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Sample records for atmospherically correct awifs

  1. Development of a scheme for atmospheric correction of Resourcesat-2 AWiFS data

    NASA Astrophysics Data System (ADS)

    Pandya, M. R.; Pathak, V. N.; Shah, D. B.; Trivedi, H. J.; Chipade, R. A.; Singh, R. P.; Kirankumar, A. S.

    2015-08-01

    This paper presents a method called SACRS2, a scheme for atmospheric correction of RS2-AWiFS (Resourcesat2-Advanced Wide Field Sensor) data. The SACRS2 is a computationally fast scheme developed from a physics-based detailed radiative transfer model 6SV for correcting large amount of data from the high-repetivity AWiFS sensor. The method is based on deriving a set of equations with coefficients which depend on the spectral bands of the RS2-AWiFS sensor through forward signal simulations by 6SV. Semi-empirical formulations provided in the SMAC method with a few improvements have been used to describe various atmospheric interactions. A total of 112 coefficients for different equations are determined using the best fit equations against the computations of the 6SV. After the specific coefficients for the RS2-AWiFS spectral bands are determined, the major inputs of the scheme are raw digital numbers recorded by RS2-AWiFS sensor, atmospheric columnar water vapour content, ozone content, aerosol optical thickness at 550 nm and viewing-illumination conditions. Results showed a good performance of the SACRS2 with a maximum relative error in the SACRS2 simulations ranged between 1% for a reflectance of 0.5 and 8.6% for reflectance of 0.05 with respect to 6SV computations. Validation of retrieved surface reflectance using the SACRS2 scheme with respect to in-situ measurements at two sites indicated a capability of this scheme to determine the surface reflectance within 10%. This is a first of its kind scheme developed for the atmospheric correction of any Indian Remote Sensing satellite data. A package containing the SACRS2 software is available on the MOSDAC website for the researchers.

  2. Ground based measurements on reflectance towards validating atmospheric correction algorithms on IRS-P6 AWiFS data

    NASA Astrophysics Data System (ADS)

    Rani Sharma, Anu; Kharol, Shailesh Kumar; Kvs, Badarinath; Roy, P. S.

    In Earth observation, the atmosphere has a non-negligible influence on the visible and infrared radiation which is strong enough to modify the reflected electromagnetic signal and at-target reflectance. Scattering of solar irradiance by atmospheric molecules and aerosol generates path radiance, which increases the apparent surface reflectance over dark surfaces while absorption by aerosols and other molecules in the atmosphere causes loss of brightness to the scene, as recorded by the satellite sensor. In order to derive precise surface reflectance from satellite image data, it is indispensable to apply the atmospheric correction which serves to remove the effects of molecular and aerosol scattering. In the present study, we have implemented a fast atmospheric correction algorithm to IRS-P6 AWiFS satellite data which can effectively retrieve surface reflectance under different atmospheric and surface conditions. The algorithm is based on MODIS climatology products and simplified use of Second Simulation of Satellite Signal in Solar Spectrum (6S) radiative transfer code, which is used to generate look-up-tables (LUTs). The algorithm requires information on aerosol optical depth for correcting the satellite dataset. The proposed method is simple and easy to implement for estimating surface reflectance from the at sensor recorded signal, on a per pixel basis. The atmospheric correction algorithm has been tested for different IRS-P6 AWiFS False color composites (FCC) covering the ICRISAT Farm, Patancheru, Hyderabad, India under varying atmospheric conditions. Ground measurements of surface reflectance representing different land use/land cover, i.e., Red soil, Chick Pea crop, Groundnut crop and Pigeon Pea crop were conducted to validate the algorithm and found a very good match between surface reflectance and atmospherically corrected reflectance for all spectral bands. Further, we aggregated all datasets together and compared the retrieved AWiFS reflectance with

  3. Retrieval of Surface Reflectance using SACRS2: a Scheme for Atmospheric Correction of ResourceSat-2 AWiFS data

    NASA Astrophysics Data System (ADS)

    Pandya, M. R.; Pathak, V. N.; Shah, D. B.; Singh, R.. P.

    2014-11-01

    The Indian Remote Sensing (IRS) satellite series has been providing data since 1988 through various Earth observation missions. Before using IRS data for the quantitative analysis and parameter retrieval, it must be corrected for the atmospheric effects because spectral bands of IRS sensors are contaminated by intervening atmosphere. Standard atmospheric correction model tuned for the IRS sensors was not available for deriving surface reflectance. Looking at this gap area, a study was carried out to develop a physicsbased method, called SACRS2- a Scheme for Atmospheric Correction of Resourcesat-2 (RS2) AWiFS data. SACRS2 is a computationally fast scheme developed for correcting large amount of data acquired by RS2-AWiFS sensor using a detailed radiative transfer model 6SV. The method is based on deriving a set of coefficients which depend on spectral bands of the RS2-AWiFS sensor through thousands of forward signal simulations by 6SV. Once precise coefficients of all the physical processes of atmospheric correction are determined for RS2-AWiFS spectral bands then a complete scheme was developed using these coefficients. Major inputs of the SACRS2 scheme are raw digital numbers recorded by RS2-AWiFS sensor, aerosol optical thickness at 550 nm, columnar water vapour content, ozone content and viewing-geometry. Results showed a good performance of SACRS2 with a maximum relative error in the SACRS2 simulations ranged between approximately 2 to 7 percent with respect to reference 6SV computations. A complete software package containing the SACRS2 model along with user guide and test dataset has been released on the website (www.mosdac.gov.in) for the researchers.

  4. Using NASA Techniques to Atmospherically Correct AWiFS Data for Carbon Sequestration Studies

    NASA Technical Reports Server (NTRS)

    Holekamp, Kara L.

    2007-01-01

    Carbon dioxide is a greenhouse gas emitted in a number of ways, including the burning of fossil fuels and the conversion of forest to agriculture. Research has begun to quantify the ability of vegetative land cover and oceans to absorb and store carbon dioxide. The USDA (U.S. Department of Agriculture) Forest Service is currently evaluating a DSS (decision support system) developed by researchers at the NASA Ames Research Center called CASA-CQUEST (Carnegie-Ames-Stanford Approach-Carbon Query and Evaluation Support Tools). CASA-CQUEST is capable of estimating levels of carbon sequestration based on different land cover types and of predicting the effects of land use change on atmospheric carbon amounts to assist land use management decisions. The CASA-CQUEST DSS currently uses land cover data acquired from MODIS (the Moderate Resolution Imaging Spectroradiometer), and the CASA-CQUEST project team is involved in several projects that use moderate-resolution land cover data derived from Landsat surface reflectance. Landsat offers higher spatial resolution than MODIS, allowing for increased ability to detect land use changes and forest disturbance. However, because of the rate at which changes occur and the fact that disturbances can be hidden by regrowth, updated land cover classifications may be required before the launch of the Landsat Data Continuity Mission, and consistent classifications will be needed after that time. This candidate solution investigates the potential of using NASA atmospheric correction techniques to produce science-quality surface reflectance data from the Indian Remote Sensing Advanced Wide-Field Sensor on the RESOURCESAT-1 mission to produce land cover classification maps for the CASA-CQUEST DSS.

  5. Absolute vicarious calibration of Landsat-8 OLI and Resourcesat-2 AWiFS sensors over Rann of Kutch site in Gujarat

    NASA Astrophysics Data System (ADS)

    Sharma, Shweta; Sridhar, V. N.; Prajapati, R. P.; Rao, K. M.; Mathur, A. K.

    2016-05-01

    In this work, vicarious calibration coefficients for all the four bands (green, red, NIR and SWIR) of Resourcesat-2 AWiFS sensor for four dates during Dec 2013-Nov 2014 and for seven bands (blue, green, red, NIR, SWIR1, SWIR2 and PAN) of OLI sensor onboard Landsat-8 for six dates during Dec 2013-Feb 2015 were estimated using field measured reflectance and measured atmospheric parameters during sensor image acquisition over Rann of Kutch site in Gujarat. The top of atmosphere (TOA) at-satellite radiances for all the bands were simulated using 6S radiative transfer code with field measured reflectance, synchronous atmospheric measurements and respective sensor's spectral response functions as an input. These predicted spectral radiances were compared with the radiances from the respective sensor's image in the respective band over the calibration site. Cross-calibration between the sensors AWiFS and OLI was also attempted using near-simultaneous same day image acquisition. Effect of spectral band adjustment factor was also studied with OLI sensor taken as reference sensor. Results show that the variation in average estimated radiance ratio for the AWiFS sensor was found to be within 10% for all the bands, whereas, for OLI sensor, the variation was found to be within 6% for all the bands except green and SWIR2 for which the variation was 8% and 11% respectively higher than the 5% uncertainty of the OLI sensor specification for TOA spectral radiance. At the 1σ level, red, NIR, SWIR1 and Panchromatic bands of OLI sensor showed close agreement between sensor-measured and vicarious TOA radiance resulting no change in calibration coefficient and hence indicating no sensor degradation. Two sets of near-simultaneous SBAFs were derived from respective ground measured target reflectance profiles and applied to the AWiFS and it was observed that overall, SBAF compensation provides a significant improvement in sensor agreement. The reduction in the difference between AWiFS and

  6. Atmospheric correction for inland waters

    NASA Astrophysics Data System (ADS)

    Vidot, Jerome; Santer, Richard P.

    2004-02-01

    Inland waters are an increasingly valuable natural resource with major impacts and benefits for population and environment. As the spatial resolution is improved for "ocean color" satellite sensors, such observations become relevant to monitor water quality for lakes. We first demonstrated that the required atmospheric correction cannot be conducted using the standard algorithms developed for ocean. The ocean color sensors have spectral bands that allow characterization of aerosol over dark land pixels (vegetation in the blue and in the red spectral bands). It is possible to use a representative aerosol model in the atmospheric correction over inland waters after validating the spatial homogeneity of the aerosol model in the lake vicinity. The performance of this new algorithm is illustrated on SeaWiFS scenes of the Balaton (Hungary; the Constance, Germany) lakes. We illustrated the good spatial homogeneity of the aerosols and the meaningfulness of the water leaving radiances derived over these two lakes. We also addressed the specificity of the computation of the Fresnel reflection. The direct to diffuse term of this Fresnel contribution is reduced because of the limited size of the lake. Based on the primary scattering approximation, we propose a simple formulation of this component.

  7. Radiometric Calibration of the AWiFS Sensor and a Cross-calibration Enhanced Vicarious Calibration Technique

    NASA Technical Reports Server (NTRS)

    Aaron, David

    2007-01-01

    Using vicarious calibration validation of moderate resolution sensors such as AWiFS is complicated by requiring more land area to ensure proper registration and sufficient pixel numbers. A trial AWiFS calibration was performed on a grass site that consisted of two dramatically different grass heights. Ground truth data was collected over relatively small areas representing only a few pixels. The radiometric gain results for each of these areas will be reported. To enhance this analysis, since a near coincidence high resolution image was collected, the high resolution data was effectively resized to produce pixels comparable to AWiFS and the atmospheric model was used to produce a top of canopy radiance map. Multiple uniform vegetated areas of several radiances were then identified and subsequently propagated to the top of atmosphere viewpoint of the moderate resolution (AWiFS) satellite. The radiometric gain was then calculated based on the vendor high resolution satellite gains (for the 3 bands with comparable wavelengths). Band-to-band conversion was performed assuming a hyperspectral reflectance based on the standard vegetated site. The initial comparison produces AWiFS radiometric gain values that agree to better than 10% of the values measured using the standard vicarious gain technique.

  8. Comparison of ground reflectance measurement with satellite derived atmospherically corrected reflectance: A case study over semi arid landscape

    NASA Astrophysics Data System (ADS)

    Rani Sharma, Anu; Badarinath, Kvs; Vikshalakshie Muthukumaraswamy Ganeshamoorthy, Ms; Roy, Parthsarathi

    Optical remote sensing data is contaminated due to scattering and absorption by aerosols, water vapour and trace gases in the atmosphere. In order to remove scattering and absorption effects and to derive precise surface reflectance from satellite image data, it is indispensable to apply the atmospheric correction. Various empirical methods and radiative transfer models that attempt to account for wavelength specific absorption and scattering are available in literature. Empirical methods include ratio, subtraction, and empirical line correction etc and the radiative transfer models include LOWTRAN, MODTRAN, 5S, 6S, SBDART and SMAC etc. Amongst these models Second Simulation of Satellite Signal in the Solar Spectrum (6S) has better options for different satellite sensors. In this study, we evaluated the potential of 6S radiative transfer model for atmospheric corrections of IRS AWiFS satellite data, in a semi-arid landscape. Ground measurements of surface reflectance over Maize and chic pea crop were conducted with spectroradiometer and compared with top of atmospheric reflectance derived from IRS-AWiFS. The 6S radiative transfer model was modified for local conditions using ground measurements on aerosol optical depth (AOD), water vapor and ozone using sun photometer. In order to extract surface reflectance from satellite data, individual bands digital numbers (DN) were first converted into spectral radiance (Li ) using pre launch calibration coefficients. The top of atmosphere (TOA) reflectance (˜(¨)i ) for each spectral band were then computed by ne converting spectral radiance to reflectance using the relation, n (¨) i =πLi d2 /E0 Cosθ (1); where, ˜ e Li is spectral radiance, d2 is Earth-Sun distance, E0 is the ex-atmospheric solar irradiance, θ is the solar zenith angle.Further the surface reflectance free from atmospheric effect, is computed as Ref = [(Aρ+ B] / [1 + ( Υ (Aρ + B))] (2); Where A= 1/αβ , B = -ρ / β and p = TOA reflectance, α is

  9. Monitoring the long term stability of the IRS-P6 AWiFS sensor using the Sonoran and RVPN sites

    NASA Astrophysics Data System (ADS)

    Chander, Gyanesh; Sampath, Aparajithan; Angal, Amit; Choi, Taeyoung; Xiong, Xiaoxiong

    2010-10-01

    This paper focuses on radiometric and geometric assessment of the Indian Remote Sensing (IRS-P6) Advanced Wide Field Sensor (AWiFS) sensor using the Sonoran desert and Railroad Valley Playa, Nevada (RVPN) ground sites. Imageto- Image (I2I) accuracy and relative band-to-band (B2B) accuracy were measured. I2I accuracy of the AWiFS imagery was assessed by measuring the imagery against Landsat Global Land Survey (GLS) 2000. The AWiFS images were typically registered to within one pixel to the GLS 2000 mosaic images. The B2B process used the same concepts as the I2I, except instead of a reference image and a search image; the individual bands of a multispectral image are tested against each other. The B2B results showed that all the AWiFS multispectral bands are registered to sub-pixel accuracy. Using the limited amount of scenes available over these ground sites, the reflective bands of AWiFS sensor indicate a long-term drift in the top-of-atmosphere (TOA) reflectance. Because of the limited availability of AWiFS scenes over these ground sites, a comprehensive evaluation of the radiometric stability using these sites is not possible. In order to overcome this limitation, a cross-comparison between AWiFS and Landsat 7 (L7) Enhanced Thematic Mapper Plus (ETM+) was performed using image statistics based on large common areas observed by the sensors within 30 minutes. Regression curves and coefficients of determination for the TOA trends from these sensors were generated to quantify the uncertainty in these relationships and to provide an assessment of the calibration differences between these sensors.

  10. Atmospheric Correction Algorithm for Hyperspectral Imagery

    SciTech Connect

    R. J. Pollina

    1999-09-01

    In December 1997, the US Department of Energy (DOE) established a Center of Excellence (Hyperspectral-Multispectral Algorithm Research Center, HyMARC) for promoting the research and development of algorithms to exploit spectral imagery. This center is located at the DOE Remote Sensing Laboratory in Las Vegas, Nevada, and is operated for the DOE by Bechtel Nevada. This paper presents the results to date of a research project begun at the center during 1998 to investigate the correction of hyperspectral data for atmospheric aerosols. Results of a project conducted by the Rochester Institute of Technology to define, implement, and test procedures for absolute calibration and correction of hyperspectral data to absolute units of high spectral resolution imagery will be presented. Hybrid techniques for atmospheric correction using image or spectral scene data coupled through radiative propagation models will be specifically addressed. Results of this effort to analyze HYDICE sensor data will be included. Preliminary results based on studying the performance of standard routines, such as Atmospheric Pre-corrected Differential Absorption and Nonlinear Least Squares Spectral Fit, in retrieving reflectance spectra show overall reflectance retrieval errors of approximately one to two reflectance units in the 0.4- to 2.5-micron-wavelength region (outside of the absorption features). These results are based on HYDICE sensor data collected from the Southern Great Plains Atmospheric Radiation Measurement site during overflights conducted in July of 1997. Results of an upgrade made in the model-based atmospheric correction techniques, which take advantage of updates made to the moderate resolution atmospheric transmittance model (MODTRAN 4.0) software, will also be presented. Data will be shown to demonstrate how the reflectance retrieval in the shorter wavelengths of the blue-green region will be improved because of enhanced modeling of multiple scattering effects.

  11. Improved target recognition with live atmospheric correction

    NASA Astrophysics Data System (ADS)

    Archer, Cynthia; Morgenstern, James

    2013-05-01

    Hyperspectral airborne sensing systems frequently employ spectral signature databases to detect materials. To achieve high detection and low false alarm rates, it is critical to retrieve accurate reflectance values from the camera's digital number (dn) output. A one-time camera calibration converts dn values to reflectance. However, changes in solar angle and atmospheric conditions distort the reflected energy, reducing detection performance of the system. Changes in solar angle and atmospheric conditions introduce both additive (offset) and multiplicative (gain) effects for each waveband. A gain and offset correction can mitigate these effects. Correction methods based on radiative transfer models require equipment to measure solar angle and atmospheric conditions. Other methods use known reference materials in the scene to calculate the correction, but require an operator to identify the location of these materials. Our unmanned airborne vehicles application can use no additional equipment or require operator intervention. Applicable automated correction approaches typically analyze gross scene statistics to find the gain and offset values. Airborne hyperspectral systems have high ground resolution but limited fields-of-view, so an individual frame does not include all the variation necessary to accurately calculate global statistics. In the present work we present our novel approach to the automatic estimation of atmospheric and solar effects from the hyperspectral data. Our approach is based on Hough transform matching of background spectral signatures with materials extracted from the scene. Scene materials are identified with low complexity agglomerative clustering. Detection results with data gathered from recent field tests are shown.

  12. Atmospheric monitoring in MAGIC and data corrections

    NASA Astrophysics Data System (ADS)

    Fruck, Christian; Gaug, Markus

    2015-03-01

    A method for analyzing returns of a custom-made "micro"-LIDAR system, operated alongside the two MAGIC telescopes is presented. This method allows for calculating the transmission through the atmospheric boundary layer as well as thin cloud layers. This is achieved by applying exponential fits to regions of the back-scattering signal that are dominated by Rayleigh scattering. Making this real-time transmission information available for the MAGIC data stream allows to apply atmospheric corrections later on in the analysis. Such corrections allow for extending the effective observation time of MAGIC by including data taken under adverse atmospheric conditions. In the future they will help reducing the systematic uncertainties of energy and flux.

  13. Atmospheric corrections for TIMS estimated emittance

    NASA Technical Reports Server (NTRS)

    Warner, T. A.; Levandowski, D. W.

    1992-01-01

    The estimated temperature of the average of 500 lines of Thermal Infrared Multispectral Scanner (TIMS) data of the Pacific Ocean, from flight line 94, collected on 30 Sep. 1988, at 1931 GMT is shown. With no atmospheric corrections, estimated temperature decreases away from nadir (the center of the scan line). A LOWTRAN modeled correction, using local radiosonde data and instrument scan angle information, results in reversed limb darkening effects for most bands, and does not adequately correct all bands to the same temperature. The atmosphere tends to re-radiate energy at the wavelengths at which it most absorbs, and thus the overall difference between corrected and uncorrected temperatures is approximately 40 C, despite the average LOWTRAN calculated transmittance of only 60 percent between 8.1 and 11.6 microns. An alternative approach to atmospheric correction is a black body normalization. This is done by calculating a normalization factor for each pixel position and wavelength, which when applied results in a single calculated temperature, as would be expected for a gray body with near uniform emittance. The black body adjustment is based on the atmospheric conditions over the sea. The ground elevation profile along the remaining 3520 scan lines (approximately 10 km) of flight line 94, up the slopes of Kilauea, determined from aircraft pressure and laser altimeter data is shown. This flight line includes a large amount of vegetation that is clearly discernible on the radiance image, being much cooler than the surrounding rocks. For each of the 3520 scan lines, pixels were classified as vegetation or 'other'. A moving average of 51 lines was applied to the composite vegetation emittance for each scan line, to reduce noise. Assuming vegetation to be like water, and to act as gray body with an emittance of 0.986 across the spectrum, it is shown that that the LOWTRAN induced artifacts are severe, and other than for the 0.9.9 micron channel, not significantly

  14. Atmospheric refractivity corrections in satellite laser ranging

    NASA Technical Reports Server (NTRS)

    Abshire, J. B.; Gardner, C. S.

    1985-01-01

    Atmospheric refraction can cause significant errors in satellite laser ranging (SLR) systems. There are two techniques which can be used to correct for these errors. Atmospheric models based upon surface measurements of pressure, temperature, and relative humidity have been shown by ray tracing to be accurate to within a few centimeters at 20 deg elevation angle. The residual errors in the models are thought to be primarily caused by horizontal gradients in the refractivity. Although models have been developed to predict the gradient effects, initial studies show that they can be sensitive to local topographic effects. Atmospheric turbulence can introduce random fluctuations in the refractivity, but only introduces centimeter level errors at elevation angles below 10 deg. Pulsed two-color ranging systems can directly measure the atmospheric delay in satellite ranging. These systems require mode-locked multiple-frequency lasers and streak-camera-based receivers and currently appear capable of measuring the atmospheric delay with an accuracy of 0.5 cm or better.

  15. Atmospheric scattering corrections to solar radiometry

    NASA Technical Reports Server (NTRS)

    Box, M. A.; Deepak, A.

    1979-01-01

    Whenever a solar radiometer is used to measure direct solar radiation, some diffuse sky radiation invariably enters the detector's field of view along with the direct beam. Therefore, the atmospheric optical depth obtained by the use of Bouguer's transmission law (also called Beer-Lambert's law), that is valid only for direct radiation, needs to be corrected by taking account of the scattered radiation. This paper discusses the correction factors needed to account for the diffuse (i,e., singly and multiply scattered) radiation and the algorithms developed for retrieving aerosol size distribution from such measurements. For a radiometer with a small field of view (half-cone angle of less than 5 deg) and relatively clear skies (optical depths less than 0.4), it is shown that the total diffuse contribution represents approximately 1% of the total intensity.

  16. Spatial Resolution Characterization for AWiFS Multispectral Images

    NASA Technical Reports Server (NTRS)

    Blonski, Slawomir; Ryan, Robert E.; Pagnutti, Mary; Stanley, Thomas

    2006-01-01

    Within the framework of the Joint Agency Commercial Imagery Evaluation program, the National Aeronautics and Space Administration, the National Geospatial-Intelligence Agency, and the U.S. Geological Survey cooperate in the characterization of high-to-moderate-resolution commercial imagery of mutual interest. One of the systems involved in this effort is the Advanced Wide Field Sensor (AWiFS) onboard the Indian Remote Sensing (IRS) Reourcesat-1 satellite, IRS-P6. Spatial resolution of the AWiFS multispectral images was characterized by estimating the value of the system Modulation Transfer Function (MTF) at the Nyquist spatial frequency. The Nyquist frequency is defined as half the sampling frequency, and the sampling frequency is equal to the inverse of the ground sample distance. The MTF was calculated as a ratio of the Fourier transform of a profile across an AWiFS image of the Lake Pontchartrain Causeway Bridge and the Fourier transform of a profile across an idealized model of the bridge for each spectral band evaluated. The mean MTF value for the AWiFS imagery evaluated was estimated to be 0.1.

  17. Spatial Resolution Characterization for AWiFS Multispectral Images

    NASA Technical Reports Server (NTRS)

    Blonski, Slawomir; Ryan, Robert E.; Pagnutti, Mary; Stanley, Thomas

    2007-01-01

    This viewgraph presentation describes the spatial resolution of the AWiFS multispectral images characterized by an estimation of the Modulation Transfer Function (MTF) at Nyquist frequency. The contents include: 1) MTF Analysis; 2) Target Analysis; 3) "Pulse Target"; 4) "Pulse" Method; 5) Target Images; 6) Bridge Profiles; 7) MTF Calculation; 8) MTF Results; and 9) Results Summary.

  18. Shuttle program: Computing atmospheric scale height for refraction corrections

    NASA Technical Reports Server (NTRS)

    Lear, W. M.

    1980-01-01

    Methods for computing the atmospheric scale height to determine radio wave refraction were investigated for different atmospheres, and different angles of elevation. Tables of refractivity versus altitude are included. The equations used to compute the refraction corrections are given. It is concluded that very accurate corrections are determined with the assumption of an exponential atmosphere.

  19. MRS proof-of-concept on atmospheric corrections. Atmospheric corrections using an orbital pointable imaging system

    NASA Technical Reports Server (NTRS)

    Slater, P. N. (Principal Investigator)

    1980-01-01

    The feasibility of using a pointable imager to determine atmospheric parameters was studied. In particular the determination of the atmospheric extinction coefficient and the path radiance, the two quantities that have to be known in order to correct spectral signatures for atmospheric effects, was simulated. The study included the consideration of the geometry of ground irradiance and observation conditions for a pointable imager in a LANDSAT orbit as a function of time of year. A simulation study was conducted on the sensitivity of scene classification accuracy to changes in atmospheric condition. A two wavelength and a nonlinear regression method for determining the required atmospheric parameters were investigated. The results indicate the feasibility of using a pointable imaging system (1) for the determination of the atmospheric parameters required to improve classification accuracies in urban-rural transition zones and to apply in studies of bi-directional reflectance distribution function data and polarization effects; and (2) for the determination of the spectral reflectances of ground features.

  20. Multi-Angle Implementation of Atmospheric Correction for MODIS (MAIAC). Part 3: Atmospheric Correction

    NASA Technical Reports Server (NTRS)

    Lyapustin, A.; Wang, Y.; Laszlo, I.; Hilker, T.; Hall, F.; Sellers, P.; Tucker, J.; Korkin, S.

    2012-01-01

    This paper describes the atmospheric correction (AC) component of the Multi-Angle Implementation of Atmospheric Correction algorithm (MAIAC) which introduces a new way to compute parameters of the Ross-Thick Li-Sparse (RTLS) Bi-directional reflectance distribution function (BRDF), spectral surface albedo and bidirectional reflectance factors (BRF) from satellite measurements obtained by the Moderate Resolution Imaging Spectroradiometer (MODIS). MAIAC uses a time series and spatial analysis for cloud detection, aerosol retrievals and atmospheric correction. It implements a moving window of up to 16 days of MODIS data gridded to 1 km resolution in a selected projection. The RTLS parameters are computed directly by fitting the cloud-free MODIS top of atmosphere (TOA) reflectance data stored in the processing queue. The RTLS retrieval is applied when the land surface is stable or changes slowly. In case of rapid or large magnitude change (as for instance caused by disturbance), MAIAC follows the MODIS operational BRDF/albedo algorithm and uses a scaling approach where the BRDF shape is assumed stable but its magnitude is adjusted based on the latest single measurement. To assess the stability of the surface, MAIAC features a change detection algorithm which analyzes relative change of reflectance in the Red and NIR bands during the accumulation period. To adjust for the reflectance variability with the sun-observer geometry and allow comparison among different days (view geometries), the BRFs are normalized to the fixed view geometry using the RTLS model. An empirical analysis of MODIS data suggests that the RTLS inversion remains robust when the relative change of geometry-normalized reflectance stays below 15%. This first of two papers introduces the algorithm, a second, companion paper illustrates its potential by analyzing MODIS data over a tropical rainforest and assessing errors and uncertainties of MAIAC compared to conventional MODIS products.

  1. Airborne experiment results for spaceborne atmospheric synchronous correction system

    NASA Astrophysics Data System (ADS)

    Cui, Wenyu; Yi, Weining; Du, Lili; Liu, Xiao

    2015-10-01

    The image quality of optical remote sensing satellite is affected by the atmosphere, thus the image needs to be corrected. Due to the spatial and temporal variability of atmospheric conditions, correction by using synchronous atmospheric parameters can effectively improve the remote sensing image quality. For this reason, a small light spaceborne instrument, the atmospheric synchronous correction device (airborne prototype), is developed by AIOFM of CAS(Anhui Institute of Optics and Fine Mechanics of Chinese Academy of Sciences). With this instrument, of which the detection mode is timing synchronization and spatial coverage, the atmospheric parameters consistent with the images to be corrected in time and space can be obtained, and then the correction is achieved by radiative transfer model. To verify the technical process and treatment effect of spaceborne atmospheric correction system, the first airborne experiment is designed and completed. The experiment is implemented by the "satellite-airborne-ground" synchronous measuring method. A high resolution(0.4 m) camera and the atmospheric correction device are equipped on the aircraft, which photograph the ground with the satellite observation over the top simultaneously. And aerosol optical depth (AOD) and columnar water vapor (CWV) in the imagery area are also acquired, which are used for the atmospheric correction for satellite and aerial images. Experimental results show that using the AOD and CWV of imagery area retrieved by the data obtained by the device to correct aviation and satellite images, can improve image definition and contrast by more than 30%, and increase MTF by more than 1 time, which means atmospheric correction for satellite images by using the data of spaceborne atmospheric synchronous correction device is accurate and effective.

  2. OPERA: An Atmospheric Correction for Land and Water

    NASA Astrophysics Data System (ADS)

    Sterckx, Sindy; Knaeps, Els; Adriaensen, Stefan; Reusen, Ils; De Keukelaere, Liesbeth; Hunter, Peter; Giardino, Claudia; Odermatt, Daniel

    2015-12-01

    Atmospheric correction is one of the most important part of the pre-processing of satellite remotely sensed data used to retrieve bio-geophysical paramters. In this paper we present the scene and sensor generic atmospheric correction scheme ‘OPERA’ allowing to correct both land and water areas in the remote sensing image. OPERA can now be used to correct for atmospheric effects in scenes acquired by MERIS, Landsat-8, hyperspectral sensors and will be applicable to Sentinel-3 and Sentinel-2.

  3. Initial Radiometric Calibration of the AWiFS Using Vicarious Calibration Techniques

    NASA Technical Reports Server (NTRS)

    Pagnutti, Mary

    2007-01-01

    The NASA team of University of Arizona, South Dakota State University, and NASA SSC produce consistent results. The AWiFS calibration coefficients agree reasonably well with the NASA team estimate. The NASA team will continue to assess AWiFS radiometric accuracy.

  4. Atmospheric corrections of land imagery using the extended radiosity method

    SciTech Connect

    Borel, C.C.; Gerstl, S.A.W.

    1992-01-01

    In this paper we describe an application of the extended radiosity method to compute atmospheric scattering effects over heterogeneous surfaces and to perform the inverse operation: to correct for such atmospheric effects. The radiosity method is used to compute point-spread-functions. (PSF's) which determine how much light is scattered from an adjacent surface into the field-of-view (FOV) of a sensor above the atmosphere. We show that the PSF's are in general asymmetric for pointable airborne or satellite sensors. A Fourier transform based method can be used to correct adjacency-effect-blurred images for these atmospheric distortions.

  5. Atmospheric corrections of land imagery using the extended radiosity method

    SciTech Connect

    Borel, C.C.; Gerstl, S.A.W.

    1992-05-01

    In this paper we describe an application of the extended radiosity method to compute atmospheric scattering effects over heterogeneous surfaces and to perform the inverse operation: to correct for such atmospheric effects. The radiosity method is used to compute point-spread-functions. (PSF`s) which determine how much light is scattered from an adjacent surface into the field-of-view (FOV) of a sensor above the atmosphere. We show that the PSF`s are in general asymmetric for pointable airborne or satellite sensors. A Fourier transform based method can be used to correct adjacency-effect-blurred images for these atmospheric distortions.

  6. Haze compensation and atmospheric correction for Sentinel-2 data

    NASA Astrophysics Data System (ADS)

    Makarau, Aliaksei; Richter, Rudolf; Zekoll, Viktoria; Reinartz, Peter

    2016-04-01

    Sentinel-2 data offer the opportunity to analyse landcover at a high spatial accuracy together with a wide swath. Nevertheless, the high data volume requires a per granule analysis. This may lead to border effects (difference in the radiance/reflectance values) between the neighbouring granules during atmospheric correction. Especially in case of high variations of the aerosol optical thickness (AOT) across the granules, especially in case of haze, the atmospherically corrected mosaicked products often show granule border effects. To overcome these artefacts a dehazing prior to the atmospheric correction is performed. The dehazing compensates only for the haze thickness keeping the AOT fraction for further estimation and compensation in the atmospheric correction chain. This approach results in a smoother AOT map estimate and a corresponding bottom of atmosphere (BOA) reflectance with low or no border artefacts. Using digital elevation models (DEMs) allows a better labelling of haze and a higher accuracy of the dehazing. The DEM analysis rejects high elevation areas where bright surfaces might erroneously be classified as haze, thus reducing the probability of misclassification. The dehazing and atmospheric correction are implemented in the DLR's ATCOR software. An example of a numeric evaluation of atmospheric correction products (AOT and BOA reflectance) is given. It demonstrates a smooth transition between the granules in the AOT map leading to a proper estimate of the BOA reflectance data.

  7. Atmospheric corrections for satellite water quality studies

    NASA Technical Reports Server (NTRS)

    Piech, K. R.; Schott, J. R.

    1975-01-01

    Variations in the relative value of the blue and green reflectances of a lake can be correlated with important optical and biological parameters measured from surface vessels. Measurement of the relative reflectance values from color film imagery requires removal of atmospheric effects. Data processing is particularly crucial because: (1) lakes are the darkest objects in a scene; (2) minor reflectance changes can correspond to important physical changes; (3) lake systems extend over broad areas in which atmospheric conditions may fluctuate; (4) seasonal changes are of importance; and, (5) effects of weather are important, precluding flights under only ideal weather conditions. Data processing can be accomplished through microdensitometry of scene shadow areas. Measurements of reflectance ratios can be made to an accuracy of plus or minus 12%, sufficient to permit monitoring of important eutrophication indices.

  8. SSC Geopositional Assessment of an AWiFS Image Orthorectified Product

    NASA Technical Reports Server (NTRS)

    Kenton, Ross; Stubbs, Ruby

    2007-01-01

    The geopositional accuracy of an AWiFS (Advanced Wide Field Sensor) orthorectified product was evaluated. Specifically, the image products were acquired by the Indian Remote Sensing Resourcesat-1 satellite, then orthorectified by GeoEye . Analysis was performed using DOQs (digital orthophoto quadrangles) and other reference sources of similar accuracy. A total of six AWiFS images were characterized. These images were acquired over the continental United States from June through September 2005. The images were equally divided between the two AWiFS cameras. Forty to fifty check points were collected manually per scene and analyzed to determine overall circular error, estimates of horizontal bias, and other systematic errors.

  9. Correction of satellite laser ranging for atmospheric refraction.

    NASA Astrophysics Data System (ADS)

    Mironov, N. T.

    Atmospheric refraction causes significant errors in satellite laser ranging (SLR) systems. Numerous formulas have been developed to partially correct laser ranging data for the effects of atmospheric refraction. These formulas were derived under the assumption that atmospheric refraction is spherically symmetric. The accuracy of the Marini-Murray's spherical correction formula are checked. The residual errors in the spherical model are thought to be primarily caused by horizontal gradients in the refractivity. The effects of horizontal refractivity gradients are investigated by ray tracing through spherically symmetric and three-dimensional refractivity profiles.

  10. Atmospheric correction for the ASTER visible data on Terra satellite

    NASA Astrophysics Data System (ADS)

    Takashima, T.; Masuda, K.; Sano, I.; Mukai, S.

    2001-01-01

    An atmospheric correction algorithm over the heterogeneous surface on the emergent radiation from the top of the atmosphere is proposed. This is an atmospheric correction code for the ASTER visible channels on Terra satellite, which have a spatial resolution of 15m. Therefore, interactions of atmospheric radiation with radiation reflected by the heterogeneous surface should be accounted for in this atmospheric correction. The surface is simulated by a checkerboard type terrain composed of land or ocean pixels. To investigate the contribution of adjacent pixels, two additional parameters based on the diffuse transmission(α) and reflection(β) function of the atmosphere are introduced. These parameters are independent of the surface reflection properties and thus may be used for any surface. The present method was developed with reference to existing numerical results based on one-dimensional radiative transfer code. Furthermore, as vicarious calibration, skylight polarization measurements were taken by a spectro-polarimeter over the Nevada desert. The measurements indicate little absorption by aerosols in the atmosphere at wavelengths from 550nm to 700nm. Furthermore the aerosols could not be spherical particles in a poly-dispersion.

  11. Crop Acreage Estimation: Landsat TM and Resourcesat-1 AWiFS Sensor Assessment of the Mississippi River Delta, 2005

    NASA Technical Reports Server (NTRS)

    Boryan, Claire; Johnson, Dave; Craig, Mike; Seffrin, Bob; Mueller, RIck

    2007-01-01

    AWiFs data are appropriate for crop acreage estimation over large, spectrally homogenous, crop areas such as the Mid-West, the Delta and the Northern Great Plains. Regression and Kappa statistics for soybean, corn, cotton, rice and sorghum produced using both the Landsat TM and AWiFS data are very similar. AWiFS data appear to be a suitable alternative or supplement to Landsat TM data for production of NASS'Cropland Data Layer product.

  12. Atmospheric turbulence correction using digital holographic detection: experimental results.

    PubMed

    Marron, Joseph C; Kendrick, Richard L; Seldomridge, Nathan; Grow, Taylor D; Höft, Thomas A

    2009-07-01

    The performance of long distance imaging systems is typically degraded by phase errors imparted by atmospheric turbulence. In this paper we apply coherent imaging methods to determine, and remove, these phase errors by digitally processing coherent recordings of the image data. In this manner we are able to remove the effects of atmospheric turbulence without needing a conventional adaptive optical system. Digital holographic detection is used to record the coherent, complex-valued, optical field for a series of atmospheric and object realizations. Correction of atmospheric phase errors is then based on maximizing an image sharpness metric to determine the aberrations present and correct the underlying image. Experimental results that demonstrate image recovery in the presence of turbulence are presented. Results obtained with severe turbulence that gives rise to anisoplanatism are also presented. PMID:19582079

  13. Atmospheric degradation correction of terahertz beams using multiscale signal restoration.

    PubMed

    Ryu, Choonwoo; Kong, Seong G

    2010-02-10

    We present atmospheric degradation correction of terahertz (THz) beams based on multiscale signal decomposition and a combination of a Wiener deconvolution filter and artificial neural networks. THz beams suffer from strong attenuation by water molecules in the air. The proposed signal restoration approach finds the filter coefficients from a pair of reference signals previously measured from low-humidity conditions and current background air signals. Experimental results with two material samples of different chemical compositions demonstrate that the multiscale signal restoration technique is effective in correcting atmospheric degradation compared to individual and non-multiscale approaches. PMID:20154764

  14. High-speed atmospheric correction for spectral image processing

    NASA Astrophysics Data System (ADS)

    Perkins, Timothy; Adler-Golden, Steven; Cappelaere, Patrice; Mandl, Daniel

    2012-06-01

    Land and ocean data product generation from visible-through-shortwave-infrared multispectral and hyperspectral imagery requires atmospheric correction or compensation, that is, the removal of atmospheric absorption and scattering effects that contaminate the measured spectra. We have recently developed a prototype software system for automated, low-latency, high-accuracy atmospheric correction based on a C++-language version of the Spectral Sciences, Inc. FLAASH™ code. In this system, pre-calculated look-up tables replace on-the-fly MODTRAN® radiative transfer calculations, while the portable C++ code enables parallel processing on multicore/multiprocessor computer systems. The initial software has been installed on the Sensor Web at NASA Goddard Space Flight Center, where it is currently atmospherically correcting new data from the EO-1 Hyperion and ALI sensors. Computation time is around 10 s per data cube per processor. Further development will be conducted to implement the new atmospheric correction software on board the upcoming HyspIRI mission's Intelligent Payload Module, where it would generate data products in nearreal time for Direct Broadcast to the ground. The rapid turn-around of data products made possible by this software would benefit a broad range of applications in areas of emergency response, environmental monitoring and national defense.

  15. Comparison of diverse methods for the correction of atmospheric effects on LANDSAT and SKYLAB images. [radiometric correction in Brazil

    NASA Technical Reports Server (NTRS)

    Parada, N. D. J. (Principal Investigator); Camara, G.; Dias, L. A. V.; Mascarenhas, N. D. D.; Desouza, R. C. M.; Pereira, A. E. C.

