A23A-0262
Comparison of Surface and Satellite Derived Aerosol Optical Depth (AOD) Measurements in Finland, Estonia, Zambia and Brazil
Aerosol Optical Depth (AOD) values derived with the new MODIS retrieval algorithm over land (Collection 5) were compared with ground-based sun photometer measurements in northern Europe, Africa and South America. Sites in northern Europe were chosen to represent clean atmosphere, whereas locations in the southern hemisphere were heavily affected by biomass burning aerosols. In Finland (Jokioinen and Sodankylä) measurements were done with Precision Filter Radiometer (PFR), while in Estonia (Toravere), Zambia (Mongu) and Brazil (Alta Floresta) level 2 AERONET data were used. Comparison results were generally good although in the aerosol model selection, particularly how dust is taken into account, there seems to be room for improvement. At all studied sites the MODIS algorithm selects occasionally dust aerosol model even though dust does not seem to be present and the air masses are not coming from arid regions. This happens especially when AOD values are small (<0.3) or during apparent cloud contamination. Moreover, the Ångström exponent in Collection 5 data is no longer an independent parameter, thus caution is required when using it. However, it is an important parameter if one tries to estimate the anthropogenic component of aerosols. Collocated measurements from the AERONET sites with the largest absolute and relative differences were studied in more detail. Based on these case studies, it seems that cloud screening algorithms are the main reason for the largest differences between satellite and ground-based instruments.
A23A-0263
MODIS aerosol product at 3 km spatial resolution for urban and air quality studies
The MODerate resolution Imaging Spectroradiometer (MODIS) aboard the Terra and Aqua satellites has been producing an aerosol product since early 2000. The original product reports aerosol optical depth and a variety of other aerosol parameters at a spatial resolution of 10 km over both land and ocean. The 10 km product is actually constructed from 500 m pixels, which permits a strict selection process to choose the "best" or "cleanest" pixels in each 10 km square for use in the aerosol retrieval. Thus, the original 10 km product provides a useful product, accurate in many applications. However, the 10 km product can miss narrow aerosol plumes and the spatial variability associated with urban air pollution. The MODIS aerosol team will be introducing a finer resolution aerosol product over land regions in the next release of the product (Collection 6). The new product will be produced at 3 km resolution. It is based on the same procedures as the original product and benefits from the same spatial variability criteria for finding and masking cloudy pixels. The 3 km product does capture the higher spatial variability associated with individual aerosol plumes. However, it is noisier than the 10 km product. Both products will be available operationally in Collection 6. The new 3km product offers new synergistic possibilities with PM2.5 monitoring networks, AERONET and various air quality models such as CMAQ.
A23A-0264
Aerosol Optical Properties Measured on the Mesoscale During the TIGERZ Campaign in the Indo-Gangetic Plain Region of Kanpur, India
The NASA AERONET TIGERZ campaign (May to June 2008) characterized aerosols during the late pre- monsoon to early monsoon period in the Indo-Gangetic Plain (IGP) of northern India. The IGP produces a large amount of anthropogenic pollution from urban, industrial, and rural combustion sources nearly continuously with convection-induced winds driving Thar Desert and locally-generated dust periodically into the atmosphere throughout the dry pre-monsoon season. During TIGERZ, up to seven ground-based AERONET passive radiometers were deployed in the vicinity of Kanpur, a major industrial city within the IGP. These first-of-a-kind AERONET spatial variability studies (SVSs) in India occurred six times during the TIGERZ campaign. For each SVS, instruments were deployed in and around Kanpur or along the CALIPSO track in eastern Kanpur anchored by the permanent IIT Kanpur AERONET site to the west. This mesoscale instrument distribution occurred within approximately a 50 km box providing higher spatial resolution in the Kanpur region. In addition, these instruments implemented higher measurement frequency (<3min) than the standard AERONET protocol (~15min). During one SVS, the Cimel radiometer performed higher frequency sky radiance measurements (2-3 almucantars and 1 principal plane per hour) in order to assess the variability of the aerosol properties from the AERONET inversions. Preliminary data for the discrete SVSs (May to June 2008) indicate that the ground-based, area-averaged AOD at 500nm ranged from 0.31 to 0.89 (overall: 0.63±0.25) and the 440-870nm Angstrom exponent ranged from 0.19 to 0.83 (overall: 0.39±0.23); these values suggest varying amounts of aerosol loading (mostly due to dust) during these SVSs. Further data will be presented detailing the spatial and temporal variability of aerosol optical and microphysical properties over Kanpur for TIGERZ SVSs, an analysis of the relation of SVS measurements to the historical record collected at the IIT-Kanpur AERONET site, and a comparison of aerosol properties with available MODIS and MISR aerosol retrievals.
