Atmospheric Sciences III Posters
Presiding: S Basu, Yale University; P Market, University of Missouri at Columbia
A13A-01 1330h
Mesoscale Model Investigation of Ocean Atmospheric Interactions and Intensity Change Associated with Hurricane Charley
The NCAR/Penn State Mesoscale Model (MM5) is used to study the role of surface fluxes including heat, momentum, and latent heat which play a dominant role in the formation and Intensity change of hurricane Charley. Charley formed over the Caribbean sea, intensified over the Gulf of Mexico and made a landfall in Florida during August 09-14, 2004. Mesoscale model simulations are used for forecasting and to receive better understanding of the structure and dynamics of hurricane activity. The model is run on a doubly nested domain centered over the central Gulf of Mexico, with grid spacing of 90 km and 30 km. MM5 is run for 6 hr periods, from August 12th to August 14th. The model is capable of simulating the surface features associated with hurricane Charley including strong heat and latent heat fluxes, intensity change and hurricane track
A13A-02 1330h
The Impact of Cloud and Radiation on the Great Plains Climate Change During 1981-2003
Relationships of surface air and soil temperature changes have been compared to downward solar radiation and cloud fraction over the Great Plains (latitudes of 37°N to 49°N, and longitudes of 95°W to 104°W). Twenty-three years of surface meteorological data have been collected, including surface air and 10 cm soil temperatures and downward solar flux from the High Plains Regional Climate Center (HPRCC) since 1981. The daily mean values of meteorological data within the states of Kansas, Nebraska, South Dakota, and North Dakota have been binned and averaged to 0.5-degree latitude intervals to study temporal and latitudinal variations of surface air and soil temperatures, as well as their correlations with downward solar flux. Preliminary results from this project have demonstrated that the surface air and soil temperatures have increased during the 1981-2003 period over the Great Plains. When broken down by latitude, the air temperature change has increased from nearly 0°C at 37°N to 1.7°C at 49°N, and the soil temperature change increased about 2.7°C. The downward solar flux has generally decreased during the 23-year period, but the downward solar flux change increases with latitude: -38 Wm-2 at 37°N and 18 Wm-2 at 49°N which is positively correlated to the air and soil temperature changes. The cloud fractions from International Satellite Cloud Climatology Project (ISCCP) during the 1983-2001 period have been used to study the impact of clouds on the surface radiation and temperatures. The Department of Energy Atmospheric Radiation Measurement (DOE ARM) downward solar fluxes over southern Kansas have been used to determine the overall quality of the results.
A13A-03 1330h
Human "Footprints" in the Atmosphere: Anthropogenic Evidence in MOPITT and TES Atmospheric Chemistry Data
The Measurements Of Pollution In The Troposphere (MOPITT) experiment was launched on board the NASA Earth Observing System (EOS) Terra Satellite in December 1999 and has accumulated more than five years of global carbon monoxide measurements. Available MOPITT data products include Level 1 radiances and Level 2 derived CO total column and mixing ratio profiles at a horizontal resolution of about 22 km at nadir and a vertical resolution of about 4 km. The primary sources of CO are biomass burning and industrial pollution, making CO an indicator of the anthropogenic influence on the atmosphere. MOPITT is the first instrument to make long-term global measurements of this species and is providing a better understanding of its transport, sources and sinks. A number of visual results will be included in this presentation. The Tropospheric Emission Spectrometer (TES) instrument is a high-resolution imaging infrared Fourier-transform spectrometer that operates in both nadir and limb-sounding modes. TES is flying aboard Aura, the third of NASA's EOS satellites, which was launched in July 2004. Tropospheric ozone is a pollutant and a greenhouse gas. It has both natural and anthropogenic sources. TES makes global 3-D measurements of ozone and other chemical species involved in its formation and destruction, including water vapor, methane, carbon monoxide, nitrogen dioxide, and nitric acid. The spatial resolution is 0.5 x 5 km in the nadir and 2.3 x 23 km in the limb. Level 1B spectral radiance data are currently available, and the Level 2 species data products will be publicly available in Summer 2005. Preliminary visual results will be shown. These data are available free of charge from the NASA Langley Atmospheric Sciences Data Center. Additional information can be found at http://eosweb.larc.nasa.gov.
