This paper summarizes recent studies on the effects of urbanization on climate in China. The effects of urbanization on local climate trends have been re-estimated based on homogenized observations and using improved ...This paper summarizes recent studies on the effects of urbanization on climate in China. The effects of urbanization on local climate trends have been re-estimated based on homogenized observations and using improved methods. In this respect, the effect of urbanization on the observed warming trend of local surface air temperatures during the last few decades is determined as being about 20% at urban stations such as the Beijing Observatory. The large-scale weakening trend of wind speed is also about 20% more prominent at the city center than its surroundings. The effect of urbanization on precipitation is not profound, but results of high-resolution regional climate modeling suggest that this effect may depend on the urban extent. Although the urban heat island(UHI) should favor local atmospheric convection and hence precipitation, the increasingly extending urban land-use may reduce precipitation over the urban cluster in North China. It is found that urbanization can play a more notable role in extreme events than usual weather. High-resolution simulations show a positive feedback between the UHI and the super-heat wave in Shanghai during Julye August 2013. Relevant studies dealing with urban climate adaptation are discussed in relation to recent ?ndings.展开更多
New challenges are emerging in fine-scale air quality modeling in China due to a lack of high-resolution emission maps.Currently,only a few emission sources have accurate geographic locations(point sources),while a la...New challenges are emerging in fine-scale air quality modeling in China due to a lack of high-resolution emission maps.Currently,only a few emission sources have accurate geographic locations(point sources),while a large part of sources,including industrial plants,are estimated as provincial totals(area sources)and spatially disaggregated onto grid cells based on proxies;this approach is reasonable to some extent but is highly questionable at fine spatial resolutions.Here,we compile a new comprehensive point source database that includes nearly 100,000 industrial facilities in China.We couple it with the frame of Multi-resolution Emission Inventory for China(MEIC),estimate point source emissions,combine point and area sources,and finally map China’s anthropogenic emissions of 2013 at the spatial resolution of 30’’*30’’(~1 km).Consequently,the percentages of point source emissions in the total emissions increase from less than 30%in the MEIC up to a maximum of 84%for SO_(2)in 2013.The new point source-based emission maps show the uncoupled distribution of emissions and populations in space at fine spatial scales,however,such a pattern cannot be reproduced by any spatial proxy used in the conventional emissions mapping.This new accurate high-resolution emission mapping approach reduces the modeled biases of air pollutant concentrations in the densely populated areas compared to the raw MEIC inventory,thus improving the assessment of population exposure.展开更多
The sensitivity of the representation of the global monsoon annual cycle to horizontal resolution is compared in three AGCMs： the Met Office Unified Model-Global Atmosphere 3.0; the Meteorological Research Institute ...The sensitivity of the representation of the global monsoon annual cycle to horizontal resolution is compared in three AGCMs： the Met Office Unified Model-Global Atmosphere 3.0; the Meteorological Research Institute AGCM3; and the Global High Resolution AGCM from the Geophysical Fluid Dynamics Laboratory. For each model, we use two horizon- tal resolution configurations for the period 1998-2008. Increasing resolution consistently improves simulated precipitation and low-level circulation of the annual mean and the first two annual cycle modes, as measured by the pattern correla- tion coefficient and equitable threat score. Improvements in simulating the summer monsoon onset and withdrawal are region-dependent. No consistent response to resolution is found in simulating summer monsoon retreat. Regionally, in- creased resolution reduces the positive bias in simulated annual mean precipitation, the two annual-cycle modes over the West African monsoon and Northwestern Pacific monsoon. An overestimation of the solstitial mode and an underestimation of the equinoctial asymmetric mode of the East Asian monsoon axe reduced in all high-resolution configurations. Systematic errors exist in lower-resolution models for simulating the onset and withdrawal of the summer monsoon. Higher resolution models consistently improve the early summer monsoon onset over East Asia and West Africa, but substantial differences exist in the responses over the Indian monsoon region, where biases differ across the three low-resolution AGCMs. This study demonstrates the importance of a multi-model comparison when examining the added value of resolution and the importance of model physical parameterizations for simulation of the Indian monsoon.展开更多
基金supported by the Chinese Academy of Sciences (XDA05090000)the National Natural Science Foundation (41475078)
文摘This paper summarizes recent studies on the effects of urbanization on climate in China. The effects of urbanization on local climate trends have been re-estimated based on homogenized observations and using improved methods. In this respect, the effect of urbanization on the observed warming trend of local surface air temperatures during the last few decades is determined as being about 20% at urban stations such as the Beijing Observatory. The large-scale weakening trend of wind speed is also about 20% more prominent at the city center than its surroundings. The effect of urbanization on precipitation is not profound, but results of high-resolution regional climate modeling suggest that this effect may depend on the urban extent. Although the urban heat island(UHI) should favor local atmospheric convection and hence precipitation, the increasingly extending urban land-use may reduce precipitation over the urban cluster in North China. It is found that urbanization can play a more notable role in extreme events than usual weather. High-resolution simulations show a positive feedback between the UHI and the super-heat wave in Shanghai during Julye August 2013. Relevant studies dealing with urban climate adaptation are discussed in relation to recent ?ndings.