A23A-0265
MISR Stereo-heights of Grassland Fire Smoke Plumes in Australia
Plume heights from wildfires are used in climate modeling to predict and understand trends in aerosol transport. This study examines whether smoke from grassland fires in the desert region of Western and central Australia ever rises above the relatively stable atmospheric boundary layer and accumulates in higher layers of relative atmospheric stability. Several methods for deriving plume heights from the Multi-angle Imaging SpectroRadiometer (MISR) instrument are examined for fire events during the summer 2000 and 2002 burning seasons. Using MISR's multi-angle stereo-imagery from its three near-nadir-viewing cameras, an automatic algorithm routinely derives the stereo-heights above the geoid of the level-of-maximum-contrast for the entire global data set, which often correspond to the heights of clouds and aerosol plumes. Most of the fires that occur in the cases studied here are small, diffuse, and difficult to detect. To increase the signal from these thin hazes, the MISR enhanced stereo product that computes stereo heights from the most steeply viewing MISR cameras is used. For some cases, a third approach to retrieving plume heights from MISR stereo imaging observations, the MISR Interactive Explorer (MINX) tool, is employed to help differentiate between smoke and cloud. To provide context and to search for correlative factors, stereo-heights are combined with data providing fire strength from the Moderate-resolution Imaging Spectroradiometer (MODIS) instrument, atmospheric structure from the NCEP/NCAR Reanalysis Project, surface cover from the Australia National Vegetation Information System, and forward and backward trajectories from the NOAA HYSPLIT model. Although most smoke plumes concentrate in the near-surface boundary layer, as expected, some appear to rise higher. These findings suggest that a closer examination of grassland fire energetics may be warranted.
A23A-0266
Factors Affecting Boreal Forest Fire Plume Vertical Profiles Near The Sources
We used both satellite observations and model simulations to analyze factors that determine the vertical profiles of aerosols emitted by boreal forest fires. The 2004 Alaska fire data observed by MISR are used for this study. MISR observation, in conjunction with related MODIS data, is unique for this purpose, since it pinpoints biomass burning (BB) plumes at their source regions, where the initial injection heights of the plumes are critical in determining their transport pathways. MISR-observed BB plume stereo heights over the Alaska region suggest that the variability of plume height is affected by multiple factors, including fire emitted heat flux and atmosphere stability. We used MODIS-observed fire radiative power as a partial surrogate for the fire-produced dynamical heat fluxes, and we used both a global data assimilation system (NASA/GEOS) and a meso-scale model (WRF) to estimate the atmosphere stability. Comparison between MISR observation and model simulation (GOCART) of BB plumes suggest that the plumes can be lifted well above the planetary boundary layer (PBL) when the boundary layer top is less stable, and the plumes are more likely to be trapped within PBL when the atmosphere is very stable, i.e. the buoyancy force caused by fire heat fluxes is competing with the barrier of the atmospheric lapse rate. The relationship between the height of MISR observed 2004 Alaska fire plumes (more than 600 plumes) with the fire released energy, atmospheric stability, and vegetation types is summarized.
