An Analysis of the Low Moving Speed of Landfalling Typhoon In-Fa in 2021

The movement speed of Typhoon In-Fa(2021)was notably slow,at 10 km h-1or less,for over 20 hours following its landfall in Zhejiang,China,in contrast to other typhoons that have made landfall.This study examines the factors contributing to the slow movement of Typhoon In-Fa,including the steering flow,diabatic heating,vertical wind shear(VWS),and surface synoptic situation,by comparing it with Typhoons Yagi(2018)and Rumbia(2018)which followed similar tracks.The findings reveal that the movement speed of Typhoons Yagi and Rumbia is most closely associated with their respective 500 h Pa environmental winds,with a steering flow of 10^(-12)m s^(-1).In contrast,Typhoon InFa’s movement speed is most strongly correlated with the 850 h Pa environmental wind field,with a steering flow speed of only 2 m s^(-1).Furthermore,as Typhoon In-Fa moves northwest after landfall,its intensity is slightly greater than that of Typhoons Yagi and Rumbia,and the pressure gradient in front of Typhoon In-Fa is notably smaller,leading to its slow movement.Additionally,the precipitation distribution of Typhoon In-Fa differs from that of the other two typhoons,resulting in a weak asymmetry of wavenumber-1 diabatic heating,which indirectly affects its movement speed.Further analysis indicates that VWS can alter the typhoon’s structure,weaken its intensity,and ultimately impact its movement.

Contrast Analysis of the Meteorological Factors between Zhongshan Station of the South Pole and Chinese Inland

[ Objective] The research aimed to contrast and analyze meteorological factors between Zhongshan station of the South Pole and Chi- nese inland. [ Method ] Based on meteorological observation data at Zhongshan station of the South Pole since established, contrast and analysis were taken on the atmospheric temperature, relative humidity and atmospheric pressure with that at Shanghe station of Chinese inland, to find out variation laws of the each meteorological factor in the two stations, and to analyze different change relations among factors. [ Result] Although geo- graphic positions of the two stations were different, and they were respectively in south and north hemispheres, each meteorological factor at the two stations had same change rules. Interannual anomaly relationship of the meteorological factor had certain rule. That was to say, variation of the positive or negative anomaly advanced or lagged for 1 -2 years. [ Conclusion] The research had reference value for studying global climatic variation.

Study on Temperature Changes in Jinan in Recent 30 Years

[ Objective] The aim was to study temperature changes in Jinan in recent 30 years. [ Method] Using temperature from 1981 to 2010 in six national ground meteorological observation stations in Jinan, and based on linear evaluation method, temperature changes in Jinan in recent 30 years were discussed. [ Result] The mean annual temperature, mean annual highest temperature and mean annual lowest temperature were rising in recent 30 years. Mean annual lowest temperature was increasing and its tendency rate was 0.502 ℃/10 a, followed by mean annual temperature whose tendency rate was 0.288℃/10 a. Mean annual highest temperature increased most slowly and its tendency rate was 0.144 ℃/10 a. The mean annual lowest temperature rose most significantly in Zhangqiu and its tendency rate was 1. 347℃/10 a. This indicated that the rising mean annual temperature in Jinan was due to the mean annual lowest temperature. The contribution of Zhangqiu City to the temperature changes in the entire Jinan was the largest. For single station, mean annual temperature, mean annual highest temperature and mean annual lowest temperature, temperature rising tendency was small and its contribution was the smallest. [ Conclusion] The study provided theoretical basis for the observation, diagnosis, evaluation and decision-making of climate changes in Jinan.

Size Distributions and Source Function of Sea Spray Aerosol over the South China Sea

The number concentrations in the radius range of 0.06 – 5 μm of aerosol particles and meteorological parameters were measured on board during a cruise in the South China Sea from August 25 to October 12, 2012. Effective fluxes in the reference height of 10 m were estimated by steady state dry deposition method based on the observed data, and the influences of different air masses on flux were discussed in this paper. The number size distribution was characterized by a bimodal mode, with the average total number concentration of(1.50 ± 0.76)×10~3 cm^(-3). The two mode radii were 0.099 μm and 0.886 μm, both of which were within the scope of accumulation mode. A typical daily average size distribution was compared with that measured in the Bay of Bengal. In the whole radius range, the number concentrations were in agreement with each other; the modes were more distinct in this study than that abtained in the Bay of Bengal. The size distribution of the fluxes was fitted with the sum of log-normal and power-law distribution. The impact of different air masses was mainly on flux magnitude, rather than the shape of spectral distribution. A semiempirical source function that is applicable in the radius range of 0.06 μm<r_(80)<0.3 μm with the wind speed varying from 1.00 m s^(-1) to 10.00 m s^(-1) was derived.

