稻麦轮作田下垫面的感热和潜热通量特征分析
发布时间：2019-03-12 14:09
【摘要】：感热和潜热通量是地表能量平衡的重要组成部分,对其的定量了解,不仅是大气动力热力过程分析的基础,也是农业生态等研究的核心内容。长江中下游农田以水稻和小麦为主要耕作物,对稻麦轮作田进行通量观测能够更好地理解长江中下游区域大气边界层能量交换特征。因此,本文基于2015年7月9日到2016年5月18日,江苏盐城东台市郊稻麦轮作田上方的通量观测数据,对稻麦轮作田下垫面的通量变化特征进行了分析,探讨了不同生长期,下垫面的平均通量和能量分配特征,重点分析了不同时期通量的日变化特征及下垫面温湿度和风速对能量分配的影响,最后,对比了大孔径闪烁仪和涡相关观测系统的观测数据,检验了仪器的可靠性。主要结论如下:(1)平均通量分析表明,在白天,小麦返青期的平均感热通量最大,而水稻拔节期的平均潜热通量最大。在夜间,下垫面仍然存在向上的潜热通量。在停耕期和小麦出苗期,整个下垫面接收到的能量要小于它向大气传递的感热和潜热通量。在整个观测过程中,各时期(H+LE)/Rn的平均值不超过80%,H/Rn的平均值不超过18%,农田下垫面主要以潜热通量的方式向大气传递能量。(2)日变化特征分析表明,水稻、裸地和小麦下垫面情况下感热通量的日变化特征十分接近,整个观测期间,感热通量的平均峰值为46.08 Wm-2。对能量分配的平均日变化特征分析表明,在水稻的生长周期,(H + LE)/Rn和LE/Rn的日变化特征较为一致,它们在水稻各个时期的日变化趋势分别为:先减后增型(插秧期),逐渐增长型(拔节期),平稳波动型(抽穗期)和逐渐增长型(成熟期)。而H/Rn的值在整个水稻生长期内都为先增后减型,其最大值一般出现在10:00左右。在小麦的种植期,(H+LE)/Rn和LE/Rn的日变化特征也较为一致,都随着小麦的生长,由逐渐增长型(出苗期,越冬期和返青期)转变为起伏增长型(拔节期和成熟期)。H/Rn的日变化特征主要分为先增后减型(出苗期,越冬期和成熟期)和平稳波动型(返青期和拔节期)。当下垫面为裸地时,(H+ LE)/Rn , LE/Rn和H/Rn的日变化特征均为波动型。(3)对土壤温湿度及地表风速的分析表明,在水稻种植期,各变量对能量分配的影响作用都较为独立,能量分配主要受土壤湿度和风速的影响。土壤湿度的增加,略微增大了H/Rn的值,降低了LE/R 的值,而风速的增大,增大了LE/Rn的值。在小麦种植期,土壤温度和湿度共同影响了地表能量分配,随着土壤温度的增加,对应的土壤湿度减小,H/Rn的值减小,LE/Rn的值增大。在整个观测期间,H/Rn和LE/Rn的日变化同时受土壤温湿度及风速的日变化的影响,当土壤温度增大时,土壤相对湿度减小,风速逐渐增大且增长速度逐渐降低,LE/Rn的值逐渐增大,而H/Rn始终保持稳定。(4)对水稻抽穗期通量观测数据的分析表明,大多数情况下,LAS观测的感热通量都要大于EC所观测的值。结合源区模型,可以发现,仪器东侧的一片桑树园影响了两个仪器的观测结果。由于桑树园上方的感热通量大于水稻田上方的感热通量。当桑树园贡献较大时,HLAS的值总是会大于HEC的值。而当桑树园对两个仪器贡献较一致时,两个仪器观测得到的感热通量也较为接近。两种仪器观测的差异是由桑树园所引起的下垫面不均匀性造成的。
[Abstract]:The heat and latent heat flux is an important part of surface energy balance, and its quantitative understanding is not only the basis of the analysis of the dynamic process of the atmospheric power, but also the core content of the agricultural ecology. The energy exchange characteristics of the atmospheric boundary layer in the middle and lower reaches of the Yangtze River can be better understood in the middle and lower reaches of the Yangtze River. Therefore, on the basis of the flux observation data from July 9,2015 to May 18,2016, the flux change characteristics of the wheat and wheat rotation field under the rice and wheat rotation field were analyzed, and the different growth phases were discussed. On the basis of the average flux and energy distribution of the lower surface, the effects of the diurnal variation of flux and the temperature and humidity and the wind speed on the distribution of energy are analyzed. Finally, the observation data of the large-aperture scintillator and the vortex-related observation system are compared, and the reliability of the instrument is verified. The main conclusions are as follows: (1) The average flux analysis shows that, during the day, the average sensible heat flux of the wheat return period is the largest, while the average latent heat flux of the rice seedling stage is the largest. The underlying surface still has an upward latent heat flux at night. At the seedling stage and the seedling stage of the wheat, the energy received by the whole underlying surface is less than the sensible and latent heat flux it transfers to the atmosphere. During the whole observation, the average value of H + LE/ Rn was not more than 80%, and the average value of