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33
Ensemble Kalman Filter Assimilation of Doppler Radar Data with a Compressible Nonhydrostatic Model: OSS Experiments
, 2004
"... A Doppler radar data assimilation system is developed based on ensemble Kalman filter (EnKF) method and tested with simulated radar data from a supercell storm. As a first implementation, we assume the forward models are perfect and radar data are sampled at the analysis grid points. A general pur ..."
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A Doppler radar data assimilation system is developed based on ensemble Kalman filter (EnKF) method and tested with simulated radar data from a supercell storm. As a first implementation, we assume the forward models are perfect and radar data are sampled at the analysis grid points. A general purpose nonhydrostatic compressible model is used with the inclusion of complex multi-class ice microphysics. New aspects compared to previous studies include the demonstration of the ability of EnKF method in retrieving multiple microphysical species associated with a multi-class ice microphysics scheme, and in accurately retrieving the wind and thermodynamic variables. Also new are the inclusion of reflectivity observations and the determination of the relative role of radial velocity and reflectivity data as well as their spatial coverage in recovering the full flow and cloud fields. In general, the system is able to reestablish the model storm extremely well after a number of assimilation cycles, and best results are obtained when both radial velocity and reflectivity data, including reflectivity information outside precipitation regions, are used. Significant positive impact of the reflectivity assimilation
IN-CLOUD AND BELOW-CLOUD SCAVENGING OF NITRIC ACID VAPOR
"... Abstract-Scavenging coefficients, A, for the removal of HNO?; vapor from the atmosphere by both cloud and rain drops have been calculated for assumed models of drop-size distribution. For cumulus clouds a value of 0.2 s- 1 is estimated for A. Evaluation of rainfall washout coefficients gives values ..."
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Abstract-Scavenging coefficients, A, for the removal of HNO?; vapor from the atmosphere by both cloud and rain drops have been calculated for assumed models of drop-size distribution. For cumulus clouds a value of 0.2 s- 1 is estimated for A. Evaluation of rainfall washout coefficients gives values of A ranging from 1.3 x 10m5 to 1.5 x 10. ‘s-t, depending upon the rainfall rate, upon the drop-size distribution function employed, and, strongly upon the lower limit of the raindrop size employed in the calculations. The concentration of soluble gas dissolved within a falling drop per unit fall distance is found to be a function of drop size, with the smaller drops accumulating the greater concentration. The long-term average rate of heterogeneous removal of HNO, is estimated in the range l---8 x 10-6s-‘, representing comparable contributions from dry deposition and rainfall scavenging. Nitrogen oxides-NO and to a lesser extent NO,-are introduced into the atmosphere as by-products of fossil fuel combustion by electric power generation and other stationary facilities, by vehicles and by aircraft. A major fraction of these oxides of nitrogen is further oxidized by gas-phase reactions to NO, and in
Simultaneous Estimation of Microphysical Parameters and the Atmospheric State Using Simulated Polarimetric Radar Data and an Ensemble Kalman Filter in the Presence of an Observation Operator Error
, 2008
"... The impacts of polarimetric radar data on the estimation of uncertain microphysical parameters are investigated through observing system simulation experiments when the effects of uncertain parameters on the observation operators are also considered. Five fundamental microphysical parameters (i.e., ..."
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The impacts of polarimetric radar data on the estimation of uncertain microphysical parameters are investigated through observing system simulation experiments when the effects of uncertain parameters on the observation operators are also considered. Five fundamental microphysical parameters (i.e., the intercept parameters of rain, snow, and hail and the bulk densities of snow and hail) are estimated individually or collectively using the ensemble square root Kalman filter. The differential reflectivity Z DR, specific differential phase KDP, and radar reflectivity at horizontal polarization ZH are used individually or in combinations for the parameter estimation while the radial velocity and ZH are used for the state estimation. In the process, the parameter values estimated in the previous analysis cycles are used in the forecast model and in observation operators in the ensuing assimilation cycle. Analyses are first performed that examine the sensitivity of various observations to the microphysical parameters with and without observation operator error. The results are used to help interpret the filter behaviors in parameter estimation. The experiments in which either a single or all five parameters contain initial errors reveal difficulties in estimating certain parameters using Z H alone when observation operator error is involved. Additional polarimetric measurements are found to be beneficial for both parameter and state estimation in general. It is found that the polarimetric data are more
Simultaneous retrieval of microphysical parameters and atmospheric state variables with radar data and ensemble Kalman filter method
- PREPRINT, 17TH CONF. NUM. WEA. PRED., WASHINGTON DC, AMER. METEOR. SOC., CDROM P1.30
, 2005
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Disdrometer and Tipping Bucket Rain Gauge Handbook
, 2009
"... This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any ..."
