The formations of different kinds of carbon structures have been studied by means of molecular dy... more The formations of different kinds of carbon structures have been studied by means of molecular dynamics simulations. A Ž . chain-like amorphous structure was obtained on diamond 111 surface with fivefold, sixfold, and sevenfold rings. At the temperature of 3500 K in the bulk region amorphous, graphite-and diamond-like structures were developed depending on the macroscopic density. q
Primary angiosarcoma of the pancreas is an extremely rare neoplasm that often mimicks severe acut... more Primary angiosarcoma of the pancreas is an extremely rare neoplasm that often mimicks severe acute pancreatitis. A 58-year-old man was admitted with clinical and laboratory signs of severe acute pancreatitis. Contrast enhanced CT scan demonstrated haemorrhagic necrotizing inflammation of the pancreas involving the pancreatic tail, splenic hilum and small bowels with multiple peripancreatic and free abdominal fluid collection. Percutaneous drainage was performed. After 13 days, laparotomy was indicated because of persistent intra-abdominal bleeding, fever and a palpable, rapidly growing mass in the left upper quadrant of the abdomen. During the operation a necrotic, haemorrhagic mass was found in the pancreatic tail; a frozen section showed malignancy, although the tumour was unresectable. Despite all conservative and surgical therapeutic attempts, the patient died within four weeks after diagnosis. Final histology justified primary angiosarcoma of the pancreas. If a patient with signs of severe acute pancreatitis has fever without elevated PCT, the presence of a malignant tumour of the pancreas should be considered.
Pinker, R.T. and Laszlo, I., 1990. Improved prospects for estimating insolation for calculating r... more Pinker, R.T. and Laszlo, I., 1990. Improved prospects for estimating insolation for calculating regional evapotranspiration from remotely sensed data. Insolation is a key parameter in most formulations for estimating regional evapotranspiration and/ or primary productivity. Many attempts have been made to replace several parameters in these formulations with remotely sensed data. Insolation, however, has been obtained from conventional observations. The objective of this paper is to demonstrate that satellite methods for deriving insolation can be improved on the regional scale beyond what is achievable on large scales. We have developed a realistic surface albedo model, which was used as an improved boundary condition in an insolation model, and also, to specify clear/cloudy thresholds. It was demonstrated that as a result, the mean bias error (MBE) was reduced by as much as 50%, to about 6 W m -2 for a monthly mean. Such improvements and accuracies have implications for local evapotranspiration estimation methods.
Since January 1996, surface climate parameters for the continental US have been produced in real ... more Since January 1996, surface climate parameters for the continental US have been produced in real time at NOAA/NESDIS from GOES-8 observations, and have been made available to the NOAA/NWS National Centers for Environmental Prediction (NCEP), to the GEWEX Continental-Scale International Project (GCIP) community, as well as to the public. The products include radiative fluxes, such as surface and top of the atmosphere short-wave radiation, photosynthetically active radiation (PAR), cloud fraction, as well as surface temperature. The data can be used for evaluating corresponding parameters as produced from the NCEP (ETA) model or other meso-scale models, as inputs to hydrological models for computing evapotranspiration and snow-melt, for estimating net primary productivity, and other applications. As of July 2000, this product has become operational at NOAA/NESDIS, and it is distributed to the public within one day after being produced. In this paper provided will be background information about this product and identified will be issues that require further attention.
As a result of increasing attention paid to aerosols in climate studies, numerous global satellit... more As a result of increasing attention paid to aerosols in climate studies, numerous global satellite aerosol products have been generated. Aerosol parameters and underlining physical processes are now incorporated in many general circulation models (GCMs) in order to account for their direct and indirect effects on the earth's climate, through their interactions with the energy and water cycles. There exists, however, an outstanding problem that these satellite products have substantial discrepancies, that must be lowered substantially for narrowing the range of the estimates of aerosol's climate effects. In this paper, numerous key uncertain factors in the retrieval of aerosol optical depth (AOD) are articulated for some widely used and relatively long satellite aerosol products including the AVHRR, TOMS, MODIS, MISR, and SeaWiFS. We systematically review the algorithms developed for these sensors in terms of four key elements that influence the quality of passive satellite aerosol retrieval: calibration, cloud screening, classification of aerosol types, and surface effects. To gain further insights into these uncertain factors, the NOAA AVHRR data are employed to conduct various tests, which help estimate the ranges of uncertainties incurred by each of the factors. At the end, recommendations are made to cope with these issues and to produce a consistent and unified aerosol database of high quality for both environment monitoring and climate studies.