    1982-01-01

    Earth's atmosphere reduces a sensors ability in currently discriminating targets. Using radiometric correction to reduce the atmospheric effects may improve considerably the performance of an automatic image interpreter. Several methods for radiometric correction from the open literature are compared leading to the development of an atmospheric correction system.

  16. The correction of infrasound signals for upper atmospheric winds

    SciTech Connect

    Mutschlecner, J.P.; Whitaker, R.W.

    1990-01-01

    Infrasound waves propagate in the atmosphere by a well known mechanism produced by refraction of the waves, return to earth, and reflection at the surface into the atmosphere for subsequent bounces. In this instance three rays are returned to earth from a region centered at about 50 kilometers in altitude and two from a region near 110 kilometers in altitude. The control of the wave refraction is largely dominated by the temperature-height profile and inversions; however, a major influence is also produced by the atmospheric wind profile. It obviously can be expected that infrasonic signal amplitudes will be greatly influenced by the winds in the atmosphere. The seasonal variation of the high altitude atmospheric winds is well documented. The very strong seasonal variation has the ability to exert a major seasonal influence on infrasonic signals. It is our purpose to obtain a method for the correction of this effect.

  17. Algorithm for Atmospheric Corrections of Aircraft and Satellite Imagery

    NASA Technical Reports Server (NTRS)

    Fraser, Robert S.; Kaufman, Yoram J.; Ferrare, Richard A.; Mattoo, Shana

    1989-01-01

    A simple and fast atmospheric correction algorithm is described which is used to correct radiances of scattered sunlight measured by aircraft and/or satellite above a uniform surface. The atmospheric effect, the basic equations, a description of the computational procedure, and a sensitivity study are discussed. The program is designed to take the measured radiances, view and illumination directions, and the aerosol and gaseous absorption optical thickness to compute the radiance just above the surface, the irradiance on the surface, and surface reflectance. Alternatively, the program will compute the upward radiance at a specific altitude for a given surface reflectance, view and illumination directions, and aerosol and gaseous absorption optical thickness. The algorithm can be applied for any view and illumination directions and any wavelength in the range 0.48 micron to 2.2 micron. The relation between the measured radiance and surface reflectance, which is expressed as a function of atmospheric properties and measurement geometry, is computed using a radiative transfer routine. The results of the computations are presented in a table which forms the basis of the correction algorithm. The algorithm can be used for atmospheric corrections in the presence of a rural aerosol. The sensitivity of the derived surface reflectance to uncertainties in the model and input data is discussed.

  18. ASTER VNIR and SWIR Radiometric Calibration and Atmospheric Correction

    NASA Astrophysics Data System (ADS)

    Arai, Kohei; Thome, Kurtis; Iwasaki, Akira; Biggar, Stuart

    As described in the previous chapter, ASTER relies on three separate subsystems to cover the full spectral range from the visible and near infrared (VNIR), short-wave infrared (SWIR), to the thermal infrared (TIR). Establishing the accuracy of data from all three subsystems requires both sensor-related calibration and atmospheric correction. The dominance of reflected solar energy in the VNIR and SWIR, and emitted terrestrial radiation in the TIR allows separate treatment of the two spectral regions. TIR calibration and correction are covered in a separate chapter. This chapter has two main goals: (1) to allow the user to understand ASTER's radiometric calibration and atmospheric correction processes that enable conversion of VNIR and SWIR digital numbers (DN) to at-sensor reflectance and spectral radiance, and (2) to provide a succinct analysis of the SWIR crosstalk problem and its solutions.

  19. Atmospheric correction of AVIRIS data in ocean waters

    NASA Technical Reports Server (NTRS)

    Terrie, Gregory; Arnone, Robert

    1992-01-01

    Hyperspectral data offers unique capabilities for characterizing the ocean environment. The spectral characterization of the composition of ocean waters can be organized into biological and terrigenous components. Biological photosynthetic pigments in ocean waters have unique spectral ocean color signatures which can be associated with different biological species. Additionally, suspended sediment has different scattering coefficients which result in ocean color signatures. Measuring the spatial distributions of these components in the maritime environments provides important tools for understanding and monitoring the ocean environment. These tools have significant applications in pollution, carbon cycle, current and water mass detection, location of fronts and eddies, sewage discharge and fate etc. Ocean color was used from satellite for describing the spatial variability of chlorophyll, water clarity (K(sub 490)), suspended sediment concentration, currents etc. Additionally, with improved atmospheric correction methods, ocean color results produced global products of spectral water leaving radiance (L(sub W)). Ocean color results clearly indicated strong applications for characterizing the spatial and temporal variability of bio-optical oceanography. These studies were largely the results of advanced atmospheric correction techniques applied to multispectral imagery. The atmosphere contributes approximately 80 percent - 90 percent of the satellite received radiance in the blue-green portion of the spectrum. In deep ocean waters, maximum transmission of visible radiance is achieved at 490nm. Conversely, nearly all of the light is absorbed by the water at wavelengths greater than about 650nm and thus appears black. These spectral ocean properties are exploited by algorithms developed for the atmospheric correction used in satellite ocean color processing. The objective was to apply atmospheric correction techniques that were used for procesing satellite Coastal

  20. Landscape scale thermography - from simple to sophisticated atmospheric data correction

    NASA Astrophysics Data System (ADS)

    Hammerle, Albin; Meier, Fred; Heinl, Michael; Egger, Angelika; Leitinger, Georg

    2014-05-01

    Surface temperature is a key variable in the study of energy and mass exchange at the surface-atmosphere interface. Surface temperatures are typically measured onsite by infrared radiometers, by infrared scanners mounted on aircrafts or on satellite platforms. While onsite measurements provide data at a high temporal resolution they cannot capture surface temperatures at the landscape scale. In contrast remotely sensed data provide surface temperature measurements on a wide area but relatively low temporal and/or spatial resolution - or in case of airborne measurements at very high costs. Recent technical advances and the improved accessibility of mobile thermal-infrared (TIR) cameras provide an instrument that can produce surface temperature measurements from close proximity to an object right up to distances of several kilometres. This measurement system provides spatial resolutions of some millimetres up to some meters at a temporal resolution down to some seconds covering areas of several square kilometers. Due to this available range of spatio-temporal resolutions this method perfectly closes that gap between point measurements onsite by infrared radiometers and remotely sensed data at relatively low costs. Therefore this method gains more and more popularity in ecological research. While remotely sensed surface temperature data are routinely corrected for atmospheric influences by this time such corrections are often neglected or waived for data retrieved with TIR cameras. This practice is defensible for short distance measurements. But for measurements on landscape-scales taken from a distance of kilometres, the bias caused by atmospheric distortion becomes highly relevant for the accuracy of the surface temperature data. In this study we compared different approaches for atmospheric correction of thermal infrared images. 2500 TIR surface temperature measurements that were retrieved during several campaigns in summer 2012 were compared with continuous on

  1. Studies of the atmospheric correction for satellite laser ranging

    NASA Astrophysics Data System (ADS)

    Angus-Leppan, P. V.; Williams, G.

    A study is reported on the factors necessary to achieve further gains in accuracy in laser ranging. The present accuracy of laser ranging is approaching plus or minus 50 mm, which indicates a need to aim for a plus or minus 5 mm accuracy in the determination of the correction for atmospheric refraction. The Marini and Murray formulae are easily programmed and are widely used. They assume hydrostatic equilibrium and a constant vertical temperature gradient in the troposphere. It appears that some refinements are necessary to achieve the accuracy required. The atmospheric correction varies from 2.4 m at the zenith to 13 m at 10 degrees elevation. A number of small effects such as the geometric correction, the water vapor correction, and horizontal temperature gradients are all about plus or minus 30 mm in magnitude. In the study reported, the integral of refractivity is evaluated using numerical methods. The effects of the varying temperature gradients in the lowest kilometer, the boundary layer, have been investigated and a form of boundary layer correction, up to plus or minus 25 mm in magnitude, is suggested. Investigations are continuing, using a theoretical approach and sets of temperature observations on high towers.

  2. Terrain effects in the atmospheric gravity and geoid corrections

    NASA Astrophysics Data System (ADS)

    Sjoberg, Lars E.

    1993-07-01

    In view of the smallness of the atmospheric mass compared to the mass variations within the Earth, it is generally assumed in physical geodesy that terrain effects are negligible. Subsequently most models assume a spherical or ellipsoidal layering of the atmosphere. The removal and restoring of the atmosphere in solving the exterior boundary value problems thus correspond to gravity and geoid corrections of the order of 0.9 mGal and -0.7 cm, respectively. We demonstrate that the gravity terrain correction for the removal of the atmosphere is of the order of 50 microGal/km of elevation with a maximum close to 0.5 mGal at the top of Mount Everest. The corresponding effect on the geoid may reach several cm in mountainous regions. The total effect on geoid determination of removal and restoring the atmosphere may contribute significantly, in particular for long wavelengths. This is not the case for the quasi-geoid in mountainous regions.

  3. Empirical corrections for atmospheric neutral density derived from thermospheric models

    NASA Astrophysics Data System (ADS)

    Forootan, Ehsan; Kusche, Jürgen; Börger, Klaus; Henze, Christina; Löcher, Anno; Eickmans, Marius; Agena, Jens

    2016-04-01

    Accurately predicting satellite positions is a prerequisite for various applications from space situational awareness to precise orbit determination (POD). Given the fact that atmospheric drag represents a dominant influence on the position of low-Earth orbit objects, an accurate evaluation of thermospheric mass density is of great importance to low Earth orbital prediction. Over decades, various empirical atmospheric models have been developed to support computation of density changes within the atmosphere. The quality of these models is, however, restricted mainly due to the complexity of atmospheric density changes and the limited resolution of indices used to account for atmospheric temperature and neutral density changes caused by solar and geomagnetic activity. Satellite missions, such as Challenging Mini-Satellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE), provide a direct measurement of non-conservative accelerations, acting on the surface of satellites. These measurements provide valuable data for improving our knowledge of thermosphere density and winds. In this paper we present two empirical frameworks to correct model-derived neutral density simulations by the along-track thermospheric density measurements of CHAMP and GRACE. First, empirical scale factors are estimated by analyzing daily CHAMP and GRACE acceleration measurements and are used to correct the density simulation of Jacchia and MSIS (Mass-Spectrometer-Incoherent-Scatter) thermospheric models. The evolution of daily scale factors is then related to solar and magnetic activity enabling their prediction in time. In the second approach, principal component analysis (PCA) is applied to extract the dominant modes of differences between CHAMP/GRACE observations and thermospheric model simulations. Afterwards an adaptive correction procedure is used to account for long-term and high-frequency differences. We conclude the study by providing recommendations on possible

  4. Analysis of Vegetation and Atmospheric Correction Indices for Landsat Images

    NASA Technical Reports Server (NTRS)

    Bush, Tasha R.; Desai, M.

    1997-01-01

    Vegetation and Atmospheric Indices are mathematical combinations of remote sensing bands which are useful in distinguishing the various values of the spectral reflectance. In this paper we study how the applications of various atmospherically corrected indices and vegetation indices can aide in retrieving the amount of surface reflectance from a remotely sensed image. Specifically, this paper studies and compares three vegetation indices and one atmospherically resistant index. These indices include the Normalized Difference Vegetation Index (NDVI), the Soil Adjusted Vegetation Index (SAVI), the Green Vegetation Index (GVI), and the Atmospherically Resistant Vegetation Index (ARVI), respectively. The algorithms attempt to estimate the optical characteristics of Thematic Mapper (TM) imagery. It will be shown that the NDVI algorithm followed by the ARVI correcting algorithm provided significant improvements in the tonal qualities of the retrieved images. The results are presented on 1987 TM images over the Kennedy Space Center (KSC) and are compared with a set of United States Geological Survey (U.S.G.S) maps.

  5. Thermal Band Atmospheric Correction Using Atmospheric Profiles Derived from Global Positioning System Radio Occultation and the Atmospheric Infrared Sounder

    NASA Technical Reports Server (NTRS)

    Pagnutti, Mary; Holekamp, Kara; Stewart, Randy; Vaughan, Ronald D.

    2006-01-01

    This Rapid Prototyping Capability study explores the potential to use atmospheric profiles derived from GPS (Global Positioning System) radio occultation measurements and by AIRS (Atmospheric Infrared Sounder) onboard the Aqua satellite to improve surface temperature retrieval from remotely sensed thermal imagery. This study demonstrates an example of a cross-cutting decision support technology whereby NASA data or models are shown to improve a wide number of observation systems or models. The ability to use one data source to improve others will be critical to the GEOSS (Global Earth Observation System of Systems) where a large number of potentially useful systems will require auxiliary datasets as input for decision support. Atmospheric correction of thermal imagery decouples TOA radiance and separates surface emission from atmospheric emission and absorption. Surface temperature can then be estimated from the surface emission with knowledge of its emissivity. Traditionally, radiosonde sounders or atmospheric models based on radiosonde sounders, such as the NOAA (National Oceanic & Atmospheric Administration) ARL (Air Resources Laboratory) READY (Real-time Environmental Application and Display sYstem), provide the atmospheric profiles required to perform atmospheric correction. Unfortunately, these types of data are too spatially sparse and too infrequently taken. The advent of high accuracy, global coverage, atmospheric data using GPS radio occultation and AIRS may provide a new avenue for filling data input gaps. In this study, AIRS and GPS radio occultation derived atmospheric profiles from the German Aerospace Center CHAMP (CHAllenging Minisatellite Payload), the Argentinean Commission on Space Activities SAC-C (Satellite de Aplicaciones Cientificas-C), and the pair of NASA GRACE (Gravity Recovery and Climate Experiment) satellites are used as input data in atmospheric radiative transport modeling based on the MODTRAN (MODerate resolution atmospheric

  6. Validation of aerosol estimation in atmospheric correction algorithm ATCOR

    NASA Astrophysics Data System (ADS)

    Pflug, B.; Main-Knorn, M.; Makarau, A.; Richter, R.

    2015-04-01

    Atmospheric correction of satellite images is necessary for many applications of remote sensing, i.e. computation of vegetation indices and biomass estimation. The first step in atmospheric correction is estimation of the actual aerosol properties. Due to the spatial and temporal variability of aerosol amount and type, this step becomes crucial for an accurate correction of satellite data. Consequently, the validation of aerosol estimation contributes to the validation of atmospheric correction algorithms. In this study we present the validation of aerosol estimation using own sun photometer measurements in Central Europe and measurements of AERONET-stations at different locations in the world. Our ground-based sun photometer measurements of vertical column aerosoloptical thickness (AOT) spectra are performed synchronously to overpasses of the satellites RapidEye, Landsat 5, Landsat 7 and Landsat 8. Selected AERONET data are collocated to Landsat 8 overflights. The validation of the aerosol retrieval is conducted by a direct comparison of ground-measured AOT with satellite derived AOT using the ATCOR tool for the selected satellite images. The mean uncertainty found in our experiments is AOT550nm ~ 0.03±0.02 for cloudless conditions with cloud+haze fraction below 1%. This AOT uncertainty approximately corresponds to an uncertainty in surface albedo of ρ ~ 0.003. Inclusion of cloudy and hazy satellite images into the analysis results in mean AOT550nm ~ 0.04±0.03 for both RapidEye and Landsat imagery. About 1/3 of samples perform with the AOT uncertainty better than 0.02 and about 2/3 perform with AOT uncertainty better than 0.05.

  7. Operational atmospheric correction of AVHRR visible and infrared data

    SciTech Connect

    Vermote, E.; El Saleous, N.; Roger, J.C.

    1995-12-31

    The satellite level radiance is affected by the presence of the atmosphere between the sensor and the target. The ozone and water vapor absorption bands affect the signal recorded by the AVHRR visible and near infrared channels respectively. The Rayleigh scattering mainly affects the visible channel and is more pronounced when dealing with small sun elevations and large view angles. The aerosol scattering affects both channels and is certainly the most challenging term for atmospheric correction because of the spatial and temporal variability of both the type and amount of particles in the atmosphere. This paper presents the equation of the satellite signal, the scheme to retrieve atmospheric properties and corrections applied to AVHRR observations. The operational process uses TOMS data and a digital elevation model to correct for ozone absorption and rayleigh scattering. The water vapor content is evaluated using the split-window technique that is validated over ocean using 1988 SSM/I data. The aerosol amount retrieval over Ocean is achieved in channels 1 and 2 and compared to sun photometer observations to check consistency of the radiative transfer model and the sensor calibration. Over land, the method developed uses reflectance at 3.75 microns to deduce target reflectance in channel 1 and retrieve aerosol optical thickness that can be extrapolated in channel 2. The method to invert the reflectance at 3.75 microns is based on MODTRAN simulations and is validated by comparison to measurements performed during FIFE 87. Finally, aerosol optical thickness retrieved over Brazil and Eastern US is compared to sun photometer measurements.

  8. Comparison between empirical and physically based models of atmospheric correction

    NASA Astrophysics Data System (ADS)

    Mandanici, E.; Franci, F.; Bitelli, G.; Agapiou, A.; Alexakis, D.; Hadjimitsis, D. G.

    2015-06-01

    A number of methods have been proposed for the atmospheric correction of the multispectral satellite images, based on either atmosphere modelling or images themselves. Full radiative transfer models require a lot of ancillary information about the atmospheric conditions at the acquisition time. Whereas, image based methods cannot account for all the involved phenomena. Therefore, the aim of this paper is the comparison of different atmospheric correction methods for multispectral satellite images. The experimentation was carried out on a study area located in the catchment area of Yialias river, 20 km South of Nicosia, the Cyprus capital. The following models were tested, both empirical and physically based: Dark object subtraction, QUAC, Empirical line, 6SV, and FLAASH. They were applied on a Landsat 8 multispectral image. The spectral signatures of ten different land cover types were measured during a field campaign in 2013 and 15 samples were collected for laboratory measurements in a second campaign in 2014. GER 1500 spectroradiometer was used; this instrument can record electromagnetic radiation from 350 up to 1050 nm, includes 512 different channels and each channel covers about 1.5 nm. The spectral signatures measured were used to simulate the reflectance values for the multispectral sensor bands by applying relative spectral response filters. These data were considered as ground truth to assess the accuracy of the different image correction models. Results do not allow to establish which method is the most accurate. The physics-based methods describe better the shape of the signatures, whereas the image-based models perform better regarding the overall albedo.

  9. Atmospheric correction for Landsat 8 over case 2 waters

    NASA Astrophysics Data System (ADS)

    Concha, Javier A.; Schott, John R.

    2015-09-01

    The most interaction between humankind and water occurs in coastal and inland waters (Case 2 waters) at a scale of tens or hundred of meters, but there is not yet an ocean color product at this spatial scale. Landsat 8 is a promising candidate to address the remote sensing of these kinds of waters due to its improved signal-to-noise ratio (SNR), spectral resolution, 12-bit quantization, and high spatial resolution. Standard atmospheric correction algorithms developed for heritage ocean color instruments (e.g. MODIS, SeaWiFS) require a sufficient SNR in two bands where the water-leaving signal is negligible, which is not always possible, particularly for Landsat 8's bands. The model-based empirical line method (MoB-ELM) atmospheric algorithm for Landsat 8 imagery does not rely on this assumption. In this work, we evaluate the performance of this algorithm. We compare the MoB-ELM algorithm with in situ data and with three standard atmospheric correction algorithms. The results from our algorithm are comparable with the standard algorithms in some bands when comparing remote-sensing reflectances. When compared with in situ remote-sensing reflectance, the MoB-ELM perform similar to the standard algorithm in most cases. A comparison of retrieved chlorophyll-a concentration was perform as well, showing that the MoB- ELM outperforms the rest at high concentrations commonly found in Case 2 waters. These results show that our atmospheric correction algorithm allows one to use Landsat 8 to study Case 2 waters as an alternative to heritage ocean color satellites.

  10. Retrieval of atmospheric properties from hyper and multispectral imagery with the FLAASH atmospheric correction algorithm

    NASA Astrophysics Data System (ADS)

    Perkins, Timothy; Adler-Golden, Steven; Matthew, Michael; Berk, Alexander; Anderson, Gail; Gardner, James; Felde, Gerald

    2005-10-01

    Atmospheric Correction Algorithms (ACAs) are used in applications of remotely sensed Hyperspectral and Multispectral Imagery (HSI/MSI) to correct for atmospheric effects on measurements acquired by air and space-borne systems. The Fast Line-of-sight Atmospheric Analysis of Spectral Hypercubes (FLAASH) algorithm is a forward-model based ACA created for HSI and MSI instruments which operate in the visible through shortwave infrared (Vis-SWIR) spectral regime. Designed as a general-purpose, physics-based code for inverting at-sensor radiance measurements into surface reflectance, FLAASH provides a collection of spectral analysis and atmospheric retrieval methods including: a per-pixel vertical water vapor column estimate, determination of aerosol optical depth, estimation of scattering for compensation of adjacency effects, detection/characterization of clouds, and smoothing of spectral structure resulting from an imperfect atmospheric correction. To further improve the accuracy of the atmospheric correction process, FLAASH will also detect and compensate for sensor-introduced artifacts such as optical smile and wavelength mis-calibration. FLAASH relies on the MODTRANTM radiative transfer (RT) code as the physical basis behind its mathematical formulation, and has been developed in parallel with upgrades to MODTRAN in order to take advantage of the latest improvements in speed and accuracy. For example, the rapid, high fidelity multiple scattering (MS) option available in MODTRAN4 can greatly improve the accuracy of atmospheric retrievals over the 2-stream approximation. In this paper, advanced features available in FLAASH are described, including the principles and methods used to derive atmospheric parameters from HSI and MSI data. Results are presented from processing of Hyperion, AVIRIS, and LANDSAT data.

  11. The correction of infrasound signals for upper atmospheric winds

    NASA Technical Reports Server (NTRS)

    Mutschlecner, J. Paul; Whitaker, Rodney W.

    1990-01-01

    Infrasound waves propagate in the atmosphere by a well known mechanism produced by refraction of the waves, return to earth, and reflection at the surface into the atmosphere for subsequent bounces. A figure illustrates this phenomenon with results from a ray trace model. In this instance three rays are returned to earth from a region centered at about 50 kilometers in altitude and two from a region near 110 kilometers in altitude. The control of the wave refraction is largely dominated by the temperature-height profile and inversions; however, a major influence is also produced by the atmospheric wind profile. Another figure illustrates the considerable ray differences for rays moving in the wind direction (to the right) and in the counter direction (to the left). It obviously can be expected that infrasonic signal amplitudes will be greatly influenced by the winds in the atmosphere. The seasonal variation of the high altitude atmospheric winds is well documented. A third figure illustrates this with average statistics on the observed zonal wind in the region of 50 plus or minus 5 kilometers in altitude. The results are based upon a survey by Webb; Webb terms this parameterization the Stratospheric Circulation Index (SCI). The very strong seasonal variation has the ability to exert a major seasonal influence on infrasonic signals. The purpose here is to obtain a method for the correction of this effect.

  12. Multiangle Implementation of Atmospheric Correction (MAIAC): 2. Aerosol Algorithm

    NASA Technical Reports Server (NTRS)

    Lyapustin, A.; Wang, Y.; Laszlo, I.; Kahn, R.; Korkin, S.; Remer, L.; Levy, R.; Reid, J. S.

    2011-01-01

    An aerosol component of a new multiangle implementation of atmospheric correction (MAIAC) algorithm is presented. MAIAC is a generic algorithm developed for the Moderate Resolution Imaging Spectroradiometer (MODIS), which performs aerosol retrievals and atmospheric correction over both dark vegetated surfaces and bright deserts based on a time series analysis and image-based processing. The MAIAC look-up tables explicitly include surface bidirectional reflectance. The aerosol algorithm derives the spectral regression coefficient (SRC) relating surface bidirectional reflectance in the blue (0.47 micron) and shortwave infrared (2.1 micron) bands; this quantity is prescribed in the MODIS operational Dark Target algorithm based on a parameterized formula. The MAIAC aerosol products include aerosol optical thickness and a fine-mode fraction at resolution of 1 km. This high resolution, required in many applications such as air quality, brings new information about aerosol sources and, potentially, their strength. AERONET validation shows that the MAIAC and MOD04 algorithms have similar accuracy over dark and vegetated surfaces and that MAIAC generally improves accuracy over brighter surfaces due to the SRC retrieval and explicit bidirectional reflectance factor characterization, as demonstrated for several U.S. West Coast AERONET sites. Due to its generic nature and developed angular correction, MAIAC performs aerosol retrievals over bright deserts, as demonstrated for the Solar Village Aerosol Robotic Network (AERONET) site in Saudi Arabia.

  13. Atmospheric Density Corrections Estimated from Fitted Drag Coefficients

    NASA Astrophysics Data System (ADS)

    McLaughlin, C. A.; Lechtenberg, T. F.; Mance, S. R.; Mehta, P.

    2010-12-01

    Fitted drag coefficients estimated using GEODYN, the NASA Goddard Space Flight Center Precision Orbit Determination and Geodetic Parameter Estimation Program, are used to create density corrections. The drag coefficients were estimated for Stella, Starlette and GFZ using satellite laser ranging (SLR) measurements; and for GEOSAT Follow-On (GFO) using SLR, Doppler, and altimeter crossover measurements. The data analyzed covers years ranging from 2000 to 2004 for Stella and Starlette, 2000 to 2002 and 2005 for GFO, and 1995 to 1997 for GFZ. The drag coefficient was estimated every eight hours. The drag coefficients over the course of a year show a consistent variation about the theoretical and yearly average values that primarily represents a semi-annual/seasonal error in the atmospheric density models used. The atmospheric density models examined were NRLMSISE-00 and MSIS-86. The annual structure of the major variations was consistent among all the satellites for a given year and consistent among all the years examined. The fitted drag coefficients can be converted into density corrections every eight hours along the orbit of the satellites. In addition, drag coefficients estimated more frequently can provide a higher frequency of density correction.

  14. Atmospheric effect on spectral signature - Measurements and corrections

    NASA Technical Reports Server (NTRS)

    Kaufman, Yoram J.

    1988-01-01

    Measurements of the atmospheric effect on the spectral signature of surface cover were conducted during hazy conditions over the Chesapeake Bay and its eastern shore. In the experiment the upward radiance was measured by an airborne scanning radiometer in nine spectral bands between 465 and 773 nm, above and below the haze layer. Simultaneous measurements of the aerosol optical thickness and its vertical distribution were conducted. The results of the measurements are used to study the spectral dependence of the atmospheric effect on remote sensing of water bodies and vegetated fields (forest, corn field, and pasture), and to verify theoretical predictions. It is suggested that the radiances over dark areas (e.g., water in the near IR and forest in the visible) can be used to derive the aerosol optical thickness as is done over oceans with the CZCS satellite images. Combined with climatological information, the derived optical thickness can be used to perform corrections of the atmospheric effect. Examples of the derivation of the aerosol optical thickness and correction of the upward radiances are given.

  15. Classification Metrics for Improved Atmospheric Correction of Multispectral VNIR Imagery

    PubMed Central

    Richter, Rudolf

    2008-01-01

    Multispectral visible/near-infrared (VNIR) earth observation satellites, e.g., Ikonos, Quickbird, ALOS AVNIR-2, and DMC, usually acquire imagery in a few (3 – 5) spectral bands. Atmospheric correction is a challenging task for these images because the standard methods require at least one shortwave infrared band (around 1.6 or 2.2 μm) or hyperspectral instruments to derive the aerosol optical thickness. New classification metrics for defining cloud, cloud over water, haze, water, and saturation are presented to achieve improvements for an automatic processing system. The background is an ESA contract for the development of a prototype atmospheric processor for the optical payload AVNIR-2 on the ALOS platform.

  16. Fractal geometry for atmospheric correction and canopy simulation

    NASA Astrophysics Data System (ADS)

    Tornow, Carmen

    1996-06-01

    Global climate modeling needs a good parameterization of the vegetative surface. Two of the main important parameters are the leaf area index (LAI) and the fraction of absorbed photosynthetically active radiation (FPAR). In order to derive these values from space and airborne spectral radiance measurements one needs information on the actual atmospheric state as well as good canopy models. First we have developed a retrieval method for the optical depth to perform an atmospheric correction of remote sensing data. The atmospheric influence reduces the global image contrast and acts as a low pass filter. We found that the autocorrelation function [ACF(lambda )(h)] of the image depends on the global image contrast C and on the fractal dimension s. Using multiple regression the spectral optical depth in the visible range can be estimated from C and s with an absolute accuracy of 0.021. This method was applied and tested for a number of rural TM scenes. Atmospheric correction allows us to calculate the canopy reflectance from the image data. The relationships between the canopy reflectance and LAI or FPAR can be determined from canopy radiative transfer modeling. Row and shadowing effects influence the bi-directional reflectance distribution function (BRDF) since the leaves and stems are real 3D objects. In order to use a ray tracer for 3D radiative transfer simulation the canopy should be described by simple shapes (discs, cylinders) and polygones. Lindenmayer systems which are based on the ideas of fractal geometry allow the construction of plants and trees in this way. We have created simple artificial plants and arranged them into rows to study shadowing and row effects and compute the BRDF in various spectral channels.

  17. Estimating gross primary production in Iowa from Advanced Wide Field Sensor (AWiFS) data

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dr. E. Raymond Hunt, Jr., USDA/ARS, will be presenting recent research on the use of AWiFS shortwave infrared band (Band 5: 1.50 to 1.70 µm wavelength) for the prediction of vegetation water content. Data from many different land cover types show there is a relationship between the normalized diffe...

  18. Estimating crop production in Iowa from Advanced Wide Field Sensor (AWiFS) data

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Indian National Remote Sensing Agency ResourceSat-1 Advanced Wide Field Sensor (AWiFS) data for the USA is being provided online by the USDA Foreign Agricultural Service (FAS) and Arctic Slope Regional Corporation – Management Services (ASRC-MS). Because of the frequent revisit time and pixel sizes...

  19. Cross-comparison of the IRS-P6 AWiFS sensor with the L5 TM, L7 ETM+, & Terra MODIS sensors

    USGS Publications Warehouse

    Chander, G.; Xiong, X.; Angal, A.; Choi, T.; Malla, R.

    2009-01-01

    As scientists and decision makers increasingly rely on multiple Earth-observing satellites to address urgent global issues, it is imperative that they can rely on the accuracy of Earth-observing data products. This paper focuses on the crosscomparison of the Indian Remote Sensing (IRS-P6) Advanced Wide Field Sensor (AWiFS) with the Landsat 5 (L5) Thematic Mapper (TM), Landsat 7 (L7) Enhanced Thematic Mapper Plus (ETM+), and Terra Moderate Resolution Imaging Spectroradiometer (MODIS) sensors. The cross-comparison was performed using image statistics based on large common areas observed by the sensors within 30 minutes. Because of the limited availability of simultaneous observations between the AWiFS and the Landsat and MODIS sensors, only a few images were analyzed. These initial results are presented. Regression curves and coefficients of determination for the top-of-atmosphere (TOA) trends from these sensors were generated to quantify the uncertainty in these relationships and to provide an assessment of the calibration differences between these sensors. ?? 2009 SPIE.

  20. Coastal Zone Color Scanner atmospheric correction algorithm: multiple scattering effects.

    PubMed

    Gordon, H R; Castaño, D J

    1987-06-01

    An analysis of the errors due to multiple scattering which are expected to be encountered in application of the current Coastal Zone Color Scanner (CZCS) atmospheric correction algorithm is presented in detail. This was prompted by the observations of others that significant errors would be encountered if the present algorithm were applied to a hypothetical instrument possessing higher radiometric sensitivity than the present CZCS. This study provides CZCS users sufficient information with which to judge the efficacy of the current algorithm with the current sensor and enables them to estimate the impact of the algorithm-induced errors on their applications in a variety of situations. The greatest source of error is the assumption that the molecular and aerosol contributions to the total radiance observed at the sensor can be computed separately. This leads to the requirement that a value epsilon'(lambda,lambda(0)) for the atmospheric correction parameter, which bears little resemblance to its theoretically meaningful counterpart, must usually be employed in the algorithm to obtain an accurate atmospheric correction. The behavior of '(lambda,lambda(0)) with the aerosol optical thickness and aerosol phase function is thoroughly investigated through realistic modeling of radiative transfer in a stratified atmosphere over a Fresnel reflecting ocean. A unique feature of the analysis is that it is carried out in scan coordinates rather than typical earth-sun coordinates allowing elucidation of the errors along typical CZCS scan lines; this is important since, in the normal application of the algorithm, it is assumed that the same value of can be used for an entire CZCS scene or at least for a reasonably large subscene. Two types of variation of ' are found in models for which it would be constant in the single scattering approximation: (1) variation with scan angle in scenes in which a relatively large portion of the aerosol scattering phase function would be examined

  1. Investigation of a new method for determination of atmospheric refractivity corrections in satellite laser ranging.

    NASA Astrophysics Data System (ADS)

    Mironov, N. T.; Prokopov, A. V.; Remaev, E. V.

    1997-08-01

    A new algorithm is investigated for calculating atmospheric refractivity corrections in satellite laser ranging in the Earth's spherically stratified atmosphere based on results of measuring meteorological parameters on the Earth's surface. A numerical experiment with 125 meteorological sounding profiles shows that the new method allows to determine atmospheric refractivity corrections with the accuracy better than the Marini-Murray method does.

  2. Atmospheric correction of hyperspectral images based on approximate solution of transmittance equation

    NASA Astrophysics Data System (ADS)

    Belov, A. M.; Myasnikov, V. V.

    2015-02-01

    The paper presents a method of atmospheric correction of remote sensing hyperspectral images. The method based on approximate solution of MODTRAN transmittance equation using simultaneous analysis of remote sensing hyperspectral image and "ideal" hyperspectral image which is free from atmospheric distortions. Experimental results show that proposed method is applicable to perform atmospheric correction.

  3. Corrective Action Decision Document/Corrective Action Plan for Corrective Action Unit 104: Area 7 Yucca Flat Atmospheric Test Sites Nevada National Security Site, Nevada, Revision 0

    SciTech Connect

    Patrick Matthews

    2012-10-01

    CAU 104 comprises the following corrective action sites (CASs): • 07-23-03, Atmospheric Test Site T-7C • 07-23-04, Atmospheric Test Site T7-1 • 07-23-05, Atmospheric Test Site • 07-23-06, Atmospheric Test Site T7-5a • 07-23-07, Atmospheric Test Site - Dog (T-S) • 07-23-08, Atmospheric Test Site - Baker (T-S) • 07-23-09, Atmospheric Test Site - Charlie (T-S) • 07-23-10, Atmospheric Test Site - Dixie • 07-23-11, Atmospheric Test Site - Dixie • 07-23-12, Atmospheric Test Site - Charlie (Bus) • 07-23-13, Atmospheric Test Site - Baker (Buster) • 07-23-14, Atmospheric Test Site - Ruth • 07-23-15, Atmospheric Test Site T7-4 • 07-23-16, Atmospheric Test Site B7-b • 07-23-17, Atmospheric Test Site - Climax These 15 CASs include releases from 30 atmospheric tests conducted in the approximately 1 square mile of CAU 104. Because releases associated with the CASs included in this CAU overlap and are not separate and distinguishable, these CASs are addressed jointly at the CAU level. The purpose of this CADD/CAP is to evaluate potential corrective action alternatives (CAAs), provide the rationale for the selection of recommended CAAs, and provide the plan for implementation of the recommended CAA for CAU 104. Corrective action investigation (CAI) activities were performed from October 4, 2011, through May 3, 2012, as set forth in the CAU 104 Corrective Action Investigation Plan.

  4. Aerosol Retrieval and Atmospheric Correction Algorithms for EPIC

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Lyapustin, A.; Marshak, A.; Korkin, S.; Herman, J. R.

    2011-12-01

    EPIC is a multi-spectral imager onboard planned Deep Space Climate ObserVatoRy (DSCOVR) designed for observations of the full illuminated disk of the Earth with high temporal and coarse spatial resolution (10 km) from Lagrangian L1 point. During the course of the day, EPIC will view the same Earth surface area in the full range of solar and view zenith angles at equator with fixed scattering angle near the backscattering direction. This talk will describe a new aerosol retrieval/atmospheric correction algorithm developed for EPIC and tested with EPIC Simulator data. This algorithm uses the time series approach and consists of two stages: the first stage is designed to periodically re-initialize the surface spectral bidirectional reflectance (BRF) on stable low AOD days. Such days can be selected based on the same measured reflectance between the morning and afternoon reciprocal view geometries of EPIC. On the second stage, the algorithm will monitor the diurnal cycle of aerosol optical depth and fine mode fraction based on the known spectral surface BRF. Testing of the developed algorithm with simulated EPIC data over continental USA showed a good accuracy of AOD retrievals (10-20%) except over very bright surfaces.

  5. Aerosol Retrieval and Atmospheric Correction Algorithms for EPIC

    NASA Technical Reports Server (NTRS)

    Wang, Yujie; Lyapustin, Alexei; Marshak, Alexander; Korkin, Sergey; Herman, Jay

    2011-01-01

    EPIC is a multi-spectral imager onboard planned Deep Space Climate ObserVatoRy (DSCOVR) designed for observations of the full illuminated disk of the Earth with high temporal and coarse spatial resolution (10 km) from Lagrangian L1 point. During the course of the day, EPIC will view the same Earth surface area in the full range of solar and view zenith angles at equator with fixed scattering angle near the backscattering direction. This talk will describe a new aerosol retrieval/atmospheric correction algorithm developed for EPIC and tested with EPIC Simulator data. This algorithm uses the time series approach and consists of two stages: the first stage is designed to periodically re-initialize the surface spectral bidirectional reflectance (BRF) on stable low AOD days. Such days can be selected based on the same measured reflectance between the morning and afternoon reciprocal view geometries of EPIC. On the second stage, the algorithm will monitor the diurnal cycle of aerosol optical depth and fine mode fraction based on the known spectral surface BRF. Testing of the developed algorithm with simulated EPIC data over continental USA showed a good accuracy of AOD retrievals (10-20%) except over very bright surfaces.

  6. Complementarity of ResourceSat-1 AWiFS and Landsat TM/ETM+ sensors

    USGS Publications Warehouse

    Goward, S.N.; Chander, G.; Pagnutti, M.; Marx, A.; Ryan, R.; Thomas, N.; Tetrault, R.

    2012-01-01

    Considerable interest has been given to forming an international collaboration to develop a virtual moderate spatial resolution land observation constellation through aggregation of data sets from comparable national observatories such as the US Landsat, the Indian ResourceSat and related systems. This study explores the complementarity of India's ResourceSat-1 Advanced Wide Field Sensor (AWiFS) with the Landsat 5 Thematic Mapper (TM) and Landsat 7 Enhanced Thematic Mapper Plus (ETM+). The analysis focuses on the comparative radiometry, geometry, and spectral properties of the two sensors. Two applied assessments of these data are also explored to examine the strengths and limitations of these alternate sources of moderate resolution land imagery with specific application domains. There are significant technical differences in these imaging systems including spectral band response, pixel dimensions, swath width, and radiometric resolution which produce differences in observation data sets. None of these differences was found to strongly limit comparable analyses in agricultural and forestry applications. Overall, we found that the AWiFS and Landsat TM/ETM+ imagery are comparable and in some ways complementary, particularly with respect to temporal repeat frequency. We have found that there are limits to our understanding of the AWiFS performance, for example, multi-camera design and stability of radiometric calibration over time, that leave some uncertainty that has been better addressed for Landsat through the Image Assessment System and related cross-sensor calibration studies. Such work still needs to be undertaken for AWiFS and similar observatories that may play roles in the Global Earth Observation System of Systems Land Surface Imaging Constellation.

  7. Impact of AWiFS derived land use land cover on simulation of heavy rainfall

    NASA Astrophysics Data System (ADS)

    Karri, Srinivasarao; Gharai, Biswadip; Sai Krishna, S. V. S.; Rao, P. V. N.

    2016-05-01

    Land use/land cover (LU/LC) changes are considered to be one of the most important factors affecting regional climate and are thus an area of public concern. The land surface plays a crucial role in boundary layer evolution and precipitation patterns thereby establishing the need for LU/LC inputs as a critical part of modeling systems. Inaccurate LU/LC information often leads to very large errors in surface energy fluxes thus leading to errors in boundary layer state. We have investigated an incident of heavy rainfall during August 2015 over West Bengal, India using Weather Research and Forecast (WRF) model by incorporating different LU/LC datasets, IRS P6 Advanced Wide Field Sensor (AWiFS) LU/LC data for 2012-13 and the default Moderate Resolution Imaging Spectro-radiometer (MODIS) derived USGS LU/LC data for 2001. In the present study, we have made a comparative assessment between AWiFS derived LU/LC and USGS LU/LC by incorporating these datasets as one of the lower boundary conditions over Indian region in WRF model version 3.5.1 to simulate, at 10km resolution, a heavy rainfall event associated with landfall of a cyclonic system over West Bengal. The results of the study suggested influence of LU/LC in occurrence of heavy rainfall with WRF model using AWiFS LU/LC showing more realistic simulation as AWiFS LU/LC is more up-to-date and features recent changes in LU/LC over India.