A23A-0267
Dust Storm Observations From OMI, MISR, and MODIS Over the Northern Africa
The advent of modern spaceborn sensors including Aura/OMI (Ozone Monitoring Instrument), Terra/MISR (Multiangle Imaging Spectroradiometer), and Aqua/MODIS (Moderate Resolution Imaging Spectroradiometer), and their advanced algorithms enables us to monitor large scale dust storms, and to quantify aerosol properties over the Northern Africa including the Saharan desert where the world's largest sources of mineral dust are located. Few ground measurements of dust aerosol properties have been available due to the limited accessibility and large geographical extent of the region. OMI's near UV unique strength for aerosol detection is the large sensitivity to aerosol absorption. OMI's 2600 km swath allows for daily global coverage. MISR's multiangle measurement design provides aerosol properties of high accuracy with less sensitivity to surface types, but limited swath coverage (360 km). Recently MODIS Deep Blue (DB) algorithm has added capability to retrieve aerosol properties over deserts with high spatial sampling resolution (10 km x 10 km). Measurements from three sensors provide a synoptic view of dust storm activity patterns, and estimate optical depth and single scattering albedo over the Northern Africa as well as adjacent coastal areas where wind-drifted dust aerosols are frequently observed. We present inter-comparison results of Aerosol Extinction Optical Depth (AOD) among OMI, MISR, and MODIS DB against AERONET ground-based measurements in 2006. The seasonal and spatial variability of aerosol absorption optical depth and single scattering albedo is also documented. Those products from three sensors are complementary to one another, and can be synergistically used for evaluating dust storm effects on climate study.
A23A-0268
Anthropogenic and Biomass Burning Aerosols Observed from Halifax, Nova Scotia
Aerosol measurements during the summer of 2007 from the Dalhousie Raman Lidar located in Halifax, Nova Scotia, are presented and analyzed. Observations of plumes from biomass burning across North America are revealed in addition to anthropogenic pollution events originating from the populated East. Satellite measurements from MODIS and CALIPSO are used to determine the horizonal extent of the events, and also to identify biomass burning hot spots. The data are interpreted using simulations from the GEOS-Chem Chemical Transport Model, and the HYSPLIT and FLEXPART particle trajectory models.
A23A-0269
TIGERZ I: Aerosols, Monsoon and Synergism
The Indo-Gangetic Plain of northern India encompasses a vast complex of urban and rural landscapes, cultures that serve as anthropogenic sources of fine mode aerosols mixed with coarse mode particles transported from SW Asia. The summer monsoon and fall Himalayan snowmelt provide the agricultural productivity to sustain an extremely high population density whose affluence is increasing. Variations in the annual monsoon precipitation of 10% define drought, normal and a wet season; the net effects on the ecosystems and quality of life can be dramatic. Clearly investigation of anthropogenic and natural aerosol impacts on the monsoon, either through the onset, monsoon breaks or end points are a great concern to understand and ultimately mitigate. Many national and international field campaigns are being planned and conducted to study various aspects of the Asian monsoon and some coordinated under the Asian Monsoon Years (AMY) umbrella. A small program called TIGERZ conducted during the pre-monsoon of 2008 in North Central India can serve as a model for contributing significant resources to existing field programs while meeting immediate project goals. This poster will discuss preliminary results of the TIGERZ effort including ground-based measurements of aerosol properties in the I-G from AERONET and synergism with various Indian programs, satellite observations and aerosol modeling efforts.
A23A-0270
Using Horizontal Transport Characteristics to Infer an Emission Height Timeseries of Volcanic SO2
Characterizing the emission height of sulfur dioxide (SO2) from volcanic eruptions yields information about the strength of volcanic activity, and is crucial for the assessment of possible climate impacts and for validation of satellite retrievals of SO2. Sensors such as the Ozone Monitoring Instrument (OMI) on the polar-orbiting Aura satellite provides accurate maps of the spatial distribution of volcanic SO2, but provide limited information on its vertical distribution. The goal of the work presented here is to explore the possibility of using a trajectory model to reconstruct both the temporal activity and injection altitude of a volcanic source from OMI column measurements of SO2 observed far from the volcano. Statistical analyses based on the distance of closest approach to the volcano of back trajectories initialized at the measurements are compared to an optimal reconstruction based on forward trajectories. The inferred altitude of the SO2 cloud is verified using the altitude of derived sulfate aerosol detected in aerosol backscatter vertical profiles form the CALIPSO instrument.
