Tropical Cyclone Research and Review最新文献

Using conventional observation data, FY2 satellite data, typhoon data and NCEP reanalysis data, the different position of Pre-TC squall line accompanying the similar tracks with “Lekima” (No. 1909) and “Matsa” (No. 0509) is studied. The article analyzes the circulation background and trigger mechanism generated by the two pre-TC squall lines, and uses various physical quantities such as low-level vertical wind shear, humidity, wind field, wet potential vorticity, and vertical vorticity. Also, try to study the dynamic mechanism of dry intrusion during the process using the Slantwise Vorticity Development (SVD) theory. The results show that: the high-altitude system and the ground trigger mechanism produced are significantly different. On the high-altitude system, the “Lekima” squall line is generated between the continental high pressure and the typhoon with the northeast jet. The “Matsa” squall line occurred between the typhoon and the subtropical high, and near the typhoon inverted trough, which was generated with the strong easterlies. On the ground trigger mechanism, the “Lekima” squall line is generated at the convergence line under the intersection of northeast and northwest air currents. The “Matsa” squall line is generated in the ground inverted trough moves westward and meridional degree increases. During the two pre-TC squall lines, low-level vertical wind shear values are above 16 m·s⁻¹.The dry air intrusion in the lower layer came from the upper and middle troposphere in the vertical direction, and in the east from the west along the latitude in the horizontal direction. Theoretical analysis base on the development of wet potential vorticity, vertical vorticity, and inclined vorticity indicate that the downward transmission of the high potential vorticity band on the upper troposphere, the level of dry invasion, and the air mixing of equivalent potential temperature at high and low levels play an important role in the generation and development of the pre-TC squall line. The slantwise vorticity has a good corresponding relationship with the vertical vorticity over the pre-TC squall line. The two development processes of the pre-TC squall line can be better explained by using the SVD theory.

The forecasts of tropical cyclones (TC) in 2017 from five official guides, six global models, six regional models and six ensemble systems were assessed to study the current capability of track and intensity forecasts for the western North Pacific. The results show that the position errors for official agencies were under 100, 165, 265,335 and 425 km at the lead times of 24, 48, 72, 96 and 120 h, respectively. As the forecast lead times increased, the forecasted TCs propagated, on average, too slow for most official guides. It is encouraging to note that all the models had positive skill scores, there is an overall upward trend in the skill scores of the models during from 2010 to 2017. Furthermore, both global and regional models' intensity forecast skill was increasing year by year from 2010 to 2017. For the ensemble prediction systems (EPSs), ECMWF-EPS was the best forecast system for the lead time less than 72 h, beyond the 72 h, the best EPS belong to NCEP-GEFS.

Characteristic features of Super Cyclonic Storm (SuCS), AMPHAN which crossed West Bengal-Bangladesh Coast on May 20, 2020 have been analyzed based on INSAT-3D & passive microwave (PMW) images with special emphasis on eye characteristics and its relationship with intensity. These satellite images/products are analyzed to determine the centre of the cyclone, its intensity and the characteristics of the eye of the cyclone. It shows the characteristic variation of intensity of SuCS with geometric and thermal characteristics of the ‘eye’. Precise changes in the eye features of the cyclone can be used for very short-range forecasting of the intensity of the cyclone.

The HWRF-POM-TC coupled model is run operationally at India Meteorological Department (IMD). This study is first attempt to assess the IMD's operational HWRF-POM-TC (Atmosphere-Ocean) coupled model forecast performance over North Indian Ocean (NIO). The two cyclonic storms one each in Arabian Sea and Bay of Bengal were examined. Among them, VSCS LUBAN formed over Arabian Sea (AS) and was followed by the formation of VSCS TITLI over Bay of Bengal (BoB). It constituted a rare case whereby two VSCS have formed in the north Indian Ocean (NIO) simultaneously.

