A51B-0339
Ozone Profiles Over the Industrial Coast of Southern Taiwan
This study presents the variations of vertical ozone profiles measured in a field study conducted nearby a costal industrial park in southern Taiwan during October 21 to November 20, 2005. The ozone profiles were measured by tethered ECC ozonesones. In each experimental day, 6-10 times of tethered ozonesondes were launched both in the daytime and night. Totally, 136 ozone profiles are acquired. The results indicate that even in the daytime the vertical ozone distributions were far from uniform. The ozone concentrations in the range of 40-160 ppb may distribute at 0-1800 m. Due to the development of sea-breeze circulations and the development of thermal internal boundary layers (TIBL) in sea breezes, three distinct ozone layers were detected, the layer in the TIBL, the layer overlaid the TIBL and under the return sea breeze, and the return sea-breeze layer. The ozone concentration in a TIBL is relatively lower than the other two layers due to the titration of fresh NO emission from surface sources. Ozone in a return sea-breeze layer is relatively higher than the other two layers possibly due to the transport of inland ozone-rich air by the return sea breeze. In the nighttime, elevated ozone-depleted layers with nearly zero ozone were detected to distribute among ozone residual layers with ozone concentrations in the range of 60-120 ppb. The elevated ozone-depleted layers are formed likely by the NO plumes from the nearby industrial park.
A51B-0340
Boundary Layer Structure Observed by a Network of Wind Profiling Radars and Simulated in Air Quality Forecast Models During the TEXAQS 2006 Field Program
Boundary Layer structure (PBL depth, wind speed, direction, and virtual temperature profiles) are analyzed from a network of eleven 915 MHz wind profilers that were operated during the TEXAQS August 01-October 15, 2006 field program. In this analysis, the data are segregated into high and low-ozone days, and high and low-PM2.5 days, where high and low days are calculated based on regional averages of surface air quality observations. Characteristics of the boundary layer structure on highly polluted days are then contrasted with that on the low pollution days. In addition, a similar analysis is carried out using the WRF-Chem and WRF-NMM/CMAQ air quality forecast models. This analysis reveals the ability of the two models to discriminate between the high and low pollution days, as well as their ability to properly simulate the corresponding PBL structure. Differences between the two models will be highlighted.
A51B-0341
Multiwavelength In-situ Aerosol Absorption, Scattering, and Hygroscopic Properties During the TEXAQS 2006 Field Campaign: Aerosol Classification and Variability
In-situ, three wavelength-measurements of optical properties of the aerosol near the coast of Texas, i.e. in the region of Houston and the Houston ship channel, as well as in the Gulf of Mexico were carried out onboard the NOAA research vessel Ronald H. Brown during the 2006 TEXAQS/GoMACCS field campaign in July through September 2006. Aerosol scattering, hemispheric backscattering and absorption-coefficients were measured for particles with diameters dp<10μm and dp<1μm using integrating nephelometers and filter-based absorption photometers (PSAPs) at 60% RH (nephelometers). Submicrometric light scattering coefficient was measured at two additional humidities, ca. 25%, and 85% RH. Together with the 60% RH data, this enabled determination of the effect of aerosol hygroscopic growth on light scattering and an empirical light scattering growth factor. The results are relevant to radiation transfer, visibility, air quality, and interpretation of remote sensing data from lidar and satellite. The extensive and intensive optical properties along with meteorological analysis are used to characterize the aerosol in the Houston, TX region and the Coastal Gulf of Mexico and to provide information critical to understanding the climatic and air quality impacts of those aerosols. Further analysis focuses on the changes that these properties undergo during chemical processing of emissions within the project area and how they are affected by changes in atmospheric relative humidity that accompany transport, diurnal cycles and vertical mixing. The results are classified by source region and flow regime of the sampled air masses to identify distinct aerosol populations. Special emphasis is given to the physico-chemical properties of aerosols measured during two periods when Saharan dust was encountered during the cruise as well as to several air pollution episodes and plumes from industrial complexes. The combination of hygroscopic growth, light scattering and absorption Ångström exponents and single scattering albedo (intensive variables) are interpreted as a source signature and analyzed in conjunction with the chemical composition of the aerosol determined by aerosol mass spectrometry, x-ray fluorescence and ion chromatography to interpret the relative influence of natural and anthropogenic sources.