The local Equator Crossing Times (EXT) of the 13 National Oceanic and Atmospheric Administration ... more The local Equator Crossing Times (EXT) of the 13 National Oceanic and Atmospheric Administration (NOAA) platforms (TIROS-N and NOAA-6 through -17) flown from 1978 until the present have been summarized as a function of time and approximated analytically. The fit equations accurately reconstruct all past EXTs to within ±2 min and also allow extrapolation in time, thus providing a useful
To understand the role of clouds in the atmospheric circulation and in the modulation of energy a... more To understand the role of clouds in the atmospheric circulation and in the modulation of energy available at the surface, their effect on the the atmospheric and surface absorption should be determined. The C1 data of the Intemational Satellite Cloud Climatology Project, along with the Satellite Algorithm for Shortwave Radiation Budget, are used to estimate the shortwave cloud effects in terms of the cloud-radiative forcing at the top of the atmosphere (TOA), at the surface and of the atmospheric column on a global scale for the July months of 1983-1985. Global means of TOA cloud forcing range from -43.6 (1983) to -39.1 Wm -2 (1985). The cloud forcing for July 1985 is underestimated, by about 8 Wm -2, compared with that obtained from the Earth Radiation Budget Experiment. The cloud forcing at the surface is almost identical to that at the TOA, indicating that the effect of clouds on the shortwave energy budget of the surface-atmosphere system is such that most of the cooling is at the surface. Regression analysis of the computed fluxes shows a strong linear correlation between the TOA and surface cloud forcing. The monthly averaged regional values of the atmospheric cloud forcing are generally less than the estimated uncertainty of 20 Wm -2. Assuming that the uncerhainties cancel, the global mean of the atmospheric cloud forcing is between 1 and 2 Wm -2, suggesting a slight warming owing to the presence of clouds.
Satellite observations, above very high clouds in the tropics, are analyzed. These observations r... more Satellite observations, above very high clouds in the tropics, are analyzed. These observations reveal the influence of warm water vapor in the stratosphere; above those clouds, the radiance (equivalent temperature) in the water vapor channel (6.7 μm) is warmer than the equivalent temperature in the window channel (11.1 μm). When the clouds are well below the tropopause, the temperature in the water vapor channel is colder than the window channel temperature. Theoretical radiative calculations support the interpretation of the satellite observations.
This paper evaluates the ability of satellite observations from GOES 7 to provide basin-scale sur... more This paper evaluates the ability of satellite observations from GOES 7 to provide basin-scale surface solar irradiance (SW) estimates in a semiarid region during a period of strong convective activity with highly variable cloud conditions. A physical inference model is used to derive the SW. Information of surface albedo is a prerequisite in all such models. In this study the
During the last few years, the feasibility of deriving surface radiation budget (SRB) components ... more During the last few years, the feasibility of deriving surface radiation budget (SRB) components from satellite observations has been demonstrated and a better understanding of the need for SRB information in climate research was formulated. Much attention has been given to the scales at which such information is needed and to the accuracies required at different spatial and temporal scales. Recently, global acts of satellite observations became available, allowing implementation of satellite models for SRB on a global scale, and international frameworks were established for validating such models. To respond to these developments, we modified and expanded an early version of a physical model to derive surface solar irradiance from satellite observations. The model is based on radiative transfer theory, and can produce both direct and diffuse spectral components in the 0.2-4.0-m interval. Attention is given to the absorption and scattering processes in the atmosphere and the interaction of radiation with the surface. The bidirectional nature of the exiting radiation at the top of the atmosphere is also accounted for. In this paper the emphasis will be on describing the current status of the model and its implementation on a global scale with the International Satellite Cloud Climatology Project (ISCCP) C1 data.
The impacts of high-frequency surface forcing in the upper ocean over the equatorial Pacific are ... more The impacts of high-frequency surface forcing in the upper ocean over the equatorial Pacific are investigated using a nonlinear reduced-gravity isopycnal ocean circulation model forced by daily and monthly mean forcing. The simulated sea surface temperature (SST) in the ...
