Download or read book Characterization of 3D Cirrus Cloud and Radiation Fields Using ARS AIRS MODIS Data and Its Application to Climate Model written by and published by . This book was released on 2016 with total page 1 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the report period, we have made the following research accomplishments. First, we performed analysis for a number of MODIS scenes comprising of heavy dust events and ice clouds, covering regions of frequent dust outbreaks in East Asia, Middle East, and West Africa, as well as areas associated with long-range dust transports over the Equatorial Tropical Atlantic Ocean. These scenes contain both dust/aerosols and clouds. We collected suitable aerosol/ice-cloud data, correlated ice cloud and aerosol parameters by means of statistical analysis, and interpreted resulting correlation trends based on the physical principles governing cloud microphysics. Aerosol and cloud optical depths and cloud effective particle size inferred from MODIS for selected domains were analyzed from which the parameters including dust aerosol number concentration, ice cloud water path, and ice particle number concentration were subsequently derived. We illustrated that the Twomey (solar albedo) effect can be statistically quantified based on the slope of best-fit straight lines in the correlation study. Analysis of aerosol and cloud retrieval products revealed that for all cases, the region with a larger dust aerosol optical depth is always characterized by a smaller cloud particle size, consistent with the Twomey hypothesis for aerosol-cloud interactions. Second, we developed mean correlation curves with uncertainties associated with small ice-crystal concentration observations for the mean effective ice crystal size (De) and ice water content (IWC) by dividing the atmosphere into three characteristic regions: Tropics cirrus, Midlatitude cirrus, including a temperature classification to improve correlation, and Arctic ice clouds. We illustrated that De has a high correlation with IWC based on theoretical consideration and analysis of thousands of observed ice crystal data obtained from a number of ARM-DOE field campaigns and other experiments. The correlation has the form: ln(De) = a + b ln(IWC) + c ((ln(IWC))2, where a, b, and c are fitting coefficients and are functions of three regions. We demonstrated that this correlation can be effectively incorporated in GCMs and climate models that predict IWC - a significant advance in ice microphysics parameterization for interactive cloud-radiation analysis and feedback. Substantial July mean differences are shown in the OLR (W/m2) and precipitation (mm/day) patterns between UCLA GCM simulations based on Des determined from the De-IWC correlations and the control run using a fixed ice crystal size. Third, in order to improve the computation of spectral radiative transfer processes in the WRF model, we developed a consistent and efficient radiation scheme that can better resolve the spectral bands, determine the cloud optical properties, and provide more reliable and accurate radiative heating fields. In the newly developed radiation module, we have implemented in WRF a modified and improved version referred to as the Fu-Liou-Gu scheme, which includes a combination of delta-four-stream and delta-two-stream approximations for solar and IR flux calculations, respectively. This combination has been proven to be computationally efficient and at the same time to produce a high degree of accuracy. The incorporation of nongray gaseous absorption in multiple scattering atmospheres was based on the correlated k-distribution method. The solar and IR spectra are divided into 6 and 12 bands, respectively, according to the location of absorption bands of H2O, CO2, O3, CH4, N2O, and CFCs. We further included absorption by the water vapor continuum and a number of minor absorbers in the solar spectrum leading to an additional absorption of solar flux in a clear atmosphere on the order of 1-3 W/m2. Additionally, we incorporated the ice microphysics parameterization that includes an interactive mean effective ice crystal size in association with radiation parameterizations. The Fu-Liou-Gu scheme is an ideal tool for t ...
