1297, 1998; Baldwin, M. P. & T. J. Dunkerton, J. Geophys. Res. 104, 30,937, 1999; Limpasuvan, V., & D. Hartmann, J. Climate, 13, 4414, 2001; Ruzmaikin, A., J, Feynman, J. Geophys. Res., 107, D14, 10.1029/2001JD001239, 2002; Ruzmaikin, A., J. K. Lawrence & A. C. Cadavid, J. Atmos. Space Phys., 68, 1311, 2006; Palmer, T. N., Bull. Amer. Meteor. Soc., 79, 1412 1998.
A52B-03
On the nature of the solar influence on climate and its contribution to climate change
The influence of solar magnetic variability on the lower atmospheric regions has been observed on different atmospheric parameters in different time scales, but a plausible mechanism to explain these observations remains unclear. It is also indistinguishable whether or not the variability on the solar-terrestrial coupling drives the present climate change. New observations suggested that the existence of a geomagnetic signal in climate data would support a direct link between solar variability and their effects on climate. Usoskin and colleagues compared 1000-year reconstructions of sunspot numbers and cosmic ray flux, derived from cosmogenic isotope dates, with air temperature history in the Northern hemisphere. They observed higher temperatures during periods of intense solar activity. In addition, they report that three different statistical tests consistently indicate that the long-term trends in the temperature correlate better with cosmic rays than with sunspot numbers. Vieira and Da Silva observed that the clouds effects on the radiative flux in the atmosphere in the southern Pacific are related to the intensity of the geomagnetic field. They have also observed a cosmic rays modulation of the variability of the long wavelength radiative flux in the atmosphere. More recently, Vieira and colleagues reported that a correlation between increasing sea-level pressure in the tropical Pacific, and decreasing magnetic field intensity is observed. This indicates that the physical processes in the magnetosphere, ionosphere and upper atmosphere are mapped downward to the Earth's surface. It was suggested that that the coupling mechanism may be linked to the ozone depletion in the lower mesosphere, and in the upper stratosphere of the auroral region, and/or the southern hemisphere magnetic anomaly region. The depletion is caused by high energy protons produced during solar proton events (SPEs) released during large solar storms. Variations in solar irradiance, and ozone levels produced by highly energetic protons and/or electron precipitation in the magnetic anomaly, or auroral region, may lead to small but significant changes in global weather patterns. Numerical experiments have shown slight changes to the stratospheric diffusion resulted in quite different tropospheric circulations, when compared to unperturbed conditions. If the solar activity modulates the mesospheric and stratospheric, temperature and dynamics in this way, most of the observed correlations between cosmic rays and cloud coverage, at least in the south Pacific, may be due to changes in the circulation patterns. This view is opposed to atmospheric ionization, and changes in the atmospheric electric field due to cosmic rays. Here we discuss the fundamental physical processes of the space environment from the Sun to Earth and the possible connection of changes of the geomagnetic field configuration and the increase of the Earth's temperature.
A52B-04
A Prediction of Global Surface Temperature Variations of Natural Origin for the Next Fifty Years
By a wavelet analysis of g length of day and geomagnetic index aa and Si time series, the last two as proxy data for the sources of energy of solar origin, the contribution to global temperature variations of solar activity and Earth rotation rate variability for the last 150 years in time scales larger than 20 years was evaluated in previous works. It is known that solar variability precedes length of the day variations by a century, so this parameter may be forecasted by this amount. Also, there are strong evidences that solar activity has started a fast declining episode. In base on these considerations the contribution of Earth rotation rate and solar activity variations to global surface temperature changes for the next half of century is predicted for three possible scenarios - solar activity is going either to the same levels that prior to 1923, or to a Dalton or a Grand minima-. It is found that the weakening of natural sources of climate change will lead to a cooling or more than 0.3º in lest that 20 years even in the more conservative of the scenarios . If this is so, the importance of solar CME's in the control of climate changes will be confirmed.
