Yang X.,Institute of Meteorological science |
Tian Z.,Shanghai Climate Center |
Chen B.,Shanghai Typhoon Institute of China Meteorological Administration
International Journal of Climatology | Year: 2013
Dense meteorological station network-derived data on daily surface air temperatures over the period 1961-2007 were used to investigate the changes in the thermal growing season (GS) indicators for east China. The 394 stations are classified into six categories: metropolises, large cities, medium-sized cities, small cities, suburbs, and rural area using satellite-measured night-time light imagery and census data. Only the temperature data on 258 small cities and rural stations were used to calculate the GS indicators to reflect more 'natural' changes in thermal GS parameters. During the studied period, the regional mean length of the GS significantly extended by 3.05 and 2.61 d decade-1 for base temperatures of 5 and 10 °C, respectively. This extension is attributed primarily to the GS initiating at an earlier time (2.49 and 2.10 d decade-1 for base temperatures of 5 and 10 °C, respectively), rather than to the delayed end of the GS (0.55 and 0.51 d decade-1 for base temperatures of 5 and 10 °C, respectively). The mean growing degree days (GDD) has increased by 51.84 and 35.89 degree days decade-1 on average at temperatures higher than 5 and 10 °C. When the temperature data from all the 394 stations(including metropolis, large city, medium city, and suburban) were used to calculate the GS indicators, urban heat island (UHI) effects were evident, especially in highly urbanized Yangtze River Delta. The GS extension and GDD increase in metropolises increased by more than onefold over those observed for rural areas. This result indicates significant UHI effects on climatic GS changes. On the basis of the GDD changes, we find that UHI effects contributed to more than 10% in the GDD increase at temperatures higher than 10 °C. Therefore, excluding the urbanization effects from station observational data in evaluating changes in GS indices is necessary, especially for regions characterized by rapid urbanization. © 2012 Royal Meteorological Society.
Yin J.F.,Nanjing University of Information Science and Technology |
Zheng Y.F.,Nanjing University of Information Science and Technology |
Wu R.J.,Nanjing University of Information Science and Technology |
Tan J.G.,Shanghai Climate Center |
And 2 more authors.
International Journal of Biometeorology | Year: 2012
A variety of research has linked high temperature to outdoor thermal comfort in summer, but it remains unclear how outdoor meteorological environments influence people's thermal sensation in subtropical monsoon climate areas, especially in China. In order to explain the process, and to better understand the related influential factors, we conducted an extensive survey of thermally comfortable conditions in open outdoor spaces. The goal of this study was to gain an insight into the subjects' perspectives on weather variables and comfort levels, and determine the factors responsible for the varying human thermal comfort response in summer. These perceptions were then compared to actual ambient conditions. The database consists of surveys rated by 205 students trained from 6:00 am to 8:00 pm outdoors from 21 to 25 August 2009, at Nanjing University of Information Science & Technology (NUIST), Nanjing, China. The multiple regression approach and simple factor analysis of variance were used to investigate the relationships between thermal comfort and meteorological environment, taking into consideration individual mood, gender, level of regular exercise, and previous environmental experiences. It was found that males and females have similar perceptions of maximum temperature; in the most comfortable environment, mood appears to have a significant influence on thermal comfort, but the influence of mood diminishes as the meteorological environment becomes increasingly uncomfortable. In addition, the study confirms the strong relationship between thermal comfort and microclimatic conditions, including solar radiation, atmospheric pressure, maximum temperature, wind speed and relative humidity, ranked by importance. There are also strong effects of illness, clothing and exercise, all of which influence thermal comfort. We also find that their former place of residence influences people's thermal comfort substantially by setting expectations. Finally, some relationships between thermal perception and amount of exercise, thermal experience, mood, clothing, illness and microclimate, etc., are established. Our findings also shed light on how to resist or adapt to outdoor hyperthermic conditions during summer in subtropical monsoon climate areas. © 2011 ISB.
Zhang H.,National Climate Center |
Wang Z.,Chinese Academy of Meteorological Sciences |
Wang Z.,National Climate Center |
Liu Q.,National Climate Center |
And 7 more authors.