A23A-0271
Comparison of satellite and ground based aerosol optical depth and surface optical and chemical measurements at the Fresno, California supersite
From 2001 through 2006, the Fresno supersite collected a large variety of aerosol and optical measurements. These included high time resolved aerosol chemical components (sulfate, nitrate, OC/EC), light scattering and light absorption, particle size distributions and aerosol optical depth using a sun photometer (AERONET site). Here we examine the relationships among surface measurements and column integrated measurements. We also compare MODIS and GOES derived AOD to the AERONET AOD measurements and evaluate their performance under varying conditions (e.g. season, aerosol composition). AERONET column total size distribution was nearly identical to surface size distribution. AERONET AOD was well correlated to surface light scattering in winter (r=0.7) , but poorly related in summer, partly due to occurrence of smoke from forest fires causing significant optical depth above the surface layer in summer. AERONET fine mode AOD correlated better to PM2.5 than did total AOD. MODIS and GOES AOD correlated poorly with AERONET AOD.
A23A-0272
Preliminary aerosol parameter retrieval from ARCTAS-II using merged RSP and HSRL data
The second phase of the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) field campaign concluded on July 13, 2008 for the Research Scanning Polarimeter (RSP) and High Spectral Resolution Lidar (HSRL) instruments onboard the NASA King Air B-200 aircraft. A total of 21 research or transit flights were conducted over a twenty day period from the base of operations in Yellowknife, Northwest Territories, Canada. Smoke aerosols were observed from boreal fires located over western Canada and eastern Siberia. This is an ideal data set to test the ability of the RSP to retrieve optical parameters of absorbing aerosols from forest fires, as the B-200 flew many coordinated flights with NASA's P- 3b and DC-8 aircraft that measured aerosol properties in situ. Previously, retrieval of absorbing aerosol parameters with the RSP has been difficult unless a priori constraints are placed on aerosol layer heights. During ARCTAS, HSRL provided layer height constraints for RSP aerosol parameter retrievals. These results were compared to retrievals without layer height constraints and the in situ measurements. Polarimeter-Lidar data merger such as this has implications for orbital instruments as well, since the RSP is the airborne prototype of the Aerosol Polarimetry Sensor (APS). APS is part of the NASA Glory satellite, due to be launched in 2009 into the "A-train" orbit, which also contains the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) instrument.
A23A-0273
Evaluation of Combined Active-Passive Aerosol Extinction Profile Retrieval Using Airborne High Spectral Resolution Lidar
Lidar remote sensing is a valuable means of measuring the vertical distribution of aerosol properties. To obtain a profile of aerosol extinction from a backscatter lidar requires an additional source of information, typically an assumed value of the aerosol extinction-to-backscatter ratio, or lidar ratio. We present results of a combined active plus passive retrieval of aerosol extinction from attenuated lidar backscatter data that avoids the need to assume the lidar ratio. Instead, the aerosol optical thickness (AOT) from a passive instrument such as the Moderate Resolution Imaging Spectroradiometer (MODIS) is used to constrain the lidar retrieval. For initial application and validation of the retrieval, data from NASA Langley's airborne High Spectral Resolution Lidar (HSRL) are used. The HSRL instrument provides backscatter data at 532~nm and 1064~nm, and also, by means of the HSRL technique, aerosol extinction at 532~nm. Applying the combined active-passive aerosol extinction retrieval to attenuated backscatter data from the HSRL instrument provides a unique opportunity to validate the technique by comparison with the HSRL derived extinction. The combined active-passive retrieval is also performed on backscatter measurements from the Cloud- Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) mission. CALIPSO provides aerosol backscatter at 1064~nm and 532~nm. Uncertainties in the lidar ratio are a major source of uncertainty in the CALIPSO extinction retrievals. We believe the combined active-passive retrieval outlined here can potentially improve the retrievals. To constrain the retrieval, we require aerosol optical thickness from a coincident measurement. MODIS on Aqua, in the A-train satellite constellation with CALIPSO, provides observations coincident with CALIPSO and with many HSRL flights. There also exist coincidences between HSRL and MODIS on Terra and the Multiangle Imaging Spectroradiometer (MISR). The satellite AOT from these instruments will be evaluated by comparison with the HSRL measured AOT. We present results of retrievals using the combined active-passive technique using HSRL attenuated backscatter data constrained with aerosol optical thickness from HSRL, MISR, and MODIS on Aqua and Terra and example extinction retrievals using CALIPSO constrained with Aqua MODIS AOT. Initial results suggest that the HSRL plus Aqua retrieval produces agreement within 35% for 66% of retrieved extinction values over water (for AOT>0.15), and within 45% for 68% over land (for AOT>0.2).
