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70
Discriminating clear-sky from cloud with MODIS algorithm theoretical basis document (MOD35
- MODIS Cloud Mask Team, Cooperative Institute for Meteorological Satellite Studies, University of Wisconsin
, 2010
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2002: Rapid calibration of operational and research meteorological satellite imagers. Part II: Comparison of infrared channels
- J. Atmos
"... Operational meteorological satellites generally lack reliable onboard calibration systems for solar-imaging channels. Current methods for calibrating these channels and for normalizing similar channels on contempo-raneous satellite imagers typically rely on a poorly calibrated reference source. To e ..."
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Cited by 39 (27 self)
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Operational meteorological satellites generally lack reliable onboard calibration systems for solar-imaging channels. Current methods for calibrating these channels and for normalizing similar channels on contempo-raneous satellite imagers typically rely on a poorly calibrated reference source. To establish a more reliable reference instrument for calibration normalization, this paper examines the use of research satellite imagers that maintain their solar-channel calibrations by using onboard diffuser systems that rely on the sun as an absolute reference. The Visible Infrared Scanner (VIRS) on the Tropical Rainfall Measuring Mission (TRMM) satellite and the second Along-Track Scanning Radiometer (ATSR-2) on the second European Remote Sensing Satellite (ERS-2) are correlated with matched data from the eighth Geostationary Operational Environmental Satellite (GOES-8), the fifth Geostationary Meteorological satellite (GMS-5), and with each other to examine trends in the solar channels. VIRS data are also correlated with the Terra satellite’s Moderate Resolution Imaging Spec-troradiometer (MODIS) provisional data as a preliminary assessment of their relative calibrations. As an additional check on their long-term stability, the VIRS data are compared to the relevant corresponding broadband shortwave radiances of the Clouds and the Earth’s Radiant Energy System (CERES) scanners on TRMM. No statistically significant trend in the calibration of the VIRS 0.65- and 1.64-mm channels could be detected from the com-
Cloud Properties Derived From GOES-7 for Spring 1994 ARM Intensive Observing Period Using Version 1.0.0 of ARM Satellite Data Analysis Program
, 1995
"... This document describes the initial formulation (Version 1.0.0) of the Atmospheric Radiation Measurement (ARM) Program satellite data analysis procedures. Techniques are presented for calibrating geostationary satellite data with Sun synchronous satellite radiances and for converting narrowband radi ..."
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Cited by 35 (15 self)
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This document describes the initial formulation (Version 1.0.0) of the Atmospheric Radiation Measurement (ARM) Program satellite data analysis procedures. Techniques are presented for calibrating geostationary satellite data with Sun synchronous satellite radiances and for converting narrowband radiances to top-of-theatmosphere fluxes and albedos. A methodology is documented for combining geostationary visible and infrared radiances with surface-based temperature observations to derive cloud amount, optical depth, height, thickness, temperature, and albedo. The analysis is limited to two grids centered over the ARM Southern Great Plains Central Facility in northcentral Oklahoma. Daytime data taken April 5 to May 1, 1994 were analyzed on the 0.3° and 0.5° latitude-longitude grids that cover areas of 0.9° × 0.9° and 10° × 14°, respectively. A variety of cloud conditions ranging from scattered low cumulus to thin cirrus and thick cumulonimbus occurred during the study period. Detailed comparisons with hourly surface observations indicate that the mean cloudiness is within a few percent of the surface-derived sky cover. Formats of the results are also provided. The data can be accessed on the Internet via the World Wide Web at the following uniform resource locator:
Diurnal variability of the hydrologic cycle and radiative fluxes: comparisons between observations and a gcm
- J. Climate
, 2000
"... The simulated diurnal cycle is in many ways an ideal test bed for new physical parameterizations. The purpose of this paper is to compare observations from the Tropical Rainfall Measurement Mission, the Earth Radiation Budget Experiment, the International Satellite Cloud Climatology Project, the Clo ..."