H/ Rn was not more than 18%. (2) The characteristic of daily variation showed that the diurnal variation of the sensible heat flux was very close to that of the lower surface of the wheat, and the average peak of the sensible heat flux was 46.08 Wm-2 during the whole observation period. The analysis of the average daily variation of energy distribution shows that the diurnal variation of the growth cycle, (H + LE)/ Rn and LE/ Rn of the rice is more consistent, and the daily variation trend of the energy distribution is as follows: Stable wave type (heading stage) and gradual growth (maturity stage). The value of H/ Rn in the whole rice growing period is the first and the second, and the maximum value of H/ Rn is about 10:00. The diurnal variation of (H + LE)/ Rn and LE/ Rn was also consistent with the growth of wheat. The diurnal variation of H/ Rn was divided into the first and the second stage (the seedling stage, the overwintering period and the maturity stage) and the steady wave type (the return period and the jointing stage). The diurnal variations of (H + LE)/ Rn, LE/ Rn and H/ Rn are of wave type when the underlying surface is bare. (3) The analysis of the temperature and humidity of the soil and the surface wind speed shows that in the rice planting period, the effect of each variable on the energy distribution is independent, and the energy distribution is mainly affected by the soil moisture and the wind speed. The increase of soil humidity slightly increases the value of H/ Rn, decreases the value of LE/ R, and increases the value of LE/ Rn. During the wheat planting period, the soil temperature and humidity have a common influence on the surface energy distribution. With the increase of soil temperature, the corresponding soil moisture is reduced, and the value of H/ Rn is reduced, and the value of LE/ Rn is increased. During the whole observation period, the diurnal variation of H/ Rn and LE/ Rn is affected by the diurnal variation of the temperature and humidity of the soil and the wind speed, and when the soil temperature is increased, the relative humidity of the soil is reduced, the wind speed is gradually increased and the growth rate is gradually decreased, and the value of LE/ Rn is gradually increased, and the H/ Rn is always stable. (4) The analysis of flux observation data of rice heading period shows that in most cases, the sensible heat flux of LAS is greater than the value observed by EC. Combined with the source region model, it can be found that a mulberry field on the east side of the instrument affects the observation results of the two instruments. As the sensible heat flux above the mulberry field is greater than the sensible heat flux above the rice field. When the mulberry field contributes significantly, the value of the HLAS is always greater than the value of the HEC. The sensible heat flux observed by the two instruments is also close when the contribution of the mulberry garden to the two instruments is consistent. The difference between the two instruments is caused by the non-uniformity of the underlying surface caused by the mulberry garden.