http://eosweb.larc.nasa.gov
A13A-04 1330h
Simulation of the Martian dust cycle with a general circulation model
The Martian seasonal dust cycle is examined with a general circulation model (GCM). On the basis of the model results and thermal and imaging data, we suggest that the background dust haze on Mars is maintained by convective processes, specifically, dust devils. Combining the convective scheme and high-threshold stress lifting, we obtain a "best fit" multiyear simulation, which produces a realistic thermal state in northern spring and summer and, for the first time, spontaneous and inter-annually variable global dust storms. Two prominent storm systems that were identified in our simulations are a) the cross equatorial flushing type of storms that are associated with frontal systems. The frontal dust features in our simulations are due to the traveling wave systems. There are two prominent periods for large flushing storm activity: Ls=200-240 and Ls=310-345. The storms later in the season are less frequent compared to the earlier ones. The flushing storm along the Acidalia channel is the most active. This baroclinic storm system matches up quite well with observations: TES temperature retrievals and MOC imagery data. As observed, the simulated storms are most closely associated with a zonal wavenumber 3. The traveling waves are shallow and stronger in the northern hemisphere as compared to the southern hemisphere. The second major storm system b) are the storms arising from the Hellas basin. The simulated storms have a lot in common with the TES observations and the MOC imagery. These storms can also be classified as early Hellas storms and the late Hellas storms. The early Hellas storms start ~Ls=180. In some instances they go global and in other instances, they are confined to the Hellas region. The early Hellas global storm propagates eastwards due to strong westerlies and spreads into the northern hemisphere. The storm starts decaying as soon as the peak opacities are reached ~Ls=220. The global storm that starts later in the season ~Ls=270, is however much bigger and propagates both eastwards and westwards. It is made stronger by the subtropical jet which activates a few active lifting centers along the zonal band. This storm has a purely seasonal decay.
A13A-05 1330h
Boundary Layer Heights: A New Method of Evaluation
Boundary layer depth and structure are important to the development of convection within the atmosphere. In general, two methods have been used to quantify the depth of the boundary layer from lidar data. These methods, the wavelet (Davis, et al. 2002) and the backscatter variance (Hooper, et al. 1986), are well established and prove valuable for obtaining the boundary layer depth and structure using lidar data. However, they do not apply for all cases because they do not fully capture the dynamics and boundary layer variability that occur in the atmosphere. A new method using the aerosol scattering ratio (ASR), which employs the ratio of the total scattering to the molecular scattering, is described and tested with data from Goddard's Holographic Aerosol Rotating Lidar Instrumentation Experiment (HARLIE), Scanning Raman Lidar (SRL), and radiosonde measurements. The HARLIE is also used to obtain information on the spatial variability of the boundary layer height. These data sets are combined with water vapor mixing ratio to quantify the convective variability within the boundary layer. A number of synoptic conditions are investigated using data collected during the IHOP project. Preliminary results show that the boundary layer heights obtained using the aerosol scattering ratio method compare well with traditional means of observations. Further statistics are being conducted to quantify the comparison.
A13A-06 1330h
Cloud and Stability Characteristics of Mid-latitude Continental Convective Snow Events as Determined From Serial Radiosonde Ascents
A field experiment is currently underway that seeks to document the evolution of tropospheric stability as well as the microphysical characteristics of the parent cloud during mid-latitude, continental convective snow events. A mobile sounding system, using radiosondes outfitted with an ice crystal replicator, is being deployed in the Midwestern United States during February and March 2005 in support of this study. Intense observing periods (IOP) involve transporting the mobile sounding system to a location where convective snowfall has been predicted. Each IOP features hourly radiosonde ascents for durations of up to 12 hours, with convective snowfall occurring near the middle of this period. Additionally, we expect to launch ice crystal replicators on one or two balloons closest to the time of convective snow occurrence. Data and analysis from these field campaigns will be presented.
http://weather.missouri.edu/ROCS
A13A-07 1330h
Trends in temperature and dew point at the summit of Mount Washington, New Hampshire, 1935-2004.