Download or read book Radiation Parameterization for Three Dimensional Inhomogeneous Cirrus Clouds Applied to ARM Data and Climate Models written by Kuo-Nan Liou and published by . This book was released on 2003 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: OAK-B135 (a) We developed a 3D radiative transfer model to simulate the transfer of solar and thermal infrared radiation in inhomogeneous cirrus clouds. The model utilized a diffusion approximation approach (four-term expansion in the intensity) employing Cartesian coordinates. The required single-scattering parameters, including the extinction coefficient, single-scattering albedo, and asymmetry factor, for input to the model, were parameterized in terms of the ice water content and mean effective ice crystal size. The incorporation of gaseous absorption in multiple scattering atmospheres was accomplished by means of the correlated k-distribution approach. In addition, the strong forward diffraction nature in the phase function was accounted for in each predivided spatial grid based on a delta-function adjustment. The radiation parameterization developed herein is applied to potential cloud configurations generated from GCMs to investigate broken clouds and cloud-overlapping effects on the domain-averaged heating rate. Cloud inhomogeneity plays an important role in the determination of flux and heating rate distributions. Clouds with maximum overlap tend to produce less heating than those with random overlap. Broken clouds show more solar heating as well as more IR cooling as compared to a continuous cloud field (Gu and Liou, 2001). (b) We incorporated a contemporary radiation parameterization scheme in the UCLA atmospheric GCM in collaboration with the UCLA GCM group. In conjunction with the cloud/radiation process studies, we developed a physically-based cloud cover formation scheme in association with radiation calculations. The model clouds were first vertically grouped in terms of low, middle, and high types. Maximum overlap was then used for each cloud type, followed by random overlap among the three cloud types. Fu and Liou's 1D radiation code with modification was subsequently employed for pixel-by-pixel radiation calculations in the UCLA GCM. We showed that the simulated cloud cover and OLR fields without special tuning are comparable to those of ISCCP dataset and the results derived from radiation budget experiments. Use of the new radiation and cloud schemes enhances the radiative warming in the middle to upper tropical troposphere and alleviates the cold bias in the UCLA atmospheric GCM. We also illustrated that ice crystal size and cloud inhomogeneous are significant factors affecting the radiation budgets at the top of the atmosphere and the surface (Gu et al. 2003). (c) An innovative approach has been developed to construct a 3D field of inhomogeneous clouds in general and cirrus in particular in terms of liquid/ice water content and particle size on the basis of a unification of satellite and ground-based cloud radar data. Satellite remote sensing employing the current narrow-band spectro-radiometers has limitation and only the vertically integrated cloud parameters (optical depth and mean particle size) can be determined. However, by combining the horizontal cloud mapping inferred from satellites with the vertical structure derived from the profiling Doppler cloud radar, a 3D cloud field can be constructed. This represents a new conceptual approach to 3D remote sensing and imaging and offers a new perspective in observing the cloud structure. We applied this novel technique to AVHRR/NOAA satellite and mm-wave cloud radar data obtained from the ARM achieve and assessed the 3D cirrus cloud field with the ice crystal size distributions independently derived from optical probe measurements aboard the University of North Dakota Citation. The retrieved 3D ice water content and mean effective ice crystal size involving an impressive cirrus cloud occurring on April 18, 1997, are shown to be comparable to those derived from the analysis of collocated and coincident in situ aircraft measurements (Liou et al. 2002). (d) Detection of thin cirrus with optical depths less than 0.5, particularly those occurring i n the tropics remains a fundamental problem in remote sensing. We developed a new detection scheme for the identification of thin cirrus based on a combination of the 1.38 and 0.65 um reflectance ratio and 8.6-11 um brightness temperature difference. Results calculated from a radiative transfer model and the data obtained from MODIS onboard the Terra satellite were employed to illustrate the applicability of this approach for the regional mapping of thin cirrus. The mm-wave radar data that was coincident and collocated with the satellite data available at the ARM site was used for validation. In all cases selected, the new method was able to detect more than 85% of the thin cirrus clouds estimated to have optical depths between 0.1 and 0.9 (Roskovensky and Liou 2003b).
Download or read book 3D Radiative Transfer in Cloudy Atmospheres written by Alexander Marshak and published by Springer Science & Business Media. This book was released on 2006-05-27 with total page 688 pages. Available in PDF, EPUB and Kindle. Book excerpt: Developments in three-dimensional cloud radiation over the past few decades are assessed and distilled into this contributed volume. Chapters are authored by subject-matter experts who address a broad audience of graduate students, researchers, and anyone interested in cloud-radiation processes in the solar and infrared spectral regions. After two introductory chapters and a section on the fundamental physics and computational techniques, the volume extensively treats two main application areas: the impact of clouds on the Earth's radiation budget, which is an essential aspect of climate modeling; and remote observation of clouds, especially with the advanced sensors on current and future satellite missions.
