This study investigates the statistical relationship between climatic variables and aspects of cotton production (G. barbadense), and the effects of climatic factors prevailing prior to flowering or subsequent to boll...This study investigates the statistical relationship between climatic variables and aspects of cotton production (G. barbadense), and the effects of climatic factors prevailing prior to flowering or subsequent to boll setting on flower and boll production and retention in cotton. The effects of specific climatic factors during both pre-?and post-anthesis periods on boll production and retention are mostly unknown. However, by determining the relationship of climatic factors with flower and boll production and retention, the overall level of production can be possibly predicted. Thus, an understanding of these relationships may help physiologists determine control mechanisms of production in cotton plants. Also, the study covers the predicted effects of climatic factors during convenient intervals (in days) on cotton flower and boll production compared with daily observations. Further, cotton flower and boll production as affected by climatic factors and soil moisture status has been considered. Evaporation, sunshine duration, relative humidity, surface soil temperature at 1800 h, and maximum air temperature, are the important climatic factors that significantly affect flower and boll production. The least important variables were found to be surface soil temperature at 600 h and minimum temperature. The five-day interval was found to be more adequately and sensibly related to yield parameters. Evaporation, minimum humidity and sunshine duration were the most effective climatic factors during preceding and succeeding periods on boll production and retention. There was a negative correlation between flower number and boll production and either evaporation or sunshine duration, while that correlation with minimum relative humidity was positive. The soil moisture status showed low and insignificant correlation with flower and boll production. Higher minimum relative humidity, short period of sunshine duration, and low temperatures enhanced flower and boll formation.展开更多
利用了加拿大地球系统模式CanE SM2(Canadian Earth System Model of the CCCma)的结果,针对百年尺度大气CO_2浓度升高和气候变化如何影响陆地生态系统碳通量这一问题,分析了1850—1989年间陆地生态系统碳通量趋势对二者响应,以及与关...利用了加拿大地球系统模式CanE SM2(Canadian Earth System Model of the CCCma)的结果,针对百年尺度大气CO_2浓度升高和气候变化如何影响陆地生态系统碳通量这一问题,分析了1850—1989年间陆地生态系统碳通量趋势对二者响应,以及与关键气候系统变量的关系。结果表明,140年间,当仅仅考虑CO_2浓度升高影响时,陆地生态系统净初级生产力(NPP)增加了117.1 gC m^(-2)a^(-1),土壤呼吸(Rh)增加了98.4 gC m^(-2)a^(-1),净生态系统生产力(NEP)平均增加了18.7 gC m^(-2)a^(-1)。相同情景下,全球陆地生态系统的NPP呈显著增加的线性趋势(约为0.30 PgC/a^2),Rh同样呈显著增加线性趋势(约为0.25 PgC/a^2)。仅仅考虑气候变化单独影响时,NPP平均减少了19.3 gC/m^2,土壤呼吸减少了8.5 gC/m^2,NEP减少了10.8 gC/m^2。在此情景下,整个陆地生态系统的NPP线性变化趋势约为-0.07 PgC/a^2(P<0.05),Rh线性变化趋势约为-0.04 PgC/a^2(P<0.05)。综合二者的影响,前者是决定陆地生态系统碳通量变化幅度和空间分布的最重要影响因子,其影响明显大于气候变化。值得注意的是,CanE SM2并没有考虑氮素的限制作用,所以CO_2浓度升高对植被的助长作用可能被高估。此外,气候变化的贡献也不容忽视,特别是在亚马逊流域,由于当温度升高、降水和土壤湿度减少,NPP和Rh均呈显著减少趋势。展开更多
基于2008—2017年全国自动气象观测站逐旬土壤相对湿度观测数据,综合评估中国气象局陆面数据同化系统(CMA Land Data Assimilation System,CLDAS)0~20 cm层融合土壤相对湿度产品在中国地区的适用性,评估表明CLDAS土壤相对湿度产品在中...基于2008—2017年全国自动气象观测站逐旬土壤相对湿度观测数据,综合评估中国气象局陆面数据同化系统(CMA Land Data Assimilation System,CLDAS)0~20 cm层融合土壤相对湿度产品在中国地区的适用性,评估表明CLDAS土壤相对湿度产品在中国东北、西北、江南大部及华南等地区存在较大系统性误差,总体上适用性较差。为消除CLDAS土壤相对湿度产品的系统性误差,采用回归订正法、7旬滑动平均订正法和临近加权前旬订正法对CLDAS土壤相对湿度产品进行误差订正处理,对订正结果评估发现:订正处理后CLDAS土壤相对湿度产品与站点观测的相关性显著增加,系统偏差基本消除,适用性明显提高,3种订正方法中临近加权前旬订正法的订正效果最优。最后,采用经不同方法订正后的CLDAS土壤相对湿度产品对2017年5月东北—华北地区一次气象干旱个例进行重现,对比验证表明:相对其他两种订正方法,经临近加权前旬订正法处理后的CLDAS土壤相对湿度产品能更为精准地重现2017年5月东北—华北地区气象干旱的落区和强度。展开更多
文摘This study investigates the statistical relationship between climatic variables and aspects of cotton production (G. barbadense), and the effects of climatic factors prevailing prior to flowering or subsequent to boll setting on flower and boll production and retention in cotton. The effects of specific climatic factors during both pre-?and post-anthesis periods on boll production and retention are mostly unknown. However, by determining the relationship of climatic factors with flower and boll production and retention, the overall level of production can be possibly predicted. Thus, an understanding of these relationships may help physiologists determine control mechanisms of production in cotton plants. Also, the study covers the predicted effects of climatic factors during convenient intervals (in days) on cotton flower and boll production compared with daily observations. Further, cotton flower and boll production as affected by climatic factors and soil moisture status has been considered. Evaporation, sunshine duration, relative humidity, surface soil temperature at 1800 h, and maximum air temperature, are the important climatic factors that significantly affect flower and boll production. The least important variables were found to be surface soil temperature at 600 h and minimum temperature. The five-day interval was found to be more adequately and sensibly related to yield parameters. Evaporation, minimum humidity and sunshine duration were the most effective climatic factors during preceding and succeeding periods on boll production and retention. There was a negative correlation between flower number and boll production and either evaporation or sunshine duration, while that correlation with minimum relative humidity was positive. The soil moisture status showed low and insignificant correlation with flower and boll production. Higher minimum relative humidity, short period of sunshine duration, and low temperatures enhanced flower and boll formation.
文摘基于2008—2017年全国自动气象观测站逐旬土壤相对湿度观测数据,综合评估中国气象局陆面数据同化系统(CMA Land Data Assimilation System,CLDAS)0~20 cm层融合土壤相对湿度产品在中国地区的适用性,评估表明CLDAS土壤相对湿度产品在中国东北、西北、江南大部及华南等地区存在较大系统性误差,总体上适用性较差。为消除CLDAS土壤相对湿度产品的系统性误差,采用回归订正法、7旬滑动平均订正法和临近加权前旬订正法对CLDAS土壤相对湿度产品进行误差订正处理,对订正结果评估发现:订正处理后CLDAS土壤相对湿度产品与站点观测的相关性显著增加,系统偏差基本消除,适用性明显提高,3种订正方法中临近加权前旬订正法的订正效果最优。最后,采用经不同方法订正后的CLDAS土壤相对湿度产品对2017年5月东北—华北地区一次气象干旱个例进行重现,对比验证表明:相对其他两种订正方法,经临近加权前旬订正法处理后的CLDAS土壤相对湿度产品能更为精准地重现2017年5月东北—华北地区气象干旱的落区和强度。
