利用2006年锦州玉米农田生态系统野外观测站动态连续的通量、气象及生物因子观测数据对玉米植株高度、叶面积指数(LAI)、粗糙度(Z0)、表层土壤湿度(SWC)、反照率的动态变化及其相互关系进行分析,旨在为建立玉米农田下垫面动态参数方案提供参考。动态LAI和株高采用相对积温方法求得,Z0通过中性条件下风速廓线方程求得。研究表明:玉米株高增长速度以拔节期为转折点先慢后快,到乳熟期达到最大;LAI呈不对称"n"型分布,最大值出现在抽雄至乳熟期,约为4;SWC冬季最小,为12%~20%,夏季最大,为30%~36%。反照率在冷季(11-翌年3月)最大,为0.2~0.3,积雪覆盖时为0.5~0.7;暖季(6-9月)最小,为0.1~0.2。生长季内反照率与LAI呈显著正相关,其月均值日变化呈U型分布,受LAI、冠层颜色及粗糙度等因素影响,白天反照率6月〈9月〈8月〈7月。在非结冻期反照率与SWC呈极显著负相关,但随着LAI增大,该关系逐渐减弱。Z0与株高和LAI呈指数正相关。
By using the continuous flux data,meteorological data,and biological data from Jinzhou agricultural ecosystem research station in 2006,the dynamic characteristics of maize plant height(H),leaf area index(LAI),surface soil water content(SWC),roughness(Z0),and albedo as well as their relationships were investigated,aimed to provide references for setting up dynamic parameterization schemes on maize field surface.The H and LAI were estimated with relative accumulated temperature method,and the Z0 was calculated with wind profile equation under neutral condition.The H increased linearly and slowly before jointing stage,and came quickly to the peak value until milk stage.The change of LAI,which emerged the maximum equal to about 4 at jointing-heading stage and reduced to 1.5 in harvesting time,showed an asymmetrical n-type pattern in the growth period.The SWC was the minimum(12%-20%)in winter and the maximum(30%-36%)in summer,while the surface albedo was greater(0.2-0.3)in cold season(from November to next March),the greatest(0.5-0.7)when ground surface was covered by snow,and the smallest(0.1-0.2)in warm season(from June to September).Albedo was significantly positively correlated to LAI during the growth season.Its monthly mean diurnal pattern showed a U-shape distribution,and was affected by the LAI,canopy color and roughness.At the daytime,albedo was in the order of June September August July.In no-freezing period,the albedo had a significant negative correlation with SWC,but this correlation became weaker with increasing LAI.The Z0 had positive exponential correlations with H and LAI.