Dry and wet bulb temperatures from sling psychrometer measurements taken every six hours from 1935 to 2004 at the summit of Mount Washington, located at 44 °16'N, 71 °18'W, 1914 m ASL have recently been digitized. Annual temperature has increased by 0.3°C, and annual dew point has decreased by 0.4°C over this 70-year period. Synoptic temperature has increased most in spring and winter, changing by 1.0°C and 0.5°C, respectively, while it has decreased slightly in summer and fall. Dew point has decreased in fall, summer, and winter, 0.9°C, 0.5°C, and 0.4°C respectively, and increased by 0.1°C in spring. Preliminary analysis suggests that some of the larger trends in winter and spring may be statistically significant; results of Monte Carlo simulations will be reported. Changes in dew point may be attributed to two factors. Decreasing dew points are expected if the temperature increases but the amount of water vapor present stays the same. Alternatively, lower dew points could be indicative of the presence of drier air. Other dew point climatologies of the continental United States for the second half of the century have shown mixed results, with increased dew points evident at some stations, decreased dew points at others, and no clear regional patterns.
A13A-08 1330h
The Sensitivity of the Northeast Colorado Moist Convective Environment to Upstream Soil Moisture Conditions
Statistical evidence supports a hydro-dynamic link between severe thunderstorm activity in Northeast Colorado and antecedent snow condition in the upstream higher elevations. Two subsets of seven runoff seasons were created, based on the criteria of anomalously high and low cumulative streamflow discharge from the Colorado Rockies. Observational evidence suggests that the morning time lower atmosphere, during the months of May and June, over Denver, is cooled and moistened following an anomalously large runoff season when compared to seasons of meager runoff. Furthermore, comparison of Northeast Colorado severe thunderstorm reports reveals that severe weather occurrences of hail greater than 1 inch in diameter, tornados, and damaging thunderstorm downdrafts, occurred on average 51 minutes earlier following years of anomalously high runoff compared to the low runoff years. The character of severe weather also appears to be altered so that high runoff years yield a significantly reduced percentage of tornadic reports over the Northeast Colorado plains. The proposed mechanism put forth to explain the presumed alteration of the lee plains' convective environment and the nature of severe thunderstorm activity, links alpine surface moisture conditions to lagged thermal and moisture attributes of the downstream elevated mixed layer which caps the convective boundary layer. Moist surfaces attributed to snowpack, ponding of melt water, and saturated soils are known to increase evapotranspiration so that the coupled boundary layer is cooler and moister than would be observed under drier conditions. The nocturnal decoupling of the boundary layer from the surface forms a residual layer which is surmised to retain the attributes imparted to it according to the degree of soil moisture present during the previous day. Mean late spring/early summer prevailing wind velocity supports the likely presence of an elevated mixed layer, with similar attributes of the aforementioned residual layer, to overly the downstream lee plains during the course of the following day. Consequently, the apparent atmospheric response over Northeast Colorado to (increased /decreased) surface moisture at upstream high elevations is to (weaken/strengthen) the capping layer. It follows that the warming of the capping layer, which would follow dry conditions in the upstream higher terrain, should lead to a reduction in boundary layer depth, a delay in the diurnal timing of thunderstorm formation, and an increase in the spacing between penetrating deep moist convective cells, all of which are known to increase the likelihood and/or magnitude of severe weather in this region, while at the same time, reducing areal coverage of convective rainfall. Observational evidence supports this conclusion.
A13A-09 1330h
A Study of Ocean-Atmospheric Interactions Associated with Hurricane Charley
Previous studies by Reddy et.al., (1998, 2003) have indicated a strong Ocean-Atmospheric coupling during the development of tropical cyclone/hurricane activity over the Gulf of Mexico. We extend these investigations to the hurricane Charley, which developed over the Caribbean and made land fall over the west coast of Florida during August 9-14, 2004. NOAA GOES satellite, NDBC Buoy and NHC dropsonde data for sea surface temperature and meteorological variables including air temperature, wind speed and sea level pressure were used for computations. The study suggested strong heat flux before and during the formation of the hurricane with an evidence of 2-5 day oscillations in heat flux. These findings are in conformity with the previous studies. Heat flux values will be used to develop regression model for the prediction of the hurricane Charley intensification.