A52B-05
Solar cycle, QBO effect to the stratosphere and troposphere
The energy flux of high energy UV radiation changes by large amounts (>5%) during the 11-year solar cycle (Kuroda and Kodera, 2002). Ozone concentration variation in the tropical lower stratosphere is effected by the 11- year solar cycle, which is also influenced by the Quasi-biennial Oscillation (QBO), volcanic eruptions. In contrast, the temperature in the polar region is modulated by the 11-year solar cycle and the QBO (Labitzke, 1987). Labitzke and van Loon (1988) shows horizontal structure of the temperature anomaly, which indicates north-south dipole structure between the north pole and mid latitude. This structure is similar to the Arctic Oscillation (AO) or the Northern Hemisphere annular mode (NAM). The Chemistry and Climate Model (CCM) runs are performed with the REF1 scenario of Chemistry -Climate Model Validation (CCMVal, Eyring et al., 2006). The model includes the effects of the 11-year solar variation, QBO, and volcanic eruptions. We also use National Centers for Environmental Prediction (NCEP) / National Center for Atmospheric Research (NCAR) reanalysis data library. The latitude-height section of the ozone mixing ratio associated with the solar cycle shows small value around equatorial 30 hPa. On the other hand, there is large around equatorial 50 hPa. Our analyses find that the large value around 10-5hPa is caused mostly by the ozone production of the oxygen photolysis, while the small and large values in 30 and 50hPa are caused by dynamical responses of the vertical ozone advection. We derive two indices of the AO/NAM over the northern mid and high latitude stratosphere and the troposphere, and correlation analysis of the indices is applied to the four groups which are classified according to the phase of the solar cycle and the QBO. In the early winter (ND), the zonal wind shows westerly anomaly centered at 60 ° N from the stratosphere to the troposphere for the westward phase of the QBO with the solar maximum. This structure is maintained by the transient wave forcing (<30 day) over the troposphere, while the forcing of residual meridional circulation maintains the westerly wind over the stratosphere.
A52B-06
Day-to-day Forcing of the Upper Atmosphere by Terrestrial Weather
The response of the upper atmosphere to space weather events from the sun have been studied for decades. The impact of terrestrial weather on the upper atmosphere has received less attention. However, the upper atmosphere and ionosphere clearly exhibit variability on global scales with periods from several hours to several days, characteristic of lower-atmospheric planetary waves and tides. To study the origin, vertical propagation, and possible effects of these planetary-scale perturbations on the coupled thermosphere-ionosphere- electrodynamics system, a new model of Integrated Dynamics through Earth Atmosphere (IDEA) has been developed under a NASA sponsored collaborative project between the University of Colorado and National Weather Service-s (NWS) Environmental Modeling and Space Environment Centers. The IDEA model interactively couples a Whole Atmosphere Model (WAM) with Global Ionosphere-Plasmasphere (GIP) and electrodynamics models. WAM is a 150-layer general circulation model based on NWS's operational weather prediction Global Forecast System (GFS), extended from its nominal top altitude of about 60 km to over 600 km. It incorporates relevant physical processes in the extended domain, ranging from the hydrological cycle, cloud physics, and atmosphere-surface exchanges in the troposphere, to solar and Joule heating and mutual diffusion of major species in the thermosphere. Preliminary simulations reveal that day-to-day modulation of the tidal forcing of the lower thermosphere drives changes in the neutral wind dynamo, electrodynamics, and a redistribution of plasma at mid and low latitudes.
A52B-07
Efficiency of Different Types of Geomagnetic Activity (and Their Solar Drivers) at Producing NOx Capable of Significantly Effecting Stratospheric Ozone
Observations demonstrate that magnetic activity produces significant stratospheric ozone loss though the transport of auroral NOx downward in the polar night. In fact, preliminary evidence suggests a solar cycle modulation in the descending NOx (and associated ozone loss) with the maximum during the peak in 2003 of coronal hole high-speed stream activity in the descending phase. The coupling between space weather and stratospheric meteorology is a key ingredient in confining the descending NOx to high latitudes and thus enhancing its ability to destroy ozone. During the maximum high-speed stream activity in 2003, auroral energy input (as indicated by the aa-index) reached a peak exceeding values during the last 4 solar cycles. A newly available 6-year data set of NOx 5.3 micron radiance from TIMED provides information on the variation in the thermospheric source of NOx due to magnetic activity (approximated by NOx radiance poleward of 60 deg MLAT) from solar maximum to solar minimum (late 2001 - 2007). These data will be used to explore the amount of NOx, which is produced in the correct location to be drawn down into the polar vortex, during selected space weather disturbances. A comparison between NOx poleward of 60 deg MLAT and global NOx provides a measure of the relative "effectiveness" of various types and strengths of magnetic activity in producing stratospheric ozone losses. Hemispheric power in particle precipitation derived from observations of auroral emissions by TIMED will be used to examine the corresponding variations in high-latitude energy inputs responsible for the NOx production.