A23A-0274
Routine measurements of aerosol extinction profiles by the ARM program and their validation
The vertical profile of aerosol extinction is needed as input for the assessment of direct, indirect, and semi- direct effects of aerosols on the Earth radiative balance. Since 1998 the U.S. Department of Energy Atmospheric Radiation Measurement program has continuously operated a fully automated Raman Lidar at its Southern Great Plains site in Oklahoma. Its capability of measuring profiles of aerosol extinction and water vapor has been critically assessed using remote sensing and in situ aircraft measurements from the 2003 Aerosol Intensive Operations Period (AIOP). These comparisons revealed that the Raman Lidar's sensitivity had degraded significantly and the derived extinction profiles had developed a significant positive bias. Major upgrades to the Raman Lidar made in 2004 resulted in dramatically improved sensitivity and reduced random errors. The ARM program also operates Micro Pulse Lidars (MPL) at all of its fixed and mobile sites. When combined with a ground-based measurement of aerosol optical depth (AOD), aerosol extinction profiles can be derived from MPL data. Finally from 2000- 2007 the ARM program has conducted in-situ aerosol profile (IAP) flights using a small aircraft measuring profiles of aerosol scattering and absorption. An aircraft campaign focused on quantifying the improvements of the Raman Lidar and on validating the MPL extinction profiles - the Aerosol Lidar Validation Campaign (ALIVE) - was conducted in 2005. In both the AIOP and ALIVE campaigns the NASA Ames Airborne 14-channel Sunphotometer (AATS-14) was used as the comparison basis for vertically resolved aerosol extinction measurements. Additionally, coordinated flights between the IAP aircraft and the aircraft carrying AATS-14 in AIOP and ALIVE allow an assessment of the IAP's capability to measure aerosol extinction. The AATS-14 instrument has been used for the same purpose in many campaigns outside the ARM program. It is increasingly seen as the solid benchmark against which other measurements of ambient extinction profile measurements are compared. In this paper we show the comparisons derived from the ALIVE data (and not previously published AIOP IAP vs. AATS-14 comparisons) and put these in context with the previously published AIOP comparisons.
A23A-0275
Evaluation of 3-D Air Quality System Remotely-Sensed Aerosol Optical Depth for the Baltimore/Washington Metropolitan Air Shed
Integrating satellite- and ground-based aerosol optical depth (AOD) observations with surface total fine particulate (PM2.5) and sulfate concentrations allows for a more comprehensive understanding of local- and urban-scale air quality. This study evaluates the utility of integrated databases being developed for NOAA and EPA through the 3D-AQS project by examining the relationship between remotely-sensed AOD and PM2.5 concentrations for each platform for the summer of 2004 and the entire year of 2005. We compare results for the Baltimore, MD/Washington, DC metropolitan air shed, incorporating AOD products from the Terra and GOES-12 satellites, AERONET sunphotometer, and ground-based lidar, and PM2.5 concentrations from five surface monitoring sites. The satellite-derived products include AOD from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Multi-angle Imaging Spectroradiometer (MISR), as well as the GOES Aerosol/Smoke Product (GASP). The vertical profile of lidar backscatter is used to retrieve the planetary boundary layer (PBL) height in an attempt to capture only that fraction of the AOD arising from near surface aerosols. Adjusting the AOD data using platform- and season-specific ratios, calculated using the parameters of the regression equations, for two case studies resulted in a more accurate representation of surface PM2.5 concentrations when compared to a constant ratio that is currently being used in the NOAA IDEA product. This work demonstrates that quantitative relationships between remotely-sensed and in-situ aerosol observations in an integrated database can be computed and applied to improve the use of remotely-sensed observations for estimating surface concentrations.
