Prediction of Cloud Cover with a Global Model PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Prediction of Cloud Cover with a Global Model PDF full book. Access full book title Prediction of Cloud Cover with a Global Model by . Download full books in PDF and EPUB format.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Get Book Here
Book Description
This is a study of diagnostic cloud schemes to examine the variability of cloud fractions in monsoon systems. Includes simulation the middle tropospheric cyclone (MTC) of the Asian monsoon. Cloud radiation is a key factor in the thermodynamic control of the local east-west circulation. Also showed is the coalescence of small vorticity elements; these coalesce to form a parent large scale mid-tropospheric cyclone The study of thermodynamics of this system constitutes this research. Various methods for determining precipitation rates associated with the MTC are included and precipitation is shown to be due to convective processes rather than stable processes which are characterized by the general monsoon pattern.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Get Book Here
Book Description
This is a study of diagnostic cloud schemes to examine the variability of cloud fractions in monsoon systems. Includes simulation the middle tropospheric cyclone (MTC) of the Asian monsoon. Cloud radiation is a key factor in the thermodynamic control of the local east-west circulation. Also showed is the coalescence of small vorticity elements; these coalesce to form a parent large scale mid-tropospheric cyclone The study of thermodynamics of this system constitutes this research. Various methods for determining precipitation rates associated with the MTC are included and precipitation is shown to be due to convective processes rather than stable processes which are characterized by the general monsoon pattern.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 116
Get Book Here
Book Description
The completed research is in the area of cloud prediction with a high resolution global model. We have extended our studies on the handling of implicit clouds (i.e. clouds specified as a function of prevailing humidity). We have also examined this problem in the context of rainfall initialization (called physical initialization). We demonstrate a strong positive impact on cloud forecasts from such an initialization. We have also made a start on the problem of explicit cloud forecasts using cloud water mixing ratio and cloud fractions as basic forecast variables. Our preliminary results, described in the final report, are very encouraging. Mannoji (1994) has in fact noted a slight superiority of the explicit over the implicit scheme. That work was performed using a low resolution global model. Further work on the improvement of the explicit scheme at higher resolution is required. Cloud prediction, Global modelling of clouds.
Author: Donald C. Norquist
Publisher:
ISBN:
Category : Cloud forecasting
Languages : en
Pages : 154
Get Book Here
Book Description
Author: Lisa Bucci
Publisher:
ISBN:
Category :
Languages : en
Pages : 47
Get Book Here
Book Description
ABSTRACT: This study addresses the issue of global and regional cloud cover forecasts. Using a suite of global models, the multimodel superensemble forecasts are constructed for total cloud coverage and layered (low, middle, and high) cloud coverage out to 7 days (168 hours). The experiments were conducted on a 1° latitude by 1° longitude spatial grid at a 24 hour temporal resolution. The multimodel superensemble carries a training and a forecast phase. Several training periods were used to determine an optimal training phase. The total period of this study includes October 2006 through February 2007. Clouds from the International Satellite Cloud Climatology Project (ISCCP) were used for training and cloud validations. The metrics for the forecast evaluation include the root mean square errors, spatial correlations, and equitable threat scores. The results show a significant improvement (~25%) of the multimodel superensemble forecasts compared to those from the member models forecasts, as well as their ensemble mean for the global and regional domains.
Author: Kenneth E. Mitchell
Publisher:
ISBN:
Category : Cloud forecasting
Languages : en
Pages : 166
Get Book Here
Book Description
Using forecast relative humidity (RH) from a global model, several pre-existing diagnostic RH-to-cloud schemes were tested to forecast global fractional cloud cover in a postprocessor format. Since none of the schemes tested provided a superior cloud forecast when compared to Air Force Global Weather Central's (AFGWC) operational 5LAYER cloud forecasts, a new RH-to-cloud scheme was developed by relating cumulative frequencies of forecast RH to cumulative frequencies of analyzed cloud cover from the AFGWC RTNEPH cloud analysis. This scheme creates a series of forecast time-dependent RH-to-cloud curves that can be temporally updated to account for changes in season, cloud analysis, or forecast model, The global model used was a spectral-type developed by the Geophysics Laboratory (GL) using parameterized diabatic physics presently incorporated in the operational GSM (global spectral model) at AFGWC.
