Suppressing Grid-Point Storms in a Numerical Forecasting Model

The convective parameterization scheme of the Korean Integrated Model (KIM) is tentatively modified to suppress grid-point storms in the Western Pacific Ocean. The KIM v3.2.11 suffers from the numerical problem that grid-point storms degrade forecasts in the tropical oceans and around the Korean Peninsula. Another convective parameterization scheme, the new Tiedtke scheme, is implemented in the KIM. The artificial storms are suppressed in the test version because the heating and drying tendencies of the new Tiedtke scheme are stronger than those of the default KIM Simplified Arakawa-Schubert (KSAS) scheme. Based on this comparison, the KSAS scheme is modified to strengthen its heating and drying tendencies by reducing the entrainment and detrainment rates. The modified KSAS scheme suppresses grid-point storms and thus decreases grid-scale precipitation in a summertime case simulation. Twenty 10-day forecasts with the default convection scheme (KSAS) and twenty forecasts with the modified scheme are conducted and compared with each other, confirming that the modified KSAS scheme successfully suppresses grid-point storms.

Prediction Model suitable for Long-term High Turbidity Events in a Reservoir

The turbidity events caused by Typhoon “Kong-rey” in 2018 were selected as the measured turbidity data required to build the CE-QUAL-W2 model. The turbidity, water temperature, climate data, and discharge measured in the main dam were used as input data for numerical simulations. To ensure the reliability of the parameters, the turbidity events caused by Typhoon “Mitak” in 2019 were additionally selected, and optimal parameters for water temperature and other parameters were selected using case by case simulation. The analysis showed that the error rate and reliability were relatively good as the turnover phase approached through the turbidity rise and fall periods. The results of the verification of the maximum and average turbidity were better than those of the verification of the period-specific simulation. Thus, the models constructed in this study were determined to be suitable for the flood season.

Energy audit and base case simulation of Ryerson buildings using the "Carrier HAP" simulation program and prism analysis for energy consumption

Modelling and simulation of energy consumption in 86% of the Ryerson campus was presented. Energy simulation models were developed with Carrier HAP for 16 Ryerson buildings. Carrier HAP, commercially available software, was used for the prediction of energy consumption and PRISM software was used for the energy consumption comparison in different locations using weather normal average temperature data. All of the possible sources and uses of energy in the building were accounted for in the modelling and simulation. From the simulation result, it showed that 26% of total energy was consumed by lighting and 19% of total energy used by plug load and 4% of total energy used by miscellaneous. Sensitivity analysis was conducted by reducing lighting schedule. As a result, annual energy savings of 10% for cooling load and 21% for hydro demand were achieved, but the heating load increased by 14%. The other part of the energy consumption was for the Heating, Ventilation and Air Conditioning (HVAC) system, 53% of total energy was demanded in this sector for the 16 Ryerson buildings. PRISM model was developed for compared Ryerson energy consumption and also compared Ryerson campus in different locations. The base case simulation result was compared with the campus planning actual consumption bill for the hydro, steam and DLWC cooling demand for the Ryerson campus. The result was under predicted from the actual bill. Simulation was under predicted hydro consumption by 5.7% and steam consumption by 6.26%. The average energy intensity was determined 1.04 GJ/m² for the 86% of total area of Ryerson campus. Also energy intensity (GJ/students) compared with different provinces in Canada, shows that Ryerson University consumed less energy and this value is 10 GJ/student.

Energy audit and base case simulation of Ryerson buildings using the "Carrier HAP" simulation program and prism analysis for energy consumption

Modelling and simulation of energy consumption in 86% of the Ryerson campus was presented. Energy simulation models were developed with Carrier HAP for 16 Ryerson buildings. Carrier HAP, commercially available software, was used for the prediction of energy consumption and PRISM software was used for the energy consumption comparison in different locations using weather normal average temperature data. All of the possible sources and uses of energy in the building were accounted for in the modelling and simulation. From the simulation result, it showed that 26% of total energy was consumed by lighting and 19% of total energy used by plug load and 4% of total energy used by miscellaneous. Sensitivity analysis was conducted by reducing lighting schedule. As a result, annual energy savings of 10% for cooling load and 21% for hydro demand were achieved, but the heating load increased by 14%. The other part of the energy consumption was for the Heating, Ventilation and Air Conditioning (HVAC) system, 53% of total energy was demanded in this sector for the 16 Ryerson buildings. PRISM model was developed for compared Ryerson energy consumption and also compared Ryerson campus in different locations. The base case simulation result was compared with the campus planning actual consumption bill for the hydro, steam and DLWC cooling demand for the Ryerson campus. The result was under predicted from the actual bill. Simulation was under predicted hydro consumption by 5.7% and steam consumption by 6.26%. The average energy intensity was determined 1.04 GJ/m² for the 86% of total area of Ryerson campus. Also energy intensity (GJ/students) compared with different provinces in Canada, shows that Ryerson University consumed less energy and this value is 10 GJ/student.

