岭南地区典型次生常绿阔叶林下垫面太阳和长波辐射特征分析

Characteristics of Solar Spectral Radiation and LongWave Radiation over the Evergreen Broad-leaved Forest in the South of the Five Ridges

基于珠海凤凰山陆气相互作用与碳通量观测塔2015年10月至2018年5月的辐射观测资料,对珠海凤凰山常绿阔叶林区冠层表面的太阳总辐射和分光辐射、长波辐射、净辐射的日变化与季节变化特征进行了比较分析。研究表明:典型晴天时太阳总辐射和分光辐射的日变化均呈常规的“正弦曲线”形式,辐射值在12:00(北京时,下同)左右达到最高;多云天时太阳辐射的日变化趋势为“锯齿状”。典型晴天条件下,白天时向上的长波辐射呈先升高后下降的趋势,一般在14:00左右达到最大;白天时向下的长波辐射变化不明显,但在夜晚常常会出现较为剧烈的变化。多云天条件下大气向下的长波辐射值与下垫面发射的向上的长波辐射值非常接近,两者的日变化幅度都很小。净辐射强度值在白天为正,夜晚为负,白天时日变化形式与向下的太阳总辐射类似,夜晚则与向上的长波辐射类似。太阳辐射和长波辐射均在夏季最大,秋季和春季次之,冬季最小;在整个观测时段内,近红外辐射、可见光辐射和紫外辐射占总辐射的平均比例分别为51.2%、43.0%和5.8%;可见光与紫外辐射所占比例在夏季最大,冬季最小;近红外辐射所占比例在夏季最小,冬季最大。研究结果可为岭南地区陆面过程模式改进提供依据。

By using the radiation observation data from October 2015 to May 2018 at Zhuhai Phoenix Mountain land-air interaction and carbon flux observation tower which represents the typical secondary evergreen broadleaf forest underlying surface around cities and villages in the South of the Five Ridges of China,statistical analysis were carried out on the characteristics of total and spectral solar radiation,long-wave radiation and net radiation.The results show that the diurnal variations of total and spectral solar radiation are the regular sinusoidal curves with highest values at noon in the typical clear days while the diurnal variations are serrated in the cloudy days.In the typical clear days,the upward long-wave radiations increase first and then decrease during the daytime and generally reach the maximum after noon,the downward long-wave radiations do not change obviously during the day,but often change violently at night.In the cloudy days,the downward long-wave radiations emitted by atmosphere are very close to the upward long wave radiations emitted by the underlying surface,but the diurnal variations of both are very small.The net radiations are positive during the daytime but negative at night.Their diurnal variations are similar to the ones of the downward total solar radiations during the daytime and similar to the ones of the upward long-wave radiations at night.The solar radiations and long-wave radiations are the largest in summer,followed by autumn and spring,and the smallest in winter.The average ratios of the near infrared radiation,visible radiation and ultraviolet radiation to total radiation are 51.2%,43.0%and 5.8%respectively during the observation period.The ratios of the visible and ultraviolet radiation to total radiation are both the largest in summer and the smallest in winter,while the ratio of near infrared radiation to total radiation is the smallest in summer and the largest in winter.These results can provide a basis for the improvement of land surface process model in the South of the Five Ridges.