全球性观测系统在检测、监测和预测地球系统的变化中发挥着越来越重要的作用。地球系统的复杂性、多尺度性、非线性性、突变性、非平衡性等要求各种全球性观测系统之间必须加强联系与协调。评述了全球性观测系统联系与协调的发展趋势，并依据《全球性观测系统实地观测的内容和体系纲要》，介绍了全球性观测系统实地观测的内容和规范要求。 

Global observing systems have been playing an increasingly important role in detecting, monitoring and predicting the various changes of the Earth system. In order to acquire various essential observational data of the Earth system, better cross connections and links among the existing operational observing systems are needed, because the global Earth system is composed of many subsystems and is very complex. This paper introduces the developing trend of strengthening the cooperation and liaision among the existed observing systems, and according to In Situ Observations For the Global Observing System——A Compendium of Requirements and Systems, briefly presents the requirements and specifications for in situ observations of global observing systems.