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Cited by 3 (0 self)
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This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the U.S. Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect
On measurements of drop size distribution
- Top. Meteor. Oceanog
, 1999
"... This paper presents a review of the current knowledge concerning the measurement and time evolution of the raindrop spectra. A survey of the methods for measuring drop size distributions (DSD´s) is given, as well as a summary of the most used techniques for its data analysis. Main results from DSD o ..."
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This paper presents a review of the current knowledge concerning the measurement and time evolution of the raindrop spectra. A survey of the methods for measuring drop size distributions (DSD´s) is given, as well as a summary of the most used techniques for its data analysis. Main results from DSD observations, at several geographic locations, are discussed. This work also presents observations of continental, stratiform rain, taken simultaneously with two different sensors. Theoretical aspects of the raindrop formation are discussed, and the description of major results from numeric simulations, by several authors, of the rain formation process is presented as well. Finally, a summary of the current dilemmas on DSD measurements is given, with a recommendation for future work in the field
Wind Tunnel Aerodynamic Characteristics of a Transport-Type Airfoil in a Simulated Heavy Rain Environment
, 1992
"... this report were obtained with an NACA 64-210 airfoil model w ith leading- and trailing-edge high-lift devices tested in cruise and landing configurations. The tests were conducted in the Langley 14- by 22-Foot Subson ic Tunnel at dynamic pressures of 30 and 50 psf, which correspond to Reynolds numb ..."
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this report were obtained with an NACA 64-210 airfoil model w ith leading- and trailing-edge high-lift devices tested in cruise and landing configurations. The tests were conducted in the Langley 14- by 22-Foot Subson ic Tunnel at dynamic pressures of 30 and 50 psf, which correspond to Reynolds numbers of 2:6
Article Performance of Using Cascade Forward Back Propagation Neural Networks for Estimating Rain Parameters with Rain Drop Size Distribution
, 2014
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Understanding the Variability of Z-R Relationships Caused by Natural Variations in Raindrop Size Distributions (DSD): Implication of Drop Size and Number, available at: http:// www.SciRP.org/journal/acs/, Atmos
- Clim. Sci
, 2011
"... In the issue of rainfall estimation by radar through the necessary relationship between radar reflectivity Z and rain rate R (Z-R), the main limitation is attributed to the variability of this relationship. Indeed, several pre-vious studies have shown the great variability of this relationship in sp ..."
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In the issue of rainfall estimation by radar through the necessary relationship between radar reflectivity Z and rain rate R (Z-R), the main limitation is attributed to the variability of this relationship. Indeed, several pre-vious studies have shown the great variability of this relationship in space and time, from a rainfall event to another and even within a single rainfall event. Recent studies have shown that the variability of raindrop size distributions and thereby Z-R relationships is therefore, more the result of complex dynamic, thermody-namic and microphysical processes within rainfall systems than a convective/stratiform classification of the ground rainfall signature. The raindrop number and size at ground being the resultant of various processes mentioned above, a suitable approach would be to analyze their variability in relation to that of Z-R relation-ship.In this study, we investigated the total raindrop concentration number NT and the median volume di-ameter D0 used in numerous studies, and have shown that the combination of these two ‘observed ’ parame-ters appears to be an interesting approach to better understand the variability of the Z-R relationships in the rainfall events, without assuming a certain analytical raindrop size distribution model (exponential, gamma, or log-normal). The present study is based on the analysis of disdrometer data collected at different seasons and places in Africa, and aims to show the degree of the raindrop size and number implication in regard to
DOE/SC-ARM/10-004 Midlatitude Continental Convective Clouds Experiment (MC3E)
, 2010
"... This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any ..."
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This report was prepared as an account of work sponsored by the U.S. Government. Neither the United States nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the U.S. Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the U.S. Government or any agency thereof. DOE/SC-ARM/10-004 Midlatitude Continental Convective