A13A-10 1330h
Easterly wave-mean flow interaction over the Caribbean Sea.
The interaction between easterly waves and the Caribbean low-level jet is examined, considering the barotropically unstable nature of this tropical circulation. Following a normal mode analysis, it is found that easterly waves with wavelengths around 15 (2600 km) may be rapidily amplified by taking energy from the low level jet. Diagnostics show that the dominant conversion of energy occur with the mean flow transferring energy to the transient (easterly wave). The vertical transfer of momentum appears to be the mechanisms through which easterly waves with largest amplitud at 700 hPa and the low-level jet at 925 hPa connect. The amplification of the easterly waves in the western Caribbean apperas to result in a meridional elongation of the convergence zone and consequently in a larger area where convective activity occurs. The implication of this type of wave mean flow interaction for the Caribbean and Mesoamerican region is discussed.
A13A-11 1330h
Micro-physical Consistent Modeling of the Deliquescence and Efflorescence Hysteresis
A difference between deliquescence and efflorescence RH values (i.e., the hysteresis effect) is commonly observed for aqueous salt particles. As the direct aerosol effect is very sensitive to the water uptake properties of the particles, the study of the hysteresis effect is of high importance. Current aerosol dynamic models take account of the deliquescence and efflorescence hysteresis based a priori knowledge of the presence of solid phases at a certain relative humidity and overall composition. They either assume crystallization of a solid in a multicomponent solution once the RH drops below the DRH of the solid salt, or do not assume solidification at all and consider all aerosol particles to be liquid droplets. In this talk, we present a modeling framework based on classical theory of nucleation kinetics to simulate the transformation from a metastable phase into a thermodynamically more favorable phase. We apply classical nucleation theory in the primal-dual active set Newton algorithm in order to predict explicitly the physical state of the aerosol particles and the deliquescence and efflorescence hysteresis. Our micro-physical consistent model is capable of modeling the phase transition and multistage growth of atmospheric aerosols in various relative humidity regimes. We present computational results to illustrate the model performance to simulate aerosol deliquescence, crystallization, solid to solid phase transitions, and acidity transitions.
A13A-12 1330h
Computational Methods for Multi-phase Multi-reaction Thermodynamical Equilibrium Problems
The computation of phase and chemical equilibria of aqueous organic electrolytes mixtures is of significant interest in atmospheric aerosol modeling. The presence of organic species in solution may substantially influence the phase transitions of the deliquescence and efflorescence of salts with changes in relative humidity. Dissolved electrolytes can have appreciable effects on the solubility of organic components in solution. We present here some computational methods for the prediction of the physical state of atmospheric particles. In the case of inorganic aerosols, an Extended UNIQUAC model is used to compute the excess of Gibbs Free energy. Our method is derived from the minimization of the total Gibbs energy. The computational difficulty is to identify the solid phases existing at the equilibrium. Our algorithm is based on a primal-dual active sets-Newton method for the solution of the Karush-Kuhn-Tucker (KKT) conditions. The inequality constraints are tracked at each iteration so that possible solid salts remain sub-saturated. The corresponding inequality constraint becomes active when the saturation is reached. In the case of organic aerosols, liquid-liquid and liquid-solid equilibria as well as phase stability and separation are considered. The UNIFAC model is used for the calculation of activity coefficients for aqueous organic mixtures. We propose a primal-dual interior-point Newton method to solve the KKT conditions of a relaxed minimization problem. We present numerical results for both inorganic and organic problems to show the ability of our approach, in the prediction of aerosol phases in the atmospheric particles.