A51B-0342
Planetary Boundary Layer (PBL) Heights Derived From NASA Langley Airborne High Spectral Resolution Lidar (HSRL) Data Acquired During TexAQS/GoMACCS, CHAPS, and MILAGRO
The NASA Langley Research Center airborne High Spectral Resolution Lidar (HSRL) was deployed on the NASA Langley B-200 King Air aircraft in the Mexico City metropolitan area during the Mega-city Initiative: Local and Global Research Observations (MILAGRO) campaign in March 2006; in the Houston metropolitan area during the Texas Air Quality Study (TexAQS)/Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS) in August and September 2006; and in the Oklahoma City area during Cumulus Humilis Aerosol Processing Study (CHAPS) in June 2007. The HSRL instrument measures profiles of aerosol extinction, backscatter and depolarization. The height of the Planetary Boundary Layer was derived by identifying sharp gradients in the HSRL 532-nm aerosol backscatter signal profiles using an automated technique based on Brooks (2003) [I.M. Brooks, Finding Boundary Layer Top: Application of Wavelet Covariance Transform to Lidar Backscatter Profiles. Journal of Atmospheric and Oceanic Technology 20, 1092-1105, 2003]. The technique uses a Haar wavelet covariance transform with multiple wavelet dilation values to adapt to non-ideal conditions where there can be gradients in the background signals and the boundary layer can be ill defined. The technique also identifies the top and bottom of the transition (i.e. entrainment) zone. We have further modified the algorithm to find PBL heights using HSRL backscatter data acquired during GoMACCS and MILAGRO, where complex terrain and overlying aerosol layers further complicate identifying the boundary layer. In addition, PBL heights are derived from HSRL backscatter data acquired during the CHAPS campaign, in another urban environment where the terrain is not as complex. We will describe the algorithm modifications we have made and show boundary layer heights and transition zone thicknesses for HSRL measurements over the Oklahoma City, Houston, and Mexico City areas during CHAPS, TexAQS/GoMACCS, and MILAGRO.
A51B-0343
Ship-based Doppler lidar estimates of mixing layer heights during TexAQS 2006
During the Texas 2006 Air Quality Study, NOAA's Chemical Sciences Division used the High Resolution Doppler Lidar (HRDL) to make continuous measurements of boundary layer winds and relative aerosol backscatter from the aft deck of the RV Brown. Such measurements, and their derived data products, provide information about aerosol transport, aerosol layering and layer heights, dust events, plume detection, and characterization of marine boundary layer dynamics including surface streaks/rolls, turbulence, and boundary layer mixing. Mixing is usually the result of convection and/or shear-induced mechanical turbulence and either of these types can effect the blending of the surface and residual aerosol/pollution layers. We have developed new methods to use Doppler lidar velocity information to estimate and visualize mixed/mixing layer heights as determined by vertical velocity variance (mixing strength) profiles. We then combine this information with wind shear and 2 µm aerosol backscatter profiles to produce mixing and/or mixed layer heights. We present an overview of the methods used in the estimation process and provide examples of marine mixed layer heights, as well as interpretation of such heights, from various conditions encountered during the experiment.