Surface downwelling and upwelling radiative fluxes are important inputs into hydrologic models th... more Surface downwelling and upwelling radiative fluxes are important inputs into hydrologic models that evaluate water budgets, and into land surface data assimilation schemes which are driven with radiative fluxes. For large-scale needs, only remote sensing methods can provide such information. The accuracy of the derived fluxes depends on the inference schemes and on the quality of auxiliary input parameters. At present, information on surface short-wave (SW) radiative fluxes over the United States is produced in real time by the National Oceanic and Atmospheric Administration (NOAA)/National Environmental Satellite Data and Information Service (NESDIS) at 0.5 • resolution, at hourly time intervals, using independently derived auxiliary inputs. Information on aerosol properties and their temporal variability is not available, and at best, is only estimated. During 1997 information on aerosol optical properties was collected at the USDA-Agricultural Research Service Walnut Gulch Experimental Watershed, Arizona, in preparation for future validation efforts in support of new satellite observations (e.g., ADEOS-II). This data set was used to test the sensitivity of a radiation inference scheme to aerosols, in particular, on the determination of clear sky fluxes and the surface albedo. Data from the Arizona meteorological network (AZMET) have been utilized to evaluate the satellite estimates for 1997. It was found that the current satellite estimates are within 70 W m −2 of the ground observations on an hourly time scale and within 24 W m −2 on a daily time scale. In the latter case this is less than 10% of the mean. Use of actual observations of aerosols, as compared to climatological values, reduces the bias substantially, while less significant changes in the r.m.s. were found.
The optical and radiative properties of dust particles in solar and thermal infrared regions are ... more The optical and radiative properties of dust particles in solar and thermal infrared regions are investigated. Dust particles are assumed to be spheres and spheroids for a comparison aimed at understanding the nonsphericity effect of these particles on the radiation at the top of a dusty atmosphere. The classical Lorenz–Mie theory is employed to compute the optical properties of spherical dust particles. To compute the single-scattering properties of spheroidal dust particles, a combination of the T-matrix method and an approximate method is used in the present study. In the approximate method, applicable to large particles, the geometric optics method is applied to the computation of the scattering phase matrix. A combination of the solution from the geometric optics method and the contribution of the so-called edge effect is used to compute the extinction efficiency of a spheroidal particle whose absorption efficiency is computed by adding the so-called above- and below-edge effect (a term from the well-known complex angular momentum theory) to the geometric optics result. Numerical results show that the results from the T-matrix method and the present approximate approach converge at a size parameter of 50 for computing the integrated scattering properties (i.e., the extinction efficiency, single-scattering albedo, and asymmetry factor). Additionally, the phase functions computed from the two methods are quite similar for size parameters larger than 40 although some considerable differences may still be noticed for other phase matrix elements. Furthermore, the effect of surface roughness on the single-scattering properties of spheroidal particles is discussed. The present radiative transfer simulations illustrate the nonsphericity effect of dust particles is significant at short wavelengths, however, not at the thermal infrared wavelengths.
The formations of different kinds of carbon structures have been studied by means of molecular dy... more The formations of different kinds of carbon structures have been studied by means of molecular dynamics simulations. A Ž . chain-like amorphous structure was obtained on diamond 111 surface with fivefold, sixfold, and sevenfold rings. At the temperature of 3500 K in the bulk region amorphous, graphite-and diamond-like structures were developed depending on the macroscopic density. q
Primary angiosarcoma of the pancreas is an extremely rare neoplasm that often mimicks severe acut... more Primary angiosarcoma of the pancreas is an extremely rare neoplasm that often mimicks severe acute pancreatitis. A 58-year-old man was admitted with clinical and laboratory signs of severe acute pancreatitis. Contrast enhanced CT scan demonstrated haemorrhagic necrotizing inflammation of the pancreas involving the pancreatic tail, splenic hilum and small bowels with multiple peripancreatic and free abdominal fluid collection. Percutaneous drainage was performed. After 13 days, laparotomy was indicated because of persistent intra-abdominal bleeding, fever and a palpable, rapidly growing mass in the left upper quadrant of the abdomen. During the operation a necrotic, haemorrhagic mass was found in the pancreatic tail; a frozen section showed malignancy, although the tumour was unresectable. Despite all conservative and surgical therapeutic attempts, the patient died within four weeks after diagnosis. Final histology justified primary angiosarcoma of the pancreas. If a patient with signs of severe acute pancreatitis has fever without elevated PCT, the presence of a malignant tumour of the pancreas should be considered.
Pinker, R.T. and Laszlo, I., 1990. Improved prospects for estimating insolation for calculating r... more Pinker, R.T. and Laszlo, I., 1990. Improved prospects for estimating insolation for calculating regional evapotranspiration from remotely sensed data. Insolation is a key parameter in most formulations for estimating regional evapotranspiration and/ or primary productivity. Many attempts have been made to replace several parameters in these formulations with remotely sensed data. Insolation, however, has been obtained from conventional observations. The objective of this paper is to demonstrate that satellite methods for deriving insolation can be improved on the regional scale beyond what is achievable on large scales. We have developed a realistic surface albedo model, which was used as an improved boundary condition in an insolation model, and also, to specify clear/cloudy thresholds. It was demonstrated that as a result, the mean bias error (MBE) was reduced by as much as 50%, to about 6 W m -2 for a monthly mean. Such improvements and accuracies have implications for local evapotranspiration estimation methods.