A23A-0276
Quantitative comparison of aerosol optical depth (AOD) and aerosol indirect effects in three polluted Asian cities
Advances in satellite technology and ground based measurement techniques have resulted in vast amount of data on aerosol and cloud parameters. Aerosol indirect effects are characterized by the effects of aerosol on cloud radiative properties. This being a subject of significant interest for climate change and human health effects, many computational and satellite data analysis studies have been made to understand this mechanism. However, most of the studies are made on understanding the global effects. In this work we attempt to understand the local effects by making quantitative analysis of aerosol and its indirect effects in three polluted Asian cities. We analyze aerosol optical depth (AOD) data from MODIS (Moderate Resolution Imaging Spectroradiometer) and MISR (Multiangle Imaging SpectroRadiometer), aerosol extinction optical depth, absorption optical depth, and aerosol index (AI) data from OMI (Ozone Monitoring Instrument) and compare with AOD data of AERONET (Aerosol Robotic Network) at Beijing, China; Dalanzadgad, Mongolia; and Kanpur, India. Cloud parameters from MODIS data are correlated with aerosol optical depth. Seasonal variation of aerosol optical depth and its effect on cloud radiative properties are discussed. Large differences in AOD are observed in the measurements by different instruments. The differences in the results of indirect effects indicate considerable influence of local environment.
A23A-0277
CUACE and its Performance in Summer Season in 2008
CUACE ( CMA Unified Atmospheric Chemistry Environmental Forecasting System) is a unified chemical weather numerical forecasting system with BC, OC, Sulfate, Nitrate, Ammonia, Dust and Sea-Salt aerosols and their sources, gas to particle processes, SOA, microphysics and transformation. It has been designed with open interface to make it easily coupled to models in different temporal and spatial scales. It has been online coupled to the mseoscale model MM5 and in the near future will be coupled onto a new NWP forecasting GRAPES, Global/Regional Assimilation and Prediction Enhanced System. With Chinese Emissions from Cao (2006), CUACE has been running in real time from July to the end of September in 2008 and issue 3-days PM10, O3 and Visibility forecasts to SEPA. Model outputs and the effect of emission control in 2008 summer time by CUACE will be carefully evaluated with surface and upper intense observation.
A23A-0278
Analysis of the impact of the Forest Fires in August 2007 on Athen's air quality using multi-sensor aerosol remote sensing data, meteorology and surface observations
Data from multiple satellite remote sensors including MISR, MODIS and OMI are integrated with ground measurements and meteorological data to study the impact of Greek forest fires in August 2007 on the air quality in Athens. Two pollution episodes were identified by ground PM10 measurements during August 23 and September 4. In the first episode, Evia and Peloponnese fires contributed substantially to the air pollution levels in Athens. In the second episode, transport of industrial pollution from Italy and Western Europe as well as forest fires in Albania contributed substantially to the air pollution levels in Athens. Local air pollution sources also contributed to the observed particle levels during these episodes. Satellite data provide valuable insight of the spatial distribution particle concentrations, thus they can be used identify pollution sources. In spite of a few weaknesses in current satellite data products identified in this analysis, combining satellite aerosol remote sensing data with trajectory models and ground measurements is a powerful tool to study intensive particle pollution events such as forest fires.