A51B-0344
Comparison of Subgrid Turbulence Closure Schemes in WRF-Chem for a Coastal Urban Area
The community WRF-Chem model has been widely used in the coastal urban regions such as the Greater Houston area. In a typical WRF model run, vertical mixing is parameterized within the boundary layer physics. It is assumed that there is a clear scale separation between the resolved and subgrid-scale eddies. This assumption may not be valid when horizontal grid spacing approaches 1 km or finer, and a fully three- dimensional subgrid turbulence closure should replace the parameterized mixing. While WRF has always had the option of applying horizontal and vertical diffusion explicitly in physical space, the surface fluxes provided by the surface layer and land-surface schemes were previously not coupled with the explicit diffusion. We have completed the coupling of heat and momentum fluxes with the subgrid turbulence closure schemes. We present results from a case study in which 200m grid spacing is used, and three different options for vertical mixing are tested: the explicit diffusion with eddy viscosities determined using a three-dimensional Smagorinsky turbulence closure, explicit diffusion with a prognostic turbulent kinetic energy closure, and a more conventional model set- up in which the Mellor-Yamada-Janjic boundary-layer parameterization is applied. The impact of these various closures on the transport and reaction of chemical constituents, as well as on the meteorological fields, is analyzed. It is found in this study that both the 1-D mixing parameterization and 3-D parameterization produce very similar vertical structure of the daytime ABL, but the simulated transport and dispersion of tracers and chemicals in the ABL are significantly.
A51B-0345
Comparisons of Observed and Simulated Atmospheric Boundary Layer Diurnal Cycle in California's Central Valley for the Summer of 2000
The diurnal cycle of the atmospheric boundary layer (ABL) in California's Central Valley is controlled by meteorological processes on various scales. Thus, errors in model simulated ABL, as revealed by comparisons of the simulation with observations, indicate that there are errors in those meteorological processes. In this study, the 5-day averaged ABL diurnal evolution simulated by the NCAR/Penn State community mesoscale model (MM5) is systematically validated and evaluated using the observations from the Central California Ozone Study (CCOS) 2000 field experiment. The model simulated ABL winds and thermal structure, as well as the corresponding diagnostic quantities such as divergence and vorticity, are compared with the observational counterparts. It is found that the ABL mixing parameterization in MM5 can simulate the ABL structure and dynamics in California's Central Valley reasonably well under clear sky when the large-scale, upper-level forcing and surface characteristics are specified correctly. Our evaluation indicates that the errors in the model simulations of ABL structure and dynamics are most often caused by errors in the model's upper level synoptic scale flow and uncertainties in the surface characteristics.
A51B-0346
The mechanism of visibility degradation over urban clusters in China
In many urban clusters in China there has been a new weather pattern, heavy haze with much lower visibility, occurred for 1/3 to 1/2 of days of the whole year in the past several years. The megacity, Shanghai, located in the center of the urban cluster areas in the Yangtze River Delta, experiencing severe visibility degradation in recent years, is taken as the typical city to investigate the mechanism of visual range degradation over the urban cluster in China. Aerosol samples were collected in Shanghai in four seasons from the spring of 2004 to the winter of 2005. Daily average particle mass, concentration of soluble ions species and black carbon and the time-matched meteorological data were subjected to analysis the visual range degradation contributors by multivariate linear regression. Water soluble ions and relative humidity (RH) were identified as the major contributors to visual range reduction. NH 4+ with RH was identified as the major contributor to visual range reduction in a lower relative humidity (spring and winter), while SO42- with RH was the major contributor in a higher humidity ambient (summer and autumn) . This might attribute to the hygroscopic species in fine particles. The haze days in spring, autumn and winter were generally influenced by air mass from inland emission. In spring, it was mainly due to the long range transport dust from north-northwest China , and in autumn and winter, the air mass generally came from the middle China. In haze days, the concentration of SO2 and NO2 in autumn and winter were all higher than that in spring, indicating that the gas-particle process were more significant in these two seasons, and contributed to the visual range degradation. In summer, air mass originated from ocean passing through south China arrived Shanghai would result in low visibility. The visibility degradation in Shanghai was largely influenced by the secondary aerosol of both local and regional emissions as well as long-range transport.
A51B-0347
Aerosol Generation And Circulation In The Shore Zone Of A Large Alpine Lake - Lake Tahoe, CA.