The HWRF-POM-TC modeling system, which was developed at National Centers for Environmental Prediction (NCEP) based on Non-hydrostatic Mesoscale Model (NMM) dynamic core, was customized for NIO conditions. For the two storms, VSCS LUBAN & VSCS TITLI, 28 and 15 consecutive 6-hourly HWRF model runs were performed. The HWRF-POM-TC coupled model showed great skill in forecasting of Track and Intensity for examined cyclones. The result shows that the model predicted the intensification and landfall of VSCS Luban & Titli in agreement with the best track data as made available by Cyclone Warning Division (CWD), India Meteorological Department which is also recognized as Regional Specialized Meteorological Center (RSMC) by WMO for NIO.

India follows a strategy of having Multi-Purpose Cyclone Shelters along the coastline for tropical cyclone risk mitigation. These shelters are meant to provide refuge to vulnerable populations at the time of a cyclonic storm and otherwise to be used as school, community centres etc. This paper aims to examine the exact role which these Multi-Purpose Cyclone Shelters seek to perform; as a safe shelter for people living in a tropical cyclone threatened region or meant for those who fail to evacuate due to various reasons. Based on qualitative method and field work conducted after four cyclones which made landfall on India's east coast during 2013–19, this study argues that lack of clarity over its role has led to an emphasis on increasing number of Multi-Purpose Cyclone Shelters proportionate to the population size without due examination of its safety and sustainability aspects.

The currently used hydrological forecast system in China is mainly focused on flood, and the flood forecasting frameworks are typically based on point discharge measurements and predictions at discrete locations, hence they can't provide spatio-temporal information of various hydrological elements, such as surface runoff, soil moisture, ground water table, and flood inundation extents over large scales and at high spatial resolutions. The use of distributed hydrological model has recently appeared to be the most suitable option to bridge this gap. An open source GIS-based distributed hydrological forecast system was established recently, and the watershed delineation and hydrological modelling were integrated together seamlessly. The time and human consuming work of processing the spatial data in building distributed hydrological model could be reduced significantly, and the spatial distribution of hydrological information could be quickly simulated and predicted using this system. The system was applied successfully to forecast the flood caused by super strong typhoon “Mangkhut” which attacked the south China in 2018.

The characteristics of raindrop size distribution during Typhoon Meranti, determined using disdrometer (LPA10) data collected from 14 to Sep. 15, 2016 in Fujian Province, China, were associated with different parts of the storm. From the front side of the rain band to the central region and then to the rear side or to the residual clouds of Typhoon Meranti, the top of the radar echo, reflectivity, raindrop number concentration and spectrum width all increased when Meranti moved close and then decreased as it moved away. Moreover, precipitation was produced from the stratiform to the oceanic convective and then to the oceanic convective-stratiform mixed clouds or to the stratiform.

Super Typhoon Mangkhut hit Hong Kong on September 16, 2018, necessitating the issuance of the highest tropical cyclone warning signal, No. 10 Hurricane Signal. Packing ferocious winds and record-breaking storm surge, Mangkhut brought the most serious and widespread destruction to the territory in the recent three decades. A series of post event information search, field visits and damage surveys has been conducted by the Hong Kong Observatory (HKO) and the findings on the damages and impacts caused by Mangkhut in different parts of the territory are documented in this paper. Moreover, by analyzing the economic loss data reported by various government departments, public utilities and organizations in Hong Kong and the statistics on insurance claims from the Hong Kong Federation of Insurers (HKFI), the estimated direct economic loss due to Mangkhut in Hong Kong is about HK$ 4.60 billion, which is about 3.8 times to that of Super Typhoon Hato in 2017. On the contrary, in the Guangdong-Hong Kong-Macao Greater Bay Area, the estimated direct economic loss due to Hato is significantly higher than that of Mangkhut. This could be attributed to the early and effective warnings for Mangkhut, increased public awareness and typhoon preparedness for Mangkhut in 2018 since the fierce attack of Hato in 2017, and infrastructure enhancement of the major impact areas.

The Publisher regrets that this article is an accidental duplication of an article that has already been published in TCRR, Volume 8, Issue 2, June 2019, Pages 95–102, https://doi.org/10.1016/j.tcrr.2019.07.009. The duplicate article has therefore been withdrawn.

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