In this research paper we present a mathematical model for COVID-19 in high-risk settings and low-risk settings which might be infection dynamics between hotspots and less risky communities. The main idea was to couple the SIR model with alternating risk levels from the two different settings high and low-risk settings. Therefore, building from this model we partition the infected class into two categories, the symptomatic and the asymptomatic. Using this approach we simulated COVID-19 dynamics in low and high-risk settings with auto- switching risk settings. Again, the model was analyzed using both analytic methods and numerical methods. The results of this study suggest that switching risk levels in different settings plays a pivotal role in COVID-19 progression dynamics. Hence, population reaction time to adhere to preventative measures and interventions ought to be implemented with flash speed targeting first the high-risk setting while containing the dynamics in low-risk settings.

Physics and Chemistry of the Earth

It is well acknowledged that there are large uncertainties associated with radar-based estimates of rainfall. Numerous sources of these errors are due to parameter estimation, the observational system and measurement principles, and not fully understood physical processes. Propagation of these uncertainties through all models for which radar-rainfall are used as input (e.g., hydrologic models) or as initial conditions (e.g., weather forecasting models) is necessary to enhance the understanding and interpretation of the obtained results. The aim of this paper is to provide an extensive literature review of the principal sources of error affecting single polarization radar-based rainfall estimates. These include radar miscalibration, attenuation, ground clutter and anomalous propagation, beam blockage, variability of the Z–R relation, range degradation, vertical variability of the precipitation system, vertical air motion and precipitation drift, and temporal sampling errors. Finally, the authors report some recent results from empirically-based modeling of the total radar-rainfall uncertainties. The bibliography comprises over 200 peer reviewed journal articles.

Review of the Different Sources of Uncertainty in Single Polarization Radar-Based Estimates of Rainfall

Rainfall erosivity and variability in the Northern Ethiopian Highlands

Kinetic energy of rain and its functional relationship with intensity

The second WetNet Precipitation Intercomparison Project (PIP-2) evaluates the performance of 20 satellite precipitation retrieval algorithms, implemented for application with Special Sensor Microwave/Imager (SSM/I) passive microwave (PMW) measurements and run for a set of rainfall case studies at full resolution‐instantaneous space‐timescales. The cases are drawn from over the globe during all seasons, for a period of 7 yr, over a 608N‐ 178S latitude range. Ground-based data were used for the intercomparisons, principally based on radar measurements but also including rain gauge measurements. The goals of PIP-2 are 1) to improve performance and accuracy of different SSM/I algorithms at full resolution‐instantaneous scales by seeking a better understanding of the relationship between microphysical signatures in the PMW measurements and physical laws employed in the algorithms; 2) to evaluate the pros and cons of individual algorithms and their subsystems in order to seek optimal ‘‘front-end’’ combined algorithms; and 3) to demonstrate that PMW algorithms generate acceptable instantaneous rain estimates. It is found that the bias uncertainty of many current PMW algorithms is on the order of 630%. This level is below that of the radar and rain gauge data specially collected for the study, so that it is not possible to objectively select a best algorithm based on the ground data validation approach. By decomposing the intercomparisons into effects due to rain detection (screening) and effects due to brightness temperature‐rain rate conversion, differences among the algorithms are partitioned by rain area and rain intensity. For ocean, the screening differences mainly affect the light rain rates, which do not contribute significantly to area-averaged rain rates. The major sources of differences in mean rain rates between individual algorithms stem from differences in how intense rain rates are calculated and the maximum rain rate allowed by a given algorithm. The general method of solution is not necessarily the determining factor in creating systematic rain-rate differences among groups of algorithms, as we find that the severity of the screen is the dominant factor in producing systematic group differences among land algorithms, while the input channel selection is the dominant factor in producing systematic group differences among ocean algorithms. The significance of these issues are examined through what is called ‘‘fan map’’ analysis. The paper concludes with a discussion on the role of intercomparison projects in seeking improvements to algorithms, and a suggestion on why moving beyond the ‘‘ground truth’’ validation approach by use of a calibration-quality forward model would be a step forward in seeking objective evaluation of individual algorithm performance and optimal algorithm design.