Open Sub-Granting Radio Resources in Overlay D2D-Based V2V Communications

Capacity, reliability, and latency are seen as key requirements of new emerging applications, namely Vehicle-to-Everything (V2X) and Machine Type Communication (MTC) in future cellular networks. Device-to-Device (D2D) communication is envisaged to be the enabler to accomplish the requirements for the applications as mentioned earlier. Due to the scarcity of radio resources, a hierarchical radio resource allocation, namely the sub-granting scheme, has been considered for the overlay D2D communication. In this paper, we investigate the assignment of underutilized radio resources from D2D communication to Device-to-Infrastructure (D2I) communication, which are moving in a dynamic environment. The sub-granting assignment problem is cast as a maximization problem of the uplink cell throughput. Firstly, we evaluate the sub-granting signaling overhead due to mobility in a centralized sub-granting resource algorithm, Dedicated Sub-Granting Radio Resource (DSGRR), and then a distributed heuristics algorithm, Open Sub-Granting Radio Resource (OSGRR) is proposed and compared with the DSGRR algorithm and no sub-granting case. Simulation results show improved cell throughput for the OSGRR compared with other algorithms. Besides, it is observed that the overhead incurred by the OSGRR is less than the DSGRR while the achieved cell throughput is yet close to the maximum achievable uplink cell throughput.

Roles of Barotropic Instability across the Moat in Inner Eyewall Decay and Outer Eyewall Intensification: Essential Dynamics

Intense tropical cyclones (TCs) often experience secondary eyewall formations and the ensuing eyewall replacement cycles. Better understanding of the underlying dynamics is crucial to make improvements to the TC intensity and structure forecasting. Radar imagery of some double-eyewall TCs and a real-case simulation study indicated that the barotropic instability (BI) across the moat (aka type-2 BI) may play a role in inner eyewall decay. A three-dimensional numerical study accompanying this paper pointed out that type-2 BI is able to withdraw the inner eyewall absolute angular momentum (AAM) and increase the outer eyewall AAM through the eddy radial transport of eddy AAM. This paper explores the reason why the eddy radial transport of eddy AAM is intrinsically nonzero. Linear and nonlinear shallow water experiments are performed and they produce expected evolutions under type-2 BI. It will be shown that only nonlinear experiments have changes in AAM over the inner and outer eyewalls, and the changes solely originate from the eddy radial transport of eddy AAM. This result highlights the importance of nonlinearity of type-2 BI. Based on the distribution of vorticity perturbations and the balanced-waves arguments, it will be demonstrated that the nonzero eddy radial transport of eddy AAM is an essential outcome from the intrinsic interaction between the mutually growing vortex Rossby waves across the moat under type-2 BI. The analyses of the most unstable mode support the findings and will further attribute the inner eyewall decay and outer eyewall intensification to the divergence and convergence of the eddy angular momentum flux, respectively.

Performance of national COVID-19 ‘symptom checkers’: a comparative case simulation study

ObjectivesIdentifying those individuals requiring medical care is a basic tenet of the pandemic response. Here, we examine the COVID-19 community triage pathways employed by four nations, specifically comparing the safety and efficacy of national online ‘symptom checkers’ used within the triage pathway.MethodsA simulation study was conducted on current, nationwide, patient-led symptom checkers from four countries (Singapore, Japan, USA and UK). 52 cases were simulated to approximate typical COVID-19 presentations (mild, moderate, severe and critical) and COVID-19 mimickers (eg, sepsis and bacterial pneumonia). The same simulations were applied to each of the four country’s symptom checkers, and the recommendations to refer on for medical care or to stay home were recorded and compared.ResultsThe symptom checkers from Singapore and Japan advised onward healthcare contact for the majority of simulations (88% and 77%, respectively). The USA and UK symptom checkers triaged 38% and 44% of cases to healthcare contact, respectively. Both the US and UK symptom checkers consistently failed to identify severe COVID-19, bacterial pneumonia and sepsis, triaging such cases to stay home.ConclusionOur results suggest that whilst ‘symptom checkers’ may be of use to the healthcare COVID-19 response, there is the potential for such patient-led assessment tools to worsen outcomes by delaying appropriate clinical assessment. The key features of the well-performing symptom checkers are discussed.