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Cited by 34 (3 self)
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The simulated diurnal cycle is in many ways an ideal test bed for new physical parameterizations. The purpose of this paper is to compare observations from the Tropical Rainfall Measurement Mission, the Earth Radiation Budget Experiment, the International Satellite Cloud Climatology Project, the Clouds and the Earth’s Radiant Energy System Experiment, and the Anglo-Brazilian Amazonian Climate Observation Study with the diurnal variability of the Amazonian hydrologic cycle and radiative energy budget as simulated by the Colorado State University general circulation model, and to evaluate improvements and deficiencies of the model physics. The model uses a prognostic cumulus kinetic energy (CKE) to relax the quasi-equilibrium closure of the Arakawa– Schubert cumulus parameterization. A parameter, a, is used to relate the CKE to the cumulus mass flux. This parameter is expected to vary with cloud depth, mean shear, and the level of convective activity, but up to now a single constant value for all cloud types has been used. The results of the present study show clearly that this approach cannot yield realistic simulations of both the diurnal cycle and the monthly mean climate state. Improved results are obtained using a version of the model in which a is permitted to vary with cloud depth. 1.
Inference of marine stratus cloud optical depths from satellite measurements: Does 1D theory apply
- J. Climate
, 1998
"... The validity of plane-parallel (1D) radiative transfer theory for cloudy atmospheres is examined by directly comparing calculated and observed visible reflectances for one month of Global Area Coverage Advanced Very High Resolution Radiometer satellite observations of marine stratus cloud layers off ..."
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Cited by 25 (0 self)
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The validity of plane-parallel (1D) radiative transfer theory for cloudy atmospheres is examined by directly comparing calculated and observed visible reflectances for one month of Global Area Coverage Advanced Very High Resolution Radiometer satellite observations of marine stratus cloud layers off the coasts of California, Peru, and Angola. Marine stratus are an excellent testbed, as they arguably are the closest to plane-parallel found in nature. Optical depths in a 1D radiative transfer model are adjusted so that 1D model reflectances match those observed at nadir on a pixel-by-pixel basis. The 1D cloud optical depth distributions are then used in the plane-parallel model to generate reflectance distributions for different sun–earth–satellite viewing ge-ometries. These reflectance distributions are directly compared with the observations. Separate analyses are performed for overcast and broken cloud layers as identified by the spatial coherence method. When 1D reflectances are directly compared with observations at different view angles, relative differences are generally small (&10%) in the backscattering direction for solar zenith angles &608 and show no systematic view angle dependence. In contrast, 1D reflectances increase much more rapidly with view angle than the observed reflectances in the forward-scattering direction. Relative differences in the forward-scattering direction are ø2–3 times larger than in the backscattering direction. At solar zenith angles *608, the 1D model under-
2000: An improved algorithm for generating global window brightness temperatures from multiple satellite infrared imagery
- J. Atmos. Oceanic Technol
"... An improved algorithm for generating global window brightness temperatures from multiple satellite infrared imagery ABCDEFB ..."
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Cited by 16 (0 self)
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An improved algorithm for generating global window brightness temperatures from multiple satellite infrared imagery ABCDEFB
Asymmetry in the Diurnal Variation of Surface Albedo
- IEEE Transactions on Geoscience and Remote Sensing
, 1988
"... This paper examines the symmetry of both surface-observed albedos and top-of-theatmosphere (TOA) albedos derived from satellite data. Broadband and visible surface albedos were measured at the Department of Energy Atmospheric Radiation Measurement (ARM) Program Southern Great Plains Central Facility ..."
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Cited by 11 (0 self)
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This paper examines the symmetry of both surface-observed albedos and top-of-theatmosphere (TOA) albedos derived from satellite data. Broadband and visible surface albedos were measured at the Department of Energy Atmospheric Radiation Measurement (ARM) Program Southern Great Plains Central Facility, at some fields near the ARM site, and over a coniferous forest in eastern Virginia. Surface and wind conditions are available for most cases. GOES-8 satellite radiance data are converted to broadband albedo using bidirectional reflectance functions and an empirical narrowband-to-broadband relationship. The initial results indicate that surface moisture has a significant effect and can change the albedo in the afternoon by 20% relative to its morning counterpart. Such effects may need to be incorporated in mesoscale and even large-scale models of atmospheric processes. INTRODUCTION Remote sensing of surface properties and estimation of clear-sky and surface albedo generally assume that the albedo depends only on the solar zenith angle (SZA). This assumption results in an albedo variation symmetrical about local noon. Both regular and irregular changes in the surface state can negate this assumption. The effects of dew, frost, and precipitation as well as evaporation and wind can lead to some systematic diurnal variability resulting in an asymmetric diurnal cycle of albedo. A combination of satellite and surface albedo measurements are used here to examine asymmetry in the diurnal cycle of clear-sky albedo. DATA Geostationary Operational Environmental Satellite (GOES) visible radiance data taken over a 0.3° grid centered on the Atmospheric Radiation Measurement (ARM) Program Southern Great Plains Central Facility (SCF) were converted to visible narrowband and shortwave broadb...
