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We compare apparent temperatures – that is a combination of 2 m air temperature, relative humidity and surface wind speed in four Earth System Models under the modest greenhouse emissions RCP4.5, the “business-as-usual" RCP8.5 and the stratospheric aerosol injection G4 geoengineering scenarios. Apparent temperatures come from both a 10 km resolution dynamically downscaled model (WRF), and a statistically bias corrected (ISIMIP) and downscaled simulation for the greater Beijing region. ISIMIP downscaling method tends to simulate apparent temperatures well at present in all seasons, and WRF produces warmer winters than does ISIMIP. WRF produces warmer winters and cooler summers than does ISIMIP in the future. These differences mean that estimates of numbers of days with extreme apparent temperatures vary systematically with downscaling method, as well as between climate models and scenarios. Air temperature changes dominate differences in apparent temperatures between future scenarios even more than they do at present because the reductions in humidity expected under solar geoengineering are overwhelmed by rising vapor pressure due to rising temperatures and the lower windspeeds expected in the region in all future scenarios. Urban centres see larger rises in extreme apparent temperatures than rural surroundings due to differences in land surface type, and since these are also the most densely populated, health impacts will be dominated by the larger rises in apparent temperatures in these urban areas. [ABSTRACT FROM AUTHOR]

We use four Earth System Model (ESM) to simulate climate under the modest greenhouse emissions RCP4.5, the "business-as-usual" RCP8.5 and the stratospheric aerosol injection G4 geoengineering scenarios. These drive a 10 km resolution dynamically downscaled model (WRF), and a statistically bias corrected (ISIMIP) and downscaled simulation in a 450×330 km domain containing the Beijing province, ranging from 2000 m elevations to sea level. The 1980s simulations of surface temperatures, humidities and windspeeds using statistical bias correction makes for a better estimate of mean climate determined by ERA5 reanalysis data than does the WRF simulation. However correcting WRF output with Quantile-Delta Mapping bias correction removes the offsets in mean state and results in WRF better reproducing observations over 2007-2017 than ISIMIP bias correction. WRF simulations show consistently 0.5°C higher mean annual temperatures than from ISIMIP due both to the better resolved city centers and also to warmer winter temperatures. In the 2060s WRF produces consistently larger spatial ranges of surface temperatures, humidities and windspeeds than ISIMIP downscaling across the three future scenarios. WRF and ISIMIP methods produce very similar spatial patterns of temperature with G4 are always cooler than RCP4.5 and RCP8.5, by a slightly larger amount with ISIMIP than WRF. Humidity scenario differences vary greatly between ESM and hence ISIMIP downscaling, while for WRF the results are far more consistent across ESM and show only small changes between scenarios. Mean windspeeds show similarly small changes over the domain, although G4 is significantly windier under WRF than either RCP scenario. [ABSTRACT FROM AUTHOR]

This paper investigates urban traffic data by analysing the long-range correlation with detrended fluctuation analysis. Through a large number of real data collected by the travel time detection system in Beijing, the variation of flow in different time periods and intersections is studied. According to the long-range correlation in different time scales, it mainly discusses the effect of intersection location in road net, people activity customs and special traffic controls on urban traffic flow. As demonstrated by the obtained results, the urban traffic flow represents three-phase characters similar to highway traffic. Moreover, compared by the two groups of data obtained before and after the special traffic restrictions (vehicles with special numbered plates only run in a special workday) enforcement, it indicates that the rules not only reduce the flow but also avoid irregular fluctuation. [ABSTRACT FROM AUTHOR]