The temporal, spatial, and size-distribution patterns of particles in ambient air over shore areas and the surface of Lake Tahoe (Nevada and California) were studied as part of the 2003-2004 Lake Tahoe Atmospheric Deposition Study (LTADS). The concentration of population along the shoreline of Lake Tahoe makes accurate characterization of local aerosol generation and transport especially important in estimation of annual particle flux onto the surface of the lake. Road dust and smoke are major components of aerosols around the lake, and strong gradients in concentrations and size distributions occur as functions of location, land use, traffic activity, and time of day. Measurements taken while cruising on the lake show that aerosol concentrations in near-shore areas are primarily controlled by a combination of diurnal cycling of land- and lake- breezes coupled with varying particle emissions driven by cycles of human activity. Source-associated particle size distributions were shown to be conserved over wide ranges of particle concentrations. Particle concentrations over water were shown to be highly localized, with highest concentrations just offshore from urbanized areas, lowest concentrations along undeveloped shoreline, and low-to-intermediate concentrations over the middle areas of the lake. Based in part on these observations, particle deposition to the lake is seen to be dominated by mesoscale processes, with only minor contributions from regional or large scale atmospheric circulation.
A51B-0348
Observations of the Nocturnal Boundary Layer and Morning Transitional Periods in Houston, Texas during the TexAQS II Campaign
High-temporal resolution tethersonde profiles taken during the TexAQS II field campaign in Houston were used to study the overnight development and progression of the nocturnal boundary layer (NBL) and the evolution of the convective boundary layer after sunrise. The measurements were made at the University of Houston campus, located approximately 4 km southeast of the downtown Houston central business district, and consisted of vertical profiles of potential temperature, water vapor mixing ratio, wind speed, wind direction, and ozone concentration. Profile heights averaged 250 m AGL with a few reaching 400 m AGL. Profiles were taken at approximately 30 min intervals throughout 4 nights during Intensive Observational Periods (IOPs), including both the evening and morning transitional periods. Tethersonde experiments also were performed during several additional morning break-up periods during the campaign. Preliminary results from the overnight experiments of Sept 7-8 and Sept 14-15, 2006 showed different NBL evolutions. Sept 7-8 exhibited a stronger and deeper inversion compared with Sept 14-15 when the inversion was weak with a fairly constant height throughout the night. The Sept 7-8 profiles showed elevated bluff-like structures in the virtual potential temperature profiles between 0300-0400 CDT, indicating neutral stability within the 40-90 m AGL level. And, just before sunrise a neutral layer with constant potential temperature developed between the surface and 75 m AGL reflecting horizontal cold air advection. Further analyses will be presented for other vertical profiles taken during the campaign, including the additional overnight profiles as well as the profiles taken during the morning transition to the convective boundary layer.
A51B-0349
Synoptic patterns of sea fogs and coastal fogs over the Incheon International Airport (IIA) area in Korea
The Incheon International Airport (hereafter IIA), located on the west coast of Korea, often is affected by both sea fogs and coastal fogs. To understand better the characteristics of the two types of fogs, satellite imageries or the reanalysis data [Global Data Assimilation System (GDAS) from NCAR], along with the weather reports around the IIA area, are analyzed. In addition, back trajectory analyses are made to designate the air mass characteristics when the fog forms. There are 181 fog events for the five year period of 2002 to 2006 over the IIA area. First they are classified into cold water fogs (108) and warm water fogs (73) based on the temperature difference between the sea surface and the air above, i.e., the SST and the temperature at 2m ASL from the reanalysis data, because it is considered that the whole mechanism of the formation, the development and the dissipation of cold water fogs is different from those of warm water fogs. Then the fogs in each group are classified into sea fogs or coastal fogs based on the relative humidity at 2m ASL from the reanalysis data. Synoptic patterns in each case are inferred from the weather charts at surface and 850 mb. Preliminarily cold water fog events are divided into 46 sea fogs and 62 coastal fogs and they can also be classified into many subcategories, depending on the synoptic patterns. For both sea fog and coastal fog groups, the westerly or southwesterly winds dominate. However, for the coastal fog type, there are some cases where northerly winds prevail over the west coast of the Korean peninsula. A complete analysis will be shown at the conference.
