Search

The aim of this paper is to assess the influence of meteorological conditions on the variability of haze in Shanghai during 1981-2013. Based on the observational data of haze and air quality in Shanghai during this period and on the National Centers for Environmental Prediction final analysis data, the long-term variability and the spatial distribution of the haze was analyzed as well as with relationship between haze and atmospheric variables, including visibility, relative humidity, and air quality. Temporal evolution showed that the annual number of haze days in Shanghai represented a rapid decline in the last decade, which was caused by the direct effects of relative humidity and visibility. Global warming-induced changes, such as a warmer temperature, lower relative humidity, and wind speed in winter, were other important factors in the decline. Spatial distribution showed that the annual number of haze days in mid-western Shanghai was higher than those in the southeastern suburbs. [ABSTRACT FROM AUTHOR]

Multisatellite data is used to analyze the characteristics of three eyewall replacement cycles (ERCs) during the lifetime of Typhoon Muifa (1109). Spiral rainbands evolutions, concentric eyewall (CE) structure modes, CE durations, and intensity changes are discussed in detail. In addition, an ERC evolution model of Typhoon Muifa is given. There are four main findings. (1) The outer spiral rainband joins end to end to form the outer eyewall after it disconnects from the original (inner) eyewall. The inner eyewall weakens as the outer eyewall becomes axisymmetric and is intensified. The contraction of the outer eyewall causes the inner eyewall to dissipate rapidly. Finally, the ERC ends with an annular eyewall or spiral rainbands. (2) Although the CE duration times of Typhoon Muifa’s three ERCs covered a large range, the CE structures were all maintained for approximately 5 h from the formation of the axisymmetric outer eyewall to the end of the cycle. (3) There is no obvious precipitation reflectivity in the eye or moat region for the subsidence flow. The convection within the two eyewalls is organized as a radially outward slope with increasing height. (4) Typhoon intensity estimation results based on ADT may not explain the intensity variations associated with ERC correctly, while the typhoon’s warm core data retrieved from AMSU-A works well. [ABSTRACT FROM AUTHOR]