Climatic Characteristics of Rainstorm during the Flood Season in Shandong Province from 1961 to 2012

Based on daily precipitation data at 35 meteorological observation stations during the flood season in Shandong Province from 1961 to2012,the spatial and temporal variation characteristics of number of rainstorm days and rainstorm intensity were analyzed by conventional statistical methods. The results show that the number of rainstorm days and rainstorm intensity during the flood season in Shandong showed a decreasing trend from 1961 to 2012,but the decreases were not statistically significant at the 0. 05 level. Annual average number of rainstorm days during the flood season in Shandong over the past 52 years was 2.2d and had the changing periods of 3. 4 and quasi-8 a; the annual average rainstorm intensity was 67. 8 mm/d and had the changing periods of 2. 3,3. 3,6. 9 and quasi-12. 0 a. From 1961 to 2012,there was no abrupt climatic change in the number of rainstorm days and rainstorm intensity during the flood season in Shandong,and the number of rainstorm days and rainstorm intensity during the flood season in Shandong reduced from the middle and late 1970 s to the late 1980 s. The annual average number of rainstorm days and rainstorm intensity during the flood season in Shandong from 1961 to 2012 rose gradually from the northwest to the southeast. Rainstorm( continuous rainstorm) during the flood season appeared frequently,and rainstorm intensity was high in the south of Shandong Province,the south and east of Shandong Peninsula.

Comparative Analysis of Two Local Heavy Rainstorms in Northwestern Shandong

[Objective] The aim was to comparatively analyze two local heavy rainstroms in northwestern Shandong Province, China. [Method] Based on the observation data from automatic weather station, sounding data and NCEP reanalysis data, two local heavy rainstorms at night on July 18 and August 9 in 2010 in northwestern Shandong was comparatively analyzed from the aspects of circulation situation, influence system and physical field, and the internal structure and possible formation mechanism of local heavy rain in Shandong were discussed further. [Result] The two rainstorms occurred in the forepart of southwest air in front of 500 hPa trough, and there was stronger atmospheric baroclinicity in the front zone near 850 hPa. The two rainstorms were affected by southwest warm and humid airflow at low level and shear line at 850 hPa; rainstorm often appeared in intensive area behind θse high-energy tongue, and rainstorm area corresponded with the area with high vertical speed well. From the differences, during the first rainstorm, there was obvious southwest low level jet and shear line at 700 hPa, and the area with high precipitation was located in the south of warm shear line at 700 hPa; during the latter rainstorm, there was no obvious southwest low level jet and shear line, and the area with high precipitation was located in the region between two high pressures. [Conclusion] The study could provide valuable thinking for the forecast of this kind of rainstorm in the future.

Influences of Meteorological Conditions on Interannual Variations of Particulate Matter Pollution during Winter in the Beijing–Tianjin–Hebei Area

To investigate the interannual variations of particulate matter （PM） pollution in winter, this paper examines the pollution characteristics of PM with aerodynamic diameters of less than 2.5 and 10 μm （i.e., PM2.5 and PM10）, and their relationship to meteorological conditions over the Beijing municipality, Tianjin municipality, and Hebei Province--an area called Jing-Jin-Ji （JJJ, hereinafter）-in December 2013-16. The meteorological conditions during this period are also analyzed. The regional average concentrations of PM2.5 （PM10） over the JJJ area during this period were 148.6 （236.4）, 100.1 （166.4）, 140.5 （204.5）, and 141.7 （203.1） μg m^-3, respectively. The high occurrence frequencies of cold air outbreaks, a strong Siberian high, high wind speeds and boundary layer height, and low temperature and relative humidity, were direct meteorological causes of the low PM concentration in December 2014. A combined analysis of PM pollution and meteorological conditions implied that control measures have resulted in an effective improvement in air quality. Using the same emissions inventory in December 2013-16, a modeling analysis showed emissions of PM2.5 to decrease by 12.7%, 8.6%, and 8.3% in December 2014, 2015, and 2016, respectively, each compared with the previous year, over the JJJ area.