Climate Dynamics | Year: 2012
An interactive system coupling the Beijing Climate Center atmospheric general circulation model (BCC_AGCM2. 0. 1) and the Canadian Aerosol Module (CAM) with updated aerosol emission sources was developed to investigate the global distributions of optical properties and direct radiative forcing (DRF) of typical aerosols and their impacts on East Asian climate. The simulated total aerosol optical depth (AOD), single scattering albedo, and asymmetry parameter were generally consistent with the ground-based measurements. Under all-sky conditions, the simulated global annual mean DRF at the top of the atmosphere was -2. 03 W m-2 for all aerosols including sulfate, organic carbon (OC), black carbon (BC), dust, and sea salt; the global annual mean DRF was -0. 23 W m-2 for sulfate, BC, and OC aerosols. The sulfate, BC, and OC aerosols led to decreases of 0. 58° and 0. 14 mm day-1 in the JJA means of surface temperature and precipitation rate in East Asia. The differences of land-sea surface temperature and surface pressure were reduced in East Asian monsoon region due to these aerosols, thus leading to the weakening of East Asian summer monsoon. Atmospheric dynamic and thermodynamic were affected due to the three types of aerosol, and the southward motion between 15°N and 30°N in lower troposphere was increased, which slowed down the northward transport of moist air carried by the East Asian summer monsoon, and moreover decreased the summer monsoon precipitation in south and east China. © 2011 Springer-Verlag.
Liu X.,National University of Ireland, Maynooth |
Liu X.,Shanghai Climate Center |
Sweeney J.,National University of Ireland, Maynooth
Energy Policy | Year: 2012
This study aims to investigate the relationship between household space heating energy use and urban form (land use characteristics) for the Greater Dublin Region. The geographical distributions of household energy use are evaluated at the Enumeration Districts (ED) level based on the building thermal balance model. Moreover, it estimates the impact of possible factors on the household space heating consumption. Results illustrate that the distribution profile of dwellings is a significant factor related to overall heating energy demand and individual dwelling energy consumption for space heating. Residents living in compact dwellings with small floor areas consume less energy for space heating than residents living in dwellings with big floor areas. Moreover, domestic heating energy demand per household was also estimated for two extreme urban development scenarios: the compact city scenario and the dispersed scenario. The results illustrate that the compact city scenario is likely to decrease the domestic heating energy consumption per household by 16.2% compared with the dispersed city scenario. Correspondingly, the energy-related CO 2 emissions could be significantly decreased by compact city scenario compared with the dispersed city scenario. © 2012 Elsevier Ltd.
Zhang H.,National Climate Center |
Shen Z.,National Climate Center |
Shen Z.,Shanghai Climate Center |
Wei X.,National Climate Center |
And 4 more authors.
Atmospheric Research | Year: 2012
In previous studies, the optical properties of sulfate aerosols were employed to estimate the direct radiative forcing (DRF) due to nitrate aerosols. Ensuing errors have not been rigorously evaluated, which is a major objective of this study. First, we compared the optical properties of nitrate and sulfate aerosols in different spectral regions. Our results show that nitrate is a strongly scattering aerosol and in some spectral regions, its scattering properties are even greater than those of sulfate aerosols. For example, nitrate aerosol single-scattering albedos are about 40% greater than those of sulfates when the wavelength is nearly 2.8 μm and the relative humidity (RH) is below 40%. We then incorporated the optical parameters of nitrate into a radiative transfer model and estimated the DRF due to nitrate aerosols at the top of the atmosphere (TOA) under both clear- and all-sky conditions and compared them with those of sulfate aerosols. We found that the local forcing due to nitrate aerosols using sulfate optical properties in the simulation can be underestimated by a maximum of 6.2% under all-sky conditions. Using model-simulated nitrate concentrations in China that reproduce observed features reasonably well, we found significant spatial and seasonal changes in DRFs due to nitrate aerosols. DRFs were stronger in winter, spring, and autumn, but much weaker in summer. The annual mean values of the forcings over China were -4.51Wm -2 and -0.95Wm -2 under clear-sky and all-sky conditions, respectively. Clouds play an important role in determining the DRF and can greatly reduce the forcing strength and its geographical extent. © 2012 Elsevier B.V.