摘要
野火频发严重影响生态系统和气候变化,研究其年际变化及机制可完善对野火发生规律的认识,为中国防火决策提供科学依据。为此,基于GFED4和MODIS两种卫星遥感火灾面积数据和ERA5再分析气象资料,采用功率谱研究中国野火面积的年际变化,并利用随机森林模型和相关/回归分析确定主导年际变化的关键气象因子及背后的环流特征。结果表明:(1)1-3月华南、2-4月西南和3-5月东北地区为中国野火面积年际变化显著区,各显著区年际周期不同。华南地区野火面积存在4~6年的年际周期,东北地区存在3年的年际周期。(2)相对湿度是华南和东北地区野火年际变化的关键气象因子,且与野火面积呈显著负相关关系;风速是西南地区的关键气象因子,与野火面积呈显著正相关关系。(3)各显著区有独自的环流特征。西南地区海平面异常低压南侧的西(西南)风正异常,增加了气候态风速,有利于火灾蔓延;东北地区在局地异常高压的控制下,下沉气流降低近地面相对湿度,导致火灾面积增加;而华南地区环流异常不显著。
Wildfire exerts great influences on the ecosystem and climate change.Analyzing its inter-annual variability and mechanisms could deepen the understanding of wildfire variability and provide scientific basis for fire prevention decision-making in China.Using the burned area data from GFED4 and MODIS satellite remote sensing and ERA5 re-analysis data,this study explores the inter-annual variability of wildfire burned area by means of power spectrum analysis.Then,the key meteorological factors,which dominate the inter-annual variation of wildfire area,and their circulation characteristics are identified by the random forest model and correlation/regression analysis.The results show that:(1)South China(January to March),Southwest China(February to April)and Northeast China(March to May)are the key wildfire regions with significant inter-annual variations in wildfire burned area in China and the interannual cycle of each significant area is different.There is an inter-annual cycle of 4 to 6 years for the wildfire burned area in South China and a 3-year cycle in Northeast China.(2)Relative humidity is a key meteorological factor for the inter-annual variation of wildfires in South China and Northeast China,and it shows a significant negative correlation with the area of wildfires.Wind speed is a key meteorological factor in Southwest China and has a significant positive correlation with the area of wildfires.(3)Distinct atmospheric circulations exist in different key regions.The westerly(southwesterly)wind on the south side of the abnormal low sea level pressure in Southwest China is positively abnormal,which increases the climatological wind speed and is conducive to the spread of fire.Local high-pressure anomaly appears in Northeast China with descending motion,and the sinking airflow reduces the near-surface relative humidity,benefiting the increase in wildfire burned area.However,no significant circulation anomaly is found in South China.
作者
杨熙婷
齐道日娜
杨艳蓉
张乐英
Yang Xiting;Chyi Dorina;Yang Yanrong;Zhang Leying(College of Ecology and Environment of Nanjing Forestry University,Nanjing 210037,China;China Meteorological Administration Training Centre,Beijing 100081,China)
出处
《气象与环境科学》
2025年第6期20-28,共9页
Meteorological and Environmental Sciences
基金
2024年复盘总结专项(FPZJ2024-175)
国家自然科学基金面上项目(31971670)。
关键词
野火面积
随机森林
年际周期
相对湿度
风速
环流特征
wildfire area
random forest
inter-annual cycle
relative humidity
wind speed
circulation characteristics
