The aerosol data, collected using shipborne and island platforms for 8 years from 1995 to 2002 along with modis onboard terra satellite data from 2000 to 2003 have been used to evolve a comprehensive characterisation of the spatial and temporal variation in the physical, chemical, and radiative properties of aerosols over the arabian sea. Over the past decade, the mean annual aerosol optical thickness aot values were in the range of 0. Aerosol optical depth is a measure of the extinction of the solar beam by dust and haze. Modis aerosol optical depth observations over urban areas. Krishna moorthy2 1centre for atmospheric and oceanic sciences. Aod is a very important quantity in building global climate models. Over 50 different global datasets are represented with daily, weekly, and monthly snapshots in a variety of formats. These particles are important to scientists because they can affect climate, weather, and peoples health. Exploring aerosol optical thickness using modis satellite. Daily global observations of aerosols under the cloud free conditions kaufman et al. Aerosol optical depth how is aerosol optical depth. Aerosol optical depth aod from the moderate resolution imaging spectroradiometer modis is a commonly used satellite product for predicting pm concentrations as it measures light extinction at. The glas operational run has no knowledge of the advected smoke and assigns a low marine s. Tiny solid and liquid particles suspended in the atmosphere are called aerosols.
A comparison of model and satellitederived aerosol. Ten years 20012010 of aerosol optical depth aod observations from the moderate. Latitude transects of aerosol optical depth and ngstr. The silver lining project aerosolcloudprecipitation interactions with controlled seawater spray duration.
We present a new approach to retrieve aerosol optical depth aod using the. Pdf nine years of uv aerosol optical depth measurements at. This dataset provides a high quality climate data record cdr of aerosol optical thickness aot. Inferring angstrom exponent and aerosol optical depth from. An aerosol optical depth product has been recently added.
Satellite measurements of aerosols, called aerosol optical thickness, are based on the fact that the particles change the way the atmosphere reflects and absorbs visible and infrared light. Misr level 2 aerosolsurface products quality statement. Cloud screening and quality control algorithms for the. Always on display, a screen feature on certain samsung devices. Pdf aerosol optical depth of the atmosphere over the ocean in the. An automated method of mfrsr calibration for aerosol optical. Nighttime measurements of atmospheric optical thickness by star photometery with a digital camera, applied optics, 46. The aerosol optical depth aod shows seasonal variation with high values in summer and low values in winter. Aerosols affect climate by scattering sunlight back into space and cooling the surface. Lahore experienced more frequency % of pdf of high aods 0.
Pacific anthropogenic aerosol optical depth aod in 2003. Aerosol optical depth aod, a dimensionless quantity which represents the total attenuation of radiation from the top of the atmosphere down to the surface caused by aerosols. Similarly, the retrieved aod under cloudfree conditions over ec in 2006 exceeded. Download daytime product algorithm theoretical basis document atbd download nighttime product algorithm theoretical basis document atbd download product readiness, implementation and management plan rimp cloud optical depth uses both the visible and the nearinfrared abi bands during the daytime and a combination of infrared bands for nighttime detection. Aerosol optical depth as a measure of particulate exposure. Review of aerosol optical depth retrieval using visibility data.
A shortcut from broadband to spectral aerosol optical depth. Air pollution epidemiological studies relying on ground measurements provided by monitoring networks are often limited by sparse and unbalanced spatial distribution of the monitors. The impact of atmospheric aerosols on the earths climate system is poorly understood, and is a subject of considerable interest for the scientific community as well as policy makers kaufman et al. The three different satellitederived optical depths differ by between20. The fire maps show the locations of actively burning fires around the world on a monthly basis, based on observations from the modis sensors on nasas terra satellite. This study aims to investigate and establish a suitable model that can help to estimate aerosol optical depth aod in order to monitor aerosol variations especially during nonretrieval time. The negative slope of langley plot gave the total optical depth comprising of rayleigh optical depth and aerosol optical depth. Rayleigh optical depth was calculated with inverse relationship between rayleigh optical depth and fourth power of wavelength 14 at mean sea level. Kodros2, chandra venkataraman3, pankaj sadavarte3,4, jeffrey r. Adult onset diabetes, a metabolic disorder, characterized by high blood glucose. Aerosol optical depth over india liji mary david 1, a. Aerosol optical depth aod is the measure of aerosols e.
Retrieval of aerosol optical depth from surface solar. Aerosol optical depth, a measure for small particles suspended in the atmosphere. In other words, particles in the atmosphere dust, smoke, pollution can block sunlight by absorbing or by scattering light. Columnar aerosol optical depth measurements have been made over indore 22. Aerosol optical depth, physical properties and radiative. Modis retrieval of aerosol optical depth over turbid. Aerosol optical thickness is the degree to which aerosols prevent the transmission of light in the atmoshpere. Over the global coastal water regions in cloudfree conditions, coastal screening leads to 20% unavailability of aod retrievals. Revised calculation of optical depth upper bound over water such that it uses the maximum scaled optical depth in each channel rather than the minimum. The aerosol optical depth dataset from the synergetic retrieval of aerosol properties algorithm.