Download or read book Climate Radiation Branch written by Goddard Space Flight Center. Climate and Radiation Branch and published by . This book was released on 1997 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analysis of Cirrus Cloud Microphysical Data written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-09-23 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: The First International Satellite Cloud Climatology Regional Experiment (FIRE) program has the goal of improving our capabilities to understand, model and detect the properties of climatically-important clouds. This is being undertaken through a three-pronged effort of modeling, long-term observations and short-term intensive field studies. Through examination of satellite and other data it is apparent that stratus and cirrus cloud types have the greatest impact on climate due to their radiative effects and ubiquitous nature. As a result, the FIRE program has developed two paths of investigation, each having its own subset of research objectives and measurement programs. The work conducted under this grant was directed toward furthering our understanding of cirrus cloud systems. While it is known that cirrus are climatically important, the magnitude and even sign of the impact is unclear. Cirrus clouds affect the transfer of radiation according to their physical depth and location in the atmosphere and their microphysical composition. However, significant uncertainties still exist in how cirrus clouds form and how they are maintained, what their physical properties are and how they can be parameterized in numerical models. Better remote sensing techniques for monitoring cirrus cloud systems and improved modeling of radiative transfer through ice particles are also needed. A critical element in resolving these issues is a better understanding of cirrus cloud microphysical properties and how they vary. The focus of the research to be conducted under this grant was th data collected in situ by the University of North Dakota Citation aircraft. The goals of this research were to add to the body of knowledge of cirrus cloud microphysics, particularly at the small end of the size spectrum; and analyze the spatial variation of cirrus clouds.Poellot, Michael R. and Grainger, Cedric A.Langley Research CenterCIRRUS CLOUDS; REMOTE SENSING; CLOUD PHYSICS; MATHEMATICAL MODELS; IS
Download or read book Cirrus written by David K. Lynch and published by Oxford University Press, USA. This book was released on 2002 with total page 499 pages. Available in PDF, EPUB and Kindle. Book excerpt: This text, devoted entirely to cirrus clouds, captures the state of knowledge of cirrus clouds and serves as a practical handbook as well.
Download or read book Analysis of Cirrus Optical Properties with Data from NASA Er2 High Resolution Interferometer Sounder His written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-16 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 8 to 13 micron spectral region is an important atmospheric window for radiometric studies of the Earth's surface and clouds. Most of the Earth-atmosphere longwave radiative loss to space occurs in this spectral region. Selective gaseous absorption in this window occurs in the 9.6 micron ozone band with the remaining absorption dominated by the water vapor continuum. Cirrus clouds have a large impact on the transmittance of this atmospheric window region; it is therefore important to understand the interaction of cirrus cloud with the radiation field for climate studies and in the interpretation of satellite radiometric measurements. The focus was to employ observations of the High-resolution Interferometer Sounder (HIS) made during First ISCCP Regional Experiment (FIRE) to improve the understanding of the radiative properties of cirrus clouds within this window region. Studies were undertaken to investigate the coupling between the microphysical properties of cirrus clouds and their spectral variation within this window region. Extensions of the HIS studies to satellite measurements, with regards to remote sensing and interpretation, were also investigated. Smith, William L. and Ackerman, Steven A. Unspecified Center NASA-CR-186365, NAS 1.26:186365 NAG1-1015...
Download or read book Characterization of Cirrus Clouds from Ground based Remote Sensing Using the Synergy of Lidar and Multi spectral Infrared Radiometry written by Friederike Hemmer and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: There is a broad consensus that cirrus clouds strongly influence the climate of the Earth. However, their net radiative effect is still poorly quantified nowadays due to an insufficient knowledge of their microphysical properties. This thesis aims to improve our understanding of the complex microphysics of this cloud type mainly composed of irregularly shaped ice crystals and thereby improve estimates of the ice water content (IWC). For this purpose, we developed an algorithm to retrieve vertical profiles of the IWC of cirrus clouds. The methodology combines the measurements of a ground-based lidar and a thermal infrared (TIR) radiometer in a common optimal estimation framework. It follows three steps: (1) An algorithm to retrieve the vertically integrated amount of ice (ice water path, IWP) from the passive TIR measurements is established. (2) The information about the vertical distribution of the IWC inside the cloud is obtained from the active lidar measurements. These retrievals strongly depend on the backscatter-to-extinction ratio of the ice crystals which is obtained from a bulk ice microphysical model. The scattering phase function of this model used to define the backscatter-to-extinction ratio assumes a flat ending without backscattering peak. We show that this assumption is unrealistic since it results in the retrieval of IWC profiles which are inconsistent with the TIR measurements. (3) Consequently, both types of measurements are combined in a synergistic algorithm allowing to estimate together with the IWC profiles a correction factor for the phase function in backscattering direction. Finally, the retrieval results and associated hypotheses are discussed.