A51B-0350
Photographic Evidence of Meso-gamma Scale Eddies in Marine Stratocumulus
Numerous examples of meso-beta scale (20-200 km) eddies in the marine boundary layer environment off the U.S. west coast, such as the Catalina Eddy, have appeared in the literature, as has satellite imagery of even smaller (small end of the meso-beta scale to the large end of the meso-gamma scale) von Karman vortices downwind of islands. This paper presents unique photographic evidence of two eddies of meso-gamma scale (2-20 km) in the marine stratocumulus near the California coast. One occurred downwind of Catalina Island, while the other was observed just offshore from Grover Beach, downwind of a headland to the northwest. The photos were taken by pilots flying commercial routes between Santa Ana and San Francisco. Marine boundary layer eddies of this size are likely to escape detection by most means but aerial photography, yet they are likely to play a role in lateral mixing at the coastal margin. With horizontal dimensions of 10 km and a 1 km cloud free "eye," they are too small to show up clearly in geostationary satellite imagery that has been used to identify some of the larger vortices. On the other hand, they may not be clearly visualized as a circulation by a surface-based observer, especially since they are found in a marine stratocumulus environment where there are few or no atmospheric measurements. Pilots of commercial airlines, with a wide view of the horizon, and an altitude that gives a relatively large-scale view of features below, may be the most likely avenue for detection of eddies such as those shown here. This submission presents these images in the interest of documenting the physical characteristics of eddies falling between the more commonly observed meso-beta and those smaller scales more traditionally thought to encompass turbulence. A preliminary mesoscale model simulation with 250 m horizontal resolution is employed to elucidate the causes for one of the eddies. We use the model output to describe and understand characteristics of the flow field in which the eddy occurred, and to determine the origins of the cyclonic vorticity apparent in the aerial image.
A51B-0351 INVITED
The Houston Urban Heat Island: Surface Temperature, Aerosol Mixing Layer Height, and Surface Wind Field Relationships
Both Dallas and Houston, Texas have comprehensive networks of surface meteorology and chemistry sensors. The similarities of the networks and lack of terrain in Dallas and Houston allow for the comparison of their urban heat islands (UHI). The Dallas UHI, unperturbed by thermal flows driven by the land/sea temperature difference, is a well-defined phenomenon over the summers of 2000-2006. Including all weather conditions, the average nighttime T(urban) - T(rural) temperature difference was between 1.5° and 2.0° C and the average daytime difference was ~ 1.0° C. Analysis of Houston temperature data, however, revealed a different picture due to the bay and gulf breezes. While the Houston UHI was a distinct phenomenon, even when including all weather conditions, the bay or gulf breeze modified the Houston UHI by cooling the city. Average nighttime T(urban) - T(rural) temperature differences in Houston were between 1.75° and 2.75° C. However, during the day, the rural areas to the north and west of the city were often warmer than the downtown area during afternoon hours as a result of the sea breeze. Averaging the Houston T(urban) - T(rural) temperature differences over the summers of 2000-2006 indicated a very small urban-rural temperature difference between 1400 to 1600 LST. In some individual years, such as 2000, 2003, 2005 and 2006, the urban areas were actually cooler than the rural areas, on average, in the mid-afternoon. These years had more bay breeze/gulf breeze activity to cool the urban area. We will also look at how land use, the UHI, and boundary-layer winds impact the horizontal distribution of boundary layer heights over the Houston area, as calculated from backscatter measurements from TOPAZ, an ozone and aerosol profiling lidar deployed on a NOAA Twin Otter in the summer of 2006 during the Texas Air Quality Study II.