Author: Donald C. Norquist
Publisher:
ISBN:
Category : Cloud forecasting
Languages : en
Pages : 0
Get Book Here
Book Description
We developed statistical relationships between fractional cloud cover and a collection of variables drawn from forecast fields from a global numerical weather prediction model. These relationships were then applied to later forecasts from the same weather prediction model to diagnose the cloud cover corresponding to the forecast states. The U.S. Air Force RTNEPH cloud analysis datasets in the Northern Hemisphere for January and July 1991 were used to represent cloud cover in separate winter and summer statistical relationship developments. Forecasts from the Phillips Laboratory Global Spectral Model at times corresponding to the cloud analyses were used to provide the weather model predictors. We used multiple linear regression and a hybrid regression estimation of event possibilities/multiple linear regression to develop the statistical relationships in the 5 percent cloud amount categories from 0 to 100 percent. We used multiple discriminant analysis with six cloud amount categories covering the range from 0 to 100 percent. Separate relationships were developed over 10-day periods for low, middle, and high cloud decks, and total cloud. The relationships developed were also distinct for different forecast durations. All relationships were applied to forecasts initialized on the day following the 10-day development period. Our results showed that multiple linear regression produced forecast diagnoses of cloud amount that were slightly better than the other methods in root-mean-square error. This method also modified the frequency distribution of cloud cover from that of the analysis. The hybrid method improved upon the frequency distribution of clear and overcast, but worsened the near-clear and near-overcast categories. Multiple discriminant analysis produced cloud cover diagnoses with the best combination of root-mean-square skill and preservation of the freque.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Get Book Here
Book Description
We have successfully implemented an explicit cloud scheme within the Florida State University Global Spectral Model. This includes the liquid water mixing ratio and cloud fractions as two additional dependant variables. The main purpose of this extension is two fold: we wished to improve our global cloud forecasting capability (low, medium and high clouds) and to have a better definition of the cloud radiative effects. A band model is being used for the short and long wave radiative transfer. A major component of this study is the initialization of clouds. For this purpose we have utilized the U.S. Air Force Real-Time Nephanalysis product called RTNEPH. The microwave radiances from the U.S. Air Force fleet of DMSP satellites is another source of data. These are the special sensor microwave instruments carried by these satellites. This information provides measures of vertically integrated liquid water mixing ratios. The liquid water mixing ratios are vertically partitioned using weights from the RTNEPH; this provides an initial definition of clouds and cloud fractions. These were further initialized using the procedure of physical initialization. The impact studies of this cloud specification and initialization appear very promising.
Author: Roger G. Barry
Publisher: Routledge
ISBN: 1134910959
Category : Nature
Languages : en
Pages : 262
Get Book Here
Book Description
This book provides a comprehensive text describing and explaining mountain weather and climate processes. It presents the results of a broad range of studies drawn from across the world. The book is useful for specialist courses in climatology as well as for scientists in related disciplines.
Author: Stéphane Vannitsem
Publisher: Elsevier
ISBN: 9780128123720
Category : Science
Languages : en
Pages : 0
Get Book Here
Book Description
Statistical Postprocessing of Ensemble Forecasts brings together chapters contributed by international subject-matter experts describing the current state of the art in the statistical postprocessing of ensemble forecasts. The book illustrates the use of these methods in several important applications including weather, hydrological and climate forecasts, and renewable energy forecasting. After an introductory section on ensemble forecasts and prediction systems, the second section of the book is devoted to exposition of the methods available for statistical postprocessing of ensemble forecasts: univariate and multivariate ensemble postprocessing are first reviewed by Wilks (Chapters 3), then Schefzik and Möller (Chapter 4), and the more specialized perspective necessary for postprocessing forecasts for extremes is presented by Friederichs, Wahl, and Buschow (Chapter 5). The second section concludes with a discussion of forecast verification methods devised specifically for evaluation of ensemble forecasts (Chapter 6 by Thorarinsdottir and Schuhen). The third section of this book is devoted to applications of ensemble postprocessing. Practical aspects of ensemble postprocessing are first detailed in Chapter 7 (Hamill), including an extended and illustrative case study. Chapters 8 (Hemri), 9 (Pinson and Messner), and 10 (Van Schaeybroeck and Vannitsem) discuss ensemble postprocessing specifically for hydrological applications, postprocessing in support of renewable energy applications, and postprocessing of long-range forecasts from months to decades. Finally, Chapter 11 (Messner) provides a guide to the ensemble-postprocessing software available in the R programming language, which should greatly help readers implement many of the ideas presented in this book. Edited by three experts with strong and complementary expertise in statistical postprocessing of ensemble forecasts, this book assesses the new and rapidly developing field of ensemble forecast postprocessing as an extension of the use of statistical corrections to traditional deterministic forecasts. Statistical Postprocessing of Ensemble Forecasts is an essential resource for researchers, operational practitioners, and students in weather, seasonal, and climate forecasting, as well as users of such forecasts in fields involving renewable energy, conventional energy, hydrology, environmental engineering, and agriculture.
Author: Kenneth E. Mitchell
Publisher:
ISBN:
Category :
Languages : en
Pages : 151
Get Book Here
Book Description