A13A-13 1330h
Comparison of In-situ Measurements of Cirrus Cloud Ice Water Content During the MidCiX Field Campaign
Accurate in-situ measurements of microphysical properties such as ice water content (IWC, mg/m3) are important for understanding the role or cirrus clouds in radiative forcing, stratosphere-troposphere exchange, and heterogenous activation of chlorine compounds. These observations also provide an important tool for both constraining GCM paramaterizations related to the radiative properties of cirrus clouds as well as "ground-truth" for satellite retrievals of cloud properties. An understanding of the contribution of small particles to IWC is especially relevant because by mass, small particles exert a relatively large influence on the radiative properties of cirrus clouds. We present observations of cirrus cloud IWC derived from measurements of "total water" made by the University of Colorado closed-path tunable diode laser hygrometer (CLH), which has flown aboard the NASA WB-57 aircraft during several recent field missions, including the Mid-latitude Cirrus Experiment (MidCiX) in April and May, 2004. The CLH measures water vapor resulting from the evaporation of cloud particles after sampling through a heated, subisokinetic inlet. When used in conjunction with knowledge of the particle enhancement properties of the inlet system and an accurate water vapor instrument, the CLH "total water" measurement can be used to derive cirrus cloud IWC for particles between about 5 Îœm and 500 Îœm. In addition to the CLH IWC measurement, two other IWC measurements with different sampling characteristics were made during the MidCix campaign. By comparing the three IWC measurements, it is possible to evaluate the contribution of small particles (diameter < 10 Îœm) to the IWC measurement.
A13A-14 1330h
On the Negative Brightness Temperature Differences Observed by Satellites Above Thick Ice Clouds in the Tropics.
Negative brightness temperature differences (BTD) between 10.5 and 12 Ym have been observed frequently from satellites or aircraft imageur above thick ice clouds in the tropics. Those negative BTD reach typically -1 to -3 K, and can not be reproduced in radiative transfer computations using reasonable ice cloud optical properties, or changing humidity and temperature profiles in standard composition of tropical atmosphere. The spatial structure of the negative BTD signature as seen by satellite and their high frequency in low latitudes seem to indicate that they are associated to tropopause overshoots. Different scenarios assuming that tropical convection introduces or allows the formation of molecules absorbing at 10.5 Ym in the tropical tropopause layer have been examined in order to understand the negative BTD. Increasing the concentration of the absorbing molecules (O3, CO2, HNO3, NO2, etc) above a thick ice cloud in the tropical tropopause layer allows to reproduce negative BTD in radiative transfer computations. In order to estimate the potential validity of this explanation, and determine which molecule is effectively involved in the process, the theoretical increases in the molecule concentration deduced from radiative transfer computation are compared to concentrations found in the literature deduced from observations and chemistry models.
A13A-15 1330h
Impacts from Aerosol and Ice Particle Multiplication on Deep Convection Simulated by a Cloud-Resolving Model with a Double-Moment Bulk Microphysics Scheme and Fully Interactive Radiation
The size of cloud particles, in both the liquid and ice phases, determines the effect of clouds on the radiation budget of the atmosphere. A novel approach is presented for predicting the number of particles, as well as their mass, for cloud-ice and cloud-liquid. This allows the average particle size to be predicted. There is an interactive aerosol component for ice nuclei and cloud condensation nuclei in the model. For cloud-ice, primary ice nucleation, Hallett-Mossop (H-M) ice particle multiplication and homogeneous freezing of aerosols and droplets provide the source of ice-number in this 'double-moment' bulk microphysics scheme. For cloud-liquid, primary and secondary droplet nucleation is represented, by predicting the supersaturation. A power-law activity spectrum for the aerosol is assumed. Sensitivity tests with respect to the environmental concentration of ice nuclei and cloud condensation nuclei, and to the inclusion of ice particle multiplication, are performed. The corresponding impacts on radiative, dynamical and microphysical cloud statistics are described.
A13A-16 1330h
Occurrence of Nocturnal Warming Events at Prototype Sites of Mississippi Mesonet
Dramatic short time scale warming events have been observed on many nights since installation of the first station of the Mississippi Mesonet. Often accompanied by dramatic drops in dewpoint, it is hypothesized that most events are probably associated with mixing of relatively warm dry air downward under thermally stable conditions. In many cases, this appears to be induced by relatively subtle increases in surface wind speed. Data from the developing mesonet will be used to develop an initial description of the seasonal, synoptic, and case-to-case variability among nocturnal warming events. Typically the events are not unambiguously detectable using standard hourly surface observations. Although a fairly benign phenomenon, there are potential implications for daily minimum temperature forecasts and surface radiation fog development/dispersal.