Compare this product to aerosol detection smokedust flag and visible, geocolor, dust rgb imagery. Pdf spectral measurements of the aerosol optical depth aod and the angstrom coefficient were conducted at thessaloniki, greece 40. Pdf documents require the free adobe reader or compatible viewing software to be viewed. Mass coefficients volume coefficientsparticle mass concentration, m. Aerosol optical depth determined by lidar and spectrometer. Stratospheric aerosol optical thicknesses used in giss climate simulations are given here. The current study focused on athens, greece during the year of 2004 and 1 demonstrates a systemized process for aligning data obtained from satellite aerosol optical depth aod with geographic location and time, 2 evaluates the ability to apply imputation methods to censored data, and 3 explores whether aod data can be used. Ofc an introduction optical fiber dispersion optics. Examples of aerosols include windblown dust, sea salts, volcanic ash, smoke from fires, and pollution from factories. The growing database requires development of a consistent, reproducible and systemwide cloud screening procedure. The concept behind the shortcut idea is a close correlation between column broadband aerosol optical depth baod and aerosol optical depth at 500 nm aod500. Frederick department of geophysical sciences, university of chicago, chicago, illinois abstract. Aerosol optical depth measurements and their impact on surface levels of ultravioletb radiation b. This demonstrates how the toms channels at 340 nm and 380 nm can be used to detect absorbing aerosols and estimate their optical depth and singlescattering albedo, because a particular pair of radiance values at 340 nm and.
Scattering and absorption by aerosol and cloud particles. Saxena department of marine, earth and atmospheric sciences, north carolina state university, raleigh, north carolina j. In physics, optical depth or optical thickness, is the natural logarithm of the ratio of incident to transmitted radiant power through a material, and spectral optical depth or spectral optical thickness is the natural logarithm of the ratio of incident to transmitted spectral radiant power through a material. Measuring aerosol optical depth aod and aerosol profiles. The product is more accurate over water surfaces than over land surfaces. Pacific anthropogenic aerosol optical depth aod in 2003 visualizations by lori perkins released on march, 2008 according to measurements taken with a satellite instrument, vast quantities of industrial aerosols and smoke from biomass burning in east asia and russia are traveling from one side of the globe to another. Esrl global monitoring laboratory global radiation and. Studies have found correlations between satellite aerosol optical depth aod and pm2.
The advanced very high resolution radiometer avhrr aot cdr provides an optical measure of aerosol column loading derived from the global ocean pixellevel patmosx avhrr clearsky reflectance cdr at 0. Nasa sport near realtime aerosol optical depth composite product aaron naeger august 3, 2016. For example, the effect of changes in the current aerosol emissions on climate depends on the background aerosol load during the preindustrial era e. Atmosphere free fulltext aerosol optical thickness over large. The relationship between actual ground measurements such as air pollution index, visibility, relative humidity, temperature, and pressure and aod obtained with a cimel sun photometer was determined. Optical depth is dimensionless, and in particular is not a length, though it is a. Plots from glas operational run black squares, glas smoke run gray asterisks, and cpl black dots showing total aerosol optical depth from october 28. Estimating aerosol absorption, optical depth, and vertical. Millet5 1department of chemistry and department of atmospheric science, colorado state university, fort collins, co, usa, 2department of atmospheric science, colorado state university, fort collins, co. For all these cases, the aerosol optical depth of the sunphotometer and the dual view retrieval over land agreed within 0. For example, the aerosol optical depth has mainly been measured using. I usually download the data in netcdf format which is a selfdescribing format that can be read by many analysis and visualisation packages e. The aerosol optical depth is then computed as the residual of the total optical depth minus the pressurecorrected rayleigh optical depth and a satellitederived total ozone mapping spectrometer toms or ozone monitoring instrument omi, depending on year ozone optical depth.
Aerosols are one of those important geophysical parameters that determine the earths energy balance and hydrological cycle. Ofc an introduction free download as powerpoint presentation. Avhrr aerosol optical thickness national centers for. Modis aerosol optical depth observations over urban areas in. Spatial analysis of modis aerosol optical depth, pm 2. Calibrating modis aerosol optical depth for predicting. The dashed lines are each drawn for a fixed optical depth and varying singlescattering albedo. Aerosol optical depth aod is a quantitative estimate. These suspended airborne particles scatter solar radiation back, absorb solar radiation in the atmosphere, and shade the earths surface. Retrieval of aerosol optical depth from surface solar radiation. Dust altitude and infrared optical depth from airs c. Geophysicae large aerosol optical depths observed at an.
First results from aerosol optical depth retrieval over land using twoview satellite radiometry, shows very promising results. Numerous studies have found adverse health effects of acute and chronic exposure to fine particulate matter pm2. The second figure is of the zonal mean stratospheric optical depths. Aod can be obtained by making a correction to the optical depth for attenuation due to rayleigh scattering, absorption by ozone and gas pollutants.
How to extract the aerosol optical depth aod from modis. Pdf a modified aerosol free vegetation index algorithm for aerosol. Aerosol optical depth aod retrieval algorithms use cloud screening techniques to disregard aod in cloudy regions due to difficultly in separating visible reflectance of aerosols and clouds. Pdf at least two problems, the climatic impact of aerosols and improvement in techniques for space. Geophysicae large aerosol optical depths observed at an urban location in southern india associated with rainde. Groundbased aerosol optical depth measurement using. Aerosol optical depth variation observed using sun. Remote sensing of aod relies on the concept that solar radiation is modi. Lastly, th e resulting aerosol optical depths are flagged to indicate. Applications of satellite data for aerosol optical depth. Aerosols are not only emitted directly into the atmosphere by anthropogenic and natural sources, but are also formed in the atmosphere. Browse and download imagery of satellite data from nasas earth observing system. Aerosol optical depth measurements and their impact. Huttunen et al retrieval of aerosol optical depth from surface solar radiation measurements the current forcing of anthropogenic aerosol.
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