scholarly journals Radiative and Microphysical Properties of Cirrus Cloud Inferred from Infrared Measurements Made by the Moderate Resolution Imaging Spectroradiometer (MODIS). Part I: Retrieval Method

2014 ◽  
Vol 53 (5) ◽  
pp. 1297-1316 ◽  
Author(s):  
Hironobu Iwabuchi ◽  
Soichiro Yamada ◽  
Shuichiro Katagiri ◽  
Ping Yang ◽  
Hajime Okamoto
Keyword(s):  
Brightness Temperature ◽  
Optical Thickness ◽  
Optimal Estimation ◽  
Particle Radius ◽  
Cirrus Cloud ◽  
Microphysical Properties ◽  
Effective Particle ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer

AbstractAn optimal estimation–based algorithm is developed to infer the global-scale distribution of cirrus cloud radiative and microphysical properties from the measurements made by the Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) at three infrared (IR) window bands centered at 8.5, 11, and 12 μm. Cloud-top and underlying surface temperatures, as a priori information, are obtained from the MODIS operational products. A fast-forward model based on semianalytical equations for the brightness temperature is used. The modeling errors in brightness temperature are mainly from the uncertainties in model parameters including surface emissivity, precipitable water, and cloud-base temperature. The total measurement–model errors are well correlated for the three bands, which are considered in the retrieval. The most important factors for the accurate retrieval of cloud optical thickness and the effective particle radius are cloud-top and surface temperatures, whereas model parameter uncertainties constitute a moderately significant error source. The three-band IR method is suitable for retrieving optical thickness and effective radius for cloud optical thicknesses within a range of 0.5–6, where the typical root-mean-square error is less than 20% in optical thickness and less than 40% in effective particle radius. A tropical-region case study demonstrates the advantages of the method—in particular, the ability to be applied to more pixels in optically thin cirrus in comparison with a solar-reflection-based method—and the ability of the optimal estimation framework to produce useful diagnostics of the retrieval quality. Collocated comparisons with spaceborne active remote sensing data exhibit reasonable consistency with respect to retrieved particle size.

scholarly journals Reconciling Simulated and Observed Views of Clouds: MODIS, ISCCP, and the Limits of Instrument Simulators

2012 ◽  
Vol 25 (13) ◽  
pp. 4699-4720 ◽  
Author(s):  
Robert Pincus ◽  
Steven Platnick ◽  
Steven A. Ackerman ◽  
Richard S. Hemler ◽  
Robert J. Patrick Hofmann
Keyword(s):  
Optical Thickness ◽  
Model Error ◽  
Diagnostic Tools ◽  
Limited Information ◽  
Global Models ◽  
Cloud Properties ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Cloud Top Pressure

Abstract The properties of clouds that may be observed by satellite instruments, such as optical thickness and cloud-top pressure, are only loosely related to the way clouds are represented in models of the atmosphere. One way to bridge this gap is through “instrument simulators,” diagnostic tools that map the model representation to synthetic observations so that differences can be interpreted as model error. But simulators may themselves be restricted by limited information or by internal assumptions. This paper considers the extent to which instrument simulators are able to capture essential differences between the Moderate Resolution Imaging Spectroradiometer (MODIS) and the International Satellite Cloud Climatology Project (ISCCP), two similar but independent estimates of cloud properties. The authors review the measurements and algorithms underlying these two cloud climatologies, introduce a MODIS simulator, and detail datasets developed for comparison with global models using ISCCP and MODIS simulators. In nature MODIS observes less midlevel cloudiness than ISCCP, consistent with the different methods used to determine cloud-top pressure; aspects of this difference are reproduced by the simulators. Differences in observed distributions of optical thickness, however, are not captured. The largest differences can be traced to different approaches to partly cloudy pixels, which MODIS excludes and ISCCP treats as homogeneous. These cover roughly 15% of the planet and account for most of the optically thinnest clouds. Instrument simulators cannot reproduce these differences because there is no way to synthesize partly cloudy pixels. Nonetheless, MODIS and ISCCP observations are consistent for all but the optically thinnest clouds, and models can be robustly evaluated using instrument simulators by integrating over the robust subset of observations.

