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Derecho radar analysis of August 11, 2017

Łuszczewski Hubert, Tuszyńska Irena

Meteorology Hydrology and Water Management. Research and Operational Applications

2022

Vol. 10, Iss. 2

26--37

This paper presents an analysis of the derecho phenomenon that occurred over Poland on August 11, 2017. The storm caused 6 fatalities, 39 injuries (Mańczak et al. 2022), and some of the greatest damage in the history of Polish forestry. Our study is based on radar meteorology and measurements from the Polish POLRAD radar network, and intended for advanced meteorologists with good knowledge of radar measurements. The research used both standard and specialized radar products as well as classic and Doppler scan data. The Doppler velocity products were especially useful for showing the characteristics of the storm. The analysis was mainly based on data from two radars: Poznań and Gdańsk, but the composite maps, consisting of data from more than one radar, were also analyzed. The derecho complex developed from unorganized thunderstorm cells over SW Poland and moved toward the NE. The various stages of the evolution of the system are presented and analyzed, accounting for the formation of a SC, the development of a rear inflow jet (RIJ), the split of the entire system, and the appearance of the bow echo signature. Significant factors affecting the scale of the wind damage were: (1) the extensive mesocyclone which evolved to the mesoscale convective vortex (MCV), and (2) a strong rear flank downdraft interacting with the rear inflow jet (RIJ).

Non-invasive measurement of blood hematocrit in artery

Secomski W., Nowicki A., Guidi F., Tortoli P., Lewin P.A.

Bulletin of the Polish Academy of Sciences. Technical Sciences

2005

Vol. 53, nr 3

245-250

Objective: The goal of this work was to develop a clinically applicable method for non-invasive acoustic determination of hematocrit m VIVO. Methods: The value of hematocrit (HCT) was determined initially in vitro from the pulse-echo measurements of acoustic attenuation. The testing was carried out using a laboratory setup with ultrasound transducer operating at 20 MHz and employing human blood samples at the temperature of 37°C. The attenuation coefficient measurements in blood in vitro and in vivo were implemented using multi-gated (128-gates), 20 MHz pulse Doppler flow meter. The Doppler signal was recorded in the brachial artery. Both in vitro and in vivo HCT data were compared with those obtained using widely accepted, conventional centrifuge method. Results: The attenuation coefficient in vitro was determined from the measurements of 168 samples with hematocrit varying between 23.9 and 51.6%. Those experiments indicated that the coefficient increased linearly with hematocrit. The HCT value was obtained from the 20 MHz data using regression analysis. The attenuation (0 was determined as a 42.14 + 1.02 . HCT (Np/m). The corresponding standard deviation (SD), and the correlation coefficient were calculated as SD = 2.4 Np/m, and R = 0.9, (p < 0.001 ), respectively The absolute accuracy of in vivo measurements in the brachial artery was determined to be within +-5% HCT. Conclusions: The method proposed appears to be promising for in vivo determination of hematocrit as 5% error is adequate to monitor changes in patients in shock or during dialysis. It was found that the multigate system largely simplified the placement of an ultrasonic probing beam in the center of the blood vessel. Current work focuses on enhancing the method's applicability to arbitrary selected vessels and reducing the HCT measurement error to well below 5%.