Since January 1996, surface climate parameters for the continental US have been produced in real ... more Since January 1996, surface climate parameters for the continental US have been produced in real time at NOAA/NESDIS from GOES-8 observations, and have been made available to the NOAA/NWS National Centers for Environmental Prediction (NCEP), to the GEWEX Continental-Scale International Project (GCIP) community, as well as to the public. The products include radiative fluxes, such as surface and top of the atmosphere short-wave radiation, photosynthetically active radiation (PAR), cloud fraction, as well as surface temperature. The data can be used for evaluating corresponding parameters as produced from the NCEP (ETA) model or other meso-scale models, as inputs to hydrological models for computing evapotranspiration and snow-melt, for estimating net primary productivity, and other applications. As of July 2000, this product has become operational at NOAA/NESDIS, and it is distributed to the public within one day after being produced. In this paper provided will be background information about this product and identified will be issues that require further attention.
As a result of increasing attention paid to aerosols in climate studies, numerous global satellit... more As a result of increasing attention paid to aerosols in climate studies, numerous global satellite aerosol products have been generated. Aerosol parameters and underlining physical processes are now incorporated in many general circulation models (GCMs) in order to account for their direct and indirect effects on the earth's climate, through their interactions with the energy and water cycles. There exists, however, an outstanding problem that these satellite products have substantial discrepancies, that must be lowered substantially for narrowing the range of the estimates of aerosol's climate effects. In this paper, numerous key uncertain factors in the retrieval of aerosol optical depth (AOD) are articulated for some widely used and relatively long satellite aerosol products including the AVHRR, TOMS, MODIS, MISR, and SeaWiFS. We systematically review the algorithms developed for these sensors in terms of four key elements that influence the quality of passive satellite aerosol retrieval: calibration, cloud screening, classification of aerosol types, and surface effects. To gain further insights into these uncertain factors, the NOAA AVHRR data are employed to conduct various tests, which help estimate the ranges of uncertainties incurred by each of the factors. At the end, recommendations are made to cope with these issues and to produce a consistent and unified aerosol database of high quality for both environment monitoring and climate studies.
The local Equator Crossing Times (EXT) of the 13 National Oceanic and Atmospheric Administration ... more The local Equator Crossing Times (EXT) of the 13 National Oceanic and Atmospheric Administration (NOAA) platforms (TIROS-N and NOAA-6 through -17) flown from 1978 until the present have been summarized as a function of time and approximated analytically. The fit equations accurately reconstruct all past EXTs to within ±2 min and also allow extrapolation in time, thus providing a useful
To understand the role of clouds in the atmospheric circulation and in the modulation of energy a... more To understand the role of clouds in the atmospheric circulation and in the modulation of energy available at the surface, their effect on the the atmospheric and surface absorption should be determined. The C1 data of the Intemational Satellite Cloud Climatology Project, along with the Satellite Algorithm for Shortwave Radiation Budget, are used to estimate the shortwave cloud effects in terms of the cloud-radiative forcing at the top of the atmosphere (TOA), at the surface and of the atmospheric column on a global scale for the July months of 1983-1985. Global means of TOA cloud forcing range from -43.6 (1983) to -39.1 Wm -2 (1985). The cloud forcing for July 1985 is underestimated, by about 8 Wm -2, compared with that obtained from the Earth Radiation Budget Experiment. The cloud forcing at the surface is almost identical to that at the TOA, indicating that the effect of clouds on the shortwave energy budget of the surface-atmosphere system is such that most of the cooling is at the surface. Regression analysis of the computed fluxes shows a strong linear correlation between the TOA and surface cloud forcing. The monthly averaged regional values of the atmospheric cloud forcing are generally less than the estimated uncertainty of 20 Wm -2. Assuming that the uncerhainties cancel, the global mean of the atmospheric cloud forcing is between 1 and 2 Wm -2, suggesting a slight warming owing to the presence of clouds.
Satellite observations, above very high clouds in the tropics, are analyzed. These observations r... more Satellite observations, above very high clouds in the tropics, are analyzed. These observations reveal the influence of warm water vapor in the stratosphere; above those clouds, the radiance (equivalent temperature) in the water vapor channel (6.7 μm) is warmer than the equivalent temperature in the window channel (11.1 μm). When the clouds are well below the tropopause, the temperature in the water vapor channel is colder than the window channel temperature. Theoretical radiative calculations support the interpretation of the satellite observations.