Influence of Scattering Model and Effective Particle Radius on Cirrus Cloud Optical Thickness Retrieval

2018 ◽  
Vol 38 (7) ◽  
pp. 0701001
Author(s):  
李树 Li Shu ◽  
孙晓兵 Sun Xiaobing ◽  
提汝芳 Ti Rufang ◽  
黄红莲 Huang Honglian ◽  
陈震霆 Chen Zhenting ◽  
...  
Keyword(s):  
Optical Thickness ◽  
Particle Radius ◽  
Cirrus Cloud ◽  
Scattering Model ◽  
Effective Particle ◽  
Cloud Optical Thickness

scholarly journals Forecasting Carbon Monoxide on a Global Scale for the ATom-1 Aircraft Mission: Insights from Airborne and Satellite Observations and Modeling

2018 ◽  
Author(s):  
Sarah A. Strode ◽  
Junhua Liu ◽  
Leslie Lait ◽  
Róisín Commane ◽  
Bruce Daube ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Optical Thickness ◽  
Global Scale ◽  
Satellite Observations ◽  
Aerosol Optical Thickness ◽  
Large Contribution ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Typical Summer

Abstract. GEOS-5 forecasts and analyses show considerable skill in predicting and simulating the CO distribution and the timing of CO enhancements observed during the ATom-1 aircraft mission. Using tagged tracers for CO, we find a dominant contribution from non-biomass burning sources along the ATom transects except over the tropical Atlantic, where African biomass burning makes a large contribution to the CO concentration. One of the goals of ATom is to provide a chemical climatology over the oceans, so it is important to consider whether August 2016 was representative of typical summer conditions. Using satellite observations of 700 hPa and column CO from the Measurement of Pollution in the Troposphere (MOPITT) instrument, 215 hPa CO from the Microwave Limb Sounder (MLS), and aerosol optical thickness from the Moderate Resolution Imaging Spectroradiometer (MODIS), we find that CO concentrations and aerosol optical thickness in August 2016 were within the observed range of the satellite observations, but below the decadal median for many of the regions sampled. This suggests that the ATom-1 measurements may represent relatively clean but not exceptional conditions for lower tropospheric CO.

scholarly journals Implications of satellite swath width on global aerosol optical thickness statistics

2012 ◽  
Vol 5 (2) ◽  
pp. 2795-2820 ◽  
Author(s):  
P. R. Colarco ◽  
L. A. Remer ◽  
R. A. Kahn ◽  
R. C. Levy ◽  
E. J. Welton
Keyword(s):  
Optical Thickness ◽  
Aerosol Optical Thickness ◽  
Temporal Scales ◽  
Spatial And Temporal Scales ◽  
Moderate Resolution ◽  
Direct Forcing ◽  
Resolution Imaging ◽  
Sun Photometer ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
The Impact

Abstract. We assess the impact of swath width on the statistics of aerosol optical thickness (AOT) retrieved by satellite, as inferred from observations made by the Moderate Resolution Imaging Spectroradiometer (MODIS). Using collocated AERONET sun photometer observations we develop a correction to the MODIS data to account for calibration and algorithmic view angle dependency in the retrieved AOT. We sub-sample and correct the AOT data from the MODIS Aqua instrument along several candidate swaths of various widths for the years 2003–2011. We find that over ocean the global, annual mean AOT is within ± 0.01 of the full swath AOT for all of our sub-samples. Over land, however, most of our sub-samples are outside of this criterion range in the global, annual mean. Moreover, at smaller spatial and temporal scales we find wide deviation in the sub-sample AOT relative to the full swath over both land and ocean. In all, the sub-sample AOT is within ± 0.01 of the full swath value less than 25% of the time over land, and less than 50% of the time over ocean (less than 35% for all but the widest of our sub-sample swaths). These results suggest that future aerosol satellite missions having only narrow swath views may not sample the true AOT distribution sufficiently to reduce significantly the uncertainty in aerosol direct forcing of climate.

scholarly journals Implementation of the Daytime Cloud Optical and Microphysical Properties Algorithm (DCOMP) in PATMOS-x