  8. Radiometric Calibration of the AWiFS Using Vicarious Calibration Techniques

    NASA Technical Reports Server (NTRS)

    Pagnutti, Mary; Holekamp, Kara

    2007-01-01

    A radiometric calibration assessment of the AWiFS (Advanced Wide Field Sensor) on the Indian Remote Sensing Resourcesat-1 satellite was performed by the NASA Applied Research & Technology Project Office (formerly the Applied Sciences Directorate) at the John C. Stennis Space Center. A reflectance-based vicarious calibration approach, requiring ground-based measurements coincident with satellite acquisitions and radiative transfer calculations, was used to estimate at-sensor radiance. The AWiFS is a 4-band, multispectral, moderate-resolution (60 m) imaging sensor that operates in the visible through short-wave infrared spectrum and is currently being considered as a Landsat-like alternative. Several study sites near the Stennis Space Center that attempted to span the dynamic range of the sensor were employed. Satellite at-sensor radiance values were compared to those estimated to determine the sensor's radiometric accuracy. The results of this evaluation provide the user community with an independent assessment of the radiometric accuracy of AWiFS image products, which are commercially available through GeoEye. These results are an extension of an independent assessment made by the University of Arizona Remote Sensing Group, the South Dakota State University Satellite Calibration Group & Image Processing Lab, and the NASA Applied Sciences Directorate at the John C. Stennis Space Center the previous year.

  9. Improved PPP Ambiguity Resolution Considering the Stochastic Characteristics of Atmospheric Corrections from Regional Networks.

    PubMed

    Li, Yihe; Li, Bofeng; Gao, Yang

    2015-01-01

    With the increased availability of regional reference networks, Precise Point Positioning (PPP) can achieve fast ambiguity resolution (AR) and precise positioning by assimilating the satellite fractional cycle biases (FCBs) and atmospheric corrections derived from these networks. In such processing, the atmospheric corrections are usually treated as deterministic quantities. This is however unrealistic since the estimated atmospheric corrections obtained from the network data are random and furthermore the interpolated corrections diverge from the realistic corrections. This paper is dedicated to the stochastic modelling of atmospheric corrections and analyzing their effects on the PPP AR efficiency. The random errors of the interpolated corrections are processed as two components: one is from the random errors of estimated corrections at reference stations, while the other arises from the atmospheric delay discrepancies between reference stations and users. The interpolated atmospheric corrections are then applied by users as pseudo-observations with the estimated stochastic model. Two data sets are processed to assess the performance of interpolated corrections with the estimated stochastic models. The results show that when the stochastic characteristics of interpolated corrections are properly taken into account, the successful fix rate reaches 93.3% within 5 min for a medium inter-station distance network and 80.6% within 10 min for a long inter-station distance network. PMID:26633400

  10. Improved PPP Ambiguity Resolution Considering the Stochastic Characteristics of Atmospheric Corrections from Regional Networks

    PubMed Central

    Li, Yihe; Li, Bofeng; Gao, Yang

    2015-01-01

    With the increased availability of regional reference networks, Precise Point Positioning (PPP) can achieve fast ambiguity resolution (AR) and precise positioning by assimilating the satellite fractional cycle biases (FCBs) and atmospheric corrections derived from these networks. In such processing, the atmospheric corrections are usually treated as deterministic quantities. This is however unrealistic since the estimated atmospheric corrections obtained from the network data are random and furthermore the interpolated corrections diverge from the realistic corrections. This paper is dedicated to the stochastic modelling of atmospheric corrections and analyzing their effects on the PPP AR efficiency. The random errors of the interpolated corrections are processed as two components: one is from the random errors of estimated corrections at reference stations, while the other arises from the atmospheric delay discrepancies between reference stations and users. The interpolated atmospheric corrections are then applied by users as pseudo-observations with the estimated stochastic model. Two data sets are processed to assess the performance of interpolated corrections with the estimated stochastic models. The results show that when the stochastic characteristics of interpolated corrections are properly taken into account, the successful fix rate reaches 93.3% within 5 min for a medium inter-station distance network and 80.6% within 10 min for a long inter-station distance network. PMID:26633400

  11. On simplified atmospheric correction procedures for shortwave bands of satellite images.

    SciTech Connect

    Song, J.; Lu, D.; Wesely, M. L.; Environmental Research; Northern Illinois Univ.; Jackson State Univ.

    2003-05-01

    Accurate corrections of Normalized Difference Vegetation Index (NDVI) for atmospheric effects are currently based on modeling the physical behavior of radiation as it passes through the atmosphere. An important requirement for application of the physical models is detailed information on atmospheric humidity and particles. Here, a method is described for making atmospheric corrections without the need for detailed atmospheric observations. A simplified approach for making atmospheric corrections to reflectances observed from satellites is developed by using the unique spectral signature of water pixels in satellite images. A radiative transfer model is applied to a variety of clear-sky conditions to generate functional relationships between the radiation due to the atmospheric scattering above water bodies and atmospheric radiative properties. Test cases indicate that the resulting estimates of surface reflectances and NDVI agree well with estimates made using a radiative transfer model applied independently and with measurements made at the surface.

  12. Atmospheric correction analysis on LANDSAT data over the Amazon region. [Manaus, Brazil

    NASA Technical Reports Server (NTRS)

    Parada, N. D. J. (Principal Investigator); Dias, L. A. V.; Dossantos, J. R.; Formaggio, A. R.

    1983-01-01

    The Amazon Region natural resources were studied in two ways and compared. A LANDSAT scene and its attributes were selected, and a maximum likelihood classification was made. The scene was atmospherically corrected, taking into account Amazonic peculiarities revealed by (ground truth) of the same area, and the subsequent classification. Comparison shows that the classification improves with the atmospherically corrected images.

  13. An algorithm for the radiometric and atmospheric correction of AVHRR data in the solar reflective channels

    NASA Astrophysics Data System (ADS)

    Teillet, P. M.

    1992-09-01

    Radiometric and atmospheric corrections are formulated with a view to computing vegetation indices such as the Normalized Difference Vegetation Index (NDVI) from surface reflectances rather than the digital signal levels recorded at the sensor. In particular, look-up table (LUT) results from an atmospheric radiative transfer code are used to save time and avoid the complexities of running and maintaining such a code in a production environment. The data flow for radiometric image correction is very similar to commonly used geometric correction data flows. The role of terrain elevation in the atmospheric correction process is discussed and the effect of topography on NDVI is highlighted.

  14. Optical depth measurements and atmospheric correction of remotely sensed data for FIFE

    NASA Technical Reports Server (NTRS)

    Wrigley, R. C.; Slye, R. E.; Pueschel, R. F.; Spanner, M. A.; Livingston, J. M.

    1990-01-01

    Data derived from an airborne tracking-sun photometer are used to provide quantitative corrections for atmospheric effects in remotely sensed data. The atmospheric correction involves the validation of radiometric and atmospheric measurements and the application of single scattering approximation which permits the separation of Rayleigh scattering from aerosol scattering. Sun-photometer data are used to generate plots of spectral optical depths, aerosol size distributions, aerosol phase functions, and aerosol single-scattering albedos. The atmospheric correction model and the atmospheric optical properties are incorporated into a program which is applied to two flightlines of data. Atmospheric corrections tested on remotely sensed data permitted the removal of limb brightening, although the results require verification by means of ground measurements.

  15. Atmospheric correction of ocean-color sensors: effects of the Earth's curvature.

    PubMed

    Ding, K; Gordon, H R

    1994-10-20

    We investigate the influence of the curvature of the Earth on a proposed atmospheric-correction scheme for the Sea-Viewing Wide-Field-of-View Sensor (SeaWiFS) by simulating the radiance exiting the top of a spherical-shell atmosphere and inserting the result into the proposed correction algorithm. The error in the derived water-leaving reflectance suggests that the effects of the curvature are negligible for solar zenith angles (θ(0)) ≤ 70°. Furthermore, for θ(0) > 70° the error in atmospheric correction can usually be reduced if the molecular-scattering component of the top of the atmosphere reflectance (ρ(r)) is computed with a spherical-shell atmosphere radiative transfer code. Also, for θ(0) > 70° the error in atmospheric correction in a spherical-shell atmosphere, when ρ(r) is computed with a spherical-shell model, can be predicted reasonably well from computations made with plane-parallel atmosphere radiative transfer codes. This implies that studies aimed at improving atmospheric correction can be made assuming plane-parallel geometry and that the investigator can be confident when θ(0)> 70° that any improvements will still be valid for a spherical-shell atmosphere as long as ρ(r) is computed in spherical-shell geometry. Finally, a scheme for computing ρ(r) in a spherical-shell atmosphere in a relatively simple manner is developed. PMID:20941262

  16. Investigation of a new method for the determination of atmospheric correction in satellite laser ranging.

    NASA Astrophysics Data System (ADS)

    Mironov, N. T.; Prokopov, A. V.; Remaev, E. V.

    The authors investigate a new algorithm for calculating atmospheric correction in satellite laser ranging in the spherically stratified terrestrial atmosphere. The algorithm is based on results of measuring meteorological parameters on the Earth's surface. A numerical experiment with 125 meteorological sounding profiles shows that the new method allows the atmospheric corrections to be determined in the range of zenith angles from 0° to 80° more accurately than with the Marini-Murray method.

  17. Atmospheric Correction Prototype Algorithm for High Spatial Resolution Multispectral Earth Observing Imaging Systems

    NASA Technical Reports Server (NTRS)

    Pagnutti, Mary

    2006-01-01

    This viewgraph presentation reviews the creation of a prototype algorithm for atmospheric correction using high spatial resolution earth observing imaging systems. The objective of the work was to evaluate accuracy of a prototype algorithm that uses satellite-derived atmospheric products to generate scene reflectance maps for high spatial resolution (HSR) systems. This presentation focused on preliminary results of only the satellite-based atmospheric correction algorithm.

  18. Multispectral Resource Sampler (MPS): Proof of Concept. Literature survey of atmospheric corrections

    NASA Technical Reports Server (NTRS)

    Schowengerdt, R. A.; Slater, P. N.

    1981-01-01

    Work done in combining spectral bands to reduce atmospheric effects on spectral signatures is described. The development of atmospheric models and their use with ground and aerial measurements in correcting spectral signatures is reviewed. An overview of studies of atmospheric effects on the accuracy of scene classification is provided.

  19. Atmospheric correction of AVHRR data for biophysical remote sensing of the Sahel

    SciTech Connect

    Hanan, N.P.; Prince, S.D.; Holben, B.N.

    1995-02-01

    The importance of atmospheric correction of reflectances measured with the Advanced Very High Resolution Radiometer(AVHRR) for biophysical studies using the normalized difference vegetation index (NDVI) is examined for a study area in the Sahel for which measurements of aerosol and water vapor were available. During the rainy season atmospheric aerosols were relatively more variable than water vapor. Atmospheric corrections were applied to Channel 1 (red) and Channel 2 (near-infrared) for the effects of molecular absorption and Rayleigh scatter, aerosol scatter and absorption, and water vapor absorption. The results were expressed as the difference between corrected and uncorrected reflectances ({Delta}{rho}). In Channel 1 the magnitude and variability of {Delta}{rho} was mostly caused by aerosols. In Channel 2 the magnitude of {Delta}{rho} was caused by water vapor, but most of the variability was caused by aerosols. Most of the degradation in the NDVI signal ({delta}{nu}{iota}) was caused by water vapor but the variability in {Delta}{nu}{iota} was caused by both water vapor and aerosol. Atmospheric corrections using seasonal averages of atmospheric water vapor and aerosol optical depths resulted in corrections that were similar to the full corrections using daily values. In the Sahel it may therefore be acceptable to use average values for the atmospheric variables to correct satellite data when sunphotometer data are not available, although the effects of interannual variability in mean atmospheric conditions are not known.

  20. Atmospheric refraction correction for Ka-band blind pointing on the DSS-13 beam waveguide antenna

    NASA Technical Reports Server (NTRS)

    Perez-Borroto, I. M.; Alvarez, L. S.

    1992-01-01

    An analysis of the atmospheric refraction corrections at the DSS-13 34-m diameter beam waveguide (BWG) antenna for the period Jul. - Dec. 1990 is presented. The current Deep Space Network (DSN) atmospheric refraction model and its sensitivity with respect to sensor accuracy are reviewed. Refraction corrections based on actual atmospheric parameters are compared with the DSS-13 station default corrections for the six-month period. Average blind-pointing improvement during the worst month would have amounted to 5 mdeg at 10 deg elevation using actual surface weather values. This would have resulted in an average gain improvement of 1.1 dB.

  1. Forward error correction for an atmospheric noise channel

    NASA Astrophysics Data System (ADS)

    Olson, Katharyn E.; Enge, Per K.

    1992-05-01

    Two Markov chains are employed to model the memory of the atmospheric noise channel. It derives the transition probabilities for these chains from atmospheric noise error processes that were recorded at 306 kHz. The models are then utilized to estimate the probability of codeword error, and compares these estimates to codeword error rates that are obtained directly from the recorded error processes. These comparisons are made for the Golay code with various bit interleaving depths, and for a Reed-Solomon code with a variety of symbol interleaving depths.

  2. Comparison of observation level versus 24-hour average atmospheric loading corrections in VLBI analysis

    NASA Astrophysics Data System (ADS)

    MacMillan, D. S.; van Dam, T. M.

    2009-04-01

    Variations in the horizontal distribution of atmospheric mass induce displacements of the Earth's surface. Theoretical estimates of the amplitude of the surface displacement indicate that the predicted surface displacement is often large enough to be detected by current geodetic techniques. In fact, the effects of atmospheric pressure loading have been detected in Global Positioning System (GPS) coordinate time series [van Dam et al., 1994; Dong et al., 2002; Scherneck et al., 2003; Zerbini et al., 2004] and very long baseline interferometery (VLBI) coordinates [Rabble and Schuh, 1986; Manabe et al., 1991; van Dam and Herring, 1994; Schuh et al., 2003; MacMillan and Gipson, 1994; and Petrov and Boy, 2004]. Some of these studies applied the atmospheric displacement at the observation level and in other studies, the predicted atmospheric and observed geodetic surface displacements have been averaged over 24 hours. A direct comparison of observation level and 24 hour corrections has not been carried out for VLBI to determine if one or the other approach is superior. In this presentation, we address the following questions: 1) Is it better to correct geodetic data at the observation level rather than applying corrections averaged over 24 hours to estimated geodetic coordinates a posteriori? 2) At the sub-daily periods, the atmospheric mass signal is composed of two components: a tidal component and a non-tidal component. If observation level corrections reduce the scatter of VLBI data more than a posteriori correction, is it sufficient to only model the atmospheric tides or must the entire atmospheric load signal be incorporated into the corrections? 3) When solutions from different geodetic techniques (or analysis centers within a technique) are combined (e.g., for ITRF2008), not all solutions may have applied atmospheric loading corrections. Are any systematic effects on the estimated TRF introduced when atmospheric loading is applied?

  3. Sensitivity of earthquake source inversions to atmospheric noise and corrections of InSAR data

    NASA Astrophysics Data System (ADS)

    Scott, Chelsea Phipps; Lohman, Rowena Benfer

    2016-05-01

    Tropospheric phase delays pose a major challenge to InSAR (interferometric synthetic aperture radar)-based studies of tectonic deformation. One approach to the mitigation of effects from tropospheric noise is the application of elevation-dependent corrections based on empirical fits between elevation and interferometric phase. We quantify the effects of corrections with a range of complexity on inferred earthquake source parameters using synthetic interferograms with known atmospheric characteristics. We infer statistical properties of the stratified component of the atmosphere using pressure, temperature, and water vapor data from the North America Regional Reanalysis model over our region of interest in the Basin and Range province of the western United States. The statistics of the simulated atmospheric turbulence are estimated from InSAR and Global Positioning System data. We demonstrate potentially significant improvements in the precision of earthquake magnitude, depth, and dip estimates for several synthetic earthquake focal mechanisms following a correction for spatially variable atmospheric characteristics, relative to cases where the correction is based on a uniform delay versus elevation relationship or where no correction is applied. We apply our approach to the 1992 M5.6 Little Skull Mountain, Nevada, earthquake and demonstrate that the earthquake source parameter error bounds decrease in size after applying the atmospheric corrections. Our approach for evaluating the impact of atmospheric noise on inferred fault parameters is easily adaptable to other regions and source mechanisms.

  4. Corrective Action Decision Document/Closure Report for Corrective Action Unit 370: T-4 Atmospheric Test Site, Nevada Test Site, Nevada, Revision 0

    SciTech Connect

    Patrick Matthews

    2009-05-01

    This Corrective Action Decision Document/Closure Report has been prepared for Corrective Action Unit (CAU) 370, T-4 Atmospheric Test Site, located in Area 4 at the Nevada Test Site, Nevada, in accordance with the Federal Facility Agreement and Consent Order (FFACO). Corrective Action Unit 370 is comprised of Corrective Action Site (CAS) 04-23-01, Atmospheric Test Site T-4. The purpose of this Corrective Action Decision Document/Closure Report is to provide justification and documentation supporting the recommendation that no further corrective action is needed for CAU 370 due to the implementation of the corrective action of closure in place with administrative controls. To achieve this, corrective action investigation (CAI) activities were performed from June 25, 2008, through April 2, 2009, as set forth in the Corrective Action Investigation Plan for Corrective Action Unit 370: T-4 Atmospheric Test Site and Record of Technical Change No. 1.

  5. Atmospheric correction of Nimbus-7 Coastal Zone Color Scanner imagery

    NASA Technical Reports Server (NTRS)

    Gordon, H. R.; Mueller, J. L.; Wrigley, R. C.

    1980-01-01

    The Coastal Zone Color Scanner (CZCS) on Nimbus-7 is a scanning radiometer designed to view the ocean in six spectral bands (centered at 443, 520, 550, 670, 750, and 11,500 nm) for the purpose of estimating sea surface chlorophyll and temperature distributions. In the visible bands, the atmosphere obscures the imagery to the extent that at 443 nm, at most, only 20 percent of the observed radiance originates from beneath the sea surface. Retrieving this subsurface radiance from the imagery is complicated by the highly variable nature of the aerosol's contribution. In this paper, an algorithm for the removal of these atmospheric effects from CZCS imagery is described, a preliminary application of the algorithm to an image with very strong horizontal variations in the aerosol optical thickness is presented, and retrieval of the spatial distribution of the aerosol optical thickness is discussed.

  6. Improved positioning by addition of atmospheric corrections to local area differential GPS

    NASA Astrophysics Data System (ADS)

    Singh, Malkiat; Reilly, Michael H.

    2006-10-01

    A local area differential GPS (DGPS) method applies corrections from a reference GPS receiver to improve positioning accuracy for a roaming GPS receiver. Increasing separation between reference and roaming receivers dilutes this improvement, largely because ionospheric and tropospheric effects differ between their two locations. We correct differential corrections for this difference and determine the improvement with this "atmospheric" DGPS method at roaming receiver positions that are separated from a Coast Guard reference receiver at Annapolis, Maryland, by 44, 67, and 228 km. For ionospheric corrections we use our Raytrace-Ionospheric conductivity and electron density-Bent-Gallagher ionospheric propagation model with driving parameters obtained from two-frequency data of surveyed reference GPS receivers. For tropospheric corrections we use the Hopfield model and weather station data for surface temperature, pressure, and relative humidity. Internet delivery of atmospheric differential corrections is used to avoid blockage or range cutoff of radio transmissions. Some comparisons are made with Wide Area Augmentation System GPS receiver performance.

  7. Corrections for atmospheric refractivity in satellite laser ranging

    NASA Technical Reports Server (NTRS)

    Iyer, R. S.; Bufton, J. L.

    1977-01-01

    The effects of departures from the spherical symmetry assumption are investigated by describing the refractivity profile on the earth's surface as a generalized function of the surface coordinates. Aspects of satellite ranging geometry are considered and the representation of the true group refractivity of the atmosphere at any point on the earth's surface is discussed. Surface meteorological data obtained from a few east coast weather stations are analyzed to obtain typical values of the higher order bias terms.

  8. Cross-sensor comparisons between Landsat 5 TM and IRS-P6 AWiFS and disturbance detection using integrated Landsat and AWiFS time-series images

    USGS Publications Warehouse

    Chen, Xuexia; Vogelmann, James E.; Chander, Gyanesh; Ji, Lei; Tolk, Brian; Huang, Chengquan; Rollins, Matthew

    2013-01-01

    Routine acquisition of Landsat 5 Thematic Mapper (TM) data was discontinued recently and Landsat 7 Enhanced Thematic Mapper Plus (ETM+) has an ongoing problem with the scan line corrector (SLC), thereby creating spatial gaps when covering images obtained during the process. Since temporal and spatial discontinuities of Landsat data are now imminent, it is therefore important to investigate other potential satellite data that can be used to replace Landsat data. We thus cross-compared two near-simultaneous images obtained from Landsat 5 TM and the Indian Remote Sensing (IRS)-P6 Advanced Wide Field Sensor (AWiFS), both captured on 29 May 2007 over Los Angeles, CA. TM and AWiFS reflectances were compared for the green, red, near-infrared (NIR), and shortwave infrared (SWIR) bands, as well as the normalized difference vegetation index (NDVI) based on manually selected polygons in homogeneous areas. All R2 values of linear regressions were found to be higher than 0.99. The temporally invariant cluster (TIC) method was used to calculate the NDVI correlation between the TM and AWiFS images. The NDVI regression line derived from selected polygons passed through several invariant cluster centres of the TIC density maps and demonstrated that both the scene-dependent polygon regression method and TIC method can generate accurate radiometric normalization. A scene-independent normalization method was also used to normalize the AWiFS data. Image agreement assessment demonstrated that the scene-dependent normalization using homogeneous polygons provided slightly higher accuracy values than those obtained by the scene-independent method. Finally, the non-normalized and relatively normalized ‘Landsat-like’ AWiFS 2007 images were integrated into 1984 to 2010 Landsat time-series stacks (LTSS) for disturbance detection using the Vegetation Change Tracker (VCT) model. Both scene-dependent and scene-independent normalized AWiFS data sets could generate disturbance maps similar to

  9. Assessment, Validation, and Refinement of the Atmospheric Correction Algorithm for the Ocean Color Sensors. Chapter 19

    NASA Technical Reports Server (NTRS)

    Wang, Menghua

    2003-01-01

    The primary focus of this proposed research is for the atmospheric correction algorithm evaluation and development and satellite sensor calibration and characterization. It is well known that the atmospheric correction, which removes more than 90% of sensor-measured signals contributed from atmosphere in the visible, is the key procedure in the ocean color remote sensing (Gordon and Wang, 1994). The accuracy and effectiveness of the atmospheric correction directly affect the remotely retrieved ocean bio-optical products. On the other hand, for ocean color remote sensing, in order to obtain the required accuracy in the derived water-leaving signals from satellite measurements, an on-orbit vicarious calibration of the whole system, i.e., sensor and algorithms, is necessary. In addition, it is important to address issues of (i) cross-calibration of two or more sensors and (ii) in-orbit vicarious calibration of the sensor-atmosphere system. The goal of these researches is to develop methods for meaningful comparison and possible merging of data products from multiple ocean color missions. In the past year, much efforts have been on (a) understanding and correcting the artifacts appeared in the SeaWiFS-derived ocean and atmospheric produces; (b) developing an efficient method in generating the SeaWiFS aerosol lookup tables, (c) evaluating the effects of calibration error in the near-infrared (NIR) band to the atmospheric correction of the ocean color remote sensors, (d) comparing the aerosol correction algorithm using the singlescattering epsilon (the current SeaWiFS algorithm) vs. the multiple-scattering epsilon method, and (e) continuing on activities for the International Ocean-Color Coordinating Group (IOCCG) atmospheric correction working group. In this report, I will briefly present and discuss these and some other research activities.

  10. [A quickly atmospheric correction method for HJ-1 CCD with deep blue algorithm].

    PubMed

    Wang, Zhong-Ting; Wang, Hong-Mei; Li, Qing; Zhao, Shao-Hua; Li, Shen-Shen; Chen, Liang-Fu

    2014-03-01

    In the present, for the characteristic of HJ-1 CCD camera, after receiving aerosol optical depth (AOD) from deep blue algorithm which was developed by Hsu et al. assisted by MODerate-resolution imaging spectroradiometer (MODIS) surface reflectance database, bidirectional reflectance distribution function (BRDF) correction with Kernel-Driven Model, and the calculation of viewing geometry with auxiliary data, a new atmospheric correction method of HJ-1 CCD was developed which can be used over vegetation, soil and so on. And, when the CCD data is processed to correct atmospheric influence, with look up table (LUT) and bilinear interpolation, atmospheric correction of HJ-1 CCD is completed quickly by grid calculation of atmospheric parameters and matrix operations of interface define language (IDL). The experiment over China North Plain on July 3rd, 2012 shows that by our method, the atmospheric influence was corrected well and quickly (one CCD image of 1 GB can be corrected in eight minutes), and the reflectance after correction over vegetation and soil was close to the spectrum of vegetation and soil. The comparison with MODIS reflectance product shows that for the advantage of high resolution, the corrected reflectance image of HJ-1 is finer than that of MODIS, and the correlation coefficient of the reflectance over typical surface is greater than 0.9. Error analysis shows that the recognition error of aerosol type leads to 0. 05 absolute error of surface reflectance in near infrared band, which is larger than that in visual bands, and the 0. 02 error of reflectance database leads to 0.01 absolute error of surface reflectance of atmospheric correction in green and red bands. PMID:25208402

  11. Improved Atmospheric Refraction Correction Models in Satellite Laser Ranging (SLR)

    NASA Astrophysics Data System (ADS)

    Hulley, Glynn

    2004-03-01

    The primary source of unmodeled error in space geodetic techniques such as VLBI, GPS and SLR is atmospheric refraction. SLR uses lasers (532 nm) to measure very precise ranges from ground tracking stations to spaceborne geodetic satellites with accuracies at the millimeter level. Improved refraction modeling is essential in reducing errors in SLR measurements that study variations in the Earth's gravitational field and vertical crustal motion as well as monitoring sea-level rise, post-glacial rebound and earthquake predictions. The Marini and Murray model developed in the 1970's has primarily been used for data analysis, but recent work by Mendes et al., 2002 provides significant improvement in modeling the elevation dependency of the zenith atmospheric delay. The elevation dependency is modeled by what are known as mapping functions. Improvements in modeling the zenith delay itself where achieved by computing the group refractivity using a procedure described by Ciddor [1996] and by including the non-hydrostatic (wet) zenith delay. Two color SLR can also be used to determine the zenith delay by measuring the dispersive delay of two laser pulses each at a different wavelength. By comparing the Mendes and Marini Murray models to this experimental technique, one is able to evaluate the accuracy of the two models. We have found errors between the two models when compared to two color SLR at the centimeter level, which increases significantly at 355 nm, indicating the need for an improvement of existing dispersion formulae.

  12. Improved Atmospheric Correction for AVIRIS Spectra from Inland Waters

    NASA Technical Reports Server (NTRS)

    Gastil, Mary; Melack, John M.

    1998-01-01

    Remote sensing reflectance (Rrs) cannot be measured directly. Comparison of Rrs calculated from field measurements to Rrs calculated from AVIRIS spectra and the atmospheric radiative transfer model modtran provides a measure of the accuracy of our method. That and other comparisons are presented here as a validation of a method of retrieving Rrs from inland waters from AVIRIS radiance. The method of collecting field measurements for Rrs is described in Hamilton, 1993. Retrieval of Rrs from AVIRIS using modtran was developed from Carder, 1993. AVIRIS radiance is reduced by the path radiance modeled by modtran and divided by one-way transmission. Skylight, modeled by modtran, specularly reflected from the lake surface, is then subtracted from this radiance, leaving only that radiance which has come from under water. This water-leaving radiance is then normalized by the downwelling irradiance incident at the surface as modeled by modtran. Our improved retrieval of Rrs has allowed us to fit a single curve to a set of 134 pairs of AVIRIS Rrs and measured chlorophyll gathered on eight experiments at Mono Lake. Previously, spectra from different surveys varied more due to lingering atmospheric effects and/or radiometric calibration imprecision than they varied due to chlorophyll.

  13. Atmospheric Correction Comparison of SPOT-5 Image Based on Model Flaash and Model Quac

    NASA Astrophysics Data System (ADS)

    Guo, Y.; ZENG, F.

    2012-07-01

    tmospheric correction of satellite remote sensing image is the precondition of quantitative remote sensing study, and also among the difficulties of it. There are various methods and models for atmospheric correction. The author makes the atmospheric correction of SPOT-5 multi-spectrum remote sensing image covering Changsha, Zhuzhou and Xiangtan by adopting Model FLAASH and Model QUAC in the trail, and then makes a contrastive analysis of the image before and after the correction from the point of sight, surface features spectral curve and RVI result. The results show that both models with their specific scope of application can both basically eliminate the atmospheric effects and can restore the typical characteristics of various surface features spectral better, emphasis the vegetation information; the one using Model FLASSH has higher accuracy than the one using Model QUAC; it is more convenient to use Model QUAL than Model FLASSH, because it has little dependence on input parameters and calibration accuracy of instruments.

  14. Radiometric calibration and atmospheric correction of satellite and aircraft data for FIFE

    NASA Technical Reports Server (NTRS)

    Goetz, Scott J.; Markham, Brian L.; Newcomer, Jeffery A.

    1992-01-01

    The satellite and aircraft radiometric calibration and atmospheric correction work carried out as part of the first International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment (FIFE) are summarized. A large volume (120 Gbytes) of radiometric data were acquired and derived from a number of different instruments on a variety of platforms. The same basic procedure was applied to each instrument: derive the most recent calibration coefficients for converting sensor counts to reflective spectral radiances; correct the radiances for earth-sun distance variations and incident solar spectral irradiance within the bandpass of each respective instrument channel at the top of the atmosphere; characterize the atmosphere for aerosols and absorbing gases; and derive apparent surface reflectance by correcting the exoatmospheric values for atmospheric attenuation. The same basic approach was used for surface temperature derivation. The results of this processing were verified by surface measurements, and corroborated by sensor intercomparisons.

  15. An Algorithm to Atmospherically Correct Visible and Thermal Airborne Imagery

    NASA Technical Reports Server (NTRS)

    Rickman, Doug L.; Luvall, Jeffrey C.; Schiller, Stephen; Arnold, James E. (Technical Monitor)

    2000-01-01

    The program Watts implements a system of physically based models developed by the authors, described elsewhere, for the removal of atmospheric effects in multispectral imagery. The band range we treat covers the visible, near IR and the thermal IR. Input to the program begins with atmospheric pal red models specifying transmittance and path radiance. The system also requires the sensor's spectral response curves and knowledge of the scanner's geometric definition. Radiometric characterization of the sensor during data acquisition is also necessary. While the authors contend that active calibration is critical for serious analytical efforts, we recognize that most remote sensing systems, either airborne or space borne, do not as yet attain that minimal level of sophistication. Therefore, Watts will also use semi-active calibration where necessary and available. All of the input is then reduced to common terms, in terms of the physical units. From this it Is then practical to convert raw sensor readings into geophysically meaningful units. There are a large number of intricate details necessary to bring an algorithm or this type to fruition and to even use the program. Further, at this stage of development the authors are uncertain as to the optimal presentation or minimal analytical techniques which users of this type of software must have. Therefore, Watts permits users to break out and analyze the input in various ways. Implemented in REXX under OS/2 the program is designed with attention to the probability that it will be ported to other systems and other languages. Further, as it is in REXX, it is relatively simple for anyone that is literate in any computer language to open the code and modify to meet their needs. The authors have employed Watts in their research addressing precision agriculture and urban heat island.

  16. Atmospheric correction of LANDSAT TM thermal band using surface energy balance

    NASA Technical Reports Server (NTRS)

    Vidal, Alain; Devaux-Ros, Claire; Moran, M. Susan

    1994-01-01

    Thermal infrared data of LANDSAT Thematic Mapper (TM) are hardly used, probably due to the difficulties met when trying to correct them for atmospheric effects. A method for correcting these data was designed, based on surface energy balance estimation of known wet and dry targets included in the TM image to be corrected. This method, only using the image itself and local meteorological data was tested and validated on various surfaces: agricultural, forest and rangeland. The root mean square error on corrected temperatures is on the order of 1C.

  17. Multispectral Resource Sampler (MRS): Proof of concept study on atmospheric corrections. Determinations of atmospheric optical parameters using the multispectral resource sampler atmospheric optical

    NASA Technical Reports Server (NTRS)

    Turner, R. E.

    1979-01-01

    An investigation was performed to determine which mathematical algorithms should be used in the calculation of atmospheric optical parameters using the Multispectral Resource Sampler (MRS) sensor. A simulation of the MRS sensor was performed using a radiative-transfer model. The simulation provides the spectral radiance at the satellite sensor in terms of various atmospheric parameters, such as optical thickness, solar zenith angle, nadir view angle, relative azimuth angle, bi-directional reflectance of the target, background albedo, and wavelength. Atmospheric correction algorithms were also developed for the determination of the total spectral optical thickness of the atmosphere for: (1) homogeneous (horizontal) hazy atmospheres with diffuse targets; (2) inhomogeneous (horizontal) hazy atmospheres with diffuse targets; and (3) homogeneous (horizontal) hazy atmospheres with non-diffuse targets.

  18. Continental-scale Validation of MODIS-based and LEDAPS Landsat ETM+ Atmospheric Correction Methods

    NASA Technical Reports Server (NTRS)

    Ju, Junchang; Roy, David P.; Vermote, Eric; Masek, Jeffrey; Kovalskyy, Valeriy

    2012-01-01

    The potential of Landsat data processing to provide systematic continental scale products has been demonstrated by several projects including the NASA Web-enabled Landsat Data (WELD) project. The recent free availability of Landsat data increases the need for robust and efficient atmospheric correction algorithms applicable to large volume Landsat data sets. This paper compares the accuracy of two Landsat atmospheric correction methods: a MODIS-based method and the Landsat Ecosystem Disturbance Adaptive Processing System (LEDAPS) method. Both methods are based on the 6SV radiative transfer code but have different atmospheric characterization approaches. The MODIS-based method uses the MODIS Terra derived dynamic aerosol type, aerosol optical thickness, and water vapor to atmospherically correct ETM+ acquisitions in each coincident orbit. The LEDAPS method uses aerosol characterizations derived independently from each Landsat acquisition and assumes a fixed continental aerosol type and uses ancillary water vapor. Validation results are presented comparing ETM+ atmospherically corrected data generated using these two methods with AERONET corrected ETM+ data for 95 10 km×10 km 30 m subsets, a total of nearly 8 million 30 m pixels, located across the conterminous United States. The results indicate that the MODIS-based method has better accuracy than the LEDAPS method for the ETM+ red and longer wavelength bands.

  19. Global 3-d weather models for the atmospheric correction of gravity time series

    NASA Astrophysics Data System (ADS)

    Klügel, Thomas; Wziontek, Hartmut

    2016-04-01

    The use of 3-dimensional weather models allows for an effective reduction of atmospheric effects in gravity time series. In the past the BKG service Atmacs (Atmospheric Attraction Computation Service) provided 3-d atmospheric correction time series only for European stations of the International Geodynamics and Earth Tide Service (IGETS, formerly Global Geodynamics Project, GGP), which are based on the high resolution regional model COSMO-EU of the German Weather Service (DWD). The provision of 3-d density data from the global weather models GME (20 km resolution) and most recently ICON (13 km resolution) by the DWD now allows the computation of 3-d atmospheric correction time series for all IGETS stations worldwide. Due to the triangular grid structure, a different procedure for mass elements close to the computation point is necessary. By increasing the spatial resolution towards the computation point by linear interpolation of the grid values, the use of a point mass approach became possible with an approximation error below 0.3 nm/s2. This approach also allows to consider horizontal density gradients and a tilted model surface of the innermost cells. By means of a variance reduction at different frequency bands a significant improvement of the atmospheric correction can be demonstrated at many IGETS stations. The limited temporal resolution of recently 3 hours can be improved by the user by including local air pressure records using a remove-restore technique. Atmospheric correction time series are online available at http://atmacs.bkg.bund.de.

  20. Atmospheric correction of remotely sensed image data by a simplified model

    NASA Technical Reports Server (NTRS)

    Wrigley, R. C.; Spanner, M. A.; Slye, R. E.; Pueschel, R. F.; Aggarwal, H. R.

    1992-01-01

    The interaction of radiation with the atmosphere is complex and has proved difficult to calculate without reference to measurements made at or close to the time and location of interest. In this paper we describe the use of data from an airborne-tracking sunphotometer mounted on a NASA C-130 aircraft to derive optical properties of the atmospheric aerosols above the aircraft when it is on the ground as well as when the aircraft is at altitude collecting remote sensing data. Furthermore, we describe the use of these optical properties for quantitative atmospheric correction of Landsat Thematic Mapper (TM) and NS001 TM simulator radiances in a simplified radiative transfer model appropriate for each pixel of entire images. Both qualitative and quantitative comparisons of results from use of the model show it provides good to excellent correction for atmospheric effects in TM and NS001 TM simulator data. Quantitative comparisons with measurements of surface radiances measured near the time of the TM overpass showed agreement within a few percent for bands 2, 3, and 4. Band 1 yielded radiances within 15 percent of the surface radiances. We think the simplified atmospheric correction model shows great promise for applying atmospheric corrections to entire images instead of individual points within images to yield surface radiances within a few percent in a computationally efficient manner.

  1. Mars: Correcting surface albedo observations for effects of atmospheric dust loading

    NASA Technical Reports Server (NTRS)

    Lee, S. W.; Clancy, R. T.

    1992-01-01

    We have developed a radiative transfer model which allows the effects of atmospheric dust loading on surface albedo to be investigated. This model incorporates atmospheric dust opacity, the single scattering albedo and particle phase function of atmospheric dust, the bidirectional reflectance of the surface, and variable lighting and viewing geometry. The most recent dust particle properties are utilized. The spatial and temporal variability of atmospheric opacity (Tan) strongly influences the radiative transfer modelling results. We are currently using the approach described to determine Tan for IRTM mapping sequences of selected regions. This approach allows Tan to be determined at the highest spatial and temporal resolution supported by the IRTM data. Applying the radiative transfer modelling and determination of Tan described, IRTM visual brightness observations can be corrected for the effects of atmospheric dust loading a variety of locations and times. This approach allows maps of 'dust-corrected surface albedo' to be constructed for selected regions. Information on the variability of surface albedo and the amount of dust deposition/erosion related to such variability results. To date, this study indicates that atmospheric dust loading has a significant effect on observations of surface albedo, amounting to albedo corrections of as much as several tens of percent. This correction is not constant or linear, but depends upon surface albedo, viewing and lighting geometry, the dust and surface phase functions, and the atmospheric opacity. It is clear that the quantitative study of surface albedo, especially where small variations in observed albedo are important (such as photometric analyses), needs to account for the effects of the atmospheric dust loading. Maps of 'dust-corrected surface albedo' will be presented for a number of regions.

  2. Atmospheric correction of HJ1-A/B images and the effects on remote sensing monitoring of cyanobacteria bloom

    NASA Astrophysics Data System (ADS)

    Ma, H.; Guo, S.; Hong, X.; Zhou, Y.

    2015-05-01

    The HJ-1A/B satellite offers free images with high spatial and temporal resolution, which are effective for dynamically monitoring cyanobacteria blooms. However, the HJ-1A/B satellite also receives distorted signals due to the influence of atmosphere. To acquire accurate information about cyanobacteria blooms, atmospheric correction is needed. HJ-1A/B images were atmosphere corrected using the FLAASH atmospheric correction model. Considering the quantum effect within a certain wavelength range, a spectral response function was included in the process. Then the model was used to process HJ-1A/B images, and the NDVI after atmospheric correction was compared with that before correction. The standard deviation improved from 0.13 to 0.158. Results indicate that atmospheric correction effectively reduces the distorted signals. Finally, NDVI was utilized to monitor the cyanobacteria bloom in Donghu Lake. The accuracy was enhanced compared with that before correction.

