Based on analysis of the air pollution observational data at 8 observation sites in Beijing including outer suburbs during the period from September 2004 to March 2005, this paper reveals synchronal and in-phase characteristics in the spatial and temporal variation of air pollutants on a city-proper scale at deferent sites; describes seasonal differences of the pollutant emission influence between the heating and non-heating periods, also significantly local differences of the pollutant emission influence between the urban district and outer suburbs, i.e. the spatial and temporal distribution of air pollutant is closely related with that of the pollutant emission intensity. This study shows that due to complexity of the spatial and temporal distribution of pollution emission sources, the new generation Community Multi-scale Air Quality (CMAQ) model developed by the EPA of USA produced forecasts, as other models did, with a systematic error of significantly lower than observations, albeit the model has better capability than previous models had in predicting the spatial distribution and variation tendency of multi-sort pollutants. The reason might be that the CMAQ adopts average amount of pollutant emission inventory, so that the model is difficult to objectively and finely describe the distribution and variation of pollution emission sources intensity on different spatial and temporal scales in the areas, in which the pollution is to be forecast. In order to correct the systematic prediction error resulting from the average pollutant emission inventory in CMAQ, this study proposes a new way of combining dynamics and statistics and establishes a statistically correcting model CMAQ-MOS for forecasts of regional air quality by utilizing the relationship of CMAQ outputs with corresponding observations, and tests the forecast capability. The investigation of experiments presents that CMAQ-MOS reduces the systematic errors of CMAQ because of the uncertainty of pollution emission inventory and improves the forecast level of air quality. Also this work employed a way of combining point and area forecasting, i.e. taking the products of CMAQ for a center site to forecast air pollution for other sites in vicinity with the scheme of model products "reanalysis" and average over the "area". 相似文献
India's growing role in the global climate debate makes it imperative to analyse emission reduction policies and strategies across a range of GHGs, especially for under-researched non-CO2 gases. Hydrofluorocarbons' (HFCs) usage in cooling equipment and subsequent emissions are expected to increase dramatically in India with the phase-out of hydrochlorofluorocarbons (HCFCs) as coolants in air-conditioning equipment. We focus on the residential air-conditioning sector in India and analyse a suite of HFC and alternative coolant gas scenarios for understanding the implications for GHG emissions from this sector within an integrated assessment modelling framework. We find that, if unabated, HFC410A emissions will contribute to 36% of the total global warming impact from the residential air-conditioner sector in India in 2050, irrespective of the future economic growth trajectory, and the remaining 64% is from energy to power residential air-conditioners. A move towards more efficient, low global warming potential (GWP) alternative refrigerants will significantly reduce the cumulative global warming footprint of this sector by 37% during the period 2010–2050, due to gains both from energy efficiency as well as low GWP alternatives. Best practices for reducing direct emissions are important, but only of limited utility, and if a sustainable lifestyle is adopted by consumers with lower floorspace, low GWP refrigerants, and higher building envelope efficiencies, cumulative emissions during 2010–2050 can be reduced by 46% compared to the Reference scenario.
Policy relevance
Our analysis has important implications for Indian climate policy. We highlight that the Indian government's amendment proposal to the Montreal Protocol is a strong signal to the Indian market that the transition away from high GWP refrigerants towards low/zero GWP alternatives will happen sooner or later. The Bureau of Energy Efficiency should extend building energy conservation code policy to residential buildings immediately, and the government should mandate it. Government authorities should set guidelines and mandate reporting of data related to air-conditioner coolant recharge frequency and recovery of scrapped air-conditioner units. For contentious issues like flammability where there is no consensus within the industry, the government needs to undertake an independent technical assessment that can provide unbiased and reliable information to the market. 相似文献
Regional and national level land cover datasets, such as the National Land Cover Database (NLCD) in the United States, have become an important resource in physical and social science research. Updates to the NLCD have been conducted every 5 years since 2001; however, the procedure for producing a new release is labor-intensive and time-consuming, taking 3 or 4 years to complete. Furthermore, in most countries very few, if any, such releases exist, and thus there is high demand for efficient production of land cover data at different points in time. In this paper, an active machine learning framework for temporal updating (or backcasting) of land cover data is proposed and tested for three study sites covered by the NLCD. The approach employs a maximum entropy classifier to extract information from one Landsat image using the NLCD, and then replicate the classification on a Landsat image for the same geographic extent from a different point in time to create land cover data of similar quality. Results show that this framework can effectively replicate the land cover database in the temporal domain with similar levels of overall and within class agreement when compared against high resolution reference land cover datasets. These results demonstrate that the land cover information encapsulated in the NLCD can effectively be extracted using solely Landsat imagery for replication purposes. The algorithm is fully automated and scalable for applications at landscape and regional scales for multiple points in time. 相似文献
The majority of emissions of nitrous oxide – a potent greenhouse gas (GHG) – are from agricultural sources, particularly nitrogen fertilizer applications. A growing focus on these emission sources has led to the development in the United States of GHG offset protocols that could enable payment to farmers for reducing fertilizer use or implementing other nitrogen management strategies. Despite the development of several protocols, the current regional scope is narrow, adoption by farmers is low, and policy implementation of protocols has a significant time lag. Here we utilize existing research and policy structures to propose an ‘umbrella’ approach for nitrogen management GHG emissions protocols that has the potential to streamline the policy implementation and acceptance of such protocols. We suggest that the umbrella protocol could set forth standard definitions common across multiple protocol options, and then modules could be further developed as scientific evidence advances. Modules could be developed for specific crops, regions, and practices. We identify a policy process that could facilitate this development in concert with emerging scientific research and conclude by acknowledging potential benefits and limitations of the approach.
Key policy insights
Agricultural greenhouse gas market options are growing, but are still underutilized
Streamlining protocol development through an umbrella process could enable quicker development of protocols across new crops, regions, and practices
Effective protocol development must not compromise best available science and should follow a rigorous pathway to ensure appropriate implementation