基金supported by the National Natural Science Foundation of China(91744310,41625020 and 41921005)the National Research Program for Key Issues in Air Pollution Control(DQGG0201)。
文摘New challenges are emerging in fine-scale air quality modeling in China due to a lack of high-resolution emission maps.Currently,only a few emission sources have accurate geographic locations(point sources),while a large part of sources,including industrial plants,are estimated as provincial totals(area sources)and spatially disaggregated onto grid cells based on proxies;this approach is reasonable to some extent but is highly questionable at fine spatial resolutions.Here,we compile a new comprehensive point source database that includes nearly 100,000 industrial facilities in China.We couple it with the frame of Multi-resolution Emission Inventory for China(MEIC),estimate point source emissions,combine point and area sources,and finally map China’s anthropogenic emissions of 2013 at the spatial resolution of 30’’*30’’(~1 km).Consequently,the percentages of point source emissions in the total emissions increase from less than 30%in the MEIC up to a maximum of 84%for SO_(2)in 2013.The new point source-based emission maps show the uncoupled distribution of emissions and populations in space at fine spatial scales,however,such a pattern cannot be reproduced by any spatial proxy used in the conventional emissions mapping.This new accurate high-resolution emission mapping approach reduces the modeled biases of air pollutant concentrations in the densely populated areas compared to the raw MEIC inventory,thus improving the assessment of population exposure.
基金jointly supported by the National Natural Science Foundation of China(Grant Nos.41420104006,41330423)Program of International S&T Cooperation under grant 2016YFE0102400+1 种基金the UK-China Research&Innovation Partnership Fund through the Met Office Climate Science for Service Partnership(CSSP)China as part of the Newton Fundfunded by an Independent Research Fellowship from the Natural Environment Research Council(Grant No.NE/L010976/1)
文摘The sensitivity of the representation of the global monsoon annual cycle to horizontal resolution is compared in three AGCMs： the Met Office Unified Model-Global Atmosphere 3.0; the Meteorological Research Institute AGCM3; and the Global High Resolution AGCM from the Geophysical Fluid Dynamics Laboratory. For each model, we use two horizon- tal resolution configurations for the period 1998-2008. Increasing resolution consistently improves simulated precipitation and low-level circulation of the annual mean and the first two annual cycle modes, as measured by the pattern correla- tion coefficient and equitable threat score. Improvements in simulating the summer monsoon onset and withdrawal are region-dependent. No consistent response to resolution is found in simulating summer monsoon retreat. Regionally, in- creased resolution reduces the positive bias in simulated annual mean precipitation, the two annual-cycle modes over the West African monsoon and Northwestern Pacific monsoon. An overestimation of the solstitial mode and an underestimation of the equinoctial asymmetric mode of the East Asian monsoon axe reduced in all high-resolution configurations. Systematic errors exist in lower-resolution models for simulating the onset and withdrawal of the summer monsoon. Higher resolution models consistently improve the early summer monsoon onset over East Asia and West Africa, but substantial differences exist in the responses over the Indian monsoon region, where biases differ across the three low-resolution AGCMs. This study demonstrates the importance of a multi-model comparison when examining the added value of resolution and the importance of model physical parameterizations for simulation of the Indian monsoon.