  3. Corrective Action Decision Document/Closure Report for Corrective Action Unit 105: Area 2 Yucca Flat Atmospheric Test Sites, Nevada National Security Site, Nevada, Revision 0

    SciTech Connect

    Matthews, Patrick

    2013-09-01

    This Corrective Action Decision Document/Closure Report presents information supporting the closure of Corrective Action Unit (CAU) 105: Area 2 Yucca Flat Atmospheric Test Sites, Nevada National Security Site, Nevada. CAU 105 comprises the following five corrective action sites (CASs): -02-23-04 Atmospheric Test Site - Whitney Closure In Place -02-23-05 Atmospheric Test Site T-2A Closure In Place -02-23-06 Atmospheric Test Site T-2B Clean Closure -02-23-08 Atmospheric Test Site T-2 Closure In Place -02-23-09 Atmospheric Test Site - Turk Closure In Place The purpose of this Corrective Action Decision Document/Closure Report is to provide justification and documentation supporting the recommendation that no further corrective action is needed for CAU 105 based on the implementation of the corrective actions. Corrective action investigation (CAI) activities were performed from October 22, 2012, through May 23, 2013, as set forth in the Corrective Action Investigation Plan for Corrective Action Unit 105: Area 2 Yucca Flat Atmospheric Test Sites; and in accordance with the Soils Activity Quality Assurance Plan, which establishes requirements, technical planning, and general quality practices.

  4. Estimation of absolute water surface temperature based on atmospherically corrected thermal infrared multispectral scanner digital data

    NASA Technical Reports Server (NTRS)

    Anderson, James E.

    1986-01-01

    Airborne remote sensing systems, as well as those on board Earth orbiting satellites, sample electromagnetic energy in discrete wavelength regions and convert the total energy sampled into data suitable for processing by digital computers. In general, however, the total amount of energy reaching a sensor system located at some distance from the target is composed not only of target related energy, but, in addition, contains a contribution originating from the atmosphere itself. Thus, some method must be devised for removing or at least minimizing the effects of the atmosphere. The LOWTRAN-6 Program was designed to estimate atmospheric transmittance and radiance for a given atmospheric path at moderate spectral resolution over an operational wavelength region from 0.25 to 28.5 microns. In order to compute the Thermal Infrared Multispectral Scanner (TIMS) digital values which were recorded in the absence of the atmosphere, the parameters derived from LOWTRAN-6 are used in a correction equation. The TIMS data were collected at 1:00 a.m. local time on November 21, 1983, over a recirculating cooling pond for a power plant in southeastern Mississippi. The TIMS data were analyzed before and after atmospheric corrections were applied using a band ratioing model to compute the absolute surface temperature of various points on the power plant cooling pond. The summarized results clearly demonstrate the desirability of applying atmospheric corrections.

  5. Analysis Of AVIRIS Data From LEO-15 Using Tafkaa Atmospheric Correction

    NASA Technical Reports Server (NTRS)

    Montes, Marcos J.; Gao, Bo-Cai; Davis, Curtiss O.; Moline, Mark

    2004-01-01

    We previously developed an algorithm named Tafkaa for atmospheric correction of remote sensing ocean color data from aircraft and satellite platforms. The algorithm allows quick atmospheric correction of hyperspectral data using lookup tables generated with a modified version of Ahmad & Fraser s vector radiative transfer code. During the past few years we have extended the capabilities of the code. Current modifications include the ability to account for within scene variation in solar geometry (important for very long scenes) and view geometries (important for wide fields of view). Additionally, versions of Tafkaa have been made for a variety of multi-spectral sensors, including SeaWiFS and MODIS. In this proceeding we present some initial results of atmospheric correction of AVIRIS data from the 2001 July Hyperspectral Coastal Ocean Dynamics Experiment (HyCODE) at LEO-15.

  6. A Useful Tool for Atmospheric Correction and Surface Temperature Estimation of Landsat Infrared Thermal Data

    NASA Astrophysics Data System (ADS)

    Rivalland, Vincent; Tardy, Benjamin; Huc, Mireille; Hagolle, Olivier; Marcq, Sébastien; Boulet, Gilles

    2016-04-01

    Land Surface temperature (LST) is a critical variable for studying the energy and water budgets at the Earth surface, and is a key component of many aspects of climate research and services. The Landsat program jointly carried out by NASA and USGS has been providing thermal infrared data for 40 years, but no associated LST product has been yet routinely proposed to community. To derive LST values, radiances measured at sensor-level need to be corrected for the atmospheric absorption, the atmospheric emission and the surface emissivity effect. Until now, existing LST products have been generated with multi channel methods such as the Temperature/Emissivity Separation (TES) adapted to ASTER data or the generalized split-window algorithm adapted to MODIS multispectral data. Those approaches are ill-adapted to the Landsat mono-window data specificity. The atmospheric correction methodology usually used for Landsat data requires detailed information about the state of the atmosphere. This information may be obtained from radio-sounding or model atmospheric reanalysis and is supplied to a radiative transfer model in order to estimate atmospheric parameters for a given coordinate. In this work, we present a new automatic tool dedicated to Landsat thermal data correction which improves the common atmospheric correction methodology by introducing the spatial dimension in the process. The python tool developed during this study, named LANDARTs for LANDsat Automatic Retrieval of surface Temperature, is fully automatic and provides atmospheric corrections for a whole Landsat tile. Vertical atmospheric conditions are downloaded from the ERA Interim dataset from ECMWF meteorological organization which provides them at 0.125 degrees resolution, at a global scale and with a 6-hour-time step. The atmospheric correction parameters are estimated on the atmospheric grid using the commercial software MODTRAN, then interpolated to 30m resolution. We detail the processing steps

  7. Methods of InSAR atmosphere correction for volcano activity monitoring

    USGS Publications Warehouse

    Gong, W.; Meyer, F.; Webley, P.W.; Lu, Zhiming

    2011-01-01

    When a Synthetic Aperture Radar (SAR) signal propagates through the atmosphere on its path to and from the sensor, it is inevitably affected by atmospheric effects. In particular, the applicability and accuracy of Interferometric SAR (InSAR) techniques for volcano monitoring is limited by atmospheric path delays. Therefore, atmospheric correction of interferograms is required to improve the performance of InSAR for detecting volcanic activity, especially in order to advance its ability to detect subtle pre-eruptive changes in deformation dynamics. In this paper, we focus on InSAR tropospheric mitigation methods and their performance in volcano deformation monitoring. Our study areas include Okmok volcano and Unimak Island located in the eastern Aleutians, AK. We explore two methods to mitigate atmospheric artifacts, namely the numerical weather model simulation and the atmospheric filtering using Persistent Scatterer processing. We investigate the capability of the proposed methods, and investigate their limitations and advantages when applied to determine volcanic processes. ?? 2011 IEEE.

  8. Speed and accuracy improvements in FLAASH atmospheric correction of hyperspectral imagery

    NASA Astrophysics Data System (ADS)

    Perkins, Timothy; Adler-Golden, Steven; Matthew, Michael W.; Berk, Alexander; Bernstein, Lawrence S.; Lee, Jamine; Fox, Marsha

    2012-11-01

    Remotely sensed spectral imagery of the earth's surface can be used to fullest advantage when the influence of the atmosphere has been removed and the measurements are reduced to units of reflectance. Here, we provide a comprehensive summary of the latest version of the Fast Line-of-sight Atmospheric Analysis of Spectral Hypercubes atmospheric correction algorithm. We also report some new code improvements for speed and accuracy. These include the re-working of the original algorithm in C-language code parallelized with message passing interface and containing a new radiative transfer look-up table option, which replaces executions of the MODTRAN model. With computation times now as low as ~10 s per image per computer processor, automated, real-time, on-board atmospheric correction of hyper- and multi-spectral imagery is within reach.

  9. Retrieval of atmospheric methane from high spectral resolution satellite measurements: a correction for cirrus cloud effects.

    PubMed

    Bril, Andrey; Oshchepkov, Sergey; Yokota, Tatsuya

    2009-04-10

    We assessed the accuracy of methane (CH(4)) retrievals from synthetic radiance spectra particular to Greenhouse Gases Observing Satellite observations. We focused on estimating the CH(4) vertical column amount from an atmosphere that includes thin cirrus clouds, taking into account uncertain meteorological conditions. A photon path-length probability density function (PPDF)-based method was adapted to correct for atmospheric scattering effects in CH(4) retrievals. This method was shown to provide similar retrieval accuracy as compared to a carbon dioxide (CO(2))-proxy-based correction approach. It infers some advantages of PPDF-based method for methane retrievals under high variability of CO(2) abundance. PMID:19363553

  10. Influence of atmospheric correction on image classification for irrigated agriculture in the Lower Colorado River Basin

    NASA Astrophysics Data System (ADS)

    Wei, X.

    2012-12-01

    Atmospheric correction is essential for accurate quantitative information retrieval from satellite imagery. In this paper, we applied the atmospheric correction algorithm, Second Simulation of a Satellite Signal in the Solar Spectrum (6S) radiative transfer code, to retrieve surface reflectance from Landsat 5 Thematic Mapper (TM) imagery for the Palo Verde Irrigation District (PVID) within the lower Colorado River basin. The 6S code was implemented with the input data of visibility, aerosol optical depth, pressure, temperature, water vapour, and ozone from local measurements. The 6S corrected image of PVID was classified into the irrigated agriculture of alfalfa, cotton, melons, corn, grass, and vegetables. We performed multiple classification methods of maximum likelihood, fuzzy means, and object-oriented classification methods. Using field crop type data, we conducted accuracy assessment for the results from 6S corrected image and uncorrected image and found a consistent improvement of classification accuracy for 6S corrected image. The study proves that 6S code is a robust atmospheric correction method in providing a better simulation of surface reflectance and improving image classification accuracy.;

  11. Development of regional wheat VI-LAI models using Resourcesat-1 AWiFS data

    NASA Astrophysics Data System (ADS)

    Chaurasia, Sasmita; Nigam, R.; Bhattacharya, B. K.; Sridhar, V. N.; Mallick, K.; Vyas, S. P.; Patel, N. K.; Mukherjee, J.; Shekhar, Chander; Kumar, Dhiraj; Singh, K. R. P.; Bairagi, G. D.; Purohit, N. L.; Parihar, J. S.

    2011-12-01

    The time of forcing of spatial LAI to crop models at single or multiple stages is important to simulate crop biomass and yield in varying agro-climatic conditions and scales. The high temporal resolution (5-day) by Advanced Wide Field Sensor (AWiFS) on-board Resourcesat-1 Satellite IRS-P6 with 56 m spatial resolution and large swath (740 km) has substantially increased the availability of regional clear sky optical remote sensing data. The present study aimed at developing empirical vegetation index VI-LAI models for wheat using AWiFS optical data in four bands and in-situ measurements sampled over five different agro-climatic regions (ACRs) during 2005-2006 followed by validation during 2006-2007. While nonlinear relations exist for all the three normalized indices such as normalized difference vegetation index (NDVI), normalized difference water index (NDWI) and Green NDVI, linear relation was the best fit for ratio vegetation index (RVI). Both NDVI and RVI models generally showed better correlation ranges (0.65-0.84 for NDVI and 0.37-0.76 for RVI) than other indices. The common NDVI-LAI model was found to produce lower root mean square errors (RMSE) between 0.5 and 1.1 from pooled model than those between 0.5 and 1.32 from regional models. The rate of substantial increase in errors from NDVI-LAI model (RMSE of modeled LAI: 0.85 to 1.28) as compared to RVI-LAI model (RMSE of modeled LAI: 1.12 to 1.17) at LAI greater than 3, than below 3 revealed the early saturation of NDVI than RVI. It is therefore recommended that LAI estimates can be used to force crop simulation model upto early vegetative stage based on NDVI and maximum vegetative to reproductive stages based on RVI.

  12. Solving for the Surface: An Automated Approach to THEMIS Atmospheric Correction

    NASA Astrophysics Data System (ADS)

    Ryan, A. J.; Salvatore, M. R.; Smith, R.; Edwards, C. S.; Christensen, P. R.

    2013-12-01

    Here we present the initial results of an automated atmospheric correction algorithm for the Thermal Emission Imaging System (THEMIS) instrument, whereby high spectral resolution Thermal Emission Spectrometer (TES) data are queried to generate numerous atmospheric opacity values for each THEMIS infrared image. While the pioneering methods of Bandfield et al. [2004] also used TES spectra to atmospherically correct THEMIS data, the algorithm presented here is a significant improvement because of the reduced dependency on user-defined inputs for individual images. Additionally, this technique is particularly useful for correcting THEMIS images that have captured a range of atmospheric conditions and/or surface elevations, issues that have been difficult to correct for using previous techniques. Thermal infrared observations of the Martian surface can be used to determine the spatial distribution and relative abundance of many common rock-forming minerals. This information is essential to understanding the planet's geologic and climatic history. However, the Martian atmosphere also has absorptions in the thermal infrared which complicate the interpretation of infrared measurements obtained from orbit. TES has sufficient spectral resolution (143 bands at 10 cm-1 sampling) to linearly unmix and remove atmospheric spectral end-members from the acquired spectra. THEMIS has the benefit of higher spatial resolution (~100 m/pixel vs. 3x5 km/TES-pixel) but has lower spectral resolution (8 surface sensitive spectral bands). As such, it is not possible to isolate the surface component by unmixing the atmospheric contribution from the THEMIS spectra, as is done with TES. Bandfield et al. [2004] developed a technique using atmospherically corrected TES spectra as tie-points for constant radiance offset correction and surface emissivity retrieval. This technique is the primary method used to correct THEMIS but is highly susceptible to inconsistent results if great care in the

  13. A comparison of atmospheric disturbance correction techniques in GBInSAR

    NASA Astrophysics Data System (ADS)

    Wang, Xueqin; Yue, Jianping; Qiu, Shanming; Qiu, Zhiwei; Yue, Shun

    2015-11-01

    Ground-Based Synthetic Aperture Radar interferometry (GBInSAR) has generated movement with sub-millimeter accuracy in line-of-sight(LOS) direction, and it can provide movement images with high spatial and temporal resolution. Though the fluctuation of atmospheric environment affects interferometric phases strongly, GBInSAR can be used for deformation measurement after removing the interference phase and transforming the displacement from LOS direction to radial and tangential. This paper provides a comparison of different atmospheric disturbance correction techniques. We made an experiment of deformation measurement about Geheyan Dam on Qingjiang to estimate the movement caused by atmosphere. In the experiment, displacement information of the dam was obtained by IBIS-L system and atmospheric parameters (humidity, temperature and barometric pressure) were collected from the weather station located on the dam. The collection process lasted for several days. By processing and analysis the data of a whole day without equipment malfunction, the results show an atmospheric delay of 15mm when the system located 1000m away from the target dam and atmospheric correction should be reinforced somehow for most Ground-Based InSAR applications. Then three correction algorithms are presented in order to weaken the influence from atmospheric disturbance. The techniques respectively based on the atmospheric parameters, Ground Control Points(GCP) and distribution model are quantitively compared using a reference dataset gotten by inverted perpendicular lines. And the accuracy of each method are finally drawn. It could be seen that the atmospheric disturbance be weaken by the three methods with reliable results and error of the technique based on distribution model was less than 2mm with the highest reliability. This analysis is followed by a discussion of the advantages and the limitations of each technique.

  14. An evaluation of atmospheric corrections to advanced very high resolution radiometer data

    USGS Publications Warehouse

    Meyer, David; Hood, Joy J.

    1993-01-01

    A data set compiled to analyze vegetation indices is used to evaluate the effect of atmospheric correction to AVHRR measurement in the solar spectrum. Such corrections include cloud screening and "clear sky" corrections. We used the "clouds from AVHRR" (CLAVR) method for cloud detection and evaluated its performance over vegetated targets. Clear sky corrections, designed to reduce the effects of molecular scattering and absorption due to ozone, water vapor, carbon dioxide, and molecular oxygen, were applied to data values determine to be cloud free. Generally, it was found that the screening and correction of the AVHRR data did not affect the maximum NDVI compositing process adversely, while at the same time improving estimates of the land-surface radiances over a compositing period.

  15. [Errors Analysis and Correction in Atmospheric Methane Retrieval Based on Greenhouse Gases Observing Satellite Data].

    PubMed

    Bu, Ting-ting; Wang, Xian-hua; Ye, Han-han; Jiang, Xin-hua

    2016-01-01

    High precision retrieval of atmospheric CH4 is influenced by a variety of factors. The uncertainties of ground properties and atmospheric conditions are important factors, such as surface reflectance, temperature profile, humidity profile and pressure profile. Surface reflectance is affected by many factors so that it is difficult to get the precise value. The uncertainty of surface reflectance will cause large error to retrieval result. The uncertainties of temperature profile, humidity profile and pressure profile are also important sources of retrieval error and they will cause unavoidable systematic error. This error is hard to eliminate only using CH4 band. In this paper, ratio spectrometry method and CO2 band correction method are proposed to reduce the error caused by these factors. Ratio spectrometry method can decrease the effect of surface reflectance in CH4 retrieval by converting absolute radiance spectrometry into ratio spectrometry. CO2 band correction method converts column amounts of CH4 into column averaged mixing ratio by using CO2 1.61 μm band and it can correct the systematic error caused by temperature profile, humidity profile and pressure profile. The combination of these two correction methods will decrease the effect caused by surface reflectance, temperature profile, humidity profile and pressure profile at the same time and reduce the retrieval error. GOSAT data were used to retrieve atmospheric CH4 to test and validate the two correction methods. The results showed that CH4 column averaged mixing ratio retrieved after correction was close to GOSAT Level2 product and the retrieval precision was up to -0.24%. The studies suggest that the error of CH4 retrieval caused by the uncertainties of ground properties and atmospheric conditions can be significantly reduced and the retrieval precision can be highly improved by using ratio spectrometry method and CO2 hand correction method. PMID:27228765

  16. Optimal Atmospheric Correction for Above-Ground Forest Biomass Estimation with the ETM+ Remote Sensor

    PubMed Central

    Nguyen, Hieu Cong; Jung, Jaehoon; Lee, Jungbin; Choi, Sung-Uk; Hong, Suk-Young; Heo, Joon

    2015-01-01

    The reflectance of the Earth’s surface is significantly influenced by atmospheric conditions such as water vapor content and aerosols. Particularly, the absorption and scattering effects become stronger when the target features are non-bright objects, such as in aqueous or vegetated areas. For any remote-sensing approach, atmospheric correction is thus required to minimize those effects and to convert digital number (DN) values to surface reflectance. The main aim of this study was to test the three most popular atmospheric correction models, namely (1) Dark Object Subtraction (DOS); (2) Fast Line-of-sight Atmospheric Analysis of Spectral Hypercubes (FLAASH) and (3) the Second Simulation of Satellite Signal in the Solar Spectrum (6S) and compare them with Top of Atmospheric (TOA) reflectance. By using the k-Nearest Neighbor (kNN) algorithm, a series of experiments were conducted for above-ground forest biomass (AGB) estimations of the Gongju and Sejong region of South Korea, in order to check the effectiveness of atmospheric correction methods for Landsat ETM+. Overall, in the forest biomass estimation, the 6S model showed the bestRMSE’s, followed by FLAASH, DOS and TOA. In addition, a significant improvement of RMSE by 6S was found with images when the study site had higher total water vapor and temperature levels. Moreover, we also tested the sensitivity of the atmospheric correction methods to each of the Landsat ETM+ bands. The results confirmed that 6S dominates the other methods, especially in the infrared wavelengths covering the pivotal bands for forest applications. Finally, we suggest that the 6S model, integrating water vapor and aerosol optical depth derived from MODIS products, is better suited for AGB estimation based on optical remote-sensing data, especially when using satellite images acquired in the summer during full canopy development. PMID:26263996

  17. Optimal Atmospheric Correction for Above-Ground Forest Biomass Estimation with the ETM+ Remote Sensor.

    PubMed

    Nguyen, Hieu Cong; Jung, Jaehoon; Lee, Jungbin; Choi, Sung-Uk; Hong, Suk-Young; Heo, Joon

    2015-01-01

    The reflectance of the Earth's surface is significantly influenced by atmospheric conditions such as water vapor content and aerosols. Particularly, the absorption and scattering effects become stronger when the target features are non-bright objects, such as in aqueous or vegetated areas. For any remote-sensing approach, atmospheric correction is thus required to minimize those effects and to convert digital number (DN) values to surface reflectance. The main aim of this study was to test the three most popular atmospheric correction models, namely (1) Dark Object Subtraction (DOS); (2) Fast Line-of-sight Atmospheric Analysis of Spectral Hypercubes (FLAASH) and (3) the Second Simulation of Satellite Signal in the Solar Spectrum (6S) and compare them with Top of Atmospheric (TOA) reflectance. By using the k-Nearest Neighbor (kNN) algorithm, a series of experiments were conducted for above-ground forest biomass (AGB) estimations of the Gongju and Sejong region of South Korea, in order to check the effectiveness of atmospheric correction methods for Landsat ETM+. Overall, in the forest biomass estimation, the 6S model showed the bestRMSE's, followed by FLAASH, DOS and TOA. In addition, a significant improvement of RMSE by 6S was found with images when the study site had higher total water vapor and temperature levels. Moreover, we also tested the sensitivity of the atmospheric correction methods to each of the Landsat ETM+ bands. The results confirmed that 6S dominates the other methods, especially in the infrared wavelengths covering the pivotal bands for forest applications. Finally, we suggest that the 6S model, integrating water vapor and aerosol optical depth derived from MODIS products, is better suited for AGB estimation based on optical remote-sensing data, especially when using satellite images acquired in the summer during full canopy development. PMID:26263996

  18. Atmospheric correction of AVIRIS data of Monterey Bay contaminated by thin cirrus clouds

    NASA Technical Reports Server (NTRS)

    Vandenbosch, Jeannette; Davis, Curtiss O.; Mobley, Curtis D.; Rhea, W. Joseph

    1993-01-01

    Point source measurements (e.g. sun photometer data, weather station observations) are often used to constrain radiative transfer models such as MODTRAN/LOWTRAN7 when atmospherically correcting AVIRIS imagery. The basic assumption is that the atmosphere is horizontally homogeneous throughout the entire area. If the target area of interest is isolated a distance away from the point measurement position, the calculated visibility and atmospheric profiles may not be characteristic of the atmosphere over the target. AVIRIS scenes are often rejected when cloud cover exceeds 10%. However, if the cloud cover is determined to be primarily cirrus rather than cumulus, in-water optical properties may still be extracted over open ocean. High altitude cirrus clouds are non-absorbing at 744 nm. If the optical properties of the AVIRIS scene can be determined from the 744 nm band itself, the atmospheric conditions during the overflight may be deduced.

  19. Applying Tafkaa For Atmospheric Correction of Aviris Over Coral Ecosystems In The Hawaiian Islands

    NASA Technical Reports Server (NTRS)

    Goodman, James A.; Montes, Marcos J.; Ustin, Susan L.

    2004-01-01

    Growing concern over the health of coastal ecosystems, particularly coral reefs, has produced increased interest in remote sensing as a tool for the management and monitoring of these valuable natural resources. Hyperspectral capabilities show promising results in this regard, but as yet remain somewhat hindered by the technical and physical issues concerning the intervening water layer. One such issue is the ability to atmospherically correct images over shallow aquatic areas, where complications arise due to varying effects from specular reflection, wind blown surface waves, and reflectance from the benthic substrate. Tafkaa, an atmospheric correction algorithm under development at the U.S. Naval Research Laboratory, addresses these variables and provides a viable approach to the atmospheric correction issue. Using imagery from the Advanced Visible InfraRed Imaging Spectrometer (AVIRIS) over two shallow coral ecosystems in the Hawai ian Islands, French Frigate Shoals and Kane ohe Bay, we first demonstrate how land-based atmospheric corrections can be limited in such an environment. We then discuss the input requirements and underlying algorithm concepts of Tafkaa and conclude with examples illustrating the improved performance of Tafkaa using the same AVIRIS images.

  20. Verification of the ASTER/TIR atmospheric correction algorithm based on water surface emissivity retrieved

    NASA Astrophysics Data System (ADS)

    Tonooka, Hideyuki; Palluconi, Frank D.

    2002-02-01

    The standard atmospheric correction algorithm for five thermal infrared (TIR) bands of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is currently based on radiative transfer computations with global assimilation data on a pixel-by-pixel basis. In the present paper, we verify this algorithm using 100 ASTER scenes globally acquired during the early mission period. In this verification, the max-min difference (MMD) of the water surface emissivity retrieved from each scene is used as an atmospheric correction error index, since the water surface emissivity is well known; if the MMD retrieved is large, an atmospheric correction error also will be possibly large. As the results, the error of the MMD retrieved by the standard atmospheric correction algorithm and a typical temperature/emissivity separation algorithm is shown to be remarkably related with precipitable water vapor, latitude, elevation, and surface temperature. It is also mentioned that the expected error on the MMD retrieved is 0.05 for the precipitable water vapor of 3 cm.

  1. Laboratory spectra of field samples as a check on two atmospheric correction methods

    NASA Technical Reports Server (NTRS)

    Xu, Pung; Greeley, Ronald

    1993-01-01

    Atmospheric correction is the first step toward quantitative analysis of imaging spectroscopy data. Two methods, MODTRAN model and the empirical line, were used to convert AVIRIS radiance values to reflectance values. A set of laboratory spectra of field samples corresponding to AVIRIS coverage was used to assess these methods. This will also serve to select bands for future quantative analyses.

  2. Shadow-insensitive material detection/classification with atmospherically corrected hyperspectral imagery

    NASA Astrophysics Data System (ADS)

    Adler-Golden, Steven M.; Levine, Robert Y.; Matthew, Michael W.; Richtsmeier, Steven C.; Bernstein, Lawrence S.; Gruninger, John H.; Felde, Gerald W.; Hoke, Michael L.; Anderson, Gail P.; Ratkowski-, Anthony

    2001-08-01

    Shadow-insensitive detection or classification of surface materials in atmospherically corrected hyperspectral imagery can be achieved by expressing the reflectance spectrum as a linear combination of spectra that correspond to illumination by the direct sum and by the sky. Some specific algorithms and applications are illustrated using HYperspectral Digital Imagery Collection Experiment (HYDICE) data.

  3. Continental-Scale Validation of Modis-Based and LEDAPS Landsat ETM + Atmospheric Correction Methods

    NASA Technical Reports Server (NTRS)

    Ju, Junchang; Roy, David P.; Vermote, Eric; Masek, Jeffrey; Kovalskyy, Valeriy

    2012-01-01

    The potential of Landsat data processing to provide systematic continental scale products has been demonstratedby several projects including the NASA Web-enabled Landsat Data (WELD) project. The recent freeavailability of Landsat data increases the need for robust and efficient atmospheric correction algorithms applicableto large volume Landsat data sets. This paper compares the accuracy of two Landsat atmospheric correctionmethods: a MODIS-based method and the Landsat Ecosystem Disturbance Adaptive ProcessingSystem (LEDAPS) method. Both methods are based on the 6SV radiative transfer code but have different atmosphericcharacterization approaches. The MODIS-based method uses the MODIS Terra derived dynamicaerosol type, aerosol optical thickness, and water vapor to atmospherically correct ETM+ acquisitions ineach coincident orbit. The LEDAPS method uses aerosol characterizations derived independently from eachLandsat acquisition and assumes a fixed continental aerosol type and uses ancillary water vapor. Validationresults are presented comparing ETM+ atmospherically corrected data generated using these two methodswith AERONET corrected ETM+ data for 95 10 km10 km 30 m subsets, a total of nearly 8 million 30 mpixels, located across the conterminous United States. The results indicate that the MODIS-based methodhas better accuracy than the LEDAPS method for the ETM+ red and longer wavelength bands.

  4. Atmospheric extinction in solar tower plants: the Absorption and Broadband Correction for MOR measurements

    NASA Astrophysics Data System (ADS)

    Hanrieder, N.; Wilbert, S.; Pitz-Paal, R.; Emde, C.; Gasteiger, J.; Mayer, B.; Polo, J.

    2015-05-01

    Losses of reflected Direct Normal Irradiance due to atmospheric extinction in concentrating solar tower plants can vary significantly with site and time. The losses of the direct normal irradiance between the heliostat field and receiver in a solar tower plant are mainly caused by atmospheric scattering and absorption by aerosol and water vapor concentration in the atmospheric boundary layer. Due to a high aerosol particle number, radiation losses can be significantly larger in desert environments compared to the standard atmospheric conditions which are usually considered in raytracing or plant optimization tools. Information about on-site atmospheric extinction is only rarely available. To measure these radiation losses, two different commercially available instruments were tested and more than 19 months of measurements were collected at the Plataforma Solar de Almería and compared. Both instruments are primarily used to determine the meteorological optical range (MOR). The Vaisala FS11 scatterometer is based on a monochromatic near-infrared light source emission and measures the strength of scattering processes in a small air volume mainly caused by aerosol particles. The Optec LPV4 long-path visibility transmissometer determines the monochromatic attenuation between a light-emitting diode (LED) light source at 532 nm and a receiver and therefore also accounts for absorption processes. As the broadband solar attenuation is of interest for solar resource assessment for Concentrating Solar Power (CSP), a correction procedure for these two instruments is developed and tested. This procedure includes a spectral correction of both instruments from monochromatic to broadband attenuation. That means the attenuation is corrected for the actual, time-dependent by the collector reflected solar spectrum. Further, an absorption correction for the Vaisala FS11 scatterometer is implemented. To optimize the Absorption and Broadband Correction (ABC) procedure, additional

  5. Correcting atmospheric effects in thermal ground observations for hyperspectral emissivity estimation

    NASA Astrophysics Data System (ADS)

    Timmermans, Joris; Buitrago, Maria

    2014-05-01

    Knowledge of Land surface temperature is of crucial importance in energy balance studies and environmental modeling. Accurate retrieval of land surface temperature (LST) demands detailed knowledge of the land surface emissivity. Measured radiation by remote sensing sensors to land surface temperature can only be performed using a-priori knowledge of the emissivity. Uncertainties in the retrieval of this emissivity can cause huge errors in LST estimations. The retrieval of emissivity (and LST) is per definition an underdetermined inversion, as only one observation is made while two variables are to be estimated. Several researches have therefore been performed on measuring emissivity, such as the normalized emissivity method, the temperature-emissivity separation (TES) using the minimum and maximum difference of emissivity and the use of vegetation indices. In each of these approaches atmospherically corrected radiance measurements by remote sensing sensors are correlated to ground measurements. Usually these ground measurements are performed with the ground equivalent of the remote sensing sensors; the CIMEL 312-2 has the same spectral bands as ASTER. This way parameterizations acquired this way are only usable for specific sensors and need to be redone for newer sensors. Recently hyperspectral thermal radiometers, such as the MIDAC, have been developed that can solve this problem. By using hyperspectral observations of emissivity, together with sensor simulators, ground measurements of different satellite sensor can be simulated. This facilitates the production of validation data for the different TES algorithms. However before such measurements can be performed extra steps of processing need to be performed. Atmospheric correction becomes more important in hyperspectral observations than for broadband observations, as energy levels measured per band is lower. As such the atmosphere has a relative larger contribution if bandwidths become smaller. The goal of this

  6. Corrective Action Decision Document/Closure Report for Corrective Action Unit 105: Area 2 Yucca Flat Atmospheric Test Sites, Nevada National Security Site, Nevada, Revision 1

    SciTech Connect

    Matthews, Patrick

    2014-01-01

    The purpose of this Corrective Action Decision Document/Closure Report is to provide justification and documentation supporting the recommendation that no further corrective action is needed for CAU 105 based on the implementation of the corrective actions. Corrective action investigation (CAI) activities were performed from October 22, 2012, through May 23, 2013, as set forth in the Corrective Action Investigation Plan for Corrective Action Unit 105: Area 2 Yucca Flat Atmospheric Test Sites; and in accordance with the Soils Activity Quality Assurance Plan, which establishes requirements, technical planning, and general quality practices.

  7. Scintillation correction for astronomical photometry on large and extremely large telescopes with tomographic atmospheric reconstruction

    NASA Astrophysics Data System (ADS)

    Osborn, J.

    2015-01-01

    We describe a new concept to correct for scintillation noise on high-precision photometry in large and extremely large telescopes using telemetry data from adaptive optics (AO) systems. Most wide-field AO systems designed for the current era of very large telescopes and the next generation of extremely large telescopes require several guide stars to probe the turbulent atmosphere in the volume above the telescope. These data can be used to tomographically reconstruct the atmospheric turbulence profile and phase aberrations of the wavefront in order to assist wide-field AO correction. If the wavefront aberrations and altitude of the atmospheric turbulent layers are known from this tomographic model, then the effect of the scintillation can be calculated numerically and used to normalize the photometric light curve. We show through detailed Monte Carlo simulation that for an 8 m telescope with a 16 × 16 AO system we can reduce the scintillation noise by an order of magnitude.

  8. Evaluation of Shortwave Infrared Atmospheric Correction for Ocean Color Remote Sensing of Chesapeake Bay

    NASA Technical Reports Server (NTRS)

    Werdell, P. Jeremy; Franz, Bryan A.; Bailey, Sean W.

    2010-01-01

    The NASA Moderate Resolution Imaging Spectroradiometer onboard the Aqua platform (MODIS-Aqua) provides a viable data stream for operational water quality monitoring of Chesapeake Bay. Marine geophysical products from MODIS-Aqua depend on the efficacy of the atmospheric correction process, which can be problematic in coastal environments. The operational atmospheric correction algorithm for MODIS-Aqua requires an assumption of negligible near-infrared water-leaving radiance, nL(sub w)(NIR). This assumption progressively degrades with increasing turbidity and, as such, methods exist to account for non-negligible nL(sub w)(NIR) within the atmospheric correction process or to use alternate radiometric bands where the assumption is satisfied, such as those positioned within shortwave infrared (SWIR) region of the spectrum. We evaluated a decade-long time-series of nL(sub w)(lambda) from MODIS-Aqua in Chesapeake Bay derived using NIR and SWIR bands for atmospheric correction. Low signal-to-noise ratios (SNR) for the SWIR bands of MODIS-Aqua added noise errors to the derived radiances, which produced broad, flat frequency distributions of nL(sub w)(lambda) relative to those produced using the NIR bands. The SWIR approach produced an increased number of negative nL(sub w)(lambda) and decreased sample size relative to the NIR approach. Revised vicarious calibration and regional tuning of the scheme to switch between the NIR and SWIR approaches may improve retrievals in Chesapeake Bay, however, poor SNR values for the MODIS-Aqua SWIR bands remain the primary deficiency of the SWIR-based atmospheric correction approach.

  9. A New Method for Atmospheric Correction of MRO/CRISM Data.

    NASA Astrophysics Data System (ADS)

    Noe Dobrea, Eldar Z.; Dressing, C.; Wolff, M. J.

    2009-09-01

    The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) aboard the Mars Reconnaissance Orbiter (MRO) collects hyperspectral images from 0.362 to 3.92 μm at 6.55 nanometers/channel, and at a spatial resolution of 20 m/pixel. The 1-2.6 μm spectral range is often used to identify and map the distribution of hydrous minerals using mineralogically diagnostic bands at 1.4 μm, 1.9 μm, and 2 - 2.5 micron region. Atmospheric correction of the 2-μm CO2 band typically employs the same methodology applied to OMEGA data (Mustard et al., Nature 454, 2008): an atmospheric opacity spectrum, obtained from the ratio of spectra from the base to spectra from the peak of Olympus Mons, is rescaled for each spectrum in the observation to fit the 2-μm CO2 band, and is subsequently used to correct the data. Three important aspects are not considered in this correction: 1) absorptions due to water vapor are improperly accounted for, 2) the band-center of each channel shifts slightly with time, and 3) multiple scattering due to atmospheric aerosols is not considered. The second issue results in miss-registration of the sharp CO2 features in the 2-μm triplet, and hence poor atmospheric correction. This leads to the necessity to ratio all spectra using the spectrum of a spectrally "bland” region in each observation in order to distinguish features 1.9 μm. Here, we present an improved atmospheric correction method, which uses emission phase function (EPF) observations to correct for molecular opacity, and a discrete ordinate radiative transfer algorithm (DISORT - Stamnes et al., Appl. Opt. 27, 1988) to correct for the effects of multiple scattering. This method results in a significant improvement in the correction of the 2-μm CO2 band, allowing us to forgo the use of spectral ratios that affect the spectral shape and preclude the derivation of reflectance values in the data.

  10. Relative Radiometric Normalization and Atmospheric Correction of a SPOT 5 Time Series

    PubMed Central

    Hajj, Mahmoud El; Bégué, Agnès; Lafrance, Bruno; Hagolle, Olivier; Dedieu, Gérard; Rumeau, Matthieu

    2008-01-01

    Multi-temporal images acquired at high spatial and temporal resolution are an important tool for detecting change and analyzing trends, especially in agricultural applications. However, to insure a reliable use of this kind of data, a rigorous radiometric normalization step is required. Normalization can be addressed by performing an atmospheric correction of each image in the time series. The main problem is the difficulty of obtaining an atmospheric characterization at a given acquisition date. In this paper, we investigate whether relative radiometric normalization can substitute for atmospheric correction. We develop an automatic method for relative radiometric normalization based on calculating linear regressions between unnormalized and reference images. Regressions are obtained using the reflectances of automatically selected invariant targets. We compare this method with an atmospheric correction method that uses the 6S model. The performances of both methods are compared using 18 images from of a SPOT 5 time series acquired over Reunion Island. Results obtained for a set of manually selected invariant targets show excellent agreement between the two methods in all spectral bands: values of the coefficient of determination (r2 exceed 0.960, and bias magnitude values are less than 2.65. There is also a strong correlation between normalized NDVI values of sugarcane fields (r2 = 0.959). Despite a relative error of 12.66% between values, very comparable NDVI patterns are observed.

  11. Large-Actuator-Number Horizontal Path Correction of Atmospheric Turbulence utilizing an Interferometric Phase Conjugate Engine

    SciTech Connect

    Baker, K L; Stappaerts, E A; Gavel, D; Tucker, J; Silva, D A; Wilks, S C; Olivier, S S; Olsen, J

    2004-08-25

    An adaptive optical system used to correct horizontal beam propagation paths has been demonstrated. This system utilizes an interferometric wave-front sensor and a large-actuator-number MEMS-based spatial light modulator to correct the aberrations incurred by the beam after propagation along the path. Horizontal path correction presents a severe challenge to adaptive optics systems due to the short atmospheric transverse coherence length and the high degree of scintillation incurred by laser propagation along these paths. Unlike wave-front sensors that detect phase gradients, however, the interferometric wave-front sensor measures the wrapped phase directly. Because the system operates with nearly monochromatic light and uses a segmented spatial light modulator, it does not require that the phase be unwrapped to provide a correction and it also does not require a global reconstruction of the wave-front to determine the phase as required by gradient detecting wave-front sensors. As a result, issues with branch points are eliminated. Because the atmospheric probe beam is mixed with a large amplitude reference beam, it can be made to operate in a photon noise limited regime making its performance relatively unaffected by scintillation. The MEMS-based spatial light modulator in the system contains 1024 pixels and is controlled to speeds in excess of 800 Hz, enabling its use for correction of horizontal path beam propagation. In this article results are shown of both atmospheric characterization with the system and open loop horizontal path correction of a 1.53 micron laser by the system. To date Strehl ratios of greater than 0.5 have been achieved.

  12. Evaluation of the atmospheric correction procedure for the APEX level 2/3 processor

    NASA Astrophysics Data System (ADS)

    Schläpfer, Daniel; Biesemans, Jan; Hueni, Andreas; Meuleman, Koen

    2008-10-01

    The Airborne Prism Experiment (APEX) is a hyperspectral instrument built in a Swiss - Belgian collaboration within the ESA-PRODEX program. It aims at highest possible accuracy of its delivered surface reflectance image data products. The atmospheric correction of hyperspectral imagery is a critical element of a complete processing chain towards unbiased reflectance and for the creation of higher level products. As the first data of APEX is expected to become available in 2009, an appropriate processing chain for higher level processing needs to be defined and evaluated. Standard products have been identified in all application fields of hyperspectral imaging, i.e., geology, vegetation, cryosphere, limnology and atmosphere. They are being implemented at the APEX science center. The according processing procedures rely on data of well-defined processing states which range from calibrated at-sensor radiance to (bihemispherical) spectral albedo. In this paper, the atmospheric processing which is implemented as part of the automated data processing chain for level 2 in the APEX processing and archiving facility (PAF) at VITO (Mol, Belgium) is evaluated together with the ATCOR-4 atmospheric correction program. The evaluation is done regarding flexibility, reflectance output accuracy and processing efficiency. Two test data sets are taken for this purpose: a well-documented set of HYMAP data and a high resolution HYSPEX data set. Both data sets exhibit areas of overlap, which are taken for self-contained analysis of the atmospheric correction procedure. The accuracy tests include plausibility checks on selected regions of interest including a variety of known surfaces in the imagery. As some of the observed effects are related to BRDF differences, the results also give an indication for the inaccuracy related to these reflectance anisotropies. Speed measurements of the processing are then compared to the demand for operational processing of series of data acquisition

  13. Atmospheric extinction in solar tower plants: absorption and broadband correction for MOR measurements

    NASA Astrophysics Data System (ADS)

    Hanrieder, N.; Wilbert, S.; Pitz-Paal, R.; Emde, C.; Gasteiger, J.; Mayer, B.; Polo, J.

