中国地区氧化亚氮浓度时空变化特征分析

氧化亚氮是一种重要的温室气体和臭氧损耗物。利用热红外反演大气温湿廓线，由于大气氧化亚氮含量较少且变化幅度不大，一般都当作常量处理。但是在反演氧化亚氮时，由于大气温湿廓线和地表温度等参数相对氧化亚氮变化较大，可能很小的扰动就会覆盖掉氧化亚氮的吸收信号。因此有必要在上千个通道中，选取信噪比最高的通道，反演分析氧化亚氮浓度的时空变化特征，进而掌握我国氧化亚氮浓度的变化规律，为研究我国氧化亚氮排放对气候变化的贡献，制定合理的氧化亚氮减排政策等，提供可靠数据支撑。采取一种优化后的最优敏感廓线通道选取法，利用AIRS数据，基于最优估计法反演氧化亚氮浓度，与TCOON观测网中加拿大站点进行比对，结果显示卫星遥感与地面观测结果一致性较好，相关系数r为0.73，该算法可以推广到IASI和CrIS等热红外高光谱数据，使对氧化亚氮的观测数据增加到20多年，这种长时间序列的产品是对目前地面观测的有效补充。在氧化亚氮反演验证的基础上分析了我国氧化亚氮的年均值变化和月均值变化情况，以及它的空间分布特征。时空变化结果显示，我国氧化亚氮浓度在低纬度地区浓度相对较高，每年在华南地区的夏季达到峰值，月度间变化幅度较大，相比于月度变化，年度之间的变化幅度相对较小。监测结果同时显示，印度、巴基斯坦等国在紧邻我国地区，夏季氧化亚氮浓度较高，因此我国氧化亚氮浓度的时空变化特征除本地排放贡献外，也有一定的外部区域传输影响。

Temporal and Spatial Characteristics of Nitrous Oxide Concentration in China

Retrieves nitrous oxide profiles from the thermal infrared satellite data,the results will be affected by the impact of atmospheric parameters such as atmo spheric temperature and humidity profiles,as well as surface parameters such as surface temperature and surface emissivity and the like.N 2O own changes to a lesser extent,so when using the optimal estimation inversion,to get a priori profile and to select the inversion channel are the keys.Therefore,the inversion of nitrous oxide is rarely seen in China.Study and analyze the absorption characteristics of nitrous oxide and other interfering gases in the thermal infrared region for channel selection,based on this,to retrieve and analyze the temporal and spatial variation characteristics of nitrous oxide concentrationis of great practical significance for the study of global climate change in China.In this paper,under the inversion framework of the optimal estimation method,an optimal sensitive profile channel selection method is used to retrieve the nitrous oxide concentration using the AIRS data.Compared with the Canadian station in the TCCON observation network,the results show that the retrieval results are in good agreement with the ground observations,and the correlation coefficient r is 0.73.This algorithm can be extended to the thermal infrared hyperspectral data such as IASI and CrIS,and increase the observation data of nitrous oxide to more than 20 years.This long-time series product is an effective supplement to the current ground observation.The annual and monthly mean changes of nitrous oxide and its spatial distribution characteristics in China are analyzed for the first time.The results show that the change of thenitrous oxide concentration is obvious with time and latitude,among which the annual change of the nitrous oxide concentration is small,and the monthly and seasonal meanvalue changes greatly.From January of each year,the concentration of nitrous oxide increased month by month,reached the maximum in July and August,and then began to decline month by month.The seasonal variation was the highest in summer(June-gust),spring and autumn are the second,while winter is the lowest.According to the annual average,the concentration of nitrous oxide in China changes obviously with latitude,and the higher the latitude is,the lower the concentration is.High-value regions are mainly concentrated in South China,especially in summer.The low-value regions are north China and southwest China.In the west of China,the concentration of nitrous oxide is higher in summer.In addition to local emissions,this seasonal or monthly mean change is also affected by air convection and transport.