Fractional vegetation cover estimation in heterogeneous areas by combining a radiative transfer model and a dynamic vegetation model     

Yixuan Tu  Shunlin Liang  Xiangqin Wei  Yunjun Yao  Xiaotong Zhang 《International Journal of Digital Earth》2020,13(4):487-503

ABSTRACT

A fractional vegetation cover (FVC) estimation method incorporating a vegetation growth model and a radiative transfer model was previously developed, which was suitable for FVC estimation in homogeneous areas because the finer-resolution pixels corresponding to one coarse-resolution FVC pixel were all assumed to have the same vegetation growth model. However, this assumption does not hold over heterogeneous areas, meaning that the method cannot be applied to large regions. Therefore, this study proposes a finer spatial resolution FVC estimation method applicable to heterogeneous areas using Landsat 8 Operational Land Imager reflectance data and Global LAnd Surface Satellite (GLASS) FVC product. The FVC product was first decomposed according to the normalized difference vegetation index from the Landsat 8 OLI data. Then, independent dynamic vegetation models were built for each finer-resolution pixel. Finally, the dynamic vegetation model and a radiative transfer model were combined to estimate FVC at the Landsat 8 scale. Validation results indicated that the proposed method (R²?=?0.7757, RMSE?=?0.0881) performed better than either the previous method (R²?=?0.7038, RMSE?=?0.1125) or a commonly used method involving look-up table inversions of the PROSAIL model (R²?=?0.7457, RMSE?=?0.1249).  相似文献   

GPU加速的水体辐射传输Monte Carlo模拟模型研究     

杜克平  薛坤 《湖泊科学》2016,28(3):654-660

水体辐射传输方程是复杂的微积分方程,只能利用数值方法求解,如Monte Carlo光线追踪法、不变嵌入法、离散坐标法等,其中,Monte Carlo方法是目前解决水体水下光场三维问题的唯一有效方法.根据辐射传输理论,开发了水下光场的Monte Carlo模拟模型,主要包含大气、水-气界面、层化水体和水底边界4个模块.实现了模拟任意太阳角度、不同水体固有光学属性和任意深度条件下,考虑大气、粗糙水面和水底边界的水下光场,能够获取辐亮度、辐照度等辐射量的空间分布.该模型暂不考虑Raman散射、偏振、内部光源的影响.实现了GPU加速水下光场Monte Carlo模拟,并用Mobley等提出的海洋光学标准问题中的问题1~6进行验证.在两种计算环境下,通过对不同边界条件下的CPU、GPU运行时间及加速比的对比,发现GPU计算可以达到几百至上千倍的加速比.  相似文献   

FY 2D静止气象卫星OLR反演模式   总被引：1，自引：0，他引：1  

吴晓 《气象科技》2008,36(5):634-638

介绍FY2D卫星OLR反演模式的建立过程以及模式与NOAA卫星OLR反演模式的相互对比,包括：地球大气红外辐射传输方程,全球3812条大气廓线的大气顶射出辐射率、射出长波辐射通量密度的模拟计算,3812条廓线FY2D窗区通道1、2、水汽通道的通道辐射率模拟计算, 通道辐射率的临边变暗订正关系式的确立、3个通道波段的窄波段辐射通量密度的模拟计算。通过3812条廓线的窄波段辐射通量密度与OLR的XY坐标散点图,建立OLR回归关系式;并通过NOAA17 AVHRR通道5 OLR反演模式与FY2D窗  相似文献   

北极地区地面辐射量和云辐射强迫特征     

刘凤景  孙俊英  张廷军  程国栋 《冰川冻土》2000,22(4):384-390

In this paper the characteristics of surface radiative fluxes and cloud-radiative forcing are reviewed with a focus on the Arctic. Three aspects are addressed, including (i) changes in radiation flux over the global surface; (ii) characteristics of surface fluxes in the Arctic; and (