【学位授予单位】：南京信息工程大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S181
本文编号：2438852
[Abstract]:The heat and latent heat flux is an important part of surface energy balance, and its quantitative understanding is not only the basis of the analysis of the dynamic process of the atmospheric power, but also the core content of the agricultural ecology. The energy exchange characteristics of the atmospheric boundary layer in the middle and lower reaches of the Yangtze River can be better understood in the middle and lower reaches of the Yangtze River. Therefore, on the basis of the flux observation data from July 9,2015 to May 18,2016, the flux change characteristics of the wheat and wheat rotation field under the rice and wheat rotation field were analyzed, and the different growth phases were discussed. On the basis of the average flux and energy distribution of the lower surface, the effects of the diurnal variation of flux and the temperature and humidity and the wind speed on the distribution of energy are analyzed. Finally, the observation data of the large-aperture scintillator and the vortex-related observation system are compared, and the reliability of the instrument is verified. The main conclusions are as follows: (1) The average flux analysis shows that, during the day, the average sensible heat flux of the wheat return period is the largest, while the average latent heat flux of the rice seedling stage is the largest. The underlying surface still has an upward latent heat flux at night. At the seedling stage and the seedling stage of the wheat, the energy received by the whole underlying surface is less than the sensible and latent heat flux it transfers to the atmosphere. During the whole observation, the average value of H + LE/ Rn was not more than 80%, and the average value of H/ Rn was not more than 18%. (2) The characteristic of daily variation showed that the diurnal variation of the sensible heat flux was very close to that of the lower surface of the wheat, and the average peak of the sensible heat flux was 46.08 Wm-2 during the whole observation period. The analysis of the average daily variation of energy distribution shows that the diurnal variation of the growth cycle, (H + LE)/ Rn and LE/ Rn of the rice is more consistent, and the daily variation trend of the energy distribution is as follows: Stable wave type (heading stage) and gradual growth (maturity stage). The value of H/ Rn in the whole rice growing period is the first and the second, and the maximum value of H/ Rn is about 10:00. The diurnal variation of (H + LE)/ Rn and LE/ Rn was also consistent with the growth of wheat. The diurnal variation of H/ Rn was divided into the first and the second stage (the seedling stage, the overwintering period and the maturity stage) and the steady wave type (the return period and the jointing stage). The diurnal variations of (H + LE)/ Rn, LE/ Rn and H/ Rn are of wave type when the underlying surface is bare. (3) The analysis of the temperature and humidity of the soil and the surface wind speed shows that in the rice planting period, the effect of each variable on the energy distribution is independent, and the energy distribution is mainly affected by the soil moisture and the wind speed. The increase of soil humidity slightly increases the value of H/ Rn, decreases the value of LE/ R, and increases the value of LE/ Rn. During the wheat planting period, the soil temperature and humidity have a common influence on the surface energy distribution. With the increase of soil temperature, the corresponding soil moisture is reduced, and the value of H/ Rn is reduced, and the value of LE/ Rn is increased. During the whole observation period, the diurnal variation of H/ Rn and LE/ Rn is affected by the diurnal variation of the temperature and humidity of the soil and the wind speed, and when the soil temperature is increased, the relative humidity of the soil is reduced, the wind speed is gradually increased and the growth rate is gradually decreased, and the value of LE/ Rn is gradually increased, and the H/ Rn is always stable. (4) The analysis of flux observation data of rice heading period shows that in most cases, the sensible heat flux of LAS is greater than the value observed by EC. Combined with the source region model, it can be found that a mulberry field on the east side of the instrument affects the observation results of the two instruments. As the sensible heat flux above the mulberry field is greater than the sensible heat flux above the rice field. When the mulberry field contributes significantly, the value of the HLAS is always greater than the value of the HEC. The sensible heat flux observed by the two instruments is also close when the contribution of the mulberry garden to the two instruments is consistent. The difference between the two instruments is caused by the non-uniformity of the underlying surface caused by the mulberry garden.
【学位授予单位】：南京信息工程大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S181
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