A13A-17 1330h
Analysis of Halogens in Antarctic Snow and Their Role in Boundary Layer Ozone Depletion Events.
It is generally accepted that tropospheric ozone depletion events in polar regions involve halogen chemistry, in particular bromine chemistry. It has also been suggested that snow has an important role in the destruction of tropospheric ozone. Blowing snow and the surface layer of the snow pack provide a large surface area for heterogeneous chemical reactions as well as being a possible source or sink for gas phase atmospheric Bromine. In the austral spring of 2004 we collected and analyzed snow samples from the Ross Island region in Antarctica to determine snow's role as a source of atmospheric bromine. Seventy snow samples were collected on the Ross Ice Shelf and in various locations on the annual and multi-year sea ice. Various types of snow were analyzed, including freshly fallen snow, wind-blown snow, and aged drifted snow. In this presentation we will describe the sampling process and locations and will discuss the results in the context of snow type and age. The samples were returned to the laboratory for analysis for anions, including bromide and chloride, through ion exchange chromatography. Analysis of the bromide-to-chloride ratio shows that bromide is significantly enhanced in wind-blown snow samples over the values expected purely from sea salt deposition. Significant variation in bromide levels was also observed as a function of geographic location and the age of the snow. In addition to collection of natural snow samples, an experiment was conducted to determine the effect of solar radiation on bromine levels on snow artificially seeded with bromide.
A13A-18 1330h
Dispersion Modeling of Inert Particulate Matter in the El Paso, TX- Cd. Juarez, MX Region
The El Paso, TX-Cd. Juarez, MX region is subject to the emission of inert particulate matter (PM) into the atmosphere, from a variety of sources. The impact of these emissions has been studied extensively in for regulatory compliance in the area of health effects, air quality and visibility. Little work has been done to study the fate and transport of the particulate matter within the region. The Environmental Physics Group at The University of Texas at El Paso has recently applied the SARMAP Air Quality Model (SAQM) to model the dispersion of inert particulate matter in the region. The meteorological data for the SAQM was created with the Penn State/NCAR meteorological modeling system, version 5 (MM5). The SAQM was used to simulate three common occurrences for large particulate emission and concentration. The first was times of heavy traffic volume at the international bridges which cause large numbers of cars to sit, with engines running, for extended periods of time. The second was moderate to high wind events that cause large amounts of coarse particulate matter to become entrained in the atmosphere and transported into and around the region. The third is a temperature inversion which traps the particulate matter at the surface during morning rush hour. The initial conditions for particulate matter, for the two cases involving mobile emissions, were derived from the 1999 version 3 national emissions inventory (NEI) mobile, on-road data from the EPA. Output from the MM5 was used to as the meteorological driver for the SAQM. The MM5 was initialized with data from the NCAR reanalysis project. Meteorological data collected in the region bye the Texas Commission on Environmental Quality (TCEQ) and the EPA was used for Four Dimensional Data Assimilation. The MM5 was nudged with gridded, surface and observational data. Statistical analysis was done on the MM5 for the variables, wind speed, wind direction, temperature and mixing ratio. The statistics performed included RMSE, RMSEs, RMSEu and index of agreement. MM5 output with low RMSE and high index of agreement was used to drive the SAQM. The MM5 grid domains were 39x39 at 36km, 47x47 at 12km, 55x55 at 4 km and 40x40 at 1.3km. The SAQM was applied on to the 1.3km domain. For the case of emission at the international bridges, the bridges' latitude and longitude were translated to grid cell locations. The NEI data derived for those locations were set as emission rates for those cells. The SAQM was run for a 24hr period starting at twelve pm local time with the emissions ending after morning rush hour. The same conditions were done for the inversion time period with the addition of emissions for major roadways and arterial feeders. No data is available for concentrations of entrained particulate matter during wind events. Thus, the entrainment episodes were simulated with varying initial concentrations along the boundary of the domain. The emission rates were varied for each simulation to give both a very intense episode, and a moderate episode lasting for 12 hrs with the SAQM simulation ending after 24 hrs. Analysis for all the simulations was done to show the spatial and temporal evolution of the PM. Temporal comparisons were done between EPA PM2.5 to show identify similarities in the evolution of the SAQM with observation.