    2015-08-01

    Losses of reflected Direct Normal Irradiance due to atmospheric extinction in concentrated solar tower plants can vary significantly with site and time. The losses of the direct normal irradiance between the heliostat field and receiver in a solar tower plant are mainly caused by atmospheric scattering and absorption by aerosol and water vapor concentration in the atmospheric boundary layer. Due to a high aerosol particle number, radiation losses can be significantly larger in desert environments compared to the standard atmospheric conditions which are usually considered in ray-tracing or plant optimization tools. Information about on-site atmospheric extinction is only rarely available. To measure these radiation losses, two different commercially available instruments were tested, and more than 19 months of measurements were collected and compared at the Plataforma Solar de Almería. Both instruments are primarily used to determine the meteorological optical range (MOR). The Vaisala FS11 scatterometer is based on a monochromatic near-infrared light source emission and measures the strength of scattering processes in a small air volume mainly caused by aerosol particles. The Optec LPV4 long-path visibility transmissometer determines the monochromatic attenuation between a light-emitting diode (LED) light source at 532 nm and a receiver and therefore also accounts for absorption processes. As the broadband solar attenuation is of interest for solar resource assessment for concentrated solar power (CSP), a correction procedure for these two instruments is developed and tested. This procedure includes a spectral correction of both instruments from monochromatic to broadband attenuation. That means the attenuation is corrected for the time-dependent solar spectrum which is reflected by the collector. Further, an absorption correction for the Vaisala FS11 scatterometer is implemented. To optimize the absorption and broadband correction (ABC) procedure, additional

  14. Topography correlated atmospheric delay correction in radar interferometry using wavelet transforms

    NASA Astrophysics Data System (ADS)

    Shirzaei, M.; Bürgmann, R.

    2012-01-01

    Atmospheric delay is one of the major sources of error in repeat pass interferometry. We propose a new approach for correcting the topography-correlated components of this artifact. To this aim we use multiresolution wavelet analysis to identify the components of the unwrapped interferogram that correlate with topography. By using a forward wavelet transform we break down the digital elevation model and the unwrapped interferogram into their building blocks based on their frequency properties. We apply a cross-correlation analysis to identify correlated coefficients that represent the effect of the atmospheric delay. Thus, the correction to the unwrapped interferogram is obtained by down-weighting the correlated coefficients during inverse wavelet transform. We test this approach on real and synthetic data sets that are generated over the San Francisco Bay Area. We find that even in the presence of tectonic signals, this method is able to reduce the correlated component of the atmospheric delay by up to 75% and improves the signal in areas of high relief. The remaining part is most likely due to 3D heterogeneities of the atmosphere and can be reduced by integrating temporal information or using complementary observations or models of atmospheric delay.

  15. The effect of finite field size on classification and atmospheric correction

    NASA Technical Reports Server (NTRS)

    Kaufman, Y. J.; Fraser, R. S.

    1981-01-01

    The atmospheric effect on the upward radiance of sunlight scattered from the Earth-atmosphere system is strongly influenced by the contrasts between fields and their sizes. For a given atmospheric turbidity, the atmospheric effect on classification of surface features is much stronger for nonuniform surfaces than for uniform surfaces. Therefore, the classification accuracy of agricultural fields and urban areas is dependent not only on the optical characteristics of the atmosphere, but also on the size of the surface do not account for the nonuniformity of the surface have only a slight effect on the classification accuracy; in other cases the classification accuracy descreases. The radiances above finite fields were computed to simulate radiances measured by a satellite. A simulation case including 11 agricultural fields and four natural fields (water, soil, savanah, and forest) was used to test the effect of the size of the background reflectance and the optical thickness of the atmosphere on classification accuracy. It is concluded that new atmospheric correction methods, which take into account the finite size of the fields, have to be developed to improve significantly the classification accuracy.

  16. A radiation model for calculating atmospheric corrections to remotely sensed infrared measurements, version 2

    NASA Technical Reports Server (NTRS)

    Boudreau, R. D.

    1973-01-01

    A numerical model is developed which calculates the atmospheric corrections to infrared radiometric measurements due to absorption and emission by water vapor, carbon dioxide, and ozone. The corrections due to aerosols are not accounted for. The transmissions functions for water vapor, carbon dioxide, and water are given. The model requires as input the vertical distribution of temperature and water vapor as determined by a standard radiosonde. The vertical distribution of carbon dioxide is assumed to be constant. The vertical distribution of ozone is an average of observed values. The model also requires as input the spectral response function of the radiometer and the nadir angle at which the measurements were made. A listing of the FORTRAN program is given with details for its use and examples of input and output listings. Calculations for four model atmospheres are presented.

  17. A New High-precision Correction Method of Temperature Distribution in Model Stellar Atmospheres

    NASA Astrophysics Data System (ADS)

    Sapar, A.; Poolamäe, R.; Sapar, L.

    The main features of the temperature correction methods, suggested and used in modeling of plane-parallel stellar atmospheres, are discussed. The main features of the new method are described. Derivation of the formulae for a version of the Unsöld-Lucy method, used by us in the SMART (Stellar Model Atmospheres and Radiative Transport) software for modeling stellar atmospheres, is presented. The method is based on a correction of the model temperature distribution based on minimizing differences of flux from its accepted constant value and on the requirement of the lack of its gradient, meaning that local source and sink terms of radiation must be equal. The final relative flux constancy obtainable by the method with the SMART code turned out to have the precision of the order of 0.5 %. Some of the rapidly converging iteration steps can be useful before starting the high-precision model correction. The corrections of both the flux value and of its gradient, like in Unsöld-Lucy method, are unavoidably needed to obtain high-precision flux constancy. A new temperature correction method to obtain high-precision flux constancy for plane-parallel LTE model stellar atmospheres is proposed and studied. The non-linear optimization is carried out by the least squares, in which the Levenberg-Marquardt correction method and thereafter additional correction by the Broyden iteration loop were applied. Small finite differences of temperature (δ T/T=10-3) are used in the computations. A single Jacobian step appears to be mostly sufficient to get flux constancy of the order 10-2 %. The dual numbers and their generalization -- the dual complex numbers (the duplex numbers) -- enable automatically to get the derivatives in the nilpotent part of the dual numbers. A version of the SMART software is in the stage of refactorization to dual and duplex numbers, what enables to get rid of the finite differences, as an additional source of lowering precision of the computed results.

  18. Atmospheric correction of satellite ocean color imagery using the ultraviolet wavelength for highly turbid waters.

    PubMed

    He, Xianqiang; Bai, Yan; Pan, Delu; Tang, Junwu; Wang, Difeng

    2012-08-27

    Instead of the conventionally atmospheric correction algorithms using the near-infrared and shortwave infrared wavelengths, an alternative practical atmospheric correction algorithm using the ultraviolet wavelength for turbid waters (named UV-AC) is proposed for satellite ocean color imagery in the paper. The principle of the algorithm is based on the fact that the water-leaving radiance at ultraviolet wavelengths can be neglected as compared with that at the visible light wavelengths or even near-infrared wavelengths in most cases of highly turbid waters due to the strong absorption by detritus and colored dissolved organic matter. The UV-AC algorithm uses the ultraviolet band to estimate the aerosol scattering radiance empirically, and it does not need any assumption of the water's optical properties. Validations by both of the simulated data and in situ data show that the algorithm is appropriate for the retrieval of the water-leaving radiance in turbid waters. The UV-AC algorithm can be used for all the current satellite ocean color sensors, and it is especially useful for those ocean color sensors lacking the shortwave infrared bands. Moreover, the algorithm can be used for any turbid waters with negligible water-leaving radiance at ultraviolet wavelength. Based on our work, we recommend the future satellite ocean color remote sensors setting the ultraviolet band to perform the atmospheric correction in turbid waters. PMID:23037125

  19. An improved dark-object subtraction technique for atmospheric scattering correction of multispectral data

    USGS Publications Warehouse

    Chavez, P.S., Jr.

    1988-01-01

    Digital analysis of remotely sensed data has become an important component of many earth-science studies. These data are often processed through a set of preprocessing or "clean-up" routines that includes a correction for atmospheric scattering, often called haze. Various methods to correct or remove the additive haze component have been developed, including the widely used dark-object subtraction technique. A problem with most of these methods is that the haze values for each spectral band are selected independently. This can create problems because atmospheric scattering is highly wavelength-dependent in the visible part of the electromagnetic spectrum and the scattering values are correlated with each other. Therefore, multispectral data such as from the Landsat Thematic Mapper and Multispectral Scanner must be corrected with haze values that are spectral band dependent. An improved dark-object subtraction technique is demonstrated that allows the user to select a relative atmospheric scattering model to predict the haze values for all the spectral bands from a selected starting band haze value. The improved method normalizes the predicted haze values for the different gain and offset parameters used by the imaging system. Examples of haze value differences between the old and improved methods for Thematic Mapper Bands 1, 2, 3, 4, 5, and 7 are 40.0, 13.0, 12.0, 8.0, 5.0, and 2.0 vs. 40.0, 13.2, 8.9, 4.9, 16.7, and 3.3, respectively, using a relative scattering model of a clear atmosphere. In one Landsat multispectral scanner image the haze value differences for Bands 4, 5, 6, and 7 were 30.0, 50.0, 50.0, and 40.0 for the old method vs. 30.0, 34.4, 43.6, and 6.4 for the new method using a relative scattering model of a hazy atmosphere. ?? 1988.

  20. Practical Atmospheric Correction Algorithms for a Multi-Spectral Sensor From the Visible Through the Thermal Spectral Regions

    SciTech Connect

    Borel, C.C.; Villeneuve, P.V.; Clodium, W.B.; Szymenski, J.J.; Davis, A.B.

    1999-04-04

    Deriving information about the Earth's surface requires atmospheric corrections of the measured top-of-the-atmosphere radiances. One possible path is to use atmospheric radiative transfer codes to predict how the radiance leaving the ground is affected by the scattering and attenuation. In practice the atmosphere is usually not well known and thus it is necessary to use more practical methods. The authors will describe how to find dark surfaces, estimate the atmospheric optical depth, estimate path radiance and identify thick clouds using thresholds on reflectance and NDVI and columnar water vapor. The authors describe a simple method to correct a visible channel contaminated by a thin cirrus clouds.

  1. [Correction Method of Atmospheric Scattering Effect Based on Three Spectrum Bands].

    PubMed

    Ye, Han-han; Wang, Xian-hua; Jiang, Xin-hua; Bu, Ting-ting

    2016-03-01

    As a major error of CO2 retrieval, atmospheric scattering effect hampers the application of satellite products. Effect of aerosol and combined effect of aerosol and ground surface are important source of atmospheric scattering, so it needs comprehensive consideration of scattering effect from aerosol and ground surface. Based on the continuum, strong and weak absorption part of three spectrum bands O2-A, CO2 1.6 μm and 2.06 μm, information of aerosol and albedo was analyzed, and improved full physics retrieval method was proposed, which can retrieve aerosol and albedo simultaneously to correct the scattering effect. Simulation study on CO2 error caused by aerosol and ground surface albedo CO2 error by correction method was carried out. CO2 error caused by aerosol optical depth and ground surface albedo can reach up to 8%, and CO2 error caused by different types of aerosol can reach up to 10%, while these two types of error can be controlled within 1% and 2% separately by this correction method, which shows that the method can correct the scattering effect effectively. Through evaluation of the results, the potential of this method for high precision satellite data retrieval is obvious, meanwhile, some problems which need to be noticed in real application were also pointed out. PMID:27400493

  2. A Portable Ground-Based Atmospheric Monitoring System (PGAMS) for the Calibration and Validation of Atmospheric Correction Algorithms Applied to Aircraft and Satellite Images

    NASA Technical Reports Server (NTRS)

    Schiller, Stephen; Luvall, Jeffrey C.; Rickman, Doug L.; Arnold, James E. (Technical Monitor)

    2000-01-01

    Detecting changes in the Earth's environment using satellite images of ocean and land surfaces must take into account atmospheric effects. As a result, major programs are underway to develop algorithms for image retrieval of atmospheric aerosol properties and atmospheric correction. However, because of the temporal and spatial variability of atmospheric transmittance it is very difficult to model atmospheric effects and implement models in an operational mode. For this reason, simultaneous in situ ground measurements of atmospheric optical properties are vital to the development of accurate atmospheric correction techniques. Presented in this paper is a spectroradiometer system that provides an optimized set of surface measurements for the calibration and validation of atmospheric correction algorithms. The Portable Ground-based Atmospheric Monitoring System (PGAMS) obtains a comprehensive series of in situ irradiance, radiance, and reflectance measurements for the calibration of atmospheric correction algorithms applied to multispectral. and hyperspectral images. The observations include: total downwelling irradiance, diffuse sky irradiance, direct solar irradiance, path radiance in the direction of the north celestial pole, path radiance in the direction of the overflying satellite, almucantar scans of path radiance, full sky radiance maps, and surface reflectance. Each of these parameters are recorded over a wavelength range from 350 to 1050 nm in 512 channels. The system is fast, with the potential to acquire the complete set of observations in only 8 to 10 minutes depending on the selected spatial resolution of the sky path radiance measurements

  3. Martian particle size based on thermal inertia corrected for elevation-dependent atmospheric properties

    NASA Technical Reports Server (NTRS)

    Bridges, N. T.

    1993-01-01

    Thermal inertia is commonly used to derive physical properties of the Martian surface. If the surface is composed of loosely consolidated grains, then the thermal conductivity derived from the inertia can theoretically be used to compute the particle size. However, one persistent difficulty associated with the interpretation of thermal inertia and the derivation of particle size from it has been the degree to which atmospheric properties affect both the radiation balance at the surface and the gas conductivity. These factors vary with atmospheric pressure so that derived thermal inertias and particle sizes are a function of elevation. By utilizing currently available thermal models and laboratory information, a fine component thermal inertia map was convolved with digital topography to produce particle size maps of the Martian surface corrected for these elevation-dependent effects. Such an approach is especially applicable for the highest elevations on Mars, where atmospheric back radiation and gas conductivity are low.

  4. Comparison of two atmospheric correction models for a vegetated Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) scene

    NASA Technical Reports Server (NTRS)

    Vandenbosch, Jeannette Marie; Alley, R. E.

    1991-01-01

    Current atmospheric correction models applied to imaging spectroscopy data include such methods as residual (scene average) and flat field correction, regression method, and the LOWTRAN 7 method. Due to the limitations of using residual and flat field corrections on vegetated scenes, regression and LOWTRAN 7 are compared. Field measured targets taken at the time of the 13 April, 1989 AVIRIS overflight of Jasper Ridge, California (U.S.) were used to formulate the regression atmospheric correction. Assuming the regressed image represents ground truth, results show that the LOWTRAN 7 method with radiosonde data does not compensate as well for atmospheric water vapor as the regression method, but it may be easier to obtain a posteriori information to perform the LOWTRAN 7 atmospheric correction.

  5. Chlorophyll Concentration Estimates for Coastal Waters using Pixel-Based Atmospheric Correction of Landsat Images

    NASA Astrophysics Data System (ADS)

    Kouba, E.; Xie, H.

    2014-12-01

    Ocean color analysis is more challenging for coastal regions than the global ocean due the effects of optical brightness, shallow and turbid water, higher phytoplankton growth rates, and the complex geometry of coastal bays and estuaries. Also, one of the key atmospheric correction assumptions (zero water leaving radiance in the near infrared) is not valid for these complex conditions. This makes it difficult to estimate the spectral radiance noise caused by atmospheric aerosols, which can vary rapidly with time and space. This project evaluated using Landsat-7 ETM+ observations over a set of coastal bays, and allowing atmospheric correction calculations to vary with time and location as much as practical. Precise satellite orbit vector data was combined with operational weather and climate data to create interpolated arrays of atmospheric profiles which varied with time and location, allowing separate calculation of the Rayleigh and aerosol radiance corrections for all pixels. The resulting normalized water-leaving radiance values were compared with chlorophyll fluorescence measurements made at five in-situ stations inside a set of Texas coastal bays: the Mission-Aransas National Estuarine Research Reserve. Curve-fitting analysis showed it was possible to estimate chlorophyll surface area concentrations by using ETM+ water-leaving radiance values and a third-order polynomial equation. Two pairs of ETM+ bands were identified as inputs (Bands 1 and 3, and the Log10 values of Bands 3 and 4), both achieving R2 of 0.69. Additional research efforts were recommended to obtain additional data, identify better curve fitting equations, and potentially extend the radiative transfer model into the water column.

  6. Adaptation of a Hyperspectral Atmospheric Correction Algorithm for Multi-spectral Ocean Color Data in Coastal Waters. Chapter 3

    NASA Technical Reports Server (NTRS)

    Gao, Bo-Cai; Montes, Marcos J.; Davis, Curtiss O.

    2003-01-01

    This SIMBIOS contract supports several activities over its three-year time-span. These include certain computational aspects of atmospheric correction, including the modification of our hyperspectral atmospheric correction algorithm Tafkaa for various multi-spectral instruments, such as SeaWiFS, MODIS, and GLI. Additionally, since absorbing aerosols are becoming common in many coastal areas, we are making the model calculations to incorporate various absorbing aerosol models into tables used by our Tafkaa atmospheric correction algorithm. Finally, we have developed the algorithms to use MODIS data to characterize thin cirrus effects on aerosol retrieval.

  7. An automated baseline correction protocol for infrared spectra of atmospheric aerosols collected on polytetrafluoroethylene (Teflon) filters

    NASA Astrophysics Data System (ADS)

    Kuzmiakova, Adele; Dillner, Ann M.; Takahama, Satoshi

    2016-06-01

    A growing body of research on statistical applications for characterization of atmospheric aerosol Fourier transform infrared (FT-IR) samples collected on polytetrafluoroethylene (PTFE) filters (e.g., Russell et al., 2011; Ruthenburg et al., 2014) and a rising interest in analyzing FT-IR samples collected by air quality monitoring networks call for an automated PTFE baseline correction solution. The existing polynomial technique (Takahama et al., 2013) is not scalable to a project with a large number of aerosol samples because it contains many parameters and requires expert intervention. Therefore, the question of how to develop an automated method for baseline correcting hundreds to thousands of ambient aerosol spectra given the variability in both environmental mixture composition and PTFE baselines remains. This study approaches the question by detailing the statistical protocol, which allows for the precise definition of analyte and background subregions, applies nonparametric smoothing splines to reproduce sample-specific PTFE variations, and integrates performance metrics from atmospheric aerosol and blank samples alike in the smoothing parameter selection. Referencing 794 atmospheric aerosol samples from seven Interagency Monitoring of PROtected Visual Environment (IMPROVE) sites collected during 2011, we start by identifying key FT-IR signal characteristics, such as non-negative absorbance or analyte segment transformation, to capture sample-specific transitions between background and analyte. While referring to qualitative properties of PTFE background, the goal of smoothing splines interpolation is to learn the baseline structure in the background region to predict the baseline structure in the analyte region. We then validate the model by comparing smoothing splines baseline-corrected spectra with uncorrected and polynomial baseline (PB)-corrected equivalents via three statistical applications: (1) clustering analysis, (2) functional group quantification

  8. ADEOS-II/GLI ocean-color atmospheric correction: early phase result

    NASA Astrophysics Data System (ADS)

    Fukushima, Hajime; Toratani, Mitsuhiro; Tanaka, Akihiko; Chen, Wen-Zhong; Murakami, Hiroshi; Frouin, Robert J.; Mitchell, B. G.; Kahru, Mati

    2003-11-01

    The paper presents initial results of atmospherically corrected ocean color data from the Global Imager (GLI), a moderate resolution spectrometer launched in December 2002 aboard ADEOS-II satellite. The standard GLI atmospheric correction algorithm, which includes an iterative procedure based on in-water optical modeling is first described, followed by brief description of standard in-water algorithms for output geophysical parameters. Ship/buoy-observed and satellite-derived marine reflectances, or normalized water-leaving radiance, are then compared, under vicarious calibration correction factors based on global GLI-SeaWiFS data comparison. The results, over 15 water-leaving radiance match-up data collected mostly off California and off Baja California, show standard errors in GLI estimate of 0.1 to 0.36 μW/cm2/nm/sr for 412, 443, 490, and 565 nm bands, with improved standard errors of 0.09 to 0.14 μW/cm2/nm/sr if in situ data set is limited to those obtained by in-water radiance measurement. Under provisional de-striping procedure, satellite-derived chlorophyll a estimates compares well with 35 ship-measured data collected off California within one day difference from the satellite observation, showing standard error factor of 1.73 (+73% or -43% error).

  9. Multiangle Implementation of Atmospheric Correction (MAIAC):. 1; Radiative Transfer Basis and Look-up Tables

    NASA Technical Reports Server (NTRS)

    Lyapustin, Alexei; Martonchik, John; Wang, Yujie; Laszlo, Istvan; Korkin, Sergey

    2011-01-01

    This paper describes a radiative transfer basis of the algorithm MAIAC which performs simultaneous retrievals of atmospheric aerosol and bidirectional surface reflectance from the Moderate Resolution Imaging Spectroradiometer (MODIS). The retrievals are based on an accurate semianalytical solution for the top-of-atmosphere reflectance expressed as an explicit function of three parameters of the Ross-Thick Li-Sparse model of surface bidirectional reflectance. This solution depends on certain functions of atmospheric properties and geometry which are precomputed in the look-up table (LUT). This paper further considers correction of the LUT functions for variations of surface pressure/height and of atmospheric water vapor, which is a common task in the operational remote sensing. It introduces a new analytical method for the water vapor correction of the multiple ]scattering path radiance. It also summarizes the few basic principles that provide a high efficiency and accuracy of the LUT ]based radiative transfer for the aerosol/surface retrievals and optimize the size of LUT. For example, the single-scattering path radiance is calculated analytically for a given surface pressure and atmospheric water vapor. The same is true for the direct surface-reflected radiance, which along with the single-scattering path radiance largely defines the angular dependence of measurements. For these calculations, the aerosol phase functions and kernels of the surface bidirectional reflectance model are precalculated at a high angular resolution. The other radiative transfer functions depend rather smoothly on angles because of multiple scattering and can be calculated at coarser angular resolution to reduce the LUT size. At the same time, this resolution should be high enough to use the nearest neighbor geometry angles to avoid costly three ]dimensional interpolation. The pressure correction is implemented via linear interpolation between two LUTs computed for the standard and reduced

  10. In-season time series analysis of Resourcesat-1 AWiFS data for estimating irrigation water requirement

    NASA Astrophysics Data System (ADS)

    Raju, P. V.; Sesha Sai, M. V. R.; Roy, P. S.

    2008-06-01

    AWiFS sensor on board IRS-P6 (Resourcesat-1), with its unique features—wide swath and 5-day revisit capability provides excellent opportunities to carry out in-season analysis of irrigated agriculture. The study carried out in Hirakud command area, Orissa State indicated that the progression of rice crop acreage could be mapped through analysis of time series AWiFS data set. The spectral emergence pattern of rice crop was found useful to identify the period of rice transplantation and its variability across the command area. This information, integrated with agro-meteorological data, was used to quantify 10-daily canal-wise irrigation water requirement. A comparison with field measured actual irrigation supplies indicated an overall supply adequacy of 88% and showed wide variability at lateral canal level ranging between 18% and 109%. The supply pattern also did not correspond with the chronological variations associated with crop water requirement, supplies were 15% excess during initial part of season (December and January) and were 20.1% deficit during later part of season (February to April). Rescheduling the excess supplies of the initial period could have reduced the deficit to 15% during peak season. The study has demonstrated the usefulness of AWiFS data to generate the irrigation water requirement by mid-season, subsequent to which 38% supplies were yet to be allocated. This would support the irrigation managers to reschedule the irrigation water supplies to achieve better synchronization between requirement and supply leading to improved water use efficiency.

  11. Atmospheric correction of satellite ocean color data in turbid coastal waters

    NASA Astrophysics Data System (ADS)

    Ahn, Yu-Hwan; Shanmugam, Palanisamy; Ryu, Joo-Hyung

    2006-12-01

    Geostationary Ocean Color Imager (GOCI) onboard its Communication Ocean and Meteorological Satellite (COMS) is scheduled for launch in 2008. GOCI includes the eight visible-to-near-infrared (NIR) bands, 0.5km pixel resolution, and a coverage region of 2500 x 2500km centered at 36N and 130E. GOCI has had the scope of its objectives broadened to understand the role of the oceans and ocean productivity in the climate system, biogeochemical variables, geological and biological response to physical dynamics and to detect and monitor toxic algal blooms of notable extension through observations of ocean color. To achieve these mission objectives, it is necessary to develop an atmospheric correction technique which is capable of delivering geophysical products, particularly for highly turbid coastal regions that are often dominated by strongly absorbing aerosols from the adjacent continental/desert areas. In this paper, we present a more realistic and cost-effective atmospheric correction method which takes into account the contribution of NIR radiances and include specialized models for strongly absorbing aerosols. This method was tested extensively on SeaWiFS ocean color imagery acquired over the Northwest Pacific waters. While the standard SeaWiFS atmospheric correction algorithm showed a pronounced overcorrection in the violet/blue or a complete failure in the presence of strongly absorbing aerosols (Asian dust or Yellow dust) over these regions, the new method was able to retrieve the water-leaving radiance and chlorophyll concentrations that were consistent with the in-situ observations. Such comparison demonstrated the efficiency of the new method in terms of removing the effects of highly absorbing aerosols and improving the accuracy of water-leaving radiance and chlorophyll retrievals with SeaWiFS imagery.

  12. Atmospheric Pressure Corrections in Geodesy and Oceanography: a Strategy for Handling Air Tides

    NASA Technical Reports Server (NTRS)

    Ponte, Rui M.; Ray, Richard D.

    2003-01-01

    Global pressure data are often needed for processing or interpreting modern geodetic and oceanographic measurements. The most common source of these data is the analysis or reanalysis products of various meteorological centers. Tidal signals in these products can be problematic for several reasons, including potentially aliased sampling of the semidiurnal solar tide as well as the presence of various modeling or timing errors. Building on the work of Van den Dool and colleagues, we lay out a strategy for handling atmospheric tides in (re)analysis data. The procedure also offers a method to account for ocean loading corrections in satellite altimeter data that are consistent with standard ocean-tide corrections. The proposed strategy has immediate application to the on-going Jason-1 and GRACE satellite missions.

  13. Shannon capacities and error-correction codes for optical atmospheric turbulent channels

    NASA Astrophysics Data System (ADS)

    Anguita, Jaime A.; Djordjevic, Ivan B.; Neifeld, Mark A.; Vasic, Bane V.

    2005-09-01

    Feature Issue on Optical Wireless Communications (OWC) The propagation of an on-off keying modulated optical signal through an optical atmospheric turbulent channel is considered. The intensity fluctuations of the signal observed at the receiver are modeled using a gamma-gamma distribution. The capacity of this channel is determined for a wide range of turbulence conditions. For a zero inner scale, the capacity decreases monotonically as the turbulence strengthens. For non-zero inner scale, the capacity is not monotonic with turbulence strength. Two error-correction schemes, based on low-density parity-check (LDPC) codes, are investigated as a means to improve the bit-error rate (BER) performance of the system. Very large coding gains--ranging from 5.5 to 14 dB, depending on the turbulence conditions--are obtained by these LDPC codes compared with Reed-Solomon error-correction codes of similar rates and lengths.

  14. A procedure for testing the quality of LANDSAT atmospheric correction algorithms

    NASA Technical Reports Server (NTRS)

    Dias, L. A. V. (Principal Investigator); Vijaykumar, N. L.; Neto, G. C.

    1982-01-01

    There are two basic methods for testing the quality of an algorithm to minimize atmospheric effects on LANDSAT imagery: (1) test the results a posteriori, using ground truth or control points; (2) use a method based on image data plus estimation of additional ground and/or atmospheric parameters. A procedure based on the second method is described. In order to select the parameters, initially the image contrast is examined for a series of parameter combinations. The contrast improves for better corrections. In addition the correlation coefficient between two subimages, taken at different times, of the same scene is used for parameter's selection. The regions to be correlated should not have changed considerably in time. A few examples using this proposed procedure are presented.

  15. Prime focus wide-field corrector designs with lossless atmospheric dispersion correction

    SciTech Connect

    Saunders, Will; Gillingham, Peter; Smith, Greg; Kent, Steve; Doel, Peter

    2014-07-18

    Wide-Field Corrector designs are presented for the Blanco and Mayall telescopes, the CFHT and the AAT. The designs are Terezibh-style, with 5 or 6 lenses, and modest negative optical power. They have 2.2-3 degree fields of view, with curved and telecentric focal surfaces suitable for fiber spectroscopy. Some variants also allow wide-field imaging, by changing the last WFC element. Apart from the adaptation of the Terebizh design for spectroscopy, the key feature is a new concept for a 'Compensating Lateral Atmospheric Dispersion Corrector', with two of the lenses being movable laterally by small amounts. This provides excellent atmospheric dispersion correction, without any additional surfaces or absorption. A novel and simple mechanism for providing the required lens motions is proposed, which requires just 3 linear actuators for each of the two moving lenses.

  16. Evaluating atmospheric correction models for retrieving surface temperatures from the AVHRR over a tallgrass prairie

    NASA Technical Reports Server (NTRS)

    Cooper, D. I.; Asrar, G.

    1989-01-01

    The effects of atmospheric attenuation on surface radiative temperatures obtained by the AVHRR over a tallgrass prairie area in the Flint Hills of Kansas are examined. Six atmospheric correction models developed primarily for sea-surface temperature studies are used to test their utility for retrieval of radiative temperatures over the land surface. An uncertainty of + or - 3.0 C was found for the AVHRR data, and used to evaluate the performance of a given model. When the difference between in situ and AVHRR surface temperatures was smaller than the uncertainty, the model was judged to be adequate. Among the six models evaluated, only the NOAA split-window model consistently adjusted the AVHRR surface temperatures within + or - 3.0 C of the in situ measurements.

  17. Remote Sensing of Tropical Ecosystems: Atmospheric Correction and Cloud Masking Matter

    NASA Technical Reports Server (NTRS)

    Hilker, Thomas; Lyapustin, Alexei I.; Tucker, Compton J.; Sellers, Piers J.; Hall, Forrest G.; Wang, Yujie

    2012-01-01

    Tropical rainforests are significant contributors to the global cycles of energy, water and carbon. As a result, monitoring of the vegetation status over regions such as Amazonia has been a long standing interest of Earth scientists trying to determine the effect of climate change and anthropogenic disturbance on the tropical ecosystems and its feedback on the Earth's climate. Satellite-based remote sensing is the only practical approach for observing the vegetation dynamics of regions like the Amazon over useful spatial and temporal scales, but recent years have seen much controversy over satellite-derived vegetation states in Amazônia, with studies predicting opposite feedbacks depending on data processing technique and interpretation. Recent results suggest that some of this uncertainty could stem from a lack of quality in atmospheric correction and cloud screening. In this paper, we assess these uncertainties by comparing the current standard surface reflectance products (MYD09, MYD09GA) and derived composites (MYD09A1, MCD43A4 and MYD13A2 - Vegetation Index) from the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Aqua satellite to results obtained from the Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm. MAIAC uses a new cloud screening technique, and novel aerosol retrieval and atmospheric correction procedures which are based on time-series and spatial analyses. Our results show considerable improvements of MAIAC processed surface reflectance compared to MYD09/MYD13 with noise levels reduced by a factor of up to 10. Uncertainties in the current MODIS surface reflectance product were mainly due to residual cloud and aerosol contamination which affected the Normalized Difference Vegetation Index (NDVI): During the wet season, with cloud cover ranging between 90 percent and 99 percent, conventionally processed NDVI was significantly depressed due to undetected clouds. A smaller reduction in NDVI due to increased

  18. A note of the simplified formula for atmospheric correction in satellite laser ranging

    NASA Astrophysics Data System (ADS)

    Lin, Q.; Tan, D.; Yang, F.

    The paper is a supplement of a previous article in which a simplified formula for atmospheric correction in satellite laser ranging was given. The deductive process of the formula is given in this paper, and in order to compare the accuracy between Marini's formula (1974) and the simplified one, numerical computations for different temperature, air pressure, and latitude have been done. It is shown that the difference between the two formulas is only 2 cm above 20 deg elevation, although the temperature factor has not been included in the equation.

  19. High-rate error-correction codes for the optical atmospheric channel

    NASA Astrophysics Data System (ADS)

    Anguita, Jaime A.; Djordjevic, Ivan B.; Neifeld, Mark A.; Vasic, Bane V.

    2005-08-01

    We evaluate two error correction systems based on low-density parity-check (LDPC) codes for free-space optical (FSO) communication channels subject to atmospheric turbulence. We simulate the effect of turbulence on the received signal by modeling the channel with a gamma-gamma distribution. We compare the bit-error rate performance of these codes with the performance of Reed-Solomon codes of similar rate and obtain coding gains from 3 to 14 dB depending on the turbulence conditions.

  20. Correcting infrared satellite estimates of sea surface temperature for atmospheric water vapor attenuation

    NASA Technical Reports Server (NTRS)

    Emery, William J.; Yu, Yunyue; Wick, Gary A.; Schluessel, Peter; Reynolds, Richard W.

    1994-01-01

    A new satellite sea surface temperature (SST) algorithm is developed that uses nearly coincident measurements from the microwave special sensor microwave imager (SSM/I) to correct for atmospheric moisture attenuation of the infrared signal from the advanced very high resolution radiometer (AVHRR). This new SST algorithm is applied to AVHRR imagery from the South Pacific and Norwegian seas, which are then compared with simultaneous in situ (ship based) measurements of both skin and bulk SST. In addition, an SST algorithm using a quadratic product of the difference between the two AVHRR thermal infrared channels is compared with the in situ measurements. While the quadratic formulation provides a considerable improvement over the older cross product (CPSST) and multichannel (MCSST) algorithms, the SSM/I corrected SST (called the water vapor or WVSST) shows overall smaller errors when compared to both the skin and bulk in situ SST observations. Applied to individual AVHRR images, the WVSST reveals an SST difference pattern (CPSST-WVSST) similar in shape to the water vapor structure while the CPSST-quadratic SST difference appears unrelated in pattern to the nearly coincident water vapor pattern. An application of the WVSST to week-long composites of global area coverage (GAC) AVHRR data demonstrates again the manner in which the WVSST corrects the AVHRR for atmospheric moisture attenuation. By comparison the quadratic SST method underestimates the SST corrections in the lower latitudes and overestimates the SST in th e higher latitudes. Correlations between the AVHRR thermal channel differences and the SSM/I water vapor demonstrate the inability of the channel difference to represent water vapor in the midlatitude and high latitudes during summer. Compared against drifting buoy data the WVSST and the quadratic SST both exhibit the same general behavior with the relatively small differences with the buoy temperatures.

  1. Ocean-atmosphere interaction and the tropical climatology. Part I. The dangers of flux correction

    SciTech Connect

    Neelin, J.D.; Dijkstra, H.A.

    1995-05-01

    This sequence of papers examines the role of dynamical feedbacks between the ocean and the atmosphere in determining features of the tropical climatology. A stripped-down, intermediate, coupled ocean-atmosphere model is used to provide a prototype problem for the Pacific basin. Here the authors contrast the fully coupled case with the case where flux correction is used to construct the climatology. In the fully coupled case, the climatology is determined largely by feedback mechanisms within the ocean basin: winds driven by gradients of sea surface temperature (SST) within the basin interact with the ocean circulation to maintain SST gradients. For all realistic cases, these lead to a unique steady solution for the tropical climatology. In the flux-corrected case, the artificially constructed climatology becomes unstable at sufficiently large coupling, leading to multiple steady states as found in a number of coupled models. Using continuation methods, we show that there is a topological change in the bifurcation structure as flux correction is relaxed toward a fully coupled case; this change is characterized as an imperfection and must occur generically for all flux-corrected cases. The cold branch is steady solutions is governed by mechanisms similar to the fully coupled case. The warm branch, however, is spurious and disappears. The dynamics of this and consequences for coupled models are discussed. Multiple steady states can be ruled out as a mechanism for El Nino in favor of oscillatory mechanisms. The important role that coupled feedbacks are suggested to play in establishing tropical climatology is referred to as {open_quotes}the climatological version of the Bjerknes hypothesis.{close_quotes} 43 refs., 10 figs., 2 tabs.

  2. Spatial heterogeneity in geothermally-influenced lakes derived from atmospherically corrected Landsat thermal imagery and three-dimensional hydrodynamic modelling

    NASA Astrophysics Data System (ADS)

    Allan, Mathew G.; Hamilton, David P.; Trolle, Dennis; Muraoka, Kohji; McBride, Christopher

    2016-08-01

    Atmospheric correction of Landsat 7 thermal data was carried out for the purpose of retrieval of lake skin water temperature in Rotorua lakes, and Lake Taupo, North Island, New Zealand. The effect of the atmosphere was modelled using four sources of atmospheric profile data as input to the MODerate resolution atmospheric TRANsmission (MODTRAN) radiative transfer model. The retrieved skin water temperatures were validated using a high-frequency temperature sensor deployed from a monitoring buoy at the water surface of Lake Rotorua. The most accurate atmospheric correction method was with Moderate Resolution Imaging Spectroradiometer (MODIS) atmospheric profile data (root-mean-square-error, RMSE, 0.48 K), followed by radiosonde (0.52 K), Atmospheric Infrared Sounder (AIRS) Level 3 (0.54 K), and the NASA atmospheric correction parameter calculator (0.94 K). Retrieved water temperature was used for assessing spatial heterogeneity and accuracy of surface water temperature simulated with a three-dimensional (3-D) hydrodynamic model of Lake Rotoehu, located approximately 20 km east of Lake Rotorua. This comparison indicated that the model was suitable for reproducing the dominant horizontal variations in surface water temperature in the lake. This study demonstrated the potential of accurate satellite-based thermal monitoring to validate temperature outputs from 3-D hydrodynamic model simulations. It also provided atmospheric correction options for local and global applications of Landsat thermal data.

  3. Chlorophyll concentration estimates for coastal water using pixel-based atmospheric correction of Landsat images

    NASA Astrophysics Data System (ADS)

    Kouba, Eric

    Ocean color analysis is more challenging for coastal regions than the global ocean due the effects of optical brightness, shallow and turbid water, higher phytoplankton growth rates, and the complex geometry of coastal bays and estuaries. Also, one of the key atmospheric correction assumptions (zero water leaving radiance in the near infrared) is not valid for these complex conditions. This makes it difficult to estimate the spectral radiance noise caused by atmospheric aerosols, which can vary rapidly with time and space. This study conducts pixel-based atmospheric correction of Landsat-7 ETM+ images over the Texas coast. Precise satellite orbit data, operational weather data, and climate data are combined to create interpolated arrays of viewing angles and atmospheric profiles. These arrays vary with time and location, allowing calculation of the Rayleigh and aerosol radiances separately for all pixels. The resulting normalized water-leaving radiances are then compared with in situ chlorophyll fluorescence measurements from five locations inside a set of Texas coastal bays: the Mission-Aransas National Estuarine Research Reserve. Curve-fitting analysis shows it is possible to estimate chlorophyll-a surface area concentrations by using ETM+ water-leaving radiance values and a third-order polynomial equation. Two pairs of ETM+ bands are identified as inputs (Bands 1 and 3, and the Log10 values of Bands 3 and 4), both achieving good performance (R2 of 0.69). Further research efforts are recommended to obtain additional data, identify better curve fitting equations, and potentially extend the radiative transfer model into the water column.