A51B-0352
A Comparison of Wind Profiler and Model-based Trajectory Calculations
During the 2000 Central California Ozone Study (CCOS 2000), NOAA and collaborative agencies deployed a network of 25 wind profilers to help document the transport and general meteorological conditions associated with air pollution events. Since then, the NOAA Earth System Research Laboratory has developed a web-based wind profiler trajectory tool that uses horizontal winds provided by profiler networks to calculate particle trajectories. In this paper we compare mesoscale (0-2 day) trajectories computed from the profiler network data with two sets of three-dimensional model-based trajectories to evaluate the benefits and deficiencies of each method. The first set of model-based trajectories uses the three-dimensional model winds interpolated to the profiler locations. The goal here is to determine the impact of the simulated vertical motion field on the trajectories. The second set of model-based trajectories uses model runs with data assimilation. The goal here is to see how strongly the model is driven by the wind profiler observations. The models used in the study are the NOAA Earth System Research Laboratory's version of the Pennsylvania State University/National Center for Atmospheric Research Mesoscale Model (MM5) and the Weather and Research Forecast Model (WRF).
A51B-0353 INVITED
Factors Controlling Peak Ozone Concentrations in the Houston Area: Wind Speed and Mixing Height
Peak daytime concentrations of pollutants such as ozone (O3) are inversely dependent on wind speed and mixing depth. Although this relationship is well known and forms the basis of schemes for forecasting maximum daily pollutant concentrations, few data sets comprehensive enough to test this dependence are available. Here we use the data sets from the Texas Air Quality Study (TexAQS) campaigns in the Houston-Galveston Bay area during the summers of 2000 and 2006 to investigate this relationship. Advantages of the TexAQS data sets are (1) the availability of airborne measurements using in-situ and ozone Differential-Absorption Lidar (DIAL) instrumentation, which are able to locate peak O3 concentrations even when they occur outside the surface measurement network, and (2) availability of a network of radar wind profilers, which provide mean boundary- layer winds above the surface at intervals of 1 hr or less. The availability of such wind data is important, because the highest O3 concentrations are associated with midday to early afternoon wind reversals due to the sea breeze. Days with both airborne and surface O3 measurements in the Houston-Galveston-Bay area were selected for analysis. Peak O3 values were determined for a given day from the airborne lidar or P-3 flight data and for the surface measurement network. 10-hr trajectories were calculated from the profiler array and used to calculate the vector-averaged wind speed during this time interval. This procedure accounts for the sea-breeze wind reversals in the accumulation of pollutants. Mixing heights were determined from the aerosol profiles from the airborne lidar when available, or otherwise from the nearest radar wind profiler. To determine the effects of background pollutant levels, background O3 concentration was determined from upstream rural sites in the surface measurement network. The background values were subtracted from the peak concentrations to determine how much O3 was due to the Houston urban / Ship Channel contribution, or urban "add-on." The results confirmed the strong dependence of maximum daily O3 concentrations on the mean wind speed. The highest concentrations and add-on concentrations occurred with vector-averaged speeds of 3 m/s or less, with strong increases to greater than 150 ppb as the speeds decreased to ~1 m/s. At higher wind speeds, peak O3 concentrations tended to be less than 100 ppb and add-ons less than 60 ppb, although some individual days had higher peak O3 associated with high background values. Mixing heights mostly had a secondary effect on peak and add-on concentrations, although this effect was stronger on individual days or at certain times of the day, such as during morning offshore flow conditions before the onset of the sea breeze.
A51B-0354 INVITED
Ozone Flux and Production Downwind of Houston and Dallas
We use airborne lidar and in situ measurements of ozone collected during the TexAQS 2000 and TexAQS 2006 field campaigns to compute total horizontal flux of ozone downwind of the Houston and Dallas metropolitan areas. Fluxes are computed for each transect by integrating excess ozone in the urban plumes (plume ozone - background ozone) between the surface and the top of boundary layer and between the horizontal plume edges and then multiplying the result with the horizontal wind speed provided by a nearby radar wind profiler. We will compare ozone flux measurements for Houston and Dallas under varying meteorological conditions and for different background ozone loadings. In addition, we will use data from multiple downwind transects to estimate ozone production rates in the Houston and Dallas plumes.