Anisotropy of land surface skin temperature derived from satellite data
- Journal of Applied Meteorology
, 2000
"... The land skin temperature, an important feature for agricultural monitoring, convective processes, and the earth’s radiation budget, is monitored from limited-view satellite imagers. The angular dependence of this parameter is examined using simultaneous views of clear areas from up to three geostat ..."
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Cited by 6 (2 self)
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The land skin temperature, an important feature for agricultural monitoring, convective processes, and the earth’s radiation budget, is monitored from limited-view satellite imagers. The angular dependence of this parameter is examined using simultaneous views of clear areas from up to three geostationary satellites. Daytime temperatures from different satellites differed by up to 6 K and varied as a function of the time of day. Larger differences are expected to occur but were not measured because of limited viewing angles. These differences suggest that biases may occur in both the magnitude and phase of the diurnal cycle of skin temperature and its mean value whenever geostationary satellite data are used to determine skin temperature. The temperature differences were found over both flat and mountainous regions with some slight dependence on vegetation. The timing and magnitude of the temperature differences provide some initial validation for relatively complex model calculations of skin temperature variability. The temperature differences are strongly correlated with terrain and the anisotropy of reflected solar radiation for typical land surfaces. These strong dependencies suggest the possibility for the development of a simple empirical approach for characterizing the temperature anisotropy. Additional research using a much greater range of viewing angles is required to confirm the potential of the suggested empirical approach. 1.
2001: Land effect on the diurnal cycle of clouds over
- the TOGA COARE area, as observed from GMS IR
"... The diurnal cycle of clouds over the western equatorial Pacific region (158S–158N, 1308E–1808) is studied analyzing hourly GMS-4 infrared brightness temperature images during the intensive observation period (Nov 1992–Feb 1993) of TOGA COARE. Although the area studied is essentially (93%) oceanic, d ..."
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Cited by 6 (0 self)
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The diurnal cycle of clouds over the western equatorial Pacific region (158S–158N, 1308E–1808) is studied analyzing hourly GMS-4 infrared brightness temperature images during the intensive observation period (Nov 1992–Feb 1993) of TOGA COARE. Although the area studied is essentially (93%) oceanic, differences of diurnal behavior of the clouds are noticed over different ocean subareas, depending both on the general circulation conditions and on the vicinity of landmasses. This study focuses on the effects of New Guinea and other major islands on the diurnal cycle within the surrounding ocean areas, as for example, the TOGA COARE Intensive Flux Array. The major observable feature of the influence of land is the presence of a diurnal, rather than semidiurnal, average cycle of cloudiness with a high day-to-day repetitivity. The signal is observed up to 600 km off the coast of New Guinea and it is characterized by a variable phase propagating at an average speed of about 15 m s21. For smaller islands, the effect extends over a distance approximately comparable to their size. The genesis of the propagating cloud systems is assumed as due to the low-level convergence between the large-scale flow and a possible land breeze. This conceptual model has been previously proposed to explain a similar signal observed offshore of Borneo. Within this framework, the influence of the large-scale circulation on the intensity and spatial organization of the propagating cloud systems is discussed. The diurnal signal vanishes
Surface emissivity derived from multispectral satellite data
- Proc. 8th Annual ARM Sci. Team Mtg., Tuscon, AZ
, 1998
"... Surface emissivity is critical for remote sensing of surface skin temperature and infrared cloud properties when the observed radiance is influenced by the surface radiation. It is also necessary to correctly compute the longwave flux ..."
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Cited by 3 (2 self)
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Surface emissivity is critical for remote sensing of surface skin temperature and infrared cloud properties when the observed radiance is influenced by the surface radiation. It is also necessary to correctly compute the longwave flux