A13A-19 1330h
The Contribution of Volcanic gas and Particle Emissions to the Troposphere
Volcanoes release considerable fluxes of gases and particles to the atmosphere, both during eruptions and during long-term non-eruptive degassing. While the volcanic fluxes of many species are very poorly known (often only to 1 or 2 orders of magnitude), the volcanic contribution to the tropospheric burden of certain gases (including SO2, HCl, HF, BrO); volatile trace metals (including Cd, Hg, Zn) and aerosol (including sulphate) is certainly significant. In terms of sulphur dioxide, most of the long-term time-averaged volcanic emission is from non-erupting volcanoes (6-9 Tg/yr), or during relatively minor eruptions (6-8 Tg/yr), rather than from large explosive eruptions (1-2 Tg/yr). Emissions from `passively degassing' volcanoes are significant since they are mostly to the free troposphere (due to the vent elevation, or the plume rise height) where species lifetimes are extended, and the impact of volcanic sources is enhanced. Volcanic emissions are not limited to species released directly from magma, but also include those produced by chemical reaction in the extreme environments associated with the volcano. Newly discovered volcano-related gases include NOx and HNO3, which form by thermal decomposition of atmospheric nitrogen at the magma-air interface, and halocarbons produced by reactions between volcanic fluids and surrounding materials. We report early progress in the development of a new temporally- and spatially resolved global volcanic emissions budget that is designed to represent a broader spectrum of volcanogenic species than is currently available, and which will be used a focus for detailed analysis of the sensitivity of the atmosphere to sustained volcanic emissions.
A13A-20 1330h
Meteorology Of The Clark Atlanta University Local Energy Balance Module
The Earth System Science Program (ESSP) at Clark Atlanta University has developed an instructional module to study energy balance at the air/land and air/sea interfaces. A graphical user interface (GUI) has been developed which is used to model each of the components (net radiation, sensible and latent heat fluxes, ground heat flux, storage, anthropomorphic, and residual) necessary to understand the partitioning of energy at the air/land and air/water interfaces. The energy balance diagram consists of sky elements (sun, moon, clouds), a line representing the air/land or water/land interface, and arrows which indicate magnitude and direction of each of the energy fluxes. The storage component is represented as a box when present. The energy balance model has been applied to numerous (33 at present) scenarios which vary by (1) climate or microclimate, (2) day and night, (2) cloudiness and sunshine, (3) windy and calm, (4) land or water surface, and (5) freezing and non-freezing temperatures. The model is available in 2 levels of rigor: (1) an elementary level (Level I), and (2) and advanced level (Level II). In the Level I model only fixed arrow lengths (e.g., zero, 1/4, 1/2, 3/4, 1) are available to express flux magnitude. This allows a qualitative illustration of the energy balance components. The Level II model requires the student to calculate arrow magnitudes and directions from diffusion, evaporation, radiative transfer, and energy storage equations. The module incorporates not only the energy balance model, but also a protocol by which meteorological observations from the ESSP's rooftop laboratory, the AEMN (Georgia Automated Environmental Monitoring Network), and other online resources. The completed module is designed to serve two audiences: (1) undergraduate introductory science classes and grades 8-12, and (2) upper-division science and engineering classes.
A13A-21 1330h
Natural variability and climate change, causes of NAO/AO observed trend
Over recent decades the North Atlantic Oscillation has undergone major low frequency variations, superimposed on an upward trend in NAO index. Because variations of NAO have a large impact on society and the environment, understanding the processes that govern its variability is essential. Mechanisms proposed to account for this variability include atmospheric response to changes in sea surface temperatures, variability of deep atmospheric convection in the tropics and natural internal modes of the atmosphere, rather than changing external forces such as anthropogenic emissions of greenhouse gases and ozone depletion. We have investigated NAO behavior using power spectrum wavelet analyses of simulations by the NASA Goddard Institute for Space Sciences global climate model, for control conditions and for increasing greenhouse gases. This analysis provides convincing evidence that anthropogenically induced changes in tropospheric-stratospheric interactions are the most important contributor to this change.