A51B-0355
The relationship among air quality, mixing heights, and winds observed during the entire TexAQS-II field study
The Texas Air Quality Study II (TexAQS-II) was designed to provide support for State Implementation Plan (SIP) revisions. The SIP revisions outline strategies for improving air quality to meet the new federal 8-hr ozone standard and regional haze requirements. As part of TexAQS-II, a field study was conducted to collect air quality and meteorological data throughout eastern Texas from May 1, 2005, through October 15, 2006. As part of the field study, various organizations made upper-air meteorological measurements at several locations. These measurements were collected by twelve 915-MHz radar wind profilers (RWPs), three 404 MHz RWPs, nine Radio Acoustic Sounding Systems (RASS), two sodars, and one lidar. These instruments provide vertically, horizontally, and temporally resolved wind, virtual temperature (Tv), and mixing height information. This presentation will address the three-dimensional and temporal characteristics of these parameters throughout the study domain for the entire study period and how these characteristic vary by season, month, and synoptic weather pattern. The presentation will also address how these characteristics influence regional and local air quality conditions throughout the study domain, including the relationship among various transport statistics, mixing height characteristics (e.g., time of peak mixing, morning mixing height growth rate, peak mixing height, average morning mixing height, etc.) and air quality. In addition, case studies will illustrate the finer-scale details of the relationship among the evolution of mixing heights, diurnal variability of winds, and air quality.
A51B-0356
Filamentary Propagation Smoke Plumes and their Interaction with the Arctic Boundary Layer Cycles
The Arctic Boundary Layer (BL) is investigated in connection with filamentary propagating smoke plumes during a period of regional haze in the summer 2005, June 29-30. A description of dynamical exchange mechanisms leading to mixing processes taken place in the continental BL is given during a smoke episode from forest fires originated in the North Eastern part of Alaska responsible for high concentration of fine particle matter in the surface. A discussion of the aerosol concentration exchanges during the BL cycles is given based on the time- height eye-safe optical reflectivity signature, surface fine particulate matter (PM2.5), mesoscale WRF modeling, meteorological and satellite information. The interaction between filamentary smoke plume propagation, the morphology of the boundary layer and the surface particle matter is assessed.
A51B-0357
Modulation of the aerosol absorption and single-scattering albedo due to synoptic scale and sea breeze circulations United Arab Emirates experiment perspective.
The spectral aerosol absorption properties in the Arabian Gulf region were observed during the United Arab Emirates Unified Aerosol Experiment (UAE2). Measurements were taken at a coastal region of the Arabian Gulf located 60 km northeast of Abu Dhabi, the capital of the United Arab Emirates, allowing characterization of pollution and dust absorption properties in a highly heterogeneous environment. A large observed change of the diurnal signal during the period under study (August, 27th trough 30 September of 2004) was due to (a) strong sea- and land-breeze and (b) changes in prevailing synoptic scale flow. During the night, stagnating air resulted in gradual accumulation of pollution with maximum absorption in the early morning hours. The rising sun increased both the depth of the boundary layer and the temperature of the interior desert, resulting in strong and sudden sea-breeze onset which ventilated the polluted air accumulated during the night. Our observations show that the onshore winds brought cleaner air resulting in decreasing values of the absorption coefficient and increasing values of the single-scattering albedo (SSA). The mean value of the absorption coefficient at 550 nm measured during the sea breeze was 10.2 ± 0.9 Mm-1 while during the land breeze it was 13.8 ± 1.2 Mm-1. Synoptic scale transport also strongly influenced particle fine/coarse partition with "northern" flow bringing pollution particles and "southern" flow bringing more dust.
