中文摘要：

大范围的可靠农情信息对粮食市场及相关政策的制定至关重要,是保障区域及全球粮食安全的重要依据,在全球气候变化、人口增长、土地利用/覆盖变化剧烈的背景下,对这一信息的需求也更加迫切。传统农情信息的获取依赖于庞大的调查队伍和大量的调查工作,信息的获取存在成本高、时效性差和结果受主观影响大的缺点。伴随着近30年遥感技术本身及其在农情信息获取领域能力的提升,一些国家与国际组织建设了各自的农情遥感监测系统,并开展了运行化的监测。对美国、欧盟、FAO、加拿大、巴西、阿根廷、俄罗斯、印度等主要的农情遥感监测系统进展进行了详细的介绍,并通过对这些系统的分析得到一些农情监测系统建设的启示。指出作物种植面积估算、单产预测、长势监测、旱情监测是农情遥感监测中最主要的4个主题。在面积估算方面,各个系统在遥感技术不断发展的同时对地面调查的依赖并没有减少,甚至得到了强化,这与遥感降低地面调查的初衷相违背,导致遥感技术在大范围农情监测中的潜力没有得到充分发挥,在单产预测方面,需要发展独立的遥感预测方法。提升遥感的作用是未来一段时间内农情遥感监测系统建设的主要方向。

英文摘要：

Dependable information on large-area agricultural production and production estimation are essential for agricultural markets and the formulation of national and international agricultural policies.It can provide information and technical support for regional or global food security.Factors like worldwide climate change,increasing population and fast changes in land use/cover make the need more urgent.Traditional collection of crop information depends on huge in-situ investigation,which is expensive,time consuming and vulnerable to subjective difference.Along with the development in remote sensing technology and its application to crop information acquirement,some operational crop monitoring systems were developed and put into operation by several countries and international organizations.The development of major crop monitoring systems worldwide（United States,Europe,FAO,Canada,Brazil,Argentina,Russia and India） was reviewed and introduced in detail.The paper points out that the crop acreage estimation,crop yield prediction,crop condition monitoring and drought monitoring are the four primary themes in remote sensing based crop monitoring.In crop acreage monitoring,along with the development of remote sensing technology,the dependence of these systems on field survey has not been reduced,or even increased for some reasons.This is against the primary intention of remote sensing application： to reduce or substitute field survey.The potential of remote sensing in large-area crop monitoring has not been fully exerted.Independent crop yield predicting method with remote sensing is also in great need.How to increase the role of remote sensing will be the major direction for the development of remote sensing based crop monitoring systems.