  4. Closure Report for Corrective Action Unit 104: Area 7 Yucca Flat Atmospheric Test Sites, Nevada National Security Site, Nevada

    SciTech Connect

    2013-06-27

    This Closure Report (CR) presents information supporting closure of Corrective Action Unit (CAU) 104, Area 7 Yucca Flat Atmospheric Test Sites, and provides documentation supporting the completed corrective actions and confirmation that closure objectives for CAU 104 were met. This CR complies with the requirements of the Federal Facility Agreement and Consent Order (FFACO) that was agreed to by the State of Nevada; the U.S. Department of Energy (DOE), Environmental Management; the U.S. Department of Defense; and DOE, Legacy Management. CAU 104 consists of the following 15 Corrective Action Sites (CASs), located in Area 7 of the Nevada National Security Site: · CAS 07-23-03, Atmospheric Test Site T-7C · CAS 07-23-04, Atmospheric Test Site T7-1 · CAS 07-23-05, Atmospheric Test Site · CAS 07-23-06, Atmospheric Test Site T7-5a · CAS 07-23-07, Atmospheric Test Site - Dog (T-S) · CAS 07-23-08, Atmospheric Test Site - Baker (T-S) · CAS 07-23-09, Atmospheric Test Site - Charlie (T-S) · CAS 07-23-10, Atmospheric Test Site - Dixie · CAS 07-23-11, Atmospheric Test Site - Dixie · CAS 07-23-12, Atmospheric Test Site - Charlie (Bus) · CAS 07-23-13, Atmospheric Test Site - Baker (Buster) · CAS 07-23-14, Atmospheric Test Site - Ruth · CAS 07-23-15, Atmospheric Test Site T7-4 · CAS 07-23-16, Atmospheric Test Site B7-b · CAS 07-23-17, Atmospheric Test Site - Climax Closure activities began in October 2012 and were completed in April 2013. Activities were conducted according to the Corrective Action Decision Document/Corrective Action Plan for CAU 104. The corrective actions included No Further Action and Clean Closure. Closure activities generated sanitary waste, mixed waste, and recyclable material. Some wastes exceeded land disposal limits and required treatment prior to disposal. Other wastes met land disposal restrictions and were disposed in appropriate onsite landfills. The U.S. Department of Energy, National Nuclear Security Administration Nevada Field Office

  5. Correction.

    PubMed

    2015-11-01

    In the article by Heuslein et al, which published online ahead of print on September 3, 2015 (DOI: 10.1161/ATVBAHA.115.305775), a correction was needed. Brett R. Blackman was added as the penultimate author of the article. The article has been corrected for publication in the November 2015 issue. PMID:26490278

  6. Corrective Action Decision Document/Closure Report for Corrective Action Unit 570: Area 9 Yucca Flat Atmospheric Test Sites, Nevada National Security Site, Nevada, Revision 0

    SciTech Connect

    Matthews, Patrick

    2013-11-01

    This Corrective Action Decision Document/Closure Report presents information supporting the closure of Corrective Action Unit (CAU) 570: Area 9 Yucca Flat Atmospheric Test Sites, Nevada National Security Site, Nevada. This complies with the requirements of the Federal Facility Agreement and Consent Order (FFACO) that was agreed to by the State of Nevada; U.S. Department of Energy (DOE), Environmental Management; U.S. Department of Defense; and DOE, Legacy Management. The purpose of the CADD/CR is to provide justification and documentation supporting the recommendation that no further corrective action is needed.

  7. Radiometric correction of atmospheric path length fluctuations in interferometric experiments. [in radio astronomy

    NASA Technical Reports Server (NTRS)

    Resch, G. M.; Hogg, D. E.; Napier, P. J.

    1984-01-01

    To support very long baseline interferometric experiments, a system has been developed for estimating atmospheric water vapor path delay. The system consists of dual microwave radiometers, one operating at 20.7 GHz and the other at 31.4 GHz. The measured atmospheric brightness temperatures at these two frequencies yield the estimate of the precipitable water present in both vapor and droplets. To determine the accuracy of the system, a series of observations were undertaken, comparing the outputs of two water vapor radiometers with the phase variation observed with two connected elements of the very large array (VLA). The results show that: (1) water vapor fluctuations dominate the residual VLA phase and (2) the microwave radiometers can measure and correct these effects. The rms phase error after correction is typically 15 deg at a wavelength of 6 cm, corresponding to an uncertainty in the path delay of 0.25 cm. The residual uncertainty is consistent with the stability of the microwave radiometer but is still considerably larger than the stability of the VLA. The technique is less successful under conditions of heavy cloud.

  8. The effect of anthropogenic emissions corrections on the seasonal cycle of atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Brooks, B. J.; Hoffman, F. M.; Mills, R. T.; Erickson, D. J.; Blasing, T. J.

    2009-12-01

    A previous study (Erickson et al. 2008) approximated the monthly global emission estimates of anthropogenic CO2 by applying a 2-harmonic Fourier expansion with coefficients as a function of latitude to annual CO2 flux estimates derived from United States data (Blasing et al. 2005) that were extrapolated globally. These monthly anthropogenic CO2 flux estimates were used to model atmospheric concentrations using the NASA GEOS-4 data assimilation system. Local variability in the amplitude of the simulated CO2 seasonal cycle were found to be on the order of 2-6 ppmv. Here we used the same Fourier expansion to seasonally adjust the global annual fossil fuel CO2 emissions from the SRES A2 scenario. For a total of four simulations, both the annual and seasonalized fluxes were advected in two configurations of the NCAR Community Atmosphere Model (CAM) used in the Carbon-Land Model Intercomparison Project (C-LAMP). One configuration used the NCAR Community Land Model (CLM) coupled with the CASA‧ (carbon only) biogeochemistry model and the other used CLM coupled with the CN (coupled carbon and nitrogen cycles) biogeochemistry model. All four simulations were forced with observed sea surface temperatures and sea ice concentrations from the Hadley Centre and a prescribed transient atmospheric CO2 concentration for the radiation and land forcing over the 20th century. The model results exhibit differences in the seasonal cycle of CO2 between the seasonally corrected and uncorrected simulations. Moreover, because of differing energy and water feedbacks between the atmosphere model and the two land biogeochemistry models, features of the CO2 seasonal cycle were different between these two model configurations. This study reinforces previous findings that suggest that regional near-surface atmospheric CO2 concentrations depend strongly on the natural sources and sinks of CO2, but also on the strength of local anthropogenic CO2 emissions and geographic position. This work further

  9. Atmospheric Correction at AERONET Locations: A New Science and Validation Data Set

    NASA Technical Reports Server (NTRS)

    Wang, Yujie; Lyapustin, Alexei; Privette, Jeffery L.; Morisette, Jeffery T.; Holben, Brent

    2008-01-01

    This paper describes an AERONET-based Surface Reflectance Validation Network (ASRVN) and its dataset of spectral surface bidirectional reflectance and albedo based on MODIS TERRA and AQUA data. The ASRVN is an operational data collection and processing system. It receives 50x50 square kilometer subsets of MODIS L1B data from MODAPS and AERONET aerosol and water vapor information. Then it performs an accurate atmospheric correction for about 100 AERONET sites based on accurate radiative transfer theory with high quality control of the input data. The ASRVN processing software consists of L1B data gridding algorithm, a new cloud mask algorithm based on a time series analysis, and an atmospheric correction algorithm. The atmospheric correction is achieved by fitting the MODIS top of atmosphere measurements, accumulated for 16-day interval, with theoretical reflectance parameterized in terms of coefficients of the LSRT BRF model. The ASRVN takes several steps to ensure high quality of results: 1) cloud mask algorithm filters opaque clouds; 2) an aerosol filter has been developed to filter residual semi-transparent and sub-pixel clouds, as well as cases with high inhomogeneity of aerosols in the processing area; 3) imposing requirement of consistency of the new solution with previously retrieved BRF and albedo; 4) rapid adjustment of the 16-day retrieval to the surface changes using the last day of measurements; and 5) development of seasonal back-up spectral BRF database to increase data coverage. The ASRVN provides a gapless or near-gapless coverage for the processing area. The gaps, caused by clouds, are filled most naturally with the latest solution for a given pixels. The ASRVN products include three parameters of LSRT model (k(sup L), k(sup G), k(sup V)), surface albedo, NBRF (a normalized BRF computed for a standard viewing geometry, VZA=0 deg., SZA=45 deg.), and IBRF (instantaneous, or one angle, BRF value derived from the last day of MODIS measurement for

  10. Model atmospheres broad-band colors, bolometric corrections and temperature calibrations for O - M stars

    NASA Astrophysics Data System (ADS)

    Bessell, M. S.; Castelli, F.; Plez, B.

    1998-05-01

    Broad band colors and bolometric corrections in the Johnson-Cousins-Glass system (Bessell, 1990; Bessell & Brett, 1988) have been computed from synthetic spectra from new model atmospheres of Kurucz (1995a), Castelli (1997), Plez, Brett & Nordlund (1992), Plez (1995-97), and Brett (1995a,b). These atmospheres are representative of larger grids that are currently being completed. We discuss differences between the different grids and compare theoretical color-temperature relations and the fundamental color temperature relations derived from: (a) the infrared-flux method (IRFM) for A-K stars (Blackwell & Lynas-Gray 1994; Alonso et al. 1996) and M dwarfs (Tsuji et al. 1996a); (b) lunar occultations (Ridgway et al. 1980) and (c) Michelson interferometry (Di Benedetto & Rabbia 1987; Dyck et al. 1996; Perrin et al. 1997) for K-M giants, and (d) eclipsing binaries for M dwarfs. We also compare color - color relations and color - bolometric correction relations and find good agreement except for a few colors. The more realistic fluxes and spectra of the new model grids should enable accurate population synthesis models to be derived and permit the ready calibration of non-standard photometric passbands. As well, the theoretical bolometric corrections and temperature - color relations will permit reliable transformation from observed color magnitude diagrams to theoretical HR diagrams. Tables 1-6 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html

  11. Implementation of Coupled Skin Temperature Analysis and Bias Correction in a Global Atmospheric Data Assimilation System

    NASA Technical Reports Server (NTRS)

    Radakovich, Jon; Bosilovich, M.; Chern, Jiun-dar; daSilva, Arlindo

    2004-01-01

    The NASA/NCAR Finite Volume GCM (fvGCM) with the NCAR CLM (Community Land Model) version 2.0 was integrated into the NASA/GMAO Finite Volume Data Assimilation System (fvDAS). A new method was developed for coupled skin temperature assimilation and bias correction where the analysis increment and bias correction term is passed into the CLM2 and considered a forcing term in the solution to the energy balance. For our purposes, the fvDAS CLM2 was run at 1 deg. x 1.25 deg. horizontal resolution with 55 vertical levels. We assimilate the ISCCP-DX (30 km resolution) surface temperature product. The atmospheric analysis was performed 6-hourly, while the skin temperature analysis was performed 3-hourly. The bias correction term, which was updated at the analysis times, was added to the skin temperature tendency equation at every timestep. In this presentation, we focus on the validation of the surface energy budget at the in situ reference sites for the Coordinated Enhanced Observation Period (CEOP). We will concentrate on sites that include independent skin temperature measurements and complete energy budget observations for the month of July 2001. In addition, MODIS skin temperature will be used for validation. Several assimilations were conducted and preliminary results will be presented.

  12. Skin Temperature Analysis and Bias Correction in a Coupled Land-Atmosphere Data Assimilation System

    NASA Technical Reports Server (NTRS)

    Bosilovich, Michael G.; Radakovich, Jon D.; daSilva, Arlindo; Todling, Ricardo; Verter, Frances

    2006-01-01

    In an initial investigation, remotely sensed surface temperature is assimilated into a coupled atmosphere/land global data assimilation system, with explicit accounting for biases in the model state. In this scheme, an incremental bias correction term is introduced in the model's surface energy budget. In its simplest form, the algorithm estimates and corrects a constant time mean bias for each gridpoint; additional benefits are attained with a refined version of the algorithm which allows for a correction of the mean diurnal cycle. The method is validated against the assimilated observations, as well as independent near-surface air temperature observations. In many regions, not accounting for the diurnal cycle of bias caused degradation of the diurnal amplitude of background model air temperature. Energy fluxes collected through the Coordinated Enhanced Observing Period (CEOP) are used to more closely inspect the surface energy budget. In general, sensible heat flux is improved with the surface temperature assimilation, and two stations show a reduction of bias by as much as 30 Wm(sup -2) Rondonia station in Amazonia, the Bowen ratio changes direction in an improvement related to the temperature assimilation. However, at many stations the monthly latent heat flux bias is slightly increased. These results show the impact of univariate assimilation of surface temperature observations on the surface energy budget, and suggest the need for multivariate land data assimilation. The results also show the need for independent validation data, especially flux stations in varied climate regimes.

  13. Atmospheric correction of MODIS thermal infrared bands by water vapor scaling method

    NASA Astrophysics Data System (ADS)

    Tonooka, Hideyuki

    2005-10-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) project has operationally provided land surface temperature (LST) and emissivity imagery produced from mid-infrared bands by either of two atmospheric correction algorithms. One is the generalized split-window algorithm. This algorithm can be applied to each observed scene, and the spatial resolution of generated products is 1 km, but the emissivity data in the products are empirically estimated by a classification-based method. Another is the physics-based day/night algorithm. In this algorithm, both LST and emissivity are physically determined using mid-infrared measurements, but a pair of day/night scenes is necessary for each processing, and the spectral resolution of generated products is degraded to 5 km. In the present paper, the water vapor scaling (WVS) method (Tonooka, 2001 and 2005) is applied to three MODIS thermal infrared (TIR) bands (29, 31, and 32) as an alternative approach. This method is an atmospheric correction algorithm for TIR multi-spectral data including land surfaces, designed mainly for the five TIR spectral bands of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on the Terra satellite. The WVS method is on the basis of a traditional approach using a radiative transfer code, such as MODTRAN, combined with external atmospheric profiles, but the errors included in profiles are reduced on a pixel-by-pixel basis using an extended multi-channel approach. In the present paper, the WVS method for the three MODIS TIR bands is proposed, and applied to actual imagery for preliminary validation.

  14. Atmospheric Correction of Satellite Imagery Using Modtran 3.5 Code

    NASA Technical Reports Server (NTRS)

    Gonzales, Fabian O.; Velez-Reyes, Miguel

    1997-01-01

    When performing satellite remote sensing of the earth in the solar spectrum, atmospheric scattering and absorption effects provide the sensors corrupted information about the target's radiance characteristics. We are faced with the problem of reconstructing the signal that was reflected from the target, from the data sensed by the remote sensing instrument. This article presents a method for simulating radiance characteristic curves of satellite images using a MODTRAN 3.5 band model (BM) code to solve the radiative transfer equation (RTE), and proposes a method for the implementation of an adaptive system for automated atmospheric corrections. The simulation procedure is carried out as follows: (1) for each satellite digital image a radiance characteristic curve is obtained by performing a digital number (DN) to radiance conversion, (2) using MODTRAN 3.5 a simulation of the images characteristic curves is generated, (3) the output of the code is processed to generate radiance characteristic curves for the simulated cases. The simulation algorithm was used to simulate Landsat Thematic Mapper (TM) images for two types of locations: the ocean surface, and a forest surface. The simulation procedure was validated by computing the error between the empirical and simulated radiance curves. While results in the visible region of the spectrum where not very accurate, those for the infrared region of the spectrum were encouraging. This information can be used for correction of the atmospheric effects. For the simulation over ocean, the lowest error produced in this region was of the order of 105 and up to 14 times smaller than errors in the visible region. For the same spectral region on the forest case, the lowest error produced was of the order of 10-4, and up to 41 times smaller than errors in the visible region,

  15. The Mars Analysis Correction Data Assimilation (MACDA): A reference atmospheric reanalysis

    NASA Astrophysics Data System (ADS)

    Montabone, Luca; Read, Peter; Lewis, Stephen; Steele, Liam; Holmes, James; Valeanu, Alexandru

    2016-07-01

    The Mars Analysis Correction Data Assimilation (MACDA) dataset version 1.0 contains the reanalysis of fundamental atmospheric and surface variables for the planet Mars covering a period of about three Martian years (late MY 24 to early MY 27). This has been produced by data assimilation of retrieved thermal profiles and column dust optical depths from NASA's Mars Global Surveyor/Thermal Emission Spectrometer (MGS/TES), which have been assimilated into a Mars global climate model (MGCM) using the Analysis Correction scheme developed at the UK Meteorological Office. The MACDA v1.0 reanalysis is publicly available, and the NetCDF files can be downloaded from the archive at the Centre for Environmental Data Analysis/British Atmospheric Data Centre (CEDA/BADC). The variables included in the dataset can be visualised using an ad-hoc graphical user interface (the "MACDA Plotter") at the following URL: http://macdap.physics.ox.ac.uk/ MACDA is an ongoing collaborative project, and work is currently undertaken to produce version 2.0 of the Mars atmospheric reanalysis. One of the key improvements is the extension of the reanalysis period to nine martian years (MY 24 through MY 32), with the assimilation of NASA's Mars Reconnaissance Orbiter/Mars Climate Sounder (MRO/MCS) retrievals of thermal and dust opacity profiles. MACDA 2.0 is also going to be based on an improved version of the underlying MGCM and an updated scheme to fully assimilate (radiative active) tracers, such as dust and water ice.

  16. Correction.

    PubMed

    2015-12-01

    In the article by Narayan et al (Narayan O, Davies JE, Hughes AD, Dart AM, Parker KH, Reid C, Cameron JD. Central aortic reservoir-wave analysis improves prediction of cardiovascular events in elderly hypertensives. Hypertension. 2015;65:629–635. doi: 10.1161/HYPERTENSIONAHA.114.04824), which published online ahead of print December 22, 2014, and appeared in the March 2015 issue of the journal, some corrections were needed.On page 632, Figure, panel A, the label PRI has been corrected to read RPI. In panel B, the text by the upward arrow, "10% increase in kd,” has been corrected to read, "10% decrease in kd." The corrected figure is shown below.The authors apologize for these errors. PMID:26558821

  17. Corrective Action Investigation Plan for Corrective Action Unit 104: Area 7 Yucca Flat Atmospheric Test Sites, Nevada National Security Site, Nevada, Revision 0

    SciTech Connect

    Patrick Matthews

    2011-08-01

    CAU 104 comprises the 15 CASs listed below: (1) 07-23-03, Atmospheric Test Site T-7C; (2) 07-23-04, Atmospheric Test Site T7-1; (3) 07-23-05, Atmospheric Test Site; (4) 07-23-06, Atmospheric Test Site T7-5a; (5) 07-23-07, Atmospheric Test Site - Dog (T-S); (6) 07-23-08, Atmospheric Test Site - Baker (T-S); (7) 07-23-09, Atmospheric Test Site - Charlie (T-S); (8) 07-23-10, Atmospheric Test Site - Dixie; (9) 07-23-11, Atmospheric Test Site - Dixie; (10) 07-23-12, Atmospheric Test Site - Charlie (Bus); (11) 07-23-13, Atmospheric Test Site - Baker (Buster); (12) 07-23-14, Atmospheric Test Site - Ruth; (13) 07-23-15, Atmospheric Test Site T7-4; (14) 07-23-16, Atmospheric Test Site B7-b; (15) 07-23-17, Atmospheric Test Site - Climax These sites are being investigated because existing information on the nature and extent of potential contamination is insufficient to evaluate and recommend corrective action alternatives (CAAs). Additional information will be obtained by conducting a corrective action investigation before evaluating CAAs and selecting the appropriate corrective action for each CAS. The results of the field investigation will support a defensible evaluation of viable CAAs that will be presented in the Corrective Action Decision Document. The sites will be investigated based on the data quality objectives (DQOs) developed on April 28, 2011, by representatives of the Nevada Division of Environmental Protection and the U.S. Department of Energy (DOE), National Nuclear Security Administration Nevada Site Office. The DQO process was used to identify and define the type, amount, and quality of data needed to develop and evaluate appropriate corrective actions for CAU 104. The releases at CAU 104 consist of surface-deposited radionuclides from 30 atmospheric nuclear tests. The presence and nature of contamination at CAU 104 will be evaluated based on information collected from a field investigation. Radiological contamination will be evaluated based on a comparison

  18. Atmospheric correction in time-series SAR interferometry for land surface deformation mapping - A case study of Taiyuan, China

    NASA Astrophysics Data System (ADS)

    Tang, Wei; Liao, Mingsheng; Yuan, Peng

    2016-08-01

    The dominant error source of Synthetic Aperture Radar Interferometry (InSAR) is atmospheric phase screen (APS), resulting in phase delay of the radar signal propagating through the atmosphere. The APS in the atmosphere can be decomposed into stratified and turbulent components. In this paper, we introduced a method to compensate for stratified component in a radar interferogram using ERA-Interim reanalysis products obtained from European Centre for Medium-Range Weather Forecasts (ECMWF). Our comparative results with radiosonde data demonstrated that atmospheric condition from ERA-Interim could produce reasonable patterns of vertical profiles of atmospheric states. The stratified atmosphere shows seasonal changes which are correlated with time. It cannot be properly estimated by temporal high-pass filtering which assumes that atmospheric effects are random in time in conventional persistent scatterer InSAR (PSI). Thus, the estimated deformation velocity fields are biased. Therefore, we propose the atmosphere-corrected PSI method that the stratified delay are corrected on each interferogram by using ERA-Interim. The atmospheric residuals after correction of stratified delay were interpreted as random variations in space and time which are mitigated by using spatial-temporal filtering. We applied the proposed method to ENVISAT ASAR images covering Taiyuan basin, China, to study the ground deformation associated with groundwater withdrawal. Experimental results show that the proposed method significantly mitigate the topography-correlated APS and the estimated ground displacements agree more closely with GPS measurements than the conventional PSI.

  19. Comparison of three atmospheric correction models for a vegetated airborne visible/infrared imaging spectrometer (AVIRIS) scene

    NASA Technical Reports Server (NTRS)

    Van Den Bosch, J. M.; Alley, R. E.

    1991-01-01

    Current atmospheric correction models applied to imaging spectroscopy data include such methods as residual or scene average, flat field correction, regression method or empirical line algorithm, the continuum interpolated band ratio (CIBR) derivation and the LOWTRAN 7 method. Due to the limitations of using residual and flat field corrections on vegetated scenes, three methods will be compared: regression, CIBR derivation and LOWTRAN 7. Field-measured bright and dark targets taken at the time of the 13 April, 1989 AVIRIS overflight of Jasper Ridge, California were used to formulate the regression method atmospheric correction. Using this corrected scene as 'ground truth', the CIBR derivation and the LOWTRAN 7 method with both input models are compared on the vegetated Jasper Ridge scene. Although representing a qualitative approach, this is a first approximation and shows the need for more quantitative analysis.

  20. Correction

    NASA Astrophysics Data System (ADS)

    1995-04-01

    Seismic images of the Brooks Range, Arctic Alaska, reveal crustal-scale duplexing: Correction Geology, v. 23, p. 65 68 (January 1995) The correct Figure 4A, for the loose insert, is given here. See Figure 4A below. Corrected inserts will be available to those requesting copies of the article from the senior author, Gary S. Fuis, U.S. Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025. Figure 4A. P-wave velocity model of Brooks Range region (thin gray contours) with migrated wide-angle reflections (heavy red lines) and migreated vertical-incidence reflections (short black lines) superimposed. Velocity contour interval is 0.25 km/s; 4,5, and 6 km/s contours are labeled. Estimated error in velocities is one contour interval. Symbols on faults shown at top are as in Figure 2 caption.

  1. An Evaluation of the Nonlinearity Correction Applied to Atmospheric Emitted Radiance Interferometer (AERI) Data Collected by the Atmospheric Radiation Measurement Program

    SciTech Connect

    Turner, D. D.; Knuteson, R. O.; Revercomb, H. E.; Dedecker, R. G.; Feltz, W. F.

    2004-09-01

    Mercury Cadmium Telluride (MCT) detectors provide excellent sensitivity to infrared radiation and are used in passive infrared remote sensors such as the Atmospheric Emitted Radiance Interferometer (AERI). However, MCT detectors have a nonlinear response and thus this nonlinearity must be characterized and corrected to provide accurate infrared radiance observations. This paper discusses the significance of the nonlinearity correction applied to AERI data and its impacts on the parameters retrieved from the AERI spectra. It also evaluates the accuracy of the scheme used to determine the nonlinearity of the MCT detectors used in the Atmospheric Radiation Measurement (ARM) Program’s AERIs.

  2. Experimental analysis of the fitting error of diffractive liquid crystal wavefront correctors for atmospheric turbulence corrections

    NASA Astrophysics Data System (ADS)

    Shao, Lina; Cao, Zhaoliang; Mu, Quanquan; Zhang, Peiguang; Yao, Lishuang; Wang, Shaoxin; Hu, Lifa; Xuan, Li

    2016-05-01

    An experimental analysis was conducted to investigate the fitting error of diffractive liquid crystal wavefront correctors (LCWFCs). First, an experiment was performed to validate the theoretical equations presented in our previous work Cao et al., 2009 [9]. The results showed an apparent discrepancy between the theoretical and measured results for the fitting error. This difference was examined and the influence of nonlinearities and rounding errors generated by the LCWFC was analyzed and discussed. Finally, the fitting error formula of the LCWFC was modified to obtain a more effective tool for the design of LCWFCs for atmospheric turbulence correction. These results will be useful for researchers who design liquid crystal adaptive optics systems for large-aperture ground-based telescopes.

  3. Energetics of the martian atmosphere using the Mars Analysis Correction Data Assimilation (MACDA) dataset

    NASA Astrophysics Data System (ADS)

    Battalio, Michael; Szunyogh, Istvan; Lemmon, Mark

    2016-09-01

    The energetics of the atmosphere of the northern hemisphere of Mars during the pre-winter solstice period are explored using the Mars Analysis Correction Data Assimilation (MACDA) dataset (v1.0) and the eddy kinetic energy equation, with the quasi-geostrophic omega equation providing vertical velocities. Traveling waves are typically triggered by geopotential flux convergence. The effect of dust on baroclinic instability is examined by comparing a year with a global-scale dust storm (GDS) to two years without a global-scale dust storm. During the non-GDS years, results agree with that of a previous study using a general circulation model simulation. In the GDS year, waves develop a mixed baroclinic/barotropic growth phase before decaying barotropically. Though the total amount of eddy kinetic energy generated by baroclinic energy conversion is lower during the GDS year, the maximum eddy intensity is not diminished. Instead, the number of intense eddies is reduced by about 50%.

  4. Clear water radiances for atmospheric correction of coastal zone color scanner imagery

    NASA Technical Reports Server (NTRS)

    Gordon, H. R.; Clark, D. K.

    1981-01-01

    The possibility of computing the inherent sea surface radiance for regions of clear water from coastal zone color scanner (CZCS) imagery given only a knowledge of the local solar zenith angle is examined. The inherent sea surface radiance is related to the upwelling and downwelling irradiances just beneath the sea surface, and an expression is obtained for a normalized inherent sea surface radiance which is nearly independent of solar zenith angle for low phytoplankton pigment concentrations. An analysis of a data base consisting of vertical profiles of upwelled spectral radiance and pigment concentration, which was used in the development of the CZCS program, confirms the virtual constancy of the normalized inherent sea surface radiance at wavelengths of 520 and 550 nm for cases when the pigment concentration is less than 0.25 mg/cu m. A strategy is then developed for using the normalized inherent sea surface radiance in the atmospheric correction of CZCS imagery.

  5. Correction.

    PubMed

    2016-02-01

    Neogi T, Jansen TLTA, Dalbeth N, et al. 2015 Gout classification criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative. Ann Rheum Dis 2015;74:1789–98. The name of the 20th author was misspelled. The correct spelling is Janitzia Vazquez-Mellado. We regret the error. PMID:26881284

  6. An improved atmospheric correction algorithm for applying MERIS data to very turbid inland waters

    NASA Astrophysics Data System (ADS)

    Jaelani, Lalu Muhamad; Matsushita, Bunkei; Yang, Wei; Fukushima, Takehiko

    2015-07-01

    Atmospheric correction (AC) is a necessary process when quantitatively monitoring water quality parameters from satellite data. However, it is still a major challenge to carry out AC for turbid coastal and inland waters. In this study, we propose an improved AC algorithm named N-GWI (new standard Gordon and Wang's algorithms with an iterative process and a bio-optical model) for applying MERIS data to very turbid inland waters (i.e., waters with a water-leaving reflectance at 864.8 nm between 0.001 and 0.01). The N-GWI algorithm incorporates three improvements to avoid certain invalid assumptions that limit the applicability of the existing algorithms in very turbid inland waters. First, the N-GWI uses a fixed aerosol type (coastal aerosol) but permits aerosol concentration to vary at each pixel; this improvement omits a complicated requirement for aerosol model selection based only on satellite data. Second, it shifts the reference band from 670 nm to 754 nm to validate the assumption that the total absorption coefficient at the reference band can be replaced by that of pure water, and thus can avoid the uncorrected estimation of the total absorption coefficient at the reference band in very turbid waters. Third, the N-GWI generates a semi-analytical relationship instead of an empirical one for estimation of the spectral slope of particle backscattering. Our analysis showed that the N-GWI improved the accuracy of atmospheric correction in two very turbid Asian lakes (Lake Kasumigaura, Japan and Lake Dianchi, China), with a normalized mean absolute error (NMAE) of less than 22% for wavelengths longer than 620 nm. However, the N-GWI exhibited poor performance in moderately turbid waters (the NMAE values were larger than 83.6% in the four American coastal waters). The applicability of the N-GWI, which includes both advantages and limitations, was discussed.

  7. Automated Burned Area Delineation Using IRS AWiFS satellite data

    NASA Astrophysics Data System (ADS)

    Singhal, J.; Kiranchand, T. R.; Rajashekar, G.; Jha, C. S.

    2014-12-01

    spectral data from the IRS AWiFS sensor. The method is intended to be used by non-specialist users for diagnostic rapid burnt area mapping.

  8. Improved Correction of Atmospheric Pressure Data Obtained by Smartphones through Machine Learning

    PubMed Central

    Kim, Yong-Hyuk; Ha, Ji-Hun; Kim, Na-Young; Im, Hyo-Hyuc; Sim, Sangjin; Choi, Reno K. Y.

    2016-01-01

    A correction method using machine learning aims to improve the conventional linear regression (LR) based method for correction of atmospheric pressure data obtained by smartphones. The method proposed in this study conducts clustering and regression analysis with time domain classification. Data obtained in Gyeonggi-do, one of the most populous provinces in South Korea surrounding Seoul with the size of 10,000 km2, from July 2014 through December 2014, using smartphones were classified with respect to time of day (daytime or nighttime) as well as day of the week (weekday or weekend) and the user's mobility, prior to the expectation-maximization (EM) clustering. Subsequently, the results were analyzed for comparison by applying machine learning methods such as multilayer perceptron (MLP) and support vector regression (SVR). The results showed a mean absolute error (MAE) 26% lower on average when regression analysis was performed through EM clustering compared to that obtained without EM clustering. For machine learning methods, the MAE for SVR was around 31% lower for LR and about 19% lower for MLP. It is concluded that pressure data from smartphones are as good as the ones from national automatic weather station (AWS) network. PMID:27524999

  9. Improved Correction of Atmospheric Pressure Data Obtained by Smartphones through Machine Learning.

    PubMed

    Kim, Yong-Hyuk; Ha, Ji-Hun; Yoon, Yourim; Kim, Na-Young; Im, Hyo-Hyuc; Sim, Sangjin; Choi, Reno K Y

    2016-01-01

    A correction method using machine learning aims to improve the conventional linear regression (LR) based method for correction of atmospheric pressure data obtained by smartphones. The method proposed in this study conducts clustering and regression analysis with time domain classification. Data obtained in Gyeonggi-do, one of the most populous provinces in South Korea surrounding Seoul with the size of 10,000 km(2), from July 2014 through December 2014, using smartphones were classified with respect to time of day (daytime or nighttime) as well as day of the week (weekday or weekend) and the user's mobility, prior to the expectation-maximization (EM) clustering. Subsequently, the results were analyzed for comparison by applying machine learning methods such as multilayer perceptron (MLP) and support vector regression (SVR). The results showed a mean absolute error (MAE) 26% lower on average when regression analysis was performed through EM clustering compared to that obtained without EM clustering. For machine learning methods, the MAE for SVR was around 31% lower for LR and about 19% lower for MLP. It is concluded that pressure data from smartphones are as good as the ones from national automatic weather station (AWS) network. PMID:27524999

  10. Convective Flow Patterns in Time-Distance Measurements and "Magnetic Corrections" in Vertically Stratified Atmosphere.

    NASA Astrophysics Data System (ADS)

    Ryutova, M.; Scherrer, P.

    1997-05-01

    Time-distance measurements for the reconstruction of subsurface flows and horizontal magnetic fields proved to be very efficient. However, if one can expect a reasonable accuracy of reconstructed maps for the annuli of the radius small compared to the characteristic scale of the convection, the situation changes when annular distances become comparable with the scale of granular, mezogranular, or supergranular convective motions: in each of these cases the uncertainty in the measurements of travel time perturbations increases dramatically. We present here a quantitative analysis of the problem for a particular model of convective motions and compute the travel time perturbations as a function of annular distances and the supergranule radius. It is shown that at annular sizes close to the size of convective cell there occurs: (1) the apparent reduction of the local velocity, and (2) appearance of additional terms in the corrections to perturbation travel time which cause a large error in reconstruction of the velocity field. We discuss the importance of "directionally sensitive" measurements and show that Fourier sin ntheta , cos ntheta transforms of travel times measured as a function of direction, "kills" the largest source of errors. We discuss the role of vertical motions. We also present the expressions for the "magnetic corrections" in a vertically stratified atmosphere. This research is supported by NASA contract NAG5-3077 at Stanford University and the MDI contract PR 9162 at Lockheed.

  11. The effect of anthropogenic emissions corrections on the seasonal cycle of atmospheric CO2

    SciTech Connect

    Hoffman, Forrest M; Erickson III, David J; Blasing, T J

    2009-01-01

    A previous study (Erickson et al. 2008) approximated the monthly global emission estimates of anthropogenic CO{sub 2} by applying a 2-harmonic Fourier expansion with coefficients as a function of latitude to annual CO{sub 2} flux estimates derived from United States data (Blasing et al. 2005) that were extrapolated globally. These monthly anthropogenic CO{sub 2} flux estimates were used to model atmospheric concentrations using the NASA GEOS-4 data assimilation system. Local variability in the amplitude of the simulated CO{sub 2} seasonal cycle were found to be on the order of 2-6 ppmv. Here we used the same Fourier expansion to seasonally adjust the global annual fossil fuel CO{sub 2} emissions from the SRES A2 scenario. For a total of four simulations, both the annual and seasonalized fluxes were advected in two configurations of the NCAR Community Atmosphere Model (CAM) used in the Carbon-Land Model Intercomparison Project (C-LAMP). One configuration used the NCAR Community Land Model (CLM) coupled with the CASA (carbon only) biogeochemistry model and the other used CLM coupled with the CN (coupled carbon and nitrogen cycles) biogeochemistry model. All four simulations were forced with observed sea surface temperatures and sea ice concentrations from the Hadley Centre and a prescribed transient atmospheric CO{sub 2} concentration for the radiation and land forcing over the 20th century. The model results exhibit differences in the seasonal cycle of CO{sub 2} between the seasonally corrected and uncorrected simulations. Moreover, because of differing energy and water feedbacks between the atmosphere model and the two land biogeochemistry models, features of the CO{sub 2} seasonal cycle were different between these two model configurations. This study reinforces previous findings that suggest that regional near-surface atmospheric CO{sub 2} concentrations depend strongly on the natural sources and sinks of CO{sub 2}, but also on the strength of local anthropogenic

  12. Iterative Atmospheric Correction Scheme and the Polarization Color of Alpine Snow

    NASA Technical Reports Server (NTRS)

    Ottaviani, Matteo; Cairns, Brian; Ferrare, Rich; Rogers, Raymond

    2012-01-01

    Characterization of the Earth's surface is crucial to remote sensing, both to map geomorphological features and because subtracting this signal is essential during retrievals of the atmospheric constituents located between the surface and the sensor. Current operational algorithms model the surface total reflectance through a weighted linear combination of a few geometry-dependent kernels, each devised to describe a particular scattering mechanism. The information content of these measurements is overwhelmed by that of instruments with polarization capabilities: proposed models in this case are based on the Fresnel reflectance of an isotropic distribution of facets. Because of its remarkable lack of spectral contrast, the polarized reflectance of land surfaces in the shortwave infrared spectral region, where atmospheric scattering is minimal, can be used to model the surface also at shorter wavelengths, where aerosol retrievals are attempted based on well-established scattering theories. In radiative transfer simulations, straightforward separation of the surface and atmospheric contributions is not possible without approximations because of the coupling introduced by multiple reflections. Within a general inversion framework, the problem can be eliminated by linearizing the radiative transfer calculation, and making the Jacobian (i.e., the derivative expressing the sensitivity of the reflectance with respect to model parameters) available at output. We present a general methodology based on a Gauss-Newton iterative search, which automates this procedure and eliminates de facto the need of an ad hoc atmospheric correction. In this case study we analyze the color variations in the polarized reflectance measured by the NASA Goddard Institute of Space Studies Research Scanning Polarimeter during a survey of late-season snowfields in the High Sierra. This insofar unique dataset presents challenges linked to the rugged topography associated with the alpine environment

  13. Algorithm for Atmospheric and Glint Corrections of Satellite Measurements of Ocean Pigment

    NASA Technical Reports Server (NTRS)

    Fraser, Robert S.; Mattoo, Shana; Yeh, Eueng-Nan; McClain, C. R.

    1997-01-01

    An algorithm is developed to correct satellite measurements of ocean color for atmospheric and surface reflection effects. The algorithm depends on taking the difference between measured and tabulated radiances for deriving water-leaving radiances. 'ne tabulated radiances are related to the measured radiance where the water-leaving radiance is negligible (670 nm). The tabulated radiances are calculated for rough surface reflection, polarization of the scattered light, and multiple scattering. The accuracy of the tables is discussed. The method is validated by simulating the effect of different wind speeds than that for which the lookup table is calculated, and aerosol models different from the maritime model for which the table is computed. The derived water-leaving radiances are accurate enough to compute the pigment concentration with an error of less than q 15% for wind speeds of 6 and 10 m/s and an urban atmosphere with aerosol optical thickness of 0.20 at lambda 443 nm and decreasing to 0.10 at lambda 670 nm. The pigment accuracy is less for wind speeds less than 6 m/s and is about 30% for a model with aeolian dust. On the other hand, in a preliminary comparison with coastal zone color scanner (CZCS) measurements this algorithm and the CZCS operational algorithm produced values of pigment concentration in one image that agreed closely.

  14. Retrieval of Marine Water Constituents Using Atmospherically Corrected AVIRIS Hyperspectral Data

    NASA Technical Reports Server (NTRS)

    Bagheri, Sima; Peters, Steef

    2004-01-01

    This paper reports on the validation of bio-optical models in estuarine and nearshore (case 2) waters of New Jersey-New York to retrieve accurate water-leaving radiance spectra and chlorophyll concentration from the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) imaging spectrometer data. MODTRAN-4 was applied to remove the effects of the atmosphere so as to infer the water-leaving radiance. The study area - Hudson/Raritan of New York and New Jersey (Figure 1) is an extremely complex estuarine system where tidal and wind-driven currents are modified by freshwater discharges from the Hudson, Raritan, Hackensack, and Passaic rivers. Over the last century, the estuarine water quality has degraded in part due to eutrophication, which has disrupted the preexisting natural balance, resulting in phytoplankton blooms of both increased frequency and intensity, increasing oxygen demand, and leading to episodes of hypoxia. As the end result, a thematic map of chlorophyll-a concentration was generated using an atmospherically corrected AVIRIS ratio image. This thematic map serves as an indication of phytoplankton concentration. Such maps are important input into the geographic information system (GIS) for use as a management tool for monitoring water resources.