A51B-0358
Relationships between Topography, Soil Type, and Vineyard Temperatures Within the Walla Walla Valley American Viticultural Area
Variations in ambient air temperatures between vineyard sites within the Walla Walla Valley American Viticultural area (AVA) are controlled largely by elevation and relative proximity to major stream valleys. The Walla Walla Valley is a structurally controlled basin centered on a broad syncline in the Columbia River basalt. It is bounded on the east by the anticlinal Blue Mountains and on the south by the Vansycle Ridge escarpment, a segment of the Olympic-Wallowa lineament (OWL). On the west, near its intersection with the Columbia River, the Walla Walla Valley is constricted by Nine Mile Hill, a ridge that impinges on the OWL produced by minor folds in the basalt bedrock. This constriction inhibits the drainage of cold air from the upper parts of the valley and commonly produces early morning temperature inversions. Cold air pooling behind the constriction reduces average temperatures, growing degree-days, and average frost-free days and increases diurnal temperature variation for lower elevations within the AVA. Average temperatures increase and diurnal variations decrease with elevation in the Walla Walla Valley AVA to an elevation of approximately 450 m. These trends reverse as elevations increase beyond 450 m in the foothills of the Blue Mountains. Average ambient air temperatures in vineyards near the base of the Vansycle Ridge escarpment are anomalously high for their elevations due to the local influence of down sloping adiabatically warmed winds. Average ambient air temperatures in vineyards near major stream channels are anomalously low for their elevations due the proximity of cold air streams derived from the higher elevations of the Blue Mountains. Average ambient air temperatures 1.5 m above the surface do not appear to be strongly affected by soil type or ground cover. Average grape cluster temperatures within the vineyards are controlled by ambient air temperature, geomorphology, average wind speed and direction, soil type, and vineyard management practices. Groundcover material and its influence on ground surface temperatures strongly influences grape cluster temperatures. In general, the increase in grape cluster temperature relative to ambient air temperature is greatest in sites dominated by exposed soil or rocks. Vineyard sites covered in grass generally have smaller increases in average surface, cluster, and shallow soil temperatures relative to ambient air temperature.
A51B-0359
Old and New Mechanisms of the Urban Heat Island: Thermal Inertia and Fractal Surface
The history of the research of the urban heat island was started from the research of Howard in 1833. At first, it was thought that the principal cause of the heat island was the large thermal inertia of the surface at the city comparing with suburbs. However, when it came to be able to measure the surface temperature at the ground level using the remote sensing technique by 1970's, the daily surface temperature fluctuation in the city part was revealed to be larger than that of suburbs. This fact indicated that the surface of the city part had small thermal inertia, and the explanation by the thermal inertia model failed if this was simply interpreted. We have observed the surface air temperature and the radiation balance of the Kyoto city from 2004 to 2006 at more than 30 points. The data showed clear heat island at the central city area in the nighttime, while no temperature differences are observed in the daytime. Using data when the radiation balance was abruptly changed by clouds at night time, the thermal inertia of the ground surface was estimated. The obtained thermal inertia shows very high value at the city area, and small value at the suburb which explains enough the difference of amplitude in the diunal air temperature change between the city area and the suburbs. These results support the original explanation of the heat island several decades ago. A question arises again why the surface of the city area (not the air temperature) becomes so hot at the daytime. The answer lies in the geometry of the ground surface. The suburbs are covered by many small leaves in natural fractal distributions, while the urban areas are covered by artificial large flat surfaces. This difference in the surface geometry causes a large difference in the heat transfer coefficient resulting large differences between the surface and the air temperatures. To confirm this, an experiment was done with a fractal roof (Sierpinskifs tetrahedron) and a flat roof with almost same area under the sun shine. The results show that the fractal roof is heated only by 10K comparing with the air temperature while the flat roof is heated more than 30K emitting uncomfortable heat radiation. Note that this temperature reduction can be done without any water evaporation.