2012 ◽  
Vol 51 (7) ◽  
pp. 1371-1390 ◽  
Author(s):  
Andi Walther ◽  
Andrew K. Heidinger
Keyword(s):  
Weather Prediction ◽  
Atmospheric Correction ◽  
Optimal Estimation ◽  
Reanalysis Data ◽  
Model Parameters ◽  
Cloud Optical Depth ◽  
Microphysical Properties ◽  
Moderate Resolution ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Set Up

AbstractThis paper describes the daytime cloud optical and microphysical properties (DCOMP) retrieval for the Pathfinder Atmosphere’s Extended (PATMOS-x) climate dataset. Within PATMOS-x, DCOMP is applied to observations from the Advanced Very High Resolution Radiometer and employs the standard bispectral approach to estimate cloud optical depth and particle size. The retrievals are performed within the optimal estimation framework. Atmospheric-correction and forward-model parameters, such as surface albedo and gaseous absorber amounts, are obtained from numerical weather prediction reanalysis data and other climate datasets. DCOMP is set up to run on sensors with similar channel settings and has been successfully exercised on most current meteorological imagers. This quality makes DCOMP particularly valuable for climate research. Comparisons with the Moderate Resolution Imaging Spectroradiometer (MODIS) collection-5 dataset are used to estimate the performance of DCOMP.

scholarly journals Estudio de la dinámica del espesor óptico de los aerosoles en Perú y América del Sur a partir de las imágenes MODIS de los satélites TERRA y AQUA en el periodo 2000-2013

2015 ◽  
Vol 18 (1) ◽  
pp. 1-20
Author(s):  
Noelia Rojas Benavente ◽  
Joel Rojas Acuña
Keyword(s):  
Optical Thickness ◽  
Aerosol Optical Thickness ◽  
La Paz ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
América Del Sur

El objetivo de este trabajo es estudiar la dinámica de los aerosoles en el Perú y América del Sur entre las latitudes 4°N-24°S y las longitudes 83°W-33°W, a partir de las imágenes de los promedios mensuales del espesor óptico de los aerosoles, Aerosol Optical Thickness, AOT, en la longitud de onda de 550 nm medidos por el sensor MODIS, Moderate Resolution Imaging Spectroradiometer, a bordo de los satélites TERRA y AQUA, para un periodo de catorce años, del 2000 al 2013. Se han usado los datos AOT in-situ en los horarios de 6 estaciones AERONET de América del Sur que incluyen cuatro de Brasil, tales como, Rio Branco, Paraná Ji, Alta Foresta y Campo Grande; uno de Chile, la estación de Arica y uno de Bolivia, la estación de La Paz; además incorporamos 166 datos imágenes AOT-MODIS-TERRA de los productos mensuales obtenidos para un periodo del 2000 al 2013 y 138 datos imágenes AOT-MODIS-AQUA de los productos mensuales obtenidos para un periodo del 2002 al 2013 estimados a partir de la herramienta de visulaización y análisis vía Web Giovanni con una resolución de 1°×1°, es decir, de 110 km×110 km. La serie de tiempos AOT-MODIS-TERRA tienen valores máximos y mínimos entre 0.0 y 0.499 y sus valores máximos se ubican en la temporada seca del Hemisferio Sur, entre agosto a noviembre, durante los 14 años. La serie de tiempos AOT-MODIS-AQUA tienen valores máximos y mínimos entre 0.0 y 0.493 y sus valores máximos se ubican en la temporada seca, durante los 12 años. La serie de tiempos AOT-AERONET en las cuatro estaciones de Brasil muestra una variación estacional con máximos en la estación seca durante los 14 años, mientras que, en las estaciones de Chile y Bolivia se muestra una variación estacional muy diferente a los datos AOT/MODIS, teniendo pocos registros de datos AOT. Las gráficas de dispersión de las series de tiempo AOT-MODIS vs AOT-AERONET muestran una alta correlación de 0.8 a 0.9 en cuatro estaciones de Brasil y una correlación baja de 0.33 a 0.39 en la estación de Chile y de 0.13 a 0.19 en la estación de Bolivia.

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