  15. Corrective Action Decision Document/Closure Report for Corrective Action Unit 106: Area 5, 11 Frenchman Flat Atmospheric Sites, Nevada National Security Site, Nevada, Revision 0

    SciTech Connect

    Patrick Matthews and Dawn Peterson

    2011-09-01

    Corrective Action Unit 106 comprises four corrective action sites (CASs): (1) 05-20-02, Evaporation Pond; (2) 05-23-05, Atmospheric Test Site - Able; (3) 05-45-04, 306 GZ Rad Contaminated Area; (4) 05-45-05, 307 GZ Rad Contaminated Area. The purpose of this CADD/CR is to provide justification and documentation supporting the recommendation that no further corrective action is needed for CAU 106 based on the implementation of corrective actions. The corrective action of clean closure was implemented at CASs 05-45-04 and 05-45-05, while no corrective action was necessary at CASs 05-20-02 and 05-23-05. Corrective action investigation (CAI) activities were performed from October 20, 2010, through June 1, 2011, as set forth in the Corrective Action Investigation Plan for Corrective Action Unit 106: Areas 5, 11 Frenchman Flat Atmospheric Sites. The approach for the CAI was divided into two facets: investigation of the primary release of radionuclides, and investigation of other releases (mechanical displacement and chemical releases). The purpose of the CAI was to fulfill data needs as defined during the data quality objective (DQO) process. The CAU 106 dataset of investigation results was evaluated based on a data quality assessment. This assessment demonstrated the dataset is complete and acceptable for use in fulfilling the DQO data needs. Investigation results were evaluated against final action levels (FALs) established in this document. A radiological dose FAL of 25 millirem per year was established based on the Industrial Area exposure scenario (2,250 hours of annual exposure). The only radiological dose exceeding the FAL was at CAS 05-45-05 and was associated with potential source material (PSM). It is also assumed that additional PSM in the form of depleted uranium (DU) and DU-contaminated debris at CASs 05-45-04 and 05-45-05 exceed the FAL. Therefore, corrective actions were undertaken at these CASs that consisted of removing PSM and collecting verification

  16. Corrective Action Investigation Plan for Corrective Action Unit 370: T-4 Atmospheric Test Site, Nevada Test Site, Nevada with ROTC-1, Revision 0

    SciTech Connect

    Pat Matthews

    2008-04-01

    Corrective Action Unit (CAU) 370 is located in Area 4 of the Nevada Test Site, which is approximately 65 miles northwest of Las Vegas, Nevada. Corrective Action Unit 370 is comprised of Corrective Action Site (CAS) 04-23-01, Atmospheric Test Site T-4. This site is being investigated because existing information on the nature and extent of potential contamination is insufficient to evaluate and/or implement a corrective action. Additional information will be obtained by conducting a corrective action investigation (CAI) before evaluating corrective action alternatives and selecting the appropriate corrective action for this CAS. The results of the field investigation will support a defensible evaluation of viable corrective action alternatives that will be presented in the Corrective Action Decision Document. The investigation results may also be used to evaluate improvements in the Soils Project strategy to be implemented. The site will be investigated based on the data quality objectives (DQOs) developed on December 10, 2007, by representatives of the Nevada Division of Environmental Protection; U.S. Department of Energy (DOE), National Nuclear Security Administration Nevada Site Office; Desert Research Institute; Stoller-Navarro Joint Venture; and National Security Technologies, LLC. The DQO process was used to identify and define the type, amount, and quality of data needed to develop and evaluate appropriate corrective actions for CAU 370. Appendix A provides a detailed discussion of the DQO methodology and the DQOs specific to the CAS. The scope of the CAI for CAU 370 includes the following activities: • Move surface debris and/or materials, as needed, to facilitate sampling. • Conduct radiological surveys. • Perform field screening. • Collect and submit environmental samples for laboratory analysis to determine whether contaminants of concern are present. • If contaminants of concern are present, collect samples to define the extent of the

  17. Validation and robustness of an atmospheric correction algorithm for hyperspectral images

    NASA Astrophysics Data System (ADS)

    Boucher, Yannick; Poutier, Laurent; Achard, Veronique; Lenot, Xavier; Miesch, Christophe

    2002-08-01

    The Optics Department of ONERA has developed and implemented an inverse algorithm, COSHISE, to correct hyperspectral images of the atmosphere effects in the visible-NIR-SWIR domain (0,4-2,5 micrometers ). This algorithm automatically determine the integrated water-vapor content for each pixel, from the radiance at sensor level by using a LIRR-type (Linear Regression Ratio) technique. It then retrieves the spectral reflectance at ground level using atmospheric parameters computed with Modtran4, included the water-vapor spatial dependence as obtained in the first stop. The adjacency effects are taken into account using spectral kernels obtained by two Monte-Carlo codes. Results obtained with COCHISE code on real hyperspectral data are first compared to ground based reflectance measurements. AVIRIS images of Railroad Valley Playa, CA, and HyMap images of Hartheim, France, are use. The inverted reflectance agrees perfectly with the measurement at ground level for the AVIRIS data set, which validates COCHISE algorithm/ for the HyMap data set, the results are still good but cannot be considered as validating the code. The robustness of COCHISE code is evaluated. For this, spectral radiance images are modeled at the sensor level, with the direct algorithm COMANCHE, which is the reciprocal code of COCHISE. The COCHISE algorithm is then used to compute the reflectance at ground level from the simulated at-sensor radiance. A sensitivity analysis has been performed, as a function of errors on several atmospheric parameter and instruments defaults, by comparing the retrieved reflectance with the original one. COCHISE code shows a quite good robustness to errors on input parameter, except for aerosol type.

  18. Correction.

    PubMed

    2016-02-01

    In the article by Guessous et al (Guessous I, Pruijm M, Ponte B, Ackermann D, Ehret G, Ansermot N, Vuistiner P, Staessen J, Gu Y, Paccaud F, Mohaupt M, Vogt B, Pechère-Bertschi A, Martin PY, Burnier M, Eap CB, Bochud M. Associations of ambulatory blood pressure with urinary caffeine and caffeine metabolite excretions. Hypertension. 2015;65:691–696. doi: 10.1161/HYPERTENSIONAHA.114.04512), which published online ahead of print December 8, 2014, and appeared in the March 2015 issue of the journal, a correction was needed.One of the author surnames was misspelled. Antoinette Pechère-Berstchi has been corrected to read Antoinette Pechère-Bertschi.The authors apologize for this error. PMID:26763012

  19. Correction of Atmospheric Haze in RESOURCESAT-1 LISS-4 MX Data for Urban Analysis: AN Improved Dark Object Subtraction Approach

    NASA Astrophysics Data System (ADS)

    Mustak, S.

    2013-09-01

    The correction of atmospheric effects is very essential because visible bands of shorter wavelength are highly affected by atmospheric scattering especially of Rayleigh scattering. The objectives of the paper is to find out the haze values present in the all spectral bands and to correct the haze values for urban analysis. In this paper, Improved Dark Object Subtraction method of P. Chavez (1988) is applied for the correction of atmospheric haze in the Resoucesat-1 LISS-4 multispectral satellite image. Dark object Subtraction is a very simple image-based method of atmospheric haze which assumes that there are at least a few pixels within an image which should be black (% reflectance) and such black reflectance termed as dark object which are clear water body and shadows whose DN values zero (0) or Close to zero in the image. Simple Dark Object Subtraction method is a first order atmospheric correction but Improved Dark Object Subtraction method which tends to correct the Haze in terms of atmospheric scattering and path radiance based on the power law of relative scattering effect of atmosphere. The haze values extracted using Simple Dark Object Subtraction method for Green band (Band2), Red band (Band3) and NIR band (band4) are 40, 34 and 18 but the haze values extracted using Improved Dark Object Subtraction method are 40, 18.02 and 11.80 for aforesaid bands. Here it is concluded that the haze values extracted by Improved Dark Object Subtraction method provides more realistic results than Simple Dark Object Subtraction method.

  20. Corrective Action Investigation Plan for Corrective Action Unit 105: Area 2 Yucca Flat Atmospheric Test Sites Nevada National Security Site, Nevada, Revision 0

    SciTech Connect

    Patrick Matthews

    2012-09-01

    Corrective Action Unit (CAU) 105 is located in Area 2 of the Nevada National Security Site, which is approximately 65 miles northwest of Las Vegas, Nevada. CAU 105 is a geographical grouping of sites where there has been a suspected release of contamination associated with atmospheric nuclear testing. This document describes the planned investigation of CAU 105, which comprises the following corrective action sites (CASs): • 02-23-04, Atmospheric Test Site - Whitney • 02-23-05, Atmospheric Test Site T-2A • 02-23-06, Atmospheric Test Site T-2B • 02-23-08, Atmospheric Test Site T-2 • 02-23-09, Atmospheric Test Site - Turk These sites are being investigated because existing information on the nature and extent of potential contamination is insufficient to evaluate and recommend corrective action alternatives (CAAs). Additional information will be obtained by conducting a corrective action investigation before evaluating CAAs and selecting the appropriate corrective action for each CAS. The results of the field investigation will support a defensible evaluation of viable CAAs that will be presented in the Corrective Action Decision Document. The sites will be investigated based on the data quality objectives (DQOs) developed on April 30, 2012, by representatives of the Nevada Division of Environmental Protection and the U.S. Department of Energy (DOE), National Nuclear Security Administration Nevada Site Office. The DQO process was used to identify and define the type, amount, and quality of data needed to develop and evaluate appropriate corrective actions for CAU 105. The site investigation process will also be conducted in accordance with the Soils Activity Quality Assurance Plan, which establishes requirements, technical planning, and general quality practices to be applied to this activity. The potential contamination sources associated with all CAU 105 CASs are from atmospheric nuclear testing activities. The presence and nature of contamination at CAU

  1. Precipitation effects on the selection of suitable non-variant targets intended for atmospheric correction of satellite remotely sensed imagery

    NASA Astrophysics Data System (ADS)

    Themistocleous, Kyriacos; Hadjimitsis, Diofantos G.; Retalis, Adrianos; Chrysoulakis, Nektarios; Michaelides, Silas

    2013-09-01

    One of the most well-established atmospheric correction methods of satellite imagery is the use of the empirical line method using non-variant targets. Non-variant targets serve as pseudo-invariant targets since their reflectance values are stable across time. A recent adaptation of the empirical line method incorporates the use of ground reflectance measurements of selected non-variant targets. Most of the users are not aware of the existing conditions of the pseudo-invariant targets; i.e., whether they are dry or wet. Any omission of such effects may cause erroneous results; therefore, remote sensing users must be aware of such effects. This study assessed the effects of precipitation on five types of commonly located surfaces, including asphalt, concrete and sand, intended as pseudo-invariant targets for atmospheric correction. Spectroradiometric measurements were taken in wet and dry conditions to obtain the spectral signatures of the targets, from January 2010 to May 2011 (46 campaigns). An atmospheric correction of eleven Landsat TM/ETM + satellite images using the empirical line method was conducted. To identify the effects of precipitation, a comparison was conducted of the atmospheric path radiance component for wet and dry conditions. It was found that precipitation conditions such as rainfall affected the reflectance values of the surfaces, especially sand. Therefore, precipitation conditions need to be considered when using non-variant targets in atmospheric correction methods.

  2. Corrective Action Investigation Plan for Corrective Action Unit 570: Area 9 Yucca Flat Atmospheric Test Sites Nevada National Security Site, Nevada, Revision 0

    SciTech Connect

    Patrick Matthews

    2012-08-01

    CAU 570 comprises the following six corrective action sites (CASs): • 02-23-07, Atmospheric Test Site - Tesla • 09-23-10, Atmospheric Test Site T-9 • 09-23-11, Atmospheric Test Site S-9G • 09-23-14, Atmospheric Test Site - Rushmore • 09-23-15, Eagle Contamination Area • 09-99-01, Atmospheric Test Site B-9A These sites are being investigated because existing information on the nature and extent of potential contamination is insufficient to evaluate and recommend corrective action alternatives (CAAs). Additional information will be obtained by conducting a corrective action investigation before evaluating CAAs and selecting the appropriate corrective action for each CAS. The results of the field investigation will support a defensible evaluation of viable CAAs that will be presented in the Corrective Action Decision Document. The sites will be investigated based on the data quality objectives (DQOs) developed on April 30, 2012, by representatives of the Nevada Division of Environmental Protection and the U.S. Department of Energy (DOE), National Nuclear Security Administration Nevada Site Office. The DQO process was used to identify and define the type, amount, and quality of data needed to develop and evaluate appropriate corrective actions for CAU 570. The site investigation process will also be conducted in accordance with the Soils Activity Quality Assurance Plan, which establishes requirements, technical planning, and general quality practices to be applied to this activity. The presence and nature of contamination at CAU 570 will be evaluated based on information collected from a field investigation. Radiological contamination will be evaluated based on a comparison of the total effective dose at sample locations to the dose-based final action level. The total effective dose will be calculated as the total of separate estimates of internal and external dose. Results from the analysis of soil samples will be used to calculate internal radiological

  3. Validation of Atmospheric Correction of Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) Radiance Data Based on Radiative Transfer Modeling

    NASA Technical Reports Server (NTRS)

    Carrare, V.; Conel, J. E.

    1993-01-01

    An evaluation of atmospheric correction of AVIRIS data using radiative transfer codes LOWTRAN7 and MODTRAN is presented. The algorithm employed is based on a simple model of radiance L at each wavelength at the sensor that can be written approximately LAV=Lp+Tp, where subscript AV referes to AVIRIS, Lp is the path radiance and Tp is the diffuse + direct transmitted radiance of the atmosphere at AVIRIS.

  4. Correction.

    PubMed

    2015-05-22

    The Circulation Research article by Keith and Bolli (“String Theory” of c-kitpos Cardiac Cells: A New Paradigm Regarding the Nature of These Cells That May Reconcile Apparently Discrepant Results. Circ Res. 2015:116:1216-1230. doi: 10.1161/CIRCRESAHA.116.305557) states that van Berlo et al (2014) observed that large numbers of fibroblasts and adventitial cells, some smooth muscle and endothelial cells, and rare cardiomyocytes originated from c-kit positive progenitors. However, van Berlo et al reported that only occasional fibroblasts and adventitial cells derived from c-kit positive progenitors in their studies. Accordingly, the review has been corrected to indicate that van Berlo et al (2014) observed that large numbers of endothelial cells, with some smooth muscle cells and fibroblasts, and more rarely cardiomyocytes, originated from c-kit positive progenitors in their murine model. The authors apologize for this error, and the error has been noted and corrected in the online version of the article, which is available at http://circres.ahajournals.org/content/116/7/1216.full ( PMID:25999426

  5. Correction

    NASA Astrophysics Data System (ADS)

    1998-12-01

    Alleged mosasaur bite marks on Late Cretaceous ammonites are limpet (patellogastropod) home scars Geology, v. 26, p. 947 950 (October 1998) This article had the following printing errors: p. 947, Abstract, line 11, “sepia” should be “septa” p. 947, 1st paragraph under Introduction, line 2, “creep” should be “deep” p. 948, column 1, 2nd paragraph, line 7, “creep” should be “deep” p. 949, column 1, 1st paragraph, line 1, “creep” should be “deep” p. 949, column 1, 1st paragraph, line 5, “19774” should be “1977)” p. 949, column 1, 4th paragraph, line 7, “in particular” should be “In particular” CORRECTION Mammalian community response to the latest Paleocene thermal maximum: An isotaphonomic study in the northern Bighorn Basin, Wyoming Geology, v. 26, p. 1011 1014 (November 1998) An error appeared in the References Cited. The correct reference appears below: Fricke, H. C., Clyde, W. C., O'Neil, J. R., and Gingerich, P. D., 1998, Evidence for rapid climate change in North America during the latest Paleocene thermal maximum: Oxygen isotope compositions of biogenic phosphate from the Bighorn Basin (Wyoming): Earth and Planetary Science Letters, v. 160, p. 193 208.

  6. Corrective Action Investigation Plan for Corrective Action Unit 106: Areas 5, 11 Frenchman Flat Atmospheric Sites, Nevada National Security Site, Nevada

    SciTech Connect

    Patrick Matthews

    2011-07-01

    Corrective Action Unit 106 comprises the four corrective action sites (CASs) listed below: • 05-20-02, Evaporation Pond • 05-23-05, Atmospheric Test Site - Able • 05-45-04, 306 GZ Rad Contaminated Area • 05-45-05, 307 GZ Rad Contaminated Area These sites are being investigated because existing information on the nature and extent of potential contamination is insufficient to evaluate and recommend corrective action alternatives (CAAs). Additional information will be obtained by conducting a corrective action investigation before evaluating CAAs and selecting the appropriate corrective action for each CAS. The results of the field investigation will support a defensible evaluation of viable CAAs that will be presented in the Corrective Action Decision Document. The sites will be investigated based on the data quality objectives (DQOs) developed on January 19, 2010, by representatives of the Nevada Division of Environmental Protection and the U.S. Department of Energy (DOE), National Nuclear Security Administration Nevada Site Office. The DQO process was used to identify and define the type, amount, and quality of data needed to develop and evaluate appropriate corrective actions for CAU 106. The presence and nature of contamination at CAU 106 will be evaluated based on information collected from a field investigation. The CAU includes land areas impacted by the release of radionuclides from groundwater pumping during the Radionuclide Migration study program (CAS 05-20-02), a weapons-related airdrop test (CAS 05-23-05), and unknown support activities at two sites (CAS 05-45-04 and CAS 05-45-05). The presence and nature of contamination from surface-deposited radiological contamination from CAS 05-23-05, Atmospheric Test Site - Able, and other types of releases (such as migration and excavation as well as any potential releases discovered during the investigation) from the remaining three CASs will be evaluated using soil samples collected from the locations

  7. Using Graphical Processing Units to Accelerate Orthorectification, Atmospheric Correction and Transformations for Big Data

    NASA Astrophysics Data System (ADS)

    O'Connor, A. S.; Justice, B.; Harris, A. T.

    2013-12-01

    Graphics Processing Units (GPUs) are high-performance multiple-core processors capable of very high computational speeds and large data throughput. Modern GPUs are inexpensive and widely available commercially. These are general-purpose parallel processors with support for a variety of programming interfaces, including industry standard languages such as C. GPU implementations of algorithms that are well suited for parallel processing can often achieve speedups of several orders of magnitude over optimized CPU codes. Significant improvements in speeds for imagery orthorectification, atmospheric correction, target detection and image transformations like Independent Components Analsyis (ICA) have been achieved using GPU-based implementations. Additional optimizations, when factored in with GPU processing capabilities, can provide 50x - 100x reduction in the time required to process large imagery. Exelis Visual Information Solutions (VIS) has implemented a CUDA based GPU processing frame work for accelerating ENVI and IDL processes that can best take advantage of parallelization. Testing Exelis VIS has performed shows that orthorectification can take as long as two hours with a WorldView1 35,0000 x 35,000 pixel image. With GPU orthorecification, the same orthorectification process takes three minutes. By speeding up image processing, imagery can successfully be used by first responders, scientists making rapid discoveries with near real time data, and provides an operational component to data centers needing to quickly process and disseminate data.

  8. Atmospheric Pre-Corrected Differential Absorption Techniques to Retrieve Columnar Water Vapor: Theory and Simulations

    NASA Technical Reports Server (NTRS)

    Borel, Christoph C.; Schlaepfer, Daniel

    1996-01-01

    Two different approaches exist to retrieve columnar water vapor from imaging spectrometer data: (1) Differential absorption techniques based on: (a) Narrow-Wide (N/W) ratio between overlapping spectrally wide and narrow channels; (b) Continuum Interpolated Band Ratio (CIBR) between a measurement channel and the weighted sum of two reference channels. (2) Non-linear fitting techniques which are based on spectral radiative transfer calculations. The advantage of the first approach is computational speed and of the second, improved retrieval accuracy. Our goal was to improve the accuracy of the first technique using physics based on radiative transfer. Using a modified version of the Duntley equation, we derived an "Atmospheric Pre-corrected Differential Absorption" (APDA) technique and described an iterative scheme to retrieve water vapor on a pixel-by-pixel basis. Next we compared both, the CIBR and the APDA using the Duntley equation for MODTRAN3 computed irradiances, transmissions and path radiance (using the DISORT option). This simulation showed that the CIBR is very sensitive to reflectance effects and that the APDA performs much better. An extensive data set was created with the radiative transfer code 6S over 379 different ground reflectance spectra. The calculated relative water vapor error was reduced significantly for the APDA. The APDA technique had about 8% (vs. over 35% for the CIBR) of the 379 spectra with a relative water vapor error of greater than +5%. The APDA has been applied to 1991 and 1995 AVIRIS scenes which visually demonstrate the improvement over the CIBR technique.

  9. Impact of atmospheric correction and image filtering on hyperspectral classification of tree species using support vector machine

    NASA Astrophysics Data System (ADS)

    Shahriari Nia, Morteza; Wang, Daisy Zhe; Bohlman, Stephanie Ann; Gader, Paul; Graves, Sarah J.; Petrovic, Milenko

    2015-01-01

    Hyperspectral images can be used to identify savannah tree species at the landscape scale, which is a key step in measuring biomass and carbon, and tracking changes in species distributions, including invasive species, in these ecosystems. Before automated species mapping can be performed, image processing and atmospheric correction is often performed, which can potentially affect the performance of classification algorithms. We determine how three processing and correction techniques (atmospheric correction, Gaussian filters, and shade/green vegetation filters) affect the prediction accuracy of classification of tree species at pixel level from airborne visible/infrared imaging spectrometer imagery of longleaf pine savanna in Central Florida, United States. Species classification using fast line-of-sight atmospheric analysis of spectral hypercubes (FLAASH) atmospheric correction outperformed ATCOR in the majority of cases. Green vegetation (normalized difference vegetation index) and shade (near-infrared) filters did not increase classification accuracy when applied to large and continuous patches of specific species. Finally, applying a Gaussian filter reduces interband noise and increases species classification accuracy. Using the optimal preprocessing steps, our classification accuracy of six species classes is about 75%.

  10. Mass-dependent Corrections and Atmospheric Invasion: Working with the Radiocarbon Content of CO2 in the Soil Gas Environment

    NASA Astrophysics Data System (ADS)

    Egan, J. E.; Bowling, D. R.; Risk, D. A.

    2014-12-01

    Radiocarbon is becoming a more commonly utilized tool for C cycling studies, as it helps constrain biotic ecosystem processes such as C turnover times and sources of production. However, for studies that focus on CO2, the sampling methods for Δ14CO2 (surface chambers and subsurface gas wells) can be affected by abiotic processes, which may bias results as a function of gas transport regime (diffusion and advection). The radiocarbon community currently uses a δ13C correction to account for mass-dependent fractionation, but to date this correction has not been validated for the soil gas environment, where atmospheric invasion and gas transport are important. This study used an analytical soil gas transport model across a range of soil diffusivities and production rates, in which we could control Δ14CO2 and δ13CO2 signatures of production and atmosphere. This synthetic situation allowed us to assess the bias that results from using the conventional correction method for estimating Δ14CO2 of soil production. We found that the conventional correction is not strictly valid in this setting for interpreting the signature of production and does not account for diffusion and atmospheric invasion. The resultant Δ14CO2 bias scales with soil diffusivity and production rates. We propose a new two-step correction for Δ14CO2 work in the soil environment that accounts for atmospheric invasion and the δ13CO2 correction, and is able to reproduce a true value of Δ14CO2 of production. This work not only assists in data interpretation, but also helps clarify a methodological window of opportunity for accurately measuring the Δ14CO2 of soil production using subsurface sampling.

  11. Performance of the high-resolution atmospheric model HRRR-AK for correcting geodetic observations from spaceborne radars

    PubMed Central

    Gong, W; Meyer, F J; Webley, P; Morton, D

    2013-01-01

    [1] Atmospheric phase delays are considered to be one of the main performance limitations for high-quality satellite radar techniques, especially when applied to ground deformation monitoring. Numerical weather prediction (NWP) models are widely seen as a promising tool for the mitigation of atmospheric delays as they can provide knowledge of the atmospheric conditions at the time of Synthetic Aperture Radar data acquisition. However, a thorough statistical analysis of the performance of using NWP production in radar signal correction is missing to date. This study provides a quantitative analysis of the accuracy in using operational NWP products for signal delay correction in satellite radar geodetic remote sensing. The study focuses on the temperate, subarctic, and Arctic climate regions due to a prevalence of relevant geophysical signals in these areas. In this study, the operational High Resolution Rapid Refresh over the Alaska region (HRRR-AK) model is used and evaluated. Five test sites were selected over Alaska (AK), USA, covering a wide range of climatic regimes that are commonly encountered in high-latitude regions. The performance of the HRRR-AK NWP model for correcting absolute atmospheric range delays of radar signals is assessed by comparing to radiosonde observations. The average estimation accuracy for the one-way zenith total atmospheric delay from 24 h simulations was calculated to be better than ∼14 mm. This suggests that the HRRR-AK operational products are a good data source for spaceborne geodetic radar observations atmospheric delay correction, if the geophysical signal to be observed is larger than 20 mm. PMID:25973360

  12. The Innsbruck/ESO sky models and telluric correction tools. The possibility of atmospheric monitoring for Čerenkov telescopes

    NASA Astrophysics Data System (ADS)

    Kimeswenger, S.; Kausch, W.; Noll, S.; Jones, A. M.

    2015-03-01

    Ground-based astronomical observations are influenced by scattering and absorption by molecules and aerosols in the Earth's atmosphere. They are additionally affected by background emission from scattered moonlight, zodiacal light, scattered starlight, the atmosphere, and the telescope. These influences vary with environmental parameters like temperature, humidity, and chemical composition. Nowadays, this is corrected during data processing, mainly using semi-empirical methods and calibration by known sources. Part of the Austrian ESO in-kind contribution was a new model of the sky background, which is more complete and comprehensive than previous models. While the ground based astronomical observatories just have to correct for the line-of-sight integral of these effects, the Čerenkov telescopes use the atmosphere as the primary detector. The measured radiation originates at lower altitudes and does not pass through the entire atmosphere. Thus, a decent knowledge of the profile of the atmosphere at any time is required. The latter cannot be achieved by photometric measurements of stellar sources. We show here the capabilities of our sky background model and data reduction tools for ground-based optical/infrared telescopes. Furthermore, we discuss the feasibility of monitoring the atmosphere above any observing site, and thus, the possible application of the method for Čerenkov telescopes. Based on ESO archival data and observations obtained in programme ID 491.L-0659 at ESO VLT.

  13. Atmospheric pre-corrected differential absorption techniques to retrieve columnar water vapor: Theory and simulations

    SciTech Connect

    Borel, C.C.; Schlaepfer, D.

    1996-03-01

    Two different approaches exist to retrieve columnar water vapor from imaging spectrometer data: (1) Differential absorption techniques based on: (a) Narrow-Wide (N/W) ratio between overlapping spectrally wide and narrow channels (b) Continuum Interpolated Band Ratio (CIBR) between a measurement channel and the weighted sum of two reference channels; and (2) Non-linear fitting techniques which are based on spectral radiative transfer calculations. The advantage of the first approach is computational speed and of the second, improved retrieval accuracy. Our goal was to improve the accuracy of the first technique using physics based on radiative transfer. Using a modified version of the Duntley equation, we derived an {open_quote}Atmospheric Pre-corrected Differential Absorption{close_quote} (APDA) technique and described an iterative scheme to retrieve water vapor on a pixel-by-pixel basis. Next we compared both, the CIBR and the APDA using the Duntley equation for MODTRAN3 computed irradiances, transmissions and path radiance (using the DISORT option). This simulation showed that the CIBR is very sensitive to reflectance effects and that the APDA performs much better. An extensive data set was created with the radiative transfer code 6S over 379 different ground reflectance spectra. The calculated relative water vapor error was reduced significantly for the APDA. The APDA technique had about 8% (vs. over 35% for the CIBR) of the 379 spectra with a relative water vapor error of greater than {+-}5%. The APDA has been applied to 1991 and 1995 AVIRIS scenes which visually demonstrate the improvement over the CIBR technique.

  14. Performance evaluation of operational atmospheric correction algorithms over the East China Seas

    NASA Astrophysics Data System (ADS)

    He, Shuangyan; He, Mingxia; Fischer, Jürgen

    2016-04-01

    To acquire high-quality operational data products for Chinese in-orbit and scheduled ocean color sensors, the performances of two operational atmospheric correction (AC) algorithms (ESA MEGS 7.4.1 and NASA SeaDAS 6.1) were evaluated over the East China Seas (ECS) using MERIS data. The spectral remote sensing reflectance R rs(λ), aerosol optical thickness (AOT), and Ångström exponent (α) retrieved using the two algorithms were validated using in situ measurements obtained between May 2002 and October 2009. Match-ups of R rs, AOT, and α between the in situ and MERIS data were obtained through strict exclusion criteria. Statistical analysis of R rs(λ) showed a mean percentage difference (MPD) of 9%-13% in the 490-560 nm spectral range, and significant overestimation was observed at 413 nm (MPD>72%). The AOTs were overestimated (MPD>32%), and although the ESA algorithm outperformed the NASA algorithm in the blue-green bands, the situation was reversed in the red-near-infrared bands. The value of α was obviously underestimated by the ESA algorithm (MPD=41%) but not by the NASA algorithm (MPD=35%). To clarify why the NASA algorithm performed better in the retrieval of α, scatter plots of the α single scattering albedo (SSA) density were prepared. These α-SSA density scatter plots showed that the applicability of the aerosol models used by the NASA algorithm over the ECS is better than that used by the ESA algorithm, although neither aerosol model is suitable for the ECS region. The results of this study provide a reference to both data users and data agencies regarding the use of operational data products and the investigation into the improvement of current AC schemes over the ECS.

  15. Atmospheric corrections in interferometric synthetic aperture radar surface deformation - a case study of the city of Mendoza, Argentina

    NASA Astrophysics Data System (ADS)

    Balbarani, S.; Euillades, P. A.; Euillades, L. D.; Casu, F.; Riveros, N. C.

    2013-09-01

    Differential interferometry is a remote sensing technique that allows studying crustal deformation produced by several phenomena like earthquakes, landslides, land subsidence and volcanic eruptions. Advanced techniques, like small baseline subsets (SBAS), exploit series of images acquired by synthetic aperture radar (SAR) sensors during a given time span. Phase propagation delay in the atmosphere is the main systematic error of interferometric SAR measurements. It affects differently images acquired at different days or even at different hours of the same day. So, datasets acquired during the same time span from different sensors (or sensor configuration) often give diverging results. Here we processed two datasets acquired from June 2010 to December 2011 by COSMO-SkyMed satellites. One of them is HH-polarized, and the other one is VV-polarized and acquired on different days. As expected, time series computed from these datasets show differences. We attributed them to non-compensated atmospheric artifacts and tried to correct them by using ERA-Interim global atmospheric model (GAM) data. With this method, we were able to correct less than 50% of the scenes, considering an area where no phase unwrapping errors were detected. We conclude that GAM-based corrections are not enough for explaining differences in computed time series, at least in the processed area of interest. We remark that no direct meteorological data for the GAM-based corrections were employed. Further research is needed in order to understand under what conditions this kind of data can be used.

  16. Long-term changes in the aerosol optical thickness in moscow and correction under strong atmospheric turbidity

    NASA Astrophysics Data System (ADS)

    Gorbarenko, E. V.; Rublev, A. N.

    2016-03-01

    We have estimated and compensated the error in long-term series of the aerosol optical thickness (AOT) calculated from the data on direct integral solar radiation measured by a standard actinometer at the Meteorological Observatory of the Moscow State University (MO MSU) for strong atmospheric turbidity conditions. The necessary corrections have been obtained by the Monte-Carlo simulation of the actinometry measurements for different atmospheric conditions, taking into account the angular size of the field of view of the instrument; and a special correctional formula has been obtained. This correction formula has been applied for all timed AOT values of above 0.5 observed at the MO MSU for the entire time period from 1955 to 2013. Changes in the long-term average AOT values in Moscow occurred only when the smoky haze from the forest and peat fires affected the aerosol turbidity of the atmosphere. Here, the significant decreasing trend of aerosol optical depth of the atmosphere from 1955 to 2013 has been retained with the same confidence level.

  17. Atmospheric correction at AERONET locations: A new science and validation data set

    USGS Publications Warehouse

    Wang, Y.; Lyapustin, A.I.; Privette, J.L.; Morisette, J.T.; Holben, B.

    2009-01-01

    This paper describes an Aerosol Robotic Network (AERONET)-based Surface Reflectance Validation Network (ASRVN) and its data set of spectral surface bidirectional reflectance and albedo based on Moderate Resolution Imaging Spectroradiometer (MODIS) TERRA and AQUA data. The ASRVN is an operational data collection and processing system. It receives 50 ?? 50 km2; subsets of MODIS level 1B (L1B) data from MODIS adaptive processing system and AERONET aerosol and water-vapor information. Then, it performs an atmospheric correction (AC) for about 100 AERONET sites based on accurate radiative-transfer theory with complex quality control of the input data. The ASRVN processing software consists of an L1B data gridding algorithm, a new cloud-mask (CM) algorithm based on a time-series analysis, and an AC algorithm using ancillary AERONET aerosol and water-vapor data. The AC is achieved by fitting the MODIS top-of-atmosphere measurements, accumulated for a 16-day interval, with theoretical reflectance parameterized in terms of the coefficients of the Li SparseRoss Thick (LSRT) model of the bidirectional reflectance factor (BRF). The ASRVN takes several steps to ensure high quality of results: 1) the filtering of opaque clouds by a CM algorithm; 2) the development of an aerosol filter to filter residual semitransparent and subpixel clouds, as well as cases with high inhomogeneity of aerosols in the processing area; 3) imposing the requirement of the consistency of the new solution with previously retrieved BRF and albedo; 4) rapid adjustment of the 16-day retrieval to the surface changes using the last day of measurements; and 5) development of a seasonal backup spectral BRF database to increase data coverage. The ASRVN provides a gapless or near-gapless coverage for the processing area. The gaps, caused by clouds, are filled most naturally with the latest solution for a given pixel. The ASRVN products include three parameters of the LSRT model (kL, kG, and kV), surface albedo

  18. The impact of the microphysical properties of aerosol on the atmospheric correction of hyperspectral data in coastal waters

    NASA Astrophysics Data System (ADS)

    Bassani, C.; Manzo, C.; Braga, F.; Bresciani, M.; Giardino, C.; Alberotanza, L.

    2015-03-01

    Hyperspectral imaging provides quantitative remote sensing of ocean colour by the high spectral resolution of the water features. The HICO™ (Hyperspectral Imager for the Coastal Ocean) is suitable for coastal studies and monitoring. The accurate retrieval of hyperspectral water-leaving reflectance from HICO™ data is still a challenge. The aim of this work is to retrieve the water-leaving reflectance from HICO™ data with a physically based algorithm, using the local microphysical properties of the aerosol in order to overcome the limitations of the standard aerosol types commonly used in atmospheric correction processing. The water-leaving reflectance was obtained using the HICO@CRI (HICO ATmospherically Corrected Reflectance Imagery) atmospheric correction algorithm by adapting the vector version of the Second Simulation of a Satellite Signal in the Solar Spectrum (6SV) radiative transfer code. The HICO@CRI algorithm was applied on to six HICO™ images acquired in the northern Mediterranean basin, using the microphysical properties measured by the Acqua Alta Oceanographic Tower (AAOT) AERONET site. The HICO@CRI results obtained with AERONET products were validated with in situ measurements showing an accuracy expressed by r2 = 0.98. Additional runs of HICO@CRI on the six images were performed using maritime, continental and urban standard aerosol types to perform the accuracy assessment when standard aerosol types implemented in 6SV are used. The results highlight that the microphysical properties of the aerosol improve the accuracy of the atmospheric correction compared to standard aerosol types. The normalized root mean square (NRMSE) and the similar spectral value (SSV) of the water-leaving reflectance show reduced accuracy in atmospheric correction results when there is an increase in aerosol loading. This is mainly when the standard aerosol type used is characterized with different optical properties compared to the local aerosol. The results suggest

  19. Corrective Action Investigation Plan for Corrective Action Unit 106: Areas 5, 11 Frenchman Flat Atmospheric Sites, Nevada Test Site, Nevada, Revision 0

    SciTech Connect

    Patrick Matthews

    2010-04-01

    Corrective Action Unit (CAU) 106 is located in Area 5 of the Nevada Test Site, which is approximately 65 miles northwest of Las Vegas, Nevada. Corrective Action Unit 106 comprises the five corrective action sites (CASs) listed below: •05-23-02, GMX Alpha Contaminated Area •05-23-05, Atmospheric Test Site - Able •05-45-01, Atmospheric Test Site - Hamilton •05-45-04, 306 GZ Rad Contaminated Area •05-45-05, 307 GZ Rad Contaminated Area These sites are being investigated because existing information on the nature and extent of potential contamination is insufficient to evaluate and recommend corrective action alternatives (CAAs). Additional information will be obtained by conducting a corrective action investigation before evaluating CAAs and selecting the appropriate corrective action for each CAS. The results of the field investigation will support a defensible evaluation of viable CAAs that will be presented in the Corrective Action Decision Document. The sites will be investigated based on the data quality objectives (DQOs) developed on January 19, 2010, by representatives of the Nevada Division of Environmental Protection and the U.S. Department of Energy (DOE), National Nuclear Security Administration Nevada Site Office. The DQO process was used to identify and define the type, amount, and quality of data needed to develop and evaluate appropriate corrective actions for CAU 106. The presence and nature of contamination at CAU 106 will be evaluated based on information collected from a field investigation. The CAU includes land areas impacted by the release of radionuclides from a weapons-effect tower test (CAS 05-45-01), a weapons-related airdrop test (CAS 05-23-05), “equation of state” experiments (CAS 05-23-02), and unknown support activities at two sites (CAS 05-45-04 and CAS 05-45-05). Surface-deposited radiological contamination will be evaluated based on a comparison of the total effective dose (TED) at sample plot locations to the dose

  20. An integrated toolbox for processing and analysis of remote sensing data of inland and coastal waters - atmospheric correction

    SciTech Connect

    Haan, J.F. de; Kokke, J.M.M.; Hoogenboom, H.J.; Dekker, A.G.

    1997-06-01

    Deriving thematic maps of water quality parameters from a remote sensing image requires a number of processing steps, such as calibration, atmospheric correction, air-water interface correction, and application of water quality algorithms. A prototype version of an integrated software environment has recently been developed that enables the user to perform and control these processing steps. Major parts of this environment are: (i) access to the MODTRAN 3 radiative transfer code, (ii) a database of water quality algorithms, and (iii) a spectral library of Dutch coastal and inland waters, containing subsurface irradiance reflectance spectra and associated water quality parameters. The atmospheric correction part of this environment is discussed here. It is shown that this part can be used to accurately retrieve spectral signatures of inland water for wavelengths between 450 and 750 nm, provided in situ measurements are used to determine atmospheric model parameters. Assessment of the usefulness of the completely integrated software system in an operational environment requires a revised version that is presently being developed.

  1. Implementation of a very large atmospheric correction lookup table for ASTER using a relational database management system

    NASA Astrophysics Data System (ADS)

    Murray, Alex T.; Eng, Bjorn T.; Thome, Kurtis J.

    1996-11-01

    The advanced spaceborne thermal emission and reflection radiometer (ASTER) is designed to provide a high resolution map of the Earth in both visible, near-infrared, and thermal spectral regions of the electromagnetic spectrum. The ASTER science team has developed several standard data product algorithms, but the most complex and computing-intensive of these is the estimation of surface radiance and reflectance values, which is done by modeling and correcting for the effects of the atmosphere. The algorithm for atmospheric correction in the visible bands sensed by ASTER calls fur the use of a very large atmospheric correction look up table (ACLUT). The ACLUT contains coefficients which describe atmospheric effects on ASTER data under various conditions. The parameters used to characterize the atmosphere and its effects on radiation in the ASTER bands include aerosol and molecular optical depth, aerosol size distribution, single scattering albedo, and solar, nadir view, and azimuth angles. The ACLUT coefficients are produced by thousands of runs of a radiative transfer code (RTC) program produced by Phil Slater and Kurt Thome of U. of A. The final version of ACLUT is expected to be in the neighborhood of 10 gigabytes. The RDBMS Sybase is used to manage the process of generating the ACLUT as well as to host the table and service queries on it. Queries on the table are made using ASTER band number and seven floating-point values as keys. The floating-point keys do not necessarily exactly match key values in the database, so the query involves a hierarchical closest-fit search. All aspects of table implementation are described.

  2. Comprehensive wind correction for a Rayleigh Doppler lidar from atmospheric temperature and pressure influences and Mie contamination

    NASA Astrophysics Data System (ADS)

    Shangguan, Ming-Jia; Xia, Hai-Yun; Dou, Xian-Kang; Wang, Chong; Qiu, Jia-Wei; Zhang, Yun-Peng; Shu, Zhi-Feng; Xue, Xiang-Hui

    2015-09-01

    A correction considering the effects of atmospheric temperature, pressure, and Mie contamination must be performed for wind retrieval from a Rayleigh Doppler lidar (RDL), since the so-called Rayleigh response is directly related to the convolution of the optical transmission of the frequency discriminator and the Rayleigh-Brillouin spectrum of the molecular backscattering. Thus, real-time and on-site profiles of atmospheric pressure, temperature, and aerosols should be provided as inputs to the wind retrieval. Firstly, temperature profiles under 35 km and above the altitude are retrieved, respectively, from a high spectral resolution lidar (HSRL) and a Rayleigh integration lidar (RIL) incorporating to the RDL. Secondly, the pressure profile is taken from the European Center for Medium range Weather Forecast (ECMWF) analysis, while radiosonde data are not available. Thirdly, the Klett-Fernald algorithms are adopted to estimate the Mie and Rayleigh components in the atmospheric backscattering. After that, the backscattering ratio is finally determined in a nonlinear fitting of the transmission of the atmospheric backscattering through the Fabry-Perot interferometer (FPI) to a proposed model. In the validation experiments, wind profiles from the lidar show good agreement with the radiosonde in the overlapping altitude. Finally, a continuous wind observation shows the stability of the correction scheme. Project supported by the National Natural Science Foundation of China (Grant Nos. 41174131, 41274151, 41304123, 41121003 and 41025016).