This paper evaluates the ability of satellite observations from GOES 7 to provide basin-scale sur... more This paper evaluates the ability of satellite observations from GOES 7 to provide basin-scale surface solar irradiance (SW) estimates in a semiarid region during a period of strong convective activity with highly variable cloud conditions. A physical inference model is used to derive the SW. Information of surface albedo is a prerequisite in all such models. In this study the
During the last few years, the feasibility of deriving surface radiation budget (SRB) components ... more During the last few years, the feasibility of deriving surface radiation budget (SRB) components from satellite observations has been demonstrated and a better understanding of the need for SRB information in climate research was formulated. Much attention has been given to the scales at which such information is needed and to the accuracies required at different spatial and temporal scales. Recently, global acts of satellite observations became available, allowing implementation of satellite models for SRB on a global scale, and international frameworks were established for validating such models. To respond to these developments, we modified and expanded an early version of a physical model to derive surface solar irradiance from satellite observations. The model is based on radiative transfer theory, and can produce both direct and diffuse spectral components in the 0.2-4.0-m interval. Attention is given to the absorption and scattering processes in the atmosphere and the interaction of radiation with the surface. The bidirectional nature of the exiting radiation at the top of the atmosphere is also accounted for. In this paper the emphasis will be on describing the current status of the model and its implementation on a global scale with the International Satellite Cloud Climatology Project (ISCCP) C1 data.
The impacts of high-frequency surface forcing in the upper ocean over the equatorial Pacific are ... more The impacts of high-frequency surface forcing in the upper ocean over the equatorial Pacific are investigated using a nonlinear reduced-gravity isopycnal ocean circulation model forced by daily and monthly mean forcing. The simulated sea surface temperature (SST) in the ...
Surface downwelling and upwelling radiative fluxes are important inputs into hydrologic models th... more Surface downwelling and upwelling radiative fluxes are important inputs into hydrologic models that evaluate water budgets, and into land surface data assimilation schemes which are driven with radiative fluxes. For large-scale needs, only remote sensing methods can provide such information. The accuracy of the derived fluxes depends on the inference schemes and on the quality of auxiliary input parameters. At present, information on surface short-wave (SW) radiative fluxes over the United States is produced in real time by the National Oceanic and Atmospheric Administration (NOAA)/National Environmental Satellite Data and Information Service (NESDIS) at 0.5 • resolution, at hourly time intervals, using independently derived auxiliary inputs. Information on aerosol properties and their temporal variability is not available, and at best, is only estimated. During 1997 information on aerosol optical properties was collected at the USDA-Agricultural Research Service Walnut Gulch Experimental Watershed, Arizona, in preparation for future validation efforts in support of new satellite observations (e.g., ADEOS-II). This data set was used to test the sensitivity of a radiation inference scheme to aerosols, in particular, on the determination of clear sky fluxes and the surface albedo. Data from the Arizona meteorological network (AZMET) have been utilized to evaluate the satellite estimates for 1997. It was found that the current satellite estimates are within 70 W m −2 of the ground observations on an hourly time scale and within 24 W m −2 on a daily time scale. In the latter case this is less than 10% of the mean. Use of actual observations of aerosols, as compared to climatological values, reduces the bias substantially, while less significant changes in the r.m.s. were found.
The optical and radiative properties of dust particles in solar and thermal infrared regions are ... more The optical and radiative properties of dust particles in solar and thermal infrared regions are investigated. Dust particles are assumed to be spheres and spheroids for a comparison aimed at understanding the nonsphericity effect of these particles on the radiation at the top of a dusty atmosphere. The classical Lorenz–Mie theory is employed to compute the optical properties of spherical dust particles. To compute the single-scattering properties of spheroidal dust particles, a combination of the T-matrix method and an approximate method is used in the present study. In the approximate method, applicable to large particles, the geometric optics method is applied to the computation of the scattering phase matrix. A combination of the solution from the geometric optics method and the contribution of the so-called edge effect is used to compute the extinction efficiency of a spheroidal particle whose absorption efficiency is computed by adding the so-called above- and below-edge effect (a term from the well-known complex angular momentum theory) to the geometric optics result. Numerical results show that the results from the T-matrix method and the present approximate approach converge at a size parameter of 50 for computing the integrated scattering properties (i.e., the extinction efficiency, single-scattering albedo, and asymmetry factor). Additionally, the phase functions computed from the two methods are quite similar for size parameters larger than 40 although some considerable differences may still be noticed for other phase matrix elements. Furthermore, the effect of surface roughness on the single-scattering properties of spheroidal particles is discussed. The present radiative transfer simulations illustrate the nonsphericity effect of dust particles is significant at short wavelengths, however, not at the thermal infrared wavelengths.
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Papers by István László