A52B-08
Main Ionospheric Trough and Equatorial Ionization Anomaly During Substorm With Current Wedge
In the given work results of numerical calculations of ionospheric effects of modeling substorm which have begun in 18 UT are presented. Calculations are executed on the basis of Global Self-consistent Model of the Thermosphere, Ionosphere and Protonosphere, developed in WD IZMIRAN, added by the new block of calculation of electric fields in the ionosphere. In calculations we considered superposition of magnetospheric convection electric field (at set of field aligned currents of the first and second zones and substorm current wedge with taking into account of particle precipitation) and dynamo field generated by thermospheric winds. It is shown, that at early stage of substorm development the longitudinal extent of main ionospheric trough increases. The trough is stretched in evening sector of southern hemisphere as narrow formation. There is increase foF2 in southern polar cap that leads to increase in steepness of trough polar edge. Longitudinal extent of equatorial anomaly in evening sector decreases. It occurs due to occurrence of area of strong negative foF2 disturbances on geomagnetic equator in vicinity of midnight meridian. In quiet conditions in southern hemisphere main ionospheric trough is the deepest in post-midnight sector. During substorm the additional minimum in evening sector is formed. In northern polar cap the substorm without taking into account current wedge leads to little changes foF2. The substorm with taking into account of current wedge causes negative disturbances foF2 in night and evening sectors of northern polar cap. Depth of main ionospheric trough in northern hemisphere decreases. Reduction of longitudinal extent of equatorial anomaly in post-sunset sector is strongly developed during substorm calculated without taking into account current wedge. In due course there are negative disturbances foF2 in subauroral latitudes of northern hemisphere in the afternoon and positive disturbances at low latitudes in both hemispheres. In the further depth of main ionospheric trough is decreased. After substorm termination there are night areas of negative disturbances foF2 on equator and day time areas of positive disturbances in the middle and low latitudes.
A52B-09
Main Ionospheric Trough and Equatorial Ionization Anomaly During Substorms With the Different UT Onset Moments
In the given work the numerical calculation results of ionospheric effects of four modeling substorms which have begun in 00, 06, 12 and 18 UT are presented. Calculations are executed on the basis of Global Self-consistent Model of the Thermosphere, Ionosphere and Protonosphere (GSM TIP), developed in WD IZMIRAN, added by the new block of calculation of electric fields in the ionosphere of the Earth for vernal equinox conditions in the minimum of solar activity. In calculations we considered superposition of magnetospheric convection electric field (at set potential differences through polar caps and field aligned currents of the second zone with taking into account of particle precipitation) and dynamo field generated by thermospheric winds without taking into account the tides. It is shown, that in the given statement of problem the substorms cause strong positive disturbances in F-region of ionosphere in night sector. Negative disturbances are much less and arise, mainly, at night in the middle and low latitudes. During substorms longitudinal extent of main ionospheric trough increases. The substorm beginning in 18 UT, causes negative disturbances in high latitudes except for a southern polar cap. Besides there is "stratification" of the main ionospheric trough. As a result in southern hemisphere the additional high-latitude trough which is absent in quiet conditions is formed. "Stratification" of the main ionospheric trough occurs in northern hemisphere at 6 hours after the beginning of the substorm. These "stratifications" are consequence non-stationary magnetospheric convection. Distinction between these events consists that "stratification" in a southern hemisphere occurs in active phase of substorm, and in northern hemisphere in recovery phase. During a substorm beginning in 00 UT, foF2 increases in all northern polar cap. Positive disturbances of foF2 in the equatorial anomaly region cause all presented substorms, except for a substorm beginning in 18 UT. This substorm causes small negative disturbances in the equatorial anomaly region in the Indian longitudinal sector.