/pdf/results-of-wetnet-pip-2-project-3jrpb39996.pdf

Results of WetNet PIP-2 Project

Radars operating in complex orographic areas usually suffer from partial or total beam blockage by surrounding targets at their lowest elevation scans. The need for radar quantitative precipitation estimates in such environments led to the development of beam blockage corrections. This paper aims at evaluating the performance of beam blockage corrections under different electromagnetic propagation conditions with particular interest in anaprop situations. Three years of radiosonde data collected at Barcelona, Spain, a typical Mediterranean coastal site, are used to characterize the behavior of the vertical refractivity gradient near a weather radar. Three different targets surrounding the radar have been chosen and used to evaluate the different beam shielding simulated under different propagation conditions. A simple interception function between the radar beam and the topography is proposed and used for the different targets and propagation conditions considered. Results show that beam blockage correction is generally robust, with departures of 1 dB from the standard propagation conditions correction less than 10% of the time. However, as the presence of extreme anaprop cases would lead to higher differences, the monitoring of the propagation conditions is suggested as a criteria to be considered, among others such as the analysis of the echo structure, as a quality control of the radar quantitative precipitation estimate.

/pdf/the-sensitivity-of-single-polarization-weather-radar-beam-1ypu0s9a5m.pdf

The Sensitivity of Single Polarization Weather Radar Beam Blockage Correction to Variability in the Vertical Refractivity Gradient

The erosive effect produced by direct raindrop impact on the soil surface may be quantified in terms of the raindrop kinetic energy (KE). This variable is usually calculated from the rainfall rate even though a precise description of the raindrop size distribution is required. In this study, raindrop size and fall velocities were measured for 2 yr in Barcelona, Spain, with an optical disdrometer. Fitted drop-size distributions were used to obtain relationships between raindrop KE and rainfall rate. A comparison between KE calculated from experimental distributions indicated that the lognormal distribution model was most suitable to provide a KE-rainfall rate relation. Predicted KE values from this relationship had better agreement with observations (differences of 7%) than predicted values from other models based on different rainfall conditions.

Modeling Rain Erosivity Using Disdrometric Techniques

The effect of atmospheric propagation on radar observations is an important topic both for radar application developers and end-users of radar products, particularly of weather radar systems. An excellent review of this subject is given by Patterson (2008), and most general books about weather radars have a chapter on the topic –see for example Battan (1973), Collier (1996), Doviak and Zrnic (2006), Rinehart (2001) or Sauvageot (1991).

/pdf/effects-of-anomalous-propagation-conditions-on-weather-radar-2rktpuem1c.pdf

Effects of Anomalous Propagation Conditions on Weather Radar Observations

The introduction of technological advancements in TV weather broadcasts has been a constant trend, particularly in the last 20 years. Rapidly evolving techniques, both from the point of view of new meteorological products or the use of advanced computer generated graphics, have offered a wide choice of possibilities to enhance information content and communication capability. However, despite the potential advantage of technological innovation, a case-by-case careful feasibility analysis is always required, including not only technical and economical aspects, but most importantly communication issues bearing in mind the education and acceptance of the audience.



In this paper two specific cases of technological advances in TV weather broadcasts, seen from the perspective of the last 20 years, are examined: the introduction of weather radar images and the use of animated characters as weathercasters. These cases are illustrated from the experience acquired in TVC, the public Television of Catalonia (NE Spain). Direct access to weather radar data was first made possible within the framework of a joint collaboration agreement with the University of Barcelona and the Meteorological Service of Catalonia, which installed a new C-band Doppler radar. The use of animated characters as weathercasters was the result of developing and advanced human-like interface accessing an already existing database fed automatically by NWP forecasts. In each case a description of both technical aspects and also of the benefits and challenges seen from the communication point of view found in their introduction in TV weather broadcasts is provided. Copyright © 2010 Royal Meteorological Society

https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/met.195

Improving TV weather broadcasts with technological advancements: two cases from a 20 year perspective

Rain acidity during a storm: Results from a simple acid-monitoring device

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