黄土高原夜间地表能量不平衡问题的初步研究  

Preliminary study on the nocturnal surface energy imbalance on the Loess Plateau

作　　者：赵建华[1] 张强[1] 王胜[1] 梁芸 张良[1] 岳平[1] 赵福年[1] ZHAO JianHua;ZHANG Qiang;WANG Sheng;LIANG Yun;ZHANG Liang;YUE Ping;ZHAO FuNian(Key Laboratory of Arid Climatic Changing and Reducing Disaster of Gansu Province(Chinese Meteorological Administration),Lanzhou Institute of Arid Meteorology of Chinese Meteorological Administration,Lanzhou 730020,China;Lanzhou Regional Climate Center,Lanzhou 730020,China)

机构地区：[1]甘肃省(中国气象局)干旱气候变化与减灾重点实验室,中国气象局兰州干旱气象研究所,兰州7300202 [2]Lanzhou Regional Climate Center,Lanzhou 730020,China

出　　处：《地球物理学报》2025年第2期385-398,共14页Chinese Journal of Geophysics

基　　金：国家自然科学基金(重点)项目(42230611,41375019,41875020);气象能力提升联合研究专项(23NLTSZ008);中国气象局创新发展专项(CXFZ2022J049);甘肃省自然科学基金(22JR5RA746,24JRRA724);中国博士后基金(2022MD713816)资助.

摘　　要：一般认为白天的地表能量不平衡(surface energy imbalance,SEI)主要由涡动相关法造成,但夜间湍流受到抑制,其产生的原因尚不清楚.本文分析了夜间与白天地表能量的区别,认为夜间土壤热量存在的双向传递慢过程、向上长波辐射位相延后与湍流相干结构是其重要原因.为此,本文利用黄土高原典型代表站的观测数据,对夜间SEI展开研究.发现:(1)考虑慢过程后,夜间土壤温度、土壤热通量、土壤热储与地表土壤热通量均有一定程度的增大,其能量闭合率(Energy BalanceRatio,EBR)提高了0.02或3%,达到0.71,能量平衡残差(Residual,Res)绝对值降低了0.8 W·m^(-2)或4%,为17.0 W·m^(-2);(2)考虑向上长波辐射位相延后,夜间向上长波辐射和净辐射均有所降低,其EBR也为0.71,也提高了0.02或3%,|Res|为15.5W·m^(-2),降低了2.3W·m^(-2)或13%;(3)考虑相干结构的贡献后,感热与潜热分别增大了53%(绝对值)和35%,其EBR未有显著变化,但|Res|降低了1.1W·m^(-2)或6%;(4)既考虑慢过程,又考虑向上长波辐射位相延后和相干结构时,夜间EBR为0.73,提高了0.04或6%,|Res|为14.8 W·m^(-2),降低了3.0 W·m^(-2)或17%.显然,这三个过程均可改善夜间地表能量闭合水平,但综合效应改善更大;(5)增加Durand(2022)提出的湍流通量漏失部分,可使EBR提高0.03,达到0.76,|Res|降低1.4 W·m^(-2),达到13.4 W·m^(-2),但也未闭合,故涡动相关法可能不是夜间SEI产生的主要原因.分析发现,长波辐射计的观测误差较大,且无世界标准;检测结果显示,长波辐射存在系统误差,且EBR和Res与长波辐射均存在显著的正相关关系,因此我们认为长波辐射的系统误差可能是夜间SEI产生的主要原因,提高长波辐射计的观测精度应该是改善夜间地表能量闭合水平的重要途径.It is generally believed that the surface energy imbalance(SEI)during the day is mainly caused by eddy covariance technique.While turbulence at night is suppressed,the reason for its occurrence is not clear.This study analyzes the differences in surface energy between nighttime and daytime,and suggests that the slow process of two-way transfer of soil heat at night,the delayed phase of upward longwave radiation and the turbulent coherent structure are important reasons for it.To investigate this,the study uses the data from an observatory on the Loess Plateau to examine the nocturnal SEI.The results show that:(1)After considering the slow process of soil heat transfer,nocturnal soil temperature,soil heat flux,soil heat storage,and surface soil heat flux all increase to a certain extent.The energy balance rate(EBR)increases by 0.02(3%)to 0.71,and the absolute value of energy balance residual(Res)decreases by 0.8 W·m^(-2)(4%)to 17.0 W·m^(-2);(2)After considering the phase delay of upward longwave radiation,both nocturnal upward longwave radiation and net radiation decrease,with an EBR also of 0.71,an increase also of 0.02(3%),and a|Res|of 15.5 W·m^(-2),a decrease of 2.3 W·m^(-2)(13%);(3)After considering the contribution of the coherent structures,sensible heat and latent heat increase by 53%(absolute value)and 35%,respectively,with an EBR unchanging significantly and a|Res|decrease of 1.1 W·m^(-2)(6%);(4)When considering the slow processes,the phase delay of upward longwave radiation and the coherent structure,the nocturnal EBR is 0.73,an increase of 0.04(6%),and the|Res|is 14.8 W·m^(-2),a decrease of 3.0 W·m^(-2)(17%).Clearly,all three processes can improve the level of nocturnal surface energy closure,but the overall effect is greater;(5)Adding the turbulent flux leakage part proposed by Durand(2022)can increase the EBR by 0.03 to 0.76 and decrease the Res by 1.4 W·m^(-2) to 13.4 W·m^(-2),but the nocturnal surface energy is still not balanced.Therefore,the eddy covariance technique may not be the main c

关 键 词：夜间地表能量不平衡 慢过程 长波辐射位相延后 湍流相干结构 长波辐射计精度 

分 类 号：P404[天文地球—大气科学及气象学]