This study investigates changes in the destructiveness of landfalling tropical cyclones (TCs) over China during 1975–2014. Using four different TC datasets, it is found that TCs making landfall over east China (TCEC) have tended to be more destructive in recent decades, with a significant increase in the power dissipation index (PDI) after landfall. Both time series analysis and diagnostic analysis reveal that such an increase in the PDI of TCEC is associated with concomitant enhancement in landfall frequency as well as landfall intensity over east China. In contrast, changes in the PDI of TCs making landfall over south China (TCSC) are less apparent. Examination of different TC-related parameters shows no obvious changes in terms of landfall frequency, duration, and maximum intensity of TCSC. Diagnostic analysis further suggests that the reduction in TC occurrence over south China offsets considerably the positive effects of the intensity and the nonlinear term. Further examination of the environmental parameters reveals significant changes in the large-scale steering flow in recent decades, which is characterized by a prominent cyclonic circulation centered over southeast China. The southeasterly flows on the eastern flank of the cyclonic circulation tend to favor subsequent landfall of TCs over east China, resulting in an increase in landfall frequency, which contributes in part to the enhanced PDI of TCs over this region. Meanwhile, the slowing down of the mean translation speed of TCEC and the weakening of vertical wind shear coupled with warmer SSTs in the WNP tend to favor the intensification of TCEC, leading to an increase in intensity and hence the PDI of TCs over east China.

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a b s t r a c tResidents wish to have outdoor spaces to enjoy walking, cycling, and other recreational activities, which are often hindered by the unfavorable thermal comfort conditions, especially in the summer. High building densities lower the average wind speed and this intensifies the urban heat island effects at city scale. The conscientious use of building morphology to create local thermal comfort zone at selected spots in a large precinct is becoming a pressing issue for sustainable urbanization. This paper is a proof of concept study via continuous monitoring of the pedestrian level winds and thermal parameters at two sample days in summer, which include instantaneous air temperature, globe temperature, wind speed and humidity. Three outdoor locations at an university campus are chosen and daytime thermal perceptions at the three sites were evaluated using PET (Physiological equivalent temperature). A PET based new index was defined, which is called the thermally-perceivable environmental parameter difference. By analyzing the simultaneous differences of radiant temperature, wind speed and air temperature between the monitored spots, it is shown that it was the wind speed and radiant temperature differences that were making significant differences in thermal comfort. This pilot study clearly indicates that wind amplification combined with shading effects can generate thermally comfortable conditions in the open ground floor beneath an elevated building, even on a sunny, hot summer day in a subtropical city. This finding helps to alert city planners of additional options available in precinct planning to encourage outdoor activities.

Information on respiratory viruses in subtropical region is limited.Incidence, mortality, and seasonality of influenza (Flu) A/B, respiratory syncytial virus (RSV), adenovirus (ADV), and parainfluenza viruses (PIV) 1/2/3 in hospitalized patients were assessed over a 15-year period (1998–2012) in Hong Kong.Male predominance and laterally transversed J-shaped distribution in age-specific incidence was observed. Incidence of Flu A, RSV, and PIV decreased sharply from infants to toddlers; whereas Flu B and ADV increased slowly. RSV conferred higher fatality than Flu, and was the second killer among hospitalized elderly. ADV and PIV were uncommon, but had the highest fatality. RSV, PIV 2/3 admissions increased over the 15 years, whereas ADV had decreased significantly. A “high season,” mainly contributed by Flu, was observed in late-winter/early-spring (February–March). The “medium season” in spring/summer (April–August) was due to Flu and RSV. The “low season” in late autumn/winter (October–December) was due to PIV and ADV. Seasonality varied between viruses, but predictable distinctive pattern for each virus existed, and temperature was the most important associating meteorological variable.Respiratory viruses exhibit strong sex- and age-predilection, and with predictable seasonality allowing strategic preparedness planning. Hospital-based surveillance is crucial for real-time assessment on severity of new variants.

The choice of proper wind comfort criterion is considered to be crucial to reliable assessment of pedestrian level wind comfort. This paper aims to propose a wind comfort criterion that can be applied to Hong Kong, in which the wind comfort is seriously deteriorated by the moderated airflow, particularly in the hot and humid summer. By thoroughly reviewing and comparing exiting wind comfort criteria, the parameters in Lawson (1978) criterion are adopted for acceptable, tolerable and intolerable category and the parameters in NEN8100 (2006) criterion are adopted for danger category in the proposed criteria. Besides, a low wind parameter suggested by AVA scheme (2005) is adopted for unfavourable category in summer criterion. The adopted parameters provide scientific foundations and they are carefully chosen to adapt the weak wind conditions. The prominent feature of the criteria is proposed seasonally (summer and winter, respectively) and the overall mean wind velocity ratio () is used as threshold wind velocity parameter. The wind tunnel tests of Hong Kong Polytechnic University (HKPolyU) campus model were used as a case study. The results show that the proposed criteria can reasonably represent the weak wind condition and provide suitable assessments of the wind comfort in Hong Kong. Moreover, the findings in this study provide scientific basis for future policy-making and the proposed criteria can also help city planners to improve the pedestrian level wind comfort.