Download or read book Retrieval of Cirrus Radiative and Spatial Properties Using Independent Satellite Data Analysis Techniques written by and published by . This book was released on 1992 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cirrus is one of the most poorly quantified clouds. As a part of International Satellite Cloud Climatology Project (ISCCP), intensive observations of cirrus clouds were taken in the autumn of 1986 over Wisconsin. During this First ISCCP Regional Experiment Cirrus Intensive Field Observation (FIRE Cirrus IFO), coordinated measurements from satellite, aircraft, and ground-based platforms were made of cirrus clouds. This paper deals with the verification of cirrus cloud information, both spatial and radiative, obtained for a 1986 FIRE cloud scene using measurements from two independent sensors onboard the NOAA-9 polar orbiting satellite. In addition to the wide variability in properties common for other types of clouds, cirrus clouds have the added complexity of transmissivity t values that span the entire possible domain 0 = t= 1. Thus, uncertainties exist in thin cirrus cloud amount, altitude, thickness, and optical properties as retrieved from satellite because the measured cirrus signal is affected additionally by an unknown radiation component from below.
Download or read book Distribution and Radiative Forcing of Tropical Thin Cirrus Clouds written by and published by . This book was released on 2009 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: To understand the radiative impact of tropical thin cirrus clouds, the frequency of occurrence and optical depths of these clouds have been derived. "Thin" cirrus clouds are defined here as being those that are not detected by the operational Moderate Resolution Imaging Spectroradiometer (MODIS) cloud mask, corresponding to an optical depth value of approximately 0.3 or smaller, but that are detectable in terms of the cirrus reflectance product based on the MODIS 1.375-micron channel. With such a definition, thin cirrus clouds were present in more than 40% of the pixels flagged as "clear sky" by the operational MODIS cloud mask algorithm. It is shown that these thin cirrus clouds are frequently observed in deep convective regions in the western Pacific. Thin cirrus optical depths were derived from the cirrus reflectance product. Regions of significant cloud fraction and large optical depths were observed in the Northern Hemisphere during the boreal spring and summer and moved southward during the boreal autumn and winter. The radiative effects of tropical thin cirrus clouds were studied on the basis of the retrieved cirrus optical depths, the atmospheric profiles derived from the Atmospheric Infrared Sounder (AIRS) observations, and a radiative transfer model in conjunction with a parameterization of ice cloud spectral optical properties. To understand how these clouds regulate the radiation field in the atmosphere, the instantaneous net fluxes at the top of the atmosphere (TOA) and at the surface were calculated. The present study shows positive and negative net forcings at the TOA and at the surface, respectively. The positive (negative) net forcing at the TOA (surface) is due to the dominance of longwave (shortwave) forcing. Both the TOA and surface forcings are in a range of 0-20 W/sq m, depending on the optical depths of thin cirrus clouds.
Download or read book Investigating the Application of a Spectrally Consistent Adiabatic Cloud Retrieval Method to MODIS written by and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Marine boundary layer clouds have a significant impact on Earth's radiative balance due to their large horizontal extent and persistent nature. They are also sensitive to changes in their microphysical properties by anthropogenic aerosols. The microphysical changes in turn modulate cloud radiative and precipitation characteristics. Uncertainty in future climate scenarios is largely driven by a lack of understanding of how clouds respond radiatively and hydrologically to a perturbed environment. Satellite radiometers offer a way of diagnosing the cloud structure through retrievals that exploit the varying cloud penetration depths of several near-infrared wavelengths. Current cloud optical property retrieval methods are based upon an assumption of a homogeneous vertical cloud structure, which is not consistent with adiabatically stratified vertical structure found in boundary layer clouds from in situ measurements. To better assess the degree to which these clouds conform to an adiabatic profile, investigated is the Adiabatic Spectrally Consistent Retrieval (ASCR). Taking advantage of the data screening and quality control measures implemented in the Moderate Resolution Imaging Spectroradiometer (MODIS) Cloud Product, the ASCR method inverts the Cloud Product's 1.6, 2.1 and 3.7 micron effective radii and optical thickness retrievals back to radiances equivalent to those originally observed by MODIS. The radiances are applied to a single adiabatically stratified cloud property retrieval utilizing all of the spectral information contained in the discrete retrievals within the MODIS Cloud Product. Through the comparison of the ASCR retrieval to bi-spectral adiabatic retrievals for each absorption channel, the degree of cloud top adiabaticity is quantified. The robustness and utility of ASCR is tested with respect to varying stratification, 3-D effects and lateral inhomogeneity through the analysis of synthetic clouds, large eddy simulations of cloud fields, and Monte Carlo simulations. Results from the application of ASCR to MODIS observations of marine stratocumuli near the South American and African continents are discussed.
Download or read book Cirrus Particle Distribution Study written by Donald J. Varley and published by . This book was released on 1980 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: Particle data obtained during C-130 cirrus sampling flights on 28 and 29 January and 2 February 1979 over the southwestern United States are described. The first flight sampled cirriform clouds ahead of a developing storm; the second flight obtained data in the tops of the cirriform clouds of a fully developed storm; and the third examined cirrus formed by a weak polar front and strong upper level winds. All flights sampled a variety of densities of cirrus; however, those sampled on 29 January, were the most complex and also at the lowest altitude. This flight provided numerous samples having as many as 350,000 particles per cubic meter in the 47 to 4700 micrometer size range. The largest particle sizes were generally less than 1100 micrometer, but some cirrus particles as large as 2.5/mm were detected at altitudes between 5.9 and 7.7 km. Generally, the calculated ice waster content (IWS) values were 0.04 g/m or less, with a maximum of 0.10 g/m in the active storm situation. On the other two days, the cirrus was of varying density with most particles less than 1400 micrometer and IWCs of 0.03 g/m or less. Particles as large as 2.5 mm were detected in the cirrus on all three flights. The in-flight meteorologist's characterization of heavy or thin clouds is better correlated with total particle number than particle size. Several atmospheric and particle spectral properties are tabulated for consecutive 15-sec data samples for the 3 flights.
Download or read book Contrails and Climate Engineering Process Studies on Natural and Artificial High Level Clouds and Their Impact on the Radiative Fluxes written by Gruber, Simon and published by KIT Scientific Publishing. This book was released on 2019-03-22 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Study of Cirrus Clouds Using Airborne and Satellite Data written by Kerry Glynne Meyer and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Cirrus clouds are known to play a key role in the earth's radiation budget, yet are one of the most uncertain components of the earth-atmosphere system. With the development of instruments such as the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) and the Moderate-resolution Infrared Spectroradiometer (MODIS), scientists now have an unprecedented ability to study cirrus clouds. To aid in the understanding of such clouds, a significant study of cirrus radiative properties has been undertaken. This research is composed of three parts: 1) the retrieval of tropical cirrus optical thickness using MODIS level-1b calibrated radiance data, 2) a survey of tropical cirrus cloud cover, including seasonal variations, using MODIS level-3 global daily gridded data, and 3) the simultaneous retrieval of cirrus optical thickness and ice crystal effective diameter using AVIRIS reflectance measurements.
Download or read book Development and Application of an Interactive Cirrus Cloud Radiative Parameterization for Global Climate Models written by Everette Joseph and published by . This book was released on 1997 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Studies in the Parameterization of Cloudiness in Climate Models and the Analysis of Radiation Fields in General Circulation Models written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-11 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: Broad-band parameterizations for atmospheric radiative transfer were developed for clear and cloudy skies. These were in the shortwave and longwave regions of the spectrum. These models were compared with other models in an international effort called ICRCCM (Intercomparison of Radiation Codes for Climate Models). The radiation package developed was used for simulations of a General Circulation Model (GCM). A synopsis is provided of the research accomplishments in the two areas separately. Details are available in the published literature. HARSHVARDHAN Unspecified Center NAG5-1088...
Download or read book Radiation and Water in the Climate System written by Ehrhard Raschke and published by Springer Science & Business Media. This book was released on 1996-09-17 with total page 640 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of the earth's climate requires reliable global data sets to validate numerical simulation models and to identify regional and global fluctuations and trends. This book presents ways to obtain such data from space-borne and ground-based measurements, both passive and active, over the entire electromagnetic spectrum. It describes the basics of such methods together with the most recent advancements and spans the field from clouds and the planetary radiation budget to surface processes and ocean properties. Each subject is backed by extensive reference lists to enable readers to probe more deeply.