  3. Characterization of Artifacts Introduced by the Empirical Volcano-Scan Atmospheric Correction Commonly Applied to CRISM and OMEGA Near-Infrared Spectra

    NASA Technical Reports Server (NTRS)

    Wiseman, S.M.; Arvidson, R.E.; Wolff, M. J.; Smith, M. D.; Seelos, F. P.; Morgan, F.; Murchie, S. L.; Mustard, J. F.; Morris, R. V.; Humm, D.; McGuire, P. C.

    2014-01-01

    The empirical volcano-scan atmospheric correction is widely applied to Martian near infrared CRISM and OMEGA spectra between 1000 and 2600 nanometers to remove prominent atmospheric gas absorptions with minimal computational investment. This correction method employs division by a scaled empirically-derived atmospheric transmission spectrum that is generated from observations of the Martian surface in which different path lengths through the atmosphere were measured and transmission calculated using the Beer-Lambert Law. Identifying and characterizing both artifacts and residual atmospheric features left by the volcano-scan correction is important for robust interpretation of CRISM and OMEGA volcano scan corrected spectra. In order to identify and determine the cause of spectral artifacts introduced by the volcano-scan correction, we simulated this correction using a multiple scattering radiative transfer algorithm (DISORT). Simulated transmission spectra that are similar to actual CRISM- and OMEGA-derived transmission spectra were generated from modeled Olympus Mons base and summit spectra. Results from the simulations were used to investigate the validity of assumptions inherent in the volcano-scan correction and to identify artifacts introduced by this method of atmospheric correction. We found that the most prominent artifact, a bowl-shaped feature centered near 2000 nanometers, is caused by the inaccurate assumption that absorption coefficients of CO2 in the Martian atmosphere are independent of column density. In addition, spectral albedo and slope are modified by atmospheric aerosols. Residual atmospheric contributions that are caused by variable amounts of dust aerosols, ice aerosols, and water vapor are characterized by the analysis of CRISM volcano-scan corrected spectra from the same location acquired at different times under variable atmospheric conditions.

  4. Characterization of artifacts introduced by the empirical volcano-scan atmospheric correction commonly applied to CRISM and OMEGA near-infrared spectra

    NASA Astrophysics Data System (ADS)

    Wiseman, S. M.; Arvidson, R. E.; Wolff, M. J.; Smith, M. D.; Seelos, F. P.; Morgan, F.; Murchie, S. L.; Mustard, J. F.; Morris, R. V.; Humm, D.; McGuire, P. C.

    2016-05-01

    The empirical 'volcano-scan' atmospheric correction is widely applied to martian near infrared CRISM and OMEGA spectra between ∼1000 and ∼2600 nm to remove prominent atmospheric gas absorptions with minimal computational investment. This correction method employs division by a scaled empirically-derived atmospheric transmission spectrum that is generated from observations of the martian surface in which different path lengths through the atmosphere were measured and transmission calculated using the Beer-Lambert Law. Identifying and characterizing both artifacts and residual atmospheric features left by the volcano-scan correction is important for robust interpretation of CRISM and OMEGA volcano-scan corrected spectra. In order to identify and determine the cause of spectral artifacts introduced by the volcano-scan correction, we simulated this correction using a multiple scattering radiative transfer algorithm (DISORT). Simulated transmission spectra that are similar to actual CRISM- and OMEGA-derived transmission spectra were generated from modeled Olympus Mons base and summit spectra. Results from the simulations were used to investigate the validity of assumptions inherent in the volcano-scan correction and to identify artifacts introduced by this method of atmospheric correction. We found that the most prominent artifact, a bowl-shaped feature centered near 2000 nm, is caused by the inaccurate assumption that absorption coefficients of CO2 in the martian atmosphere are independent of column density. In addition, spectral albedo and slope are modified by atmospheric aerosols. Residual atmospheric contributions that are caused by variable amounts of dust aerosols, ice aerosols, and water vapor are characterized by the analysis of CRISM volcano-scan corrected spectra from the same location acquired at different times under variable atmospheric conditions.

  5. Correction for water vapor in the measurement of atmospheric trace gases.

    PubMed

    Butenhoff, C L; Khalil, M A K

    2002-06-01

    The presence of water vapor in a sample of air reduces the concentration of a trace gas measured from the sample. We present a methodology to correct for this effect for those cases when the concentration of the trace gas has already been measured from a wet sample. The conversion or correction factor that takes the wet mole fraction to a dry mole fraction is determined by the mixing ratio of water vapor inside the sampling canister. For those samples where the water vapor is saturated inside the canister, the water vapor mixing ratio is largely determined by laboratory conditions; for the unsaturated samples, the mixing ratio is determined by station conditions. If the meteorology at the sampling station is known, the equations presented here can be used directly to calculate the appropriate correction factor. For convenience, we use climatological data to derive average monthly correction factors for seven common global sampling sites: Barrow, AK, US (71 degrees N, 157degrees W); Cape Meares, OR, US (45 degrees N, 124 degrees W); Mauna Loa, HI, US (19 degrees N, 155 degrees W); Ragged Point, Barbados (13 degrees N, 59 degrees W); American Samoa (14 degrees S, 171 degrees W); Cape Grim, Tasmania, Australia (41 degrees S, 145 degrees E); South Pole (90 degrees S). These factors adjust wet mole fractions upwards within a range of 0.002% for the South Pole to over 0.8% for saturated sites. We apply the correction factors to wet nitrous oxide (N2O) mole fractions. The corrected data are more consistent with our understanding of N2O sources. PMID:12079077

  6. Methods for correcting microwave scattering and emission measurements for atmospheric effects

    NASA Technical Reports Server (NTRS)

    Komen, M. (Principal Investigator)

    1975-01-01

    The author has identified the following significant results. Algorithms were developed to permit correction of scattering coefficient and brightness temperature for the Skylab S193 Radscat for the effects of cloud attenuation. These algorithms depend upon a measurement of the vertically polarized excess brightness temperature at 50 deg incidence angle. This excess temperature is converted to an equivalent 50 deg attenuation, which may then be used to estimate the horizontally polarized excess brightness temperature and reduced scattering coefficient at 50 deg. For angles other than 50 deg, the correction also requires use of the variation of emissivity with salinity and water temperature.

  7. The study of atmospheric correction of satellite remotely sensed images intended for air pollution using sun-photometers (AERONET) and lidar system in Lemesos, Cyprus

    NASA Astrophysics Data System (ADS)

    Hadjimitsis, Diofantos G.; Themistocleous, Kyriacos; Nisantzi, Argyro; Matsas, Alexandros

    2010-10-01

    Solar radiation reflected by the Earth's surface to satellite sensors is modified by its interaction with the atmosphere. The objective of atmospheric correction is to determine true surface reflectance values by removing atmospheric effects from satellite images. Atmospheric correction is arguably the most important part of the pre-processing of satellite remotely sensed data. The most important parameter in applying any atmospheric correction is the aerosol optical thickness which is also used for assessing air pollution. This paper explores how the AOT is extracted from atmospheric corrected satellite imagery acquired from Landsat ETM + and how then AOT values are used to assess air pollution. The atmospheric correction algorihm developed by Hadjimitsis and Clayton (2009) is applied to short wavelengths like Landsat TM band 1 and 2 (0.45-0.52μm, 0.52-0.60 μm). The results are also assessed using Lidar system and Cimel Sunphotometer located in the premises of the Cyprus University of Technology in Limassol. The authors run the atmospheric correction developed by Hadjimitsis and Clayton (2009) in MATLAB and sample AOT results for the Landsat ETM+ images acquired on the 15/01/2010, 20/4/2010, 09/06/2010 are shown. For the Landsat ETM+ image acquired on 20/4/2010, the AOT was found 1.4 after the application of the atmospheric correction. Such value complies with the AOT value measured by the Cimel Sun-photometer (AERONET) during the satellite overpass. An example of how Lidar is used to assess the existing atmospheric conditions which is useful for assessing air pollution is also presented.

  8. Towards correcting atmospheric beam wander via pump beam control in a down conversion process.

    PubMed

    Pugh, Christopher J; Kolenderski, Piotr; Scarcella, Carmelo; Tosi, Alberto; Jennewein, Thomas

    2016-09-01

    Correlated photon pairs produced by a spontaneous parametric down conversion (SPDC) process can be used for secure quantum communication over long distances including free space transmission over a link through turbulent atmosphere. We experimentally investigate the possibility to utilize the intrinsic strong correlation between the pump and output photon spatial modes to mitigate the negative targeting effects of atmospheric beam wander. Our approach is based on a demonstration observing the deflection of the beam on a spatially resolved array of single photon avalanche diodes (SPAD-array). PMID:27607697

  9. An operational model for filling the black strips of the MODIS 1640 band and application to atmospheric correction

    NASA Astrophysics Data System (ADS)

    Chen, Jun; Cui, Tingwei; Lin, Changsong

    2013-11-01

    In this study, a LIMM (linear interpolation model for rebuilding the black strips of MODIS 1640 nm) model is proposed to rebuild the black strips of MODIS (moderate resolution imaging spectroradiometer) 1640 images, and for improving the performance of TSWNR (traditional 1240 nm band-based SWIR-NIR atmospheric correction model) model in deriving remote sensing reflectance in turbid coastal waters. By comparison with the field measurements, both the L3MAC (LIMM model-derived MODIS 1640 band-based atmospheric correction model) and TSWNR models can be used to derive remote sensing reflectance in the green and red regions, but the former is superior to the latter. Especially in summer in the Bohai Sea, use of the L3MAC model in estimating remote sensing reflectance decreases the MRE (mean root mean square error) values of estimation by >14% from the TSWNR model. Due to the great amount of detector noise in the MODIS SWIR wavelengths, there is still a >19% residual uncertainty in the L3MAC model-derived remote sensing, particularly in the NIR (near-infrared) and shortest blue regions, and both the L3MAC and TSWNR models produce >60% uncertainty in remote sensing reflectance retrievals. The success of the application of the L3MAC model to satellite data depends heavily on the detector noise in the MODIS SWIR (shortwave infrared) wavelengths. Our study suggests that more attention should be paid to how to minimize the effects of detector noise on the atmospheric correction results in the future.

  10. Open-loop control of liquid-crystal spatial light modulators for vertical atmospheric turbulence wavefront correction.

    PubMed

    Liu, Chao; Hu, Lifa; Mu, Quanquan; Cao, Zhaoliang; Xuan, Li

    2011-01-01

    We present an open-loop adaptive optics (AO) system based on two liquid-crystal spatial light modulators (LCSLMs) that profit from high precision wavefront generation and good repeatability. A wide optical bandwidth of 300 nm is designed for the system, and a new open-loop optical layout is invented to conveniently switch between the open and closed loop. The corresponding control algorithm is introduced with a loop frequency (the reciprocal of the total time delay of a correction loop) of 103 Hz. The system was mounted onto a 2.16 m telescope for vertical atmospheric turbulence correction. The full width at half-maximum of the image of the star α Boo reached 0.636 arc sec after the open-loop correction, while it was 2.12 arc sec before the correction. The result indicates that the open-loop AO system based on LCSLMs potentially has the ability to be used for general astronomical applications. PMID:21221164

  11. Atmospheric Correction, Vicarious Calibration and Development of Algorithms for Quantifying Cyanobacteria Blooms from Oceansat-1 OCM Satellite Data

    NASA Astrophysics Data System (ADS)

    Dash, P.; Walker, N. D.; Mishra, D. R.; Hu, C.; D'Sa, E. J.; Pinckney, J. L.

    2011-12-01

    Cyanobacteria represent a major harmful algal group in fresh to brackish water environments. Lac des Allemands, a freshwater lake located southwest of New Orleans, Louisiana on the upper end of the Barataria Estuary, provides a natural laboratory for remote characterization of cyanobacteria blooms because of their seasonal occurrence. The Ocean Colour Monitor (OCM) sensor provides radiance measurements similar to SeaWiFS but with higher spatial resolution. However, OCM does not have a standard atmospheric correction procedure, and it is difficult to find a detailed description of the entire atmospheric correction procedure for ocean (or lake) in one place. Atmospheric correction of satellite data over small lakes and estuaries (Case 2 waters) is also challenging due to difficulties in estimation of aerosol scattering accurately in these areas. Therefore, an atmospheric correction procedure was written for processing OCM data, based on the extensive work done for SeaWiFS. Since OCM-retrieved radiances were abnormally low in the blue wavelength region, a vicarious calibration procedure was also developed. Empirical inversion algorithms were developed to convert the OCM remote sensing reflectance (Rrs) at bands centered at 510.6 and 556.4 nm to concentrations of phycocyanin (PC), the primary cyanobacterial pigment. A holistic approach was followed to minimize the influence of other optically active constituents on the PC algorithm. Similarly, empirical algorithms to estimate chlorophyll a (Chl a) concentrations were developed using OCM bands centered at 556.4 and 669 nm. The best PC algorithm (R2=0.7450, p<0.0001, n=72) yielded a root mean square error (RMSE) of 36.92 μg/L with a relative RMSE of 10.27% (PC from 2.75-363.50 μg/L, n=48). The best algorithm for Chl a (R2=0.7510, p<0.0001, n=72) produced an RMSE of 31.19 μg/L with a relative RMSE of 16.56% (Chl a from 9.46-212.76 μg/L, n=48). While more field data are required to further validate the long

  12. Correcting the Errors in the Writing of University Students in the Comfortable Atmosphere

    ERIC Educational Resources Information Center

    Lu, Tuanhua

    2010-01-01

    This paper analyzed the common errors in university students' writing. At the same time, it showed some methods based on activities designed to give students practice in these problem areas. The activities are meant to be carried out in a comfortable, non-threatening atmosphere in which students can make positive steps toward reducing their errors…

  13. The Algorithm Theoretical Basis Document for the Atmospheric Delay Correction to GLAS Laser Altimeter Ranges. Volume 8

    NASA Technical Reports Server (NTRS)

    Herring, Thomas A.; Quinn, Katherine J.

    2012-01-01

    NASA s Ice, Cloud, and Land Elevation Satellite (ICESat) mission will be launched late 2001. It s primary instrument is the Geoscience Laser Altimeter System (GLAS) instrument. The main purpose of this instrument is to measure elevation changes of the Greenland and Antarctic icesheets. To accurately measure the ranges it is necessary to correct for the atmospheric delay of the laser pulses. The atmospheric delay depends on the integral of the refractive index along the path that the laser pulse travels through the atmosphere. The refractive index of air at optical wavelengths is a function of density and molecular composition. For ray paths near zenith and closed form equations for the refractivity, the atmospheric delay can be shown to be directly related to surface pressure and total column precipitable water vapor. For ray paths off zenith a mapping function relates the delay to the zenith delay. The closed form equations for refractivity recommended by the International Union of Geodesy and Geophysics (IUGG) are optimized for ground based geodesy techniques and in the next section we will consider whether these equations are suitable for satellite laser altimetry.

  14. Caracterisation, modelisation et validation du transfert radiatif d'atmospheres non standard; impact sur les corrections atmospheriques d'images de teledetection

    NASA Astrophysics Data System (ADS)

    Zidane, Shems

    This study is based on data acquired with an airborne multi-altitude sensor on July 2004 during a nonstandard atmospheric event in the region of Saint-Jean-sur-Richelieu, Quebec. By non-standard atmospheric event we mean an aerosol atmosphere that does not obey the typical monotonic, scale height variation employed in virtually all atmospheric correction codes. The surfaces imaged during this field campaign included a diverse variety of targets : agricultural land, water bodies, urban areas and forests. The multi-altitude approach employed in this campaign allowed us to better understand the altitude dependent influence of the atmosphere over the array of ground targets and thus to better characterize the perturbation induced by a non-standard (smoke) plume. The transformation of the apparent radiance at 3 different altitudes into apparent reflectance and the insertion of the plume optics into an atmospheric correction model permitted an atmospheric correction of the apparent reflectance at the two higher altitudes. The results showed consistency with the apparent validation reflectances derived from the lowest altitude radiances. This approach effectively confirmed the accuracy of our non-standard atmospheric correction approach. This test was particularly relevant at the highest altitude of 3.17 km : the apparent reflectances at this altitude were above most of the plume and therefore represented a good test of our ability to adequately correct for the influence of the perturbation. Standard atmospheric disturbances are obviously taken into account in most atmospheric correction models, but these are based on monotonically decreasing aerosol variations with increasing altitude. When the atmospheric radiation is affected by a plume or a local, non-standard pollution event, one must adapt the existing models to the radiative transfer constraints of the local perturbation and to the reality of the measurable parameters available for ingestion into the model. The

  15. Radiative transfer codes for atmospheric correction and aerosol retrieval: intercomparison study.

    PubMed

    Kotchenova, Svetlana Y; Vermote, Eric F; Levy, Robert; Lyapustin, Alexei

    2008-05-01

    Results are summarized for a scientific project devoted to the comparison of four atmospheric radiative transfer codes incorporated into different satellite data processing algorithms, namely, 6SV1.1 (second simulation of a satellite signal in the solar spectrum, vector, version 1.1), RT3 (radiative transfer), MODTRAN (moderate resolution atmospheric transmittance and radiance code), and SHARM (spherical harmonics). The performance of the codes is tested against well-known benchmarks, such as Coulson's tabulated values and a Monte Carlo code. The influence of revealed differences on aerosol optical thickness and surface reflectance retrieval is estimated theoretically by using a simple mathematical approach. All information about the project can be found at http://rtcodes.ltdri.org. PMID:18449285

  16. The Ocean Colour Climate Change Initiative: I. A Methodology for Assessing Atmospheric Correction Processors Based on In-Situ Measurements

    NASA Technical Reports Server (NTRS)

    Muller, Dagmar; Krasemann, Hajo; Brewin, Robert J. W.; Deschamps, Pierre-Yves; Doerffer, Roland; Fomferra, Norman; Franz, Bryan A.; Grant, Mike G.; Groom, Steve B.; Melin, Frederic; Platt, Trevor; Regner, Peter; Sathyendranath, Shubha; Steinmetz, Francois; Swinton, John

    2015-01-01

    The Ocean Colour Climate Change Initiative intends to provide a long-term time series of ocean colour data and investigate the detectable climate impact. A reliable and stable atmospheric correction procedure is the basis for ocean colour products of the necessary high quality. In order to guarantee an objective selection from a set of four atmospheric correction processors, the common validation strategy of comparisons between in-situ and satellite derived water leaving reflectance spectra, is extended by a ranking system. In principle, the statistical parameters such as root mean square error, bias, etc. and measures of goodness of fit, are transformed into relative scores, which evaluate the relationship of quality dependent on the algorithms under study. The sensitivity of these scores to the selected database has been assessed by a bootstrapping exercise, which allows identification of the uncertainty in the scoring results. Although the presented methodology is intended to be used in an algorithm selection process, this paper focusses on the scope of the methodology rather than the properties of the individual processors.

  17. Influence of atmospheric correction and number of sampling points on the accuracy of water clarity assessment using remote sensing application

    NASA Astrophysics Data System (ADS)

    Sriwongsitanon, Nutchanart; Surakit, Kritsanat; Thianpopirug, Sansarith

    2011-05-01

    SummaryThe main objectives of the research described in this paper are to assess the influence of atmospheric correction and the number of sampling points on the accuracy of lake water clarity using remote sensing. For this purpose field experiments were carried out at Bung Boraphet - the largest fresh water lake in Central Thailand. Two clarity parameters, secchi disk transparency (SDT), at 80 locations for three events on April 15th 2008 and March 24th and 31st 2009, and suspended sediment concentration (SSC) for the last two events were collected. These field data were collected nearly contemporaneous or contemporaneous to three Landsat 5 TM images, which were acquired on April 13th 2008 and March 24th and 31st 2009, respectively. Digital numbers of the Thematic Mapper (TM) image bands were transformed to at-sensor radiance by a radiometric correction process and then atmospheric correction was made using the Second Simulation of Satellite Signal in the Solar Spectrum (6S) code to acquire the surface reflectance. Linear regression equations between the log-transformed of clarity parameters and surface reflectance of each band and their band ratios at the same pixels were then determined. The band combinations TM1/TM3 and TM1 to estimate ln(SDT), and TM3/TM1 and TM1 to determine ln(SSC) for all satellite images were selected. These equations were later used to estimate the SDT and SSC values distributed across the whole lake. The results showed that lake wide average values of SDT for the three images are approximately 37, 97 and 81 cm, respectively, while the values of SSC for the second and third images are around 11 and 13 mg/l, respectively. The application of atmospheric correction to the TM data has proved to have the effect on the average values of SDT and SSC, and especially on their maximum and minimum values. Finally, it is possible to reduce the ground observation data of SDT and SSC substantially and still obtain reliable empirical relationships for

  18. Comparison of atmospheric correction algorithms for the Coastal Zone Color Scanner

    NASA Technical Reports Server (NTRS)

    Tanis, F. J.; Jain, S. C.

    1984-01-01

    Before Nimbus-7 Costal Zone Color Scanner (CZC) data can be used to distinguish between coastal water types, methods must be developed for the removal of spatial variations in aerosol path radiance. These can dominate radiance measurements made by the satellite. An assessment is presently made of the ability of four different algorithms to quantitatively remove haze effects; each was adapted for the extraction of the required scene-dependent parameters during an initial pass through the data set The CZCS correction algorithms considered are (1) the Gordon (1981, 1983) algorithm; (2) the Smith and Wilson (1981) iterative algorityhm; (3) the pseudooptical depth method; and (4) the residual component algorithm.

  19. Steps Toward Real-Time Atmospheric Phase Fluctuation Correction for a High Resolution Radar System

    NASA Astrophysics Data System (ADS)

    Denn, Grant R.; Geldzahler, Barry; Birr, Rick; Brown, Robert; Hoblitzell, Richard; Grant, Kevin; Miller, Michael; Woods, Gary; Archuleta, Arby; Ciminera, Michael; Cornish, Timothy; davarian, faramaz; kocz, jonathan; lee, dennis; Morabito, David Dominic; Soriano, Melissa; Tsao, Philip; Vilnrotter, Victor; Jakeman-Flores, Hali; Ott, melanie; Thomes, W. Joe; Soloff, Jason; NASA Kennedy Space Center, Jet Propulsion Laboratory, NASA Goddard Space Flight Center, NASA Johnson Space Flight Center, Metropolitan State University of Denver

    2016-01-01

    NASA is pursuing a demonstration of coherent uplink arraying at 7.145-7.190 GHz (X-band) and 30-31 GHz (Ka-band) using three 12m diameter COTS antennas separated by 60m at the Kennedy Space Center in Florida, with the goal of a high-power, high-resolution radar array that employs real-time correction for tropospheric phase fluctuation. The major uses for this array will be (a) observations of Near Earth Objects, (b) detection and tracking of orbital debris, (c) high power emergency uplink capability for spacecraft, and (d) radio science experiments.

  20. The use of high-resolution atmospheric simulations over mountainous terrain for deriving error correction functions of satellite precipitation products

    NASA Astrophysics Data System (ADS)

    Bartsotas, Nikolaos S.; Nikolopoulos, Efthymios I.; Anagnostou, Emmanouil N.; Kallos, George

    2015-04-01

    Mountainous regions account for a significant part of the Earth's surface. Such areas are persistently affected by heavy precipitation episodes, which induce flash floods and landslides. The limitation of inadequate in-situ observations has put remote sensing rainfall estimates on a pedestal concerning the analyses of these events, as in many mountainous regions worldwide they serve as the only available data source. However, well-known issues of remote sensing techniques over mountainous areas, such as the strong underestimation of precipitation associated with low-level orographic enhancement, limit the way these estimates can accommodate operational needs. Even locations that fall within the range of weather radars suffer from strong biases in precipitation estimates due to terrain blockage and vertical rainfall profile issues. A novel approach towards the reduction of error in quantitative precipitation estimates lies upon the utilization of high-resolution numerical simulations in order to derive error correction functions for corresponding satellite precipitation data. The correction functions examined consist of 1) mean field bias adjustment and 2) pdf matching, two procedures that are simple and have been widely used in gauge-based adjustment techniques. For the needs of this study, more than 15 selected storms over the mountainous Upper Adige region of Northern Italy were simulated at 1-km resolution from a state-of-the-art atmospheric model (RAMS/ICLAMS), benefiting from the explicit cloud microphysical scheme, prognostic treatment of natural pollutants such as dust and sea-salt and the detailed SRTM90 topography that are implemented in the model. The proposed error correction approach is applied on three quasi-global and widely used satellite precipitation datasets (CMORPH, TRMM 3B42 V7 and PERSIANN) and the evaluation of the error model is based on independent in situ precipitation measurements from a dense rain gauge network (1 gauge / 70 km2

  1. The effect of meteorological data on atmospheric pressure loading corrections in VLBI data analysis

    NASA Astrophysics Data System (ADS)

    Balidakis, Kyriakos; Glaser, Susanne; Karbon, Maria; Soja, Benedikt; Nilsson, Tobias; Lu, Cuixian; Anderson, James; Liu, Li; Andres Mora-Diaz, Julian; Raposo-Pulido, Virginia; Xu, Minghui; Heinkelmann, Robert; Schuh, Harald

    2015-04-01

    Earth's crustal deformation is a manifestation of numerous geophysical processes, which entail the atmosphere and ocean general circulation and tidal attraction, climate change, and the hydrological circle. The present study deals with the elastic deformations induced by atmospheric pressure variations. At geodetic sites, APL (Atmospheric Pressure Loading) results in displacements covering a wide range of temporal scales which is undesirable when rigorous geodetic/geophysical analysis is intended. Hence, it is of paramount importance that the APL signal are removed at the observation level in the space geodetic data analysis. In this study, elastic non-tidal components of loading displacements were calculated in the local topocentric frame for all VLBI (Very Long Baseline Interferometry) stations with respect to the center-of-figure of the solid Earth surface and the center-of-mass of the total Earth system. The response of the Earth to the load variation at the surface was computed by convolving Farrell Green's function with the homogenized in situ surface pressure observations (in the time span 1979-2014) after the subtraction of the reference pressure and the S1, S2 and S3 thermal tidal signals. The reference pressure was calculated through a hypsometric adjustment of the absolute pressure level determined from World Meteorological Organization stations in the vicinity of each VLBI observatory. The tidal contribution was calculated following the 2010 International Earth Rotation and Reference Systems Service conventions. Afterwards, this approach was implemented into the VLBI software VieVS@GFZ and the entirety of available VLBI sessions was analyzed. We rationalize our new approach on the basis that the potential error budget is substantially reduced, since several common errors are not applicable in our approach, e.g. those due to the finite resolution of NWM (Numerical Weather Models), the accuracy of the orography model necessary for adjusting the former as

  2. Two-laser optical distance-measuring instrument that corrects for the atmospheric index of refraction.

    NASA Technical Reports Server (NTRS)

    Earnshaw, K. B.; Hernandez, E. N.

    1972-01-01

    The Wave Propagation Laboratory of the Environmental Research Laboratories of the National Oceanic and Atmospheric Administration has been engaged in the development of dual-wavelength, optical distance-measuring instruments. Recently a new generation of this type of high-accuracy instrument has been completed. Preliminary testing of the new instrument indicates that the original goal of the project, accuracy of better than one part in a million over distances of 5-10 km using averaging times of less than 1 min, is being met. This paper describes the instrument and preliminary test results.

  3. Atmospheric correction for satellite-based volcanic ash mapping and retrievals using ``split window'' IR data from GOES and AVHRR

    NASA Astrophysics Data System (ADS)

    Yu, Tianxu; Rose, William I.; Prata, A. J.

    2002-08-01

    Volcanic ash in volcanic clouds can be mapped in two dimensions using two-band thermal infrared data available from meteorological satellites. Wen and Rose [1994] developed an algorithm that allows retrieval of the effective particle size, the optical depth of the volcanic cloud, and the mass of fine ash in the cloud. Both the mapping and the retrieval scheme are less accurate in the humid tropical atmosphere. In this study we devised and tested a scheme for atmospheric correction of volcanic ash mapping and retrievals. The scheme utilizes infrared (IR) brightness temperature (BT) information in two infrared channels (both between 10 and 12.5 μm) and the brightness temperature differences (BTD) to estimate the amount of BTD shift caused by lower tropospheric water vapor. It is supported by the moderate resolution transmission (MODTRAN) analysis. The discrimination of volcanic clouds in the new scheme also uses both BT and BTD data but corrects for the effects of the water vapor. The new scheme is demonstrated and compared with the old scheme using two well-documented examples: (1) the 18 August 1992 volcanic cloud of Crater Peak, Mount Spurr, Alaska, and (2) the 26 December 1997 volcanic cloud from Soufriere Hills, Montserrat. The Spurr example represents a relatively ``dry'' subarctic atmospheric condition. The new scheme sees a volcanic cloud that is about 50% larger than the old. The mean optical depth and effective radii of cloud particles are lower by 22% and 9%, and the fine ash mass in the cloud is 14% higher. The Montserrat cloud is much smaller than Spurr and is more sensitive to atmospheric moisture. It also was located in a moist tropical atmosphere. For the Montserrat example the new scheme shows larger differences, with the area of the volcanic cloud being about 5.5 times larger, the optical depth and effective radii of particles lower by 56% and 28%, and the total fine particle mass in the cloud increased by 53%. The new scheme can be automated and

  4. Measurement and limitations of optical orbital angular momentum through corrected atmospheric turbulence.

    PubMed

    Neo, Richard; Goodwin, Michael; Zheng, Jessica; Lawrence, Jon; Leon-Saval, Sergio; Bland-Hawthorn, Joss; Molina-Terriza, Gabriel

    2016-02-01

    In recent years, there have been a series of proposals to exploit the orbital angular momentum (OAM) of light for astronomical applications. The OAM of light potentially represents a new way in which to probe the universe. The study of this property of light entails the development of new instrumentation and problems which must be addressed. One of the key issues is whether we can overcome the loss of the information carried by OAM due to atmospheric turbulence. We experimentally analyze the effect of atmospheric turbulence on the OAM content of a signal over a range of realistic turbulence strengths typical for astronomical observations. With an adaptive optics system we are able to recover up to 89% power in an initial non-zero OAM mode (ℓ = 1) at low turbulence strengths (0.30" FWHM seeing). However, for poorer seeing conditions (1.1" FWHM seeing), the amount of power recovered is significantly lower (5%), showing that for the terrestrial detection of astronomical OAM, a careful design of the adaptive optics system is needed. PMID:26906859

  5. Major improvement of altimetry sea level estimations using pressure-derived corrections based on ERA-Interim atmospheric reanalysis

    NASA Astrophysics Data System (ADS)

    Carrere, Loren; Faugère, Yannice; Ablain, Michaël

    2016-06-01

    The new dynamic atmospheric correction (DAC) and dry tropospheric (DT) correction derived from the ERA-Interim meteorological reanalysis have been computed for the 1992-2013 altimeter period. Using these new corrections significantly improves sea level estimations for short temporal signals (< 2 months); the impact is stronger if considering old altimeter missions (ERS-1, ERS-2, and Topex/Poseidon), for which DAC_ERA (DAC derived from ERA-Interim meteorological reanalysis) allows reduction of the along-track altimeter sea surface height (SSH) error by more than 3 cm in the Southern Ocean and in some shallow water regions. The impact of DT_ERA (DT derived from ERA-Interim meteorological reanalysis) is also significant in the southern high latitudes for these missions. Concerning more recent missions (Jason-1, Jason-2, and Envisat), results are very similar between ERA-Interim and ECMWF-based corrections: on average for the global ocean, the operational DAC becomes slightly better than DAC_ERA only from the year 2006, likely due to the switch of the operational forcing to a higher spatial resolution. At regional scale, both DACs are similar in the deep ocean but DAC_ERA raises the residual crossovers' variance in some shallow water regions, indicating a slight degradation in the most recent years of the study. In the second decade of altimetry, unexpectedly DT_ERA still gives better results compared to the operational DT. Concerning climate signals, both DAC_ERA and DT_ERA have a low impact on global mean sea level rise (MSL) trends, but they can have a strong impact on long-term regional trends' estimation, up to several millimeters per year locally.

  6. Effects of stratospheric aerosols and thin cirrus clouds on the atmospheric correction of ocean color imagery: simulations.

    PubMed

    Gordon, H R; Zhang, T; He, F; Ding, K

    1997-01-20

    Using simulations, we determine the influence of stratospheric aerosol and thin cirrus clouds on the performance of the proposed atmospheric correction algorithm for the moderate resolution imaging spectroradiometer (MODIS) data over the oceans. Further, we investigate the possibility of using the radiance exiting the top of the atmosphere in the 1.38-microm water vapor absorption band to remove their effects prior to application of the algorithm. The computations suggest that for moderate optical thicknesses in the stratosphere, i.e., tau(s) < or approximately 0.15, the stratospheric aerosol-cirrus cloud contamination does not seriously degrade the MODIS except for the combination of large (approximately 60 degrees) solar zenith angles and large (approximately 45 degrees) viewing angles, for which multiple-scattering effects can be expected to be particularly severe. The performance of a hierarchy of stratospheric aerosol/cirrus cloud removal procedures for employing the 1.38-microm water vapor absorption band to correct for stratospheric aerosol/cirrus clouds, ranging from simply subtracting the reflectance at 1.38 microm from that in the visible bands, to assuming that their optical properties are known and carrying out multiple-scattering computations of their effect by the use of the 1.38-microm reflectance-derived concentration, are studied for stratospheric aerosol optical thicknesses at 865 nm as large as 0.15 and for cirrus cloud optical thicknesses at 865 nm as large as 1.0. Typically, those procedures requiring the most knowledge concerning the aerosol optical properties (and also the most complex) performed the best; however, for tau(s) < or approximately 0.15, their performance is usually not significantly better than that found by applying the simplest correction procedure. A semiempirical algorithm is presented that permits accurate correction for thin cirrus clouds with tau(s) as large as unity when an accurate estimate of the cirrus cloud

  7. Real-time GPS sensing of atmospheric water vapor: Precise point positioning with orbit, clock, and phase delay corrections

    NASA Astrophysics Data System (ADS)

    Li, Xingxing; Dick, Galina; Ge, Maorong; Heise, Stefan; Wickert, Jens; Bender, Michael

    2014-05-01

    The recent development of the International Global Navigation Satellite Systems Service Real-Time Pilot Project and the enormous progress in precise point positioning (PPP) techniques provide a promising opportunity for real-time determination of Integrated Water Vapor (IWV) using GPS ground networks for various geodetic and meteorological applications. In this study, we develop a new real-time GPS water vapor processing system based on the PPP ambiguity fixing technique with real-time satellite orbit, clock, and phase delay corrections. We demonstrate the performance of the new real-time water vapor estimates using the currently operationally used near-real-time GPS atmospheric data and collocated microwave radiometer measurements as an independent reference. The results show that an accuracy of 1.0 ~ 2.0 mm is achievable for the new real-time GPS based IWV value. Data of such accuracy might be highly valuable for time-critical geodetic (positioning) and meteorological applications.

  8. MACCS : Multi-Mission Atmospheric Correction and Cloud Screening tool for high-frequency revisit data processing

    NASA Astrophysics Data System (ADS)

    Petrucci, B.; Huc, M.; Feuvrier, T.; Ruffel, C.; Hagolle, O.; Lonjou, V.; Desjardins, C.

    2015-10-01

    For the production of Level2A products during Sentinel-2 commissioning in the Technical Expertise Center Sentinel-2 in CNES, CESBIO proposed to adapt the Venus Level-2 , taking advantage of the similarities between the two missions: image acquisition at a high frequency (2 days for Venus, 5 days with the two Sentinel-2), high resolution (5m for Venus, 10, 20 and 60m for Sentinel-2), images acquisition under constant viewing conditions. The Multi-Mission Atmospheric Correction and Cloud Screening (MACCS) tool was born: based on CNES Orfeo Toolbox Library, Venμs processor which was already able to process Formosat2 and VENμS data, was adapted to process Sentinel-2 and Landsat5-7 data; since then, a great effort has been made reviewing MACCS software architecture in order to ease the add-on of new missions that have also the peculiarity of acquiring images at high resolution, high revisit and under constant viewing angles, such as Spot4/Take5 and Landsat8. The recursive and multi-temporal algorithm is implemented in a core that is the same for all the sensors and that combines several processing steps: estimation of cloud cover, cloud shadow, water, snow and shadows masks, of water vapor content, aerosol optical thickness, atmospheric correction. This core is accessed via a number of plug-ins where the specificity of the sensor and of the user project are taken into account: products format, algorithmic processing chaining and parameters. After a presentation of MACCS architecture and functionalities, the paper will give an overview of the production facilities integrating MACCS and the associated specificities: the interest for this tool has grown worldwide and MACCS will be used for extensive production within the THEIA land data center and Agri-S2 project. Finally the paper will zoom on the use of MACCS during Sentinel-2 In Orbit Test phase showing the first Level-2A products.

  9. Evaluation of atmospheric correction procedures for ocean color data processing using hyper- and multi-spectral radiometric measurements from the Long Island Sound Coastal Observatory

    NASA Astrophysics Data System (ADS)

    Ahmed, S.; Gilerson, A.; Harmel, T.; Hlaing, S.; Tonizzo, A.; Weidemann, A.; Arnone, R.

    2012-06-01

    In Ocean Color (OC) data processing one of the most critical steps is the atmospheric correction procedure used to separate the water leaving radiance, which contains information on water constituents, from the total radiance measured by space borne sensors, which contains atmospheric contributions. To ensure reliability of retrieved water leaving radiance values, and OC information derived from them, the quality of the atmospheric correction procedures applied needs to be assessed and validated. In this regard, the Long Island Sound Coastal Observatory (LISCO), jointly established by the City College of New York and the Naval Research Laboratory is becoming one of the key elements for OC sensors validation efforts, in part because of its capabilities for co-located hyper and multi-spectral measurements using HyperSAS and SeaPRISM radiometers respectively, with the latter being part of the NASA AERONET - OC network. Accordingly, the impact of the procedures used for atmospheric correction on the retrieval of remote sensing reflectance (Rrs) data can then be evaluated based on satellite OC data acquired from the LISCO site over the last two years. From this, the qualities of atmospheric correction procedures are assessed by performing matchup comparisons between the satellites retrieved atmospheric data and that of LISCO.

  10. Atmospheric correction for ocean spectra retrievals from high-altitude multi-angle, multi-spectral photo-polarimetric remote sensing observations: Results for coastal ocean waters.

    NASA Astrophysics Data System (ADS)

    Chowdhary, J.; van Diedenhoven, B.; Knobelspiesse, K. D.; Cairns, B.; Wasilewski, A. P.; McCubbin, I.

    2015-12-01

    A major challenge for spaceborne observations of ocean color is to correct for atmospheric scattering, which typically contributes ≥85% to the top-of-atmosphere (TOA) radiance and varies substantially with aerosols. Ocean color missions traditionally analyze TOA radiance in the near-infrared (NIR), where the ocean is black, to constrain the TOA atmospheric scattering in the visible (VIS). However, this procedure is limited by insufficient sensitivity of NIR radiance to absorption and vertical distribution of aerosols, and by uncertainties in the extrapolation of aerosol properties from the NIR to the VIS.To improve atmospheric correction for ocean color observations, one needs to change the traditional procedure for this correction and/or increase the aerosol information. The instruments proposed to increase the aerosol information content for the Pre-Aerosol, Clouds, and ocean Ecosystem (PACE) mission include ultraviolet and Oxygen A-band observations, as well as multispectral and multiangle polarimetry. However few systematic studies have been performed to quantify the improvement such measurements bring to atmospheric correction. To study the polarimetric atmospheric correction capabilities of PACE-like instruments, we conducted field experiments off the Coast of California to obtain high-altitude (65,000 ft) and ship-based observations of water-leaving radiance. The airborne data sets consist of hyperspectral radiance between 380-2500 nm by the Airborne Visible/Infrared Imaging Spectrometer, and multi-spectral multi-angle polarimetric data between 410-2250 nm by the Research Scanning Polarimeter. We discuss examples of retrieved atmosphere and ocean state vectors, and of corresponding ocean color spectra obtained by subtracting the computed atmospheric scattering contribution from the high-altitude radiance measurements. The ocean color spectra thus obtained are compared with those measured from the ship.