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Author: Volkan Huseyin Firat Publisher: ISBN: Category : Languages : en Pages :
Book Description
Clouds are still one of the largest uncertainties of the current climate models. While satellites provide suitable global datasets for comparing with cloud properties derived from models, satellite retrievals are inferences of cloud properties, rather than direct measurements, and therefore have errors. Therefore, it is important to evaluate satellite cloud products and gain advanced understanding of the products to accurately interpret the observations. This study investigates Aqua AIRS version 6 Level 2 cloud thermodynamic phase, ice cloud optical thickness, and ice cloud effective diameter, which released in April, 2013 and are available for all 13 years of the AIRS record. A filtering and gridding algorithm is used to create customized globally gridded datasets to evaluate the effects of satellite's viewing zenith angle, effective cloud fraction, cloud layers, cloud top temperature, time of the year, and geographic region. Viewing zenith angle does not strongly affect AIRS ice-phase, but higher viewing zenith angles lead to more water and fewer unknown pixels; the viewing zenith angle dependence is not strongly affected by the time of the year. Higher effective cloud fraction yields more ice- and water-phase, and less unknown-phase retrievals. Also, higher effective cloud fractions lead to greater values of ice cloud optical thickness. In addition, especially in high latitudes, ice-phase frequency is greater for two-layer clouds than single-layer clouds. On the other hand, water- and unknown-phase frequencies are greater for single layer clouds. Also, higher viewing zenith angles slightly decrease upper cloud top temperature. Approximately 90% of ice-phase cases have upper cloud top temperature values between 210 K and 235 K, ~80% of water-phase cases are found at 243-273 K upper cloud top temperature interval, and ~80% of the unknown cases have upper cloud top temperature values between 230 and 264 K. For ice cloud optical thickness and ice cloud effective diameter, no strong effects of satellite viewing zenith angle or cloud layering are observed. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/155521
Author: Volkan Huseyin Firat Publisher: ISBN: Category : Languages : en Pages :
Book Description
Clouds are still one of the largest uncertainties of the current climate models. While satellites provide suitable global datasets for comparing with cloud properties derived from models, satellite retrievals are inferences of cloud properties, rather than direct measurements, and therefore have errors. Therefore, it is important to evaluate satellite cloud products and gain advanced understanding of the products to accurately interpret the observations. This study investigates Aqua AIRS version 6 Level 2 cloud thermodynamic phase, ice cloud optical thickness, and ice cloud effective diameter, which released in April, 2013 and are available for all 13 years of the AIRS record. A filtering and gridding algorithm is used to create customized globally gridded datasets to evaluate the effects of satellite's viewing zenith angle, effective cloud fraction, cloud layers, cloud top temperature, time of the year, and geographic region. Viewing zenith angle does not strongly affect AIRS ice-phase, but higher viewing zenith angles lead to more water and fewer unknown pixels; the viewing zenith angle dependence is not strongly affected by the time of the year. Higher effective cloud fraction yields more ice- and water-phase, and less unknown-phase retrievals. Also, higher effective cloud fractions lead to greater values of ice cloud optical thickness. In addition, especially in high latitudes, ice-phase frequency is greater for two-layer clouds than single-layer clouds. On the other hand, water- and unknown-phase frequencies are greater for single layer clouds. Also, higher viewing zenith angles slightly decrease upper cloud top temperature. Approximately 90% of ice-phase cases have upper cloud top temperature values between 210 K and 235 K, ~80% of water-phase cases are found at 243-273 K upper cloud top temperature interval, and ~80% of the unknown cases have upper cloud top temperature values between 230 and 264 K. For ice cloud optical thickness and ice cloud effective diameter, no strong effects of satellite viewing zenith angle or cloud layering are observed. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/155521
Author: David Michael Loveless Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Profiles, or soundings, of atmospheric temperature and water vapor from remotely sensed platforms provide critical observations within the temporal and spatial gaps of the radiosonde network. The 2017 National Academies of Science Decadal Survey highlighted that observations of the planetary boundary layer (PBL) from the current space-based observing system are not of the necessary accuracy or resolution for monitoring and predicting high impact weather phenomena. The National Research Council (NRC, 2009) suggested the development of a network of ground-based profilers to supplement the existing space-based observing system in order to improve observations of the PBL. One instrument that fits the requirements outlined by the NRC (2009) for the ground-based network for profilers is the Atmospheric Emitted Radiance Interferometer (AERI). This dissertation advances the understanding of the benefits of a synergy between the ground-based AERI and space-based hyperspectral infrared (IR) sounders as a method for improving thermodynamic sounding using three studies: 1) A synthetic information content analysis in clear sky conditions to quantify improvements offered by the synergy of profilers in terms of degrees of freedom, vertical resolution, and uncertainties. 2) A synthetic information content study in three cloudy sky scenes to assess the potential of the ground-based and space-based synergy as a possible solution to IR sounding in cloudy environments. 3) Develop an optimal estimation retrieval that combines AERI with the space-based Cross-track Infrared Sounder (CrIS) on S-NPP and NOAA-20 to assess the performance of the synergy in practice, outside of synthetic studies. The clear sky information content study shows that a combination of AERI with any of the three polar-orbiting IR sounders: The Atmospheric Infrared Sounder (AIRS), the Cross-track Infrared Sounder (CrIS), or the Infrared Atmospheric Sounding Interferometer (IASI), results in a 30-40% increase in degrees of freedom (DOF) in the surface to 700 hPa layer compared to the space-based instrument alone. Introducing AERI measurements to the observing system also results in significant improvements to vertical resolution and uncertainties in the bottom 1000 m of the atmosphere compared to CrIS measurements alone. The cloudy sky information content analysis show that the synergy of CrIS+AERI has greater temperature information in cloudy sky conditions than in clear sky because the cloud provides an opaque layer that sharpens the Jacobians enabling a temperature retrieval at that layer. AERI and CrIS both lose water vapor information as the cloud becomes optically thick, though a synergy of CrIS+AERI would minimize those losses. In partly cloudy scenes, the information content of the synergy is most sensitive to cloud cover at greater than 50% aerial cloud fraction. The combined CrIS+AERI retrieval is assessed for a single case study. CrIS+AERI did not produce the best comparison to the radiosonde profile when compared to the individual instrument retrievals and was found to have greater uncertainty as well. It is shown that this is likely due to the small uncertainties used for each instrument. The synergy of CrIS+AERI was found to replicate the improvements in vertical resolution identified in the information content analysis. The vertical resolution of the combined retrieval in this case study is found to exceed the 1 km resolution goal stated by the 2017 Decadal Survey.
Author: Publisher: ISBN: Category : Languages : en Pages : 238
Book Description
Satellite measurements are an important source of global observations in support of numerical weather prediction (NWP). The assimilation of satellite radiances under clear skies has greatly improved NWP forecast scores. Since most of the data assimilation models are used for the clear radiances assimilation, an important step for satellite radiances assimilation is the clear location detection. Good clear detection could effectively remove the cloud contamination and keep the clear observations for assimilation. In this dissertation, a new detection method uses collocated high spatial resolution imager data onboard the same platform as the satellite sounders to help IR sounders subpixel cloud detection, such as the Atmospheric Infrared Sounder (AIRS) and Moderate Resolution Imaging Spectroradiometer (MODIS), the Crosstrack Infrared Sounder (CrIS) and Visible Infrared Imaging Radiometer Suite (VIIRS). The MODIS cloud mask provides a level of confidence for the observed skies to help AIRS Field-of-View (FOVs) cloud detection. By reducing the cloud contamination, a cold bias in the temperature field and a wet bias in the moisture field are corrected for the atmospheric analysis fields. These less cloud affected analysis fields further improve hurricane track and intensity forecast. The availability of satellite observations that can be assimilated in the model is limited if only the clear radiances are assimilation. An effective way to use the thermodynamic information under partially cloudy regions is to assimilate the “cloud-cleared” radiances (CCRs); CCRs are also called clear equivalent radiances. Because the CCRs are the equivalent clear radiances from the partially cloudy FOVs, they can be directly assimilated into the current data assimilation models without modifications. The AIRS CCRs are assimilated and compared with the AIRS using stand-alone cloud detection and collocated cloud detection. The assimilation of AIRS cloud-cleared radiances directly affects the atmospheric fields in the surroundings away from the hurricane center at the analysis time. With the improvement of the atmospheric fields, the assimilation of cloud-cleared AIRS gives the smallest root mean square error (RMSE) of hurricane tract 72-hour forecast compared to the AIRS radiances using stand-alone cloud detection and collocated cloud mask cloud detection.
Author: Kuo-Nan Liou Publisher: Cambridge University Press ISBN: 0521889162 Category : Science Languages : en Pages : 461
Book Description
This volume outlines the fundamentals and applications of light scattering, absorption and polarization processes involving ice crystals.
Author: Peter Ray Publisher: Springer ISBN: 1935704206 Category : Science Languages : en Pages : 803
Book Description
This book is a collection of selected lectures presented at the ‘Intensive Course on Mesoscale Meteorology and Forecasting’ in Boulder, USA, in 1984. It includes mesoscale classifications, observing techniques and systems, internally generated circulations, mesoscale convective systems, externally forced circulations, modeling and short-range forecasting techniques. This is a highly illustrated book and comprehensive work, including extensive bibliographic references. It is aimed at graduates in meteorology and for professionals working in the field.
Author: Volkan Huseyin Firat
Author: Volkan Huseyin Firat
Author: 
Author: David Michael Loveless
Author: 
Author: Kuo-Nan Liou
Author: 
Author: Joseph G. Sela
Author: 
Author: Peter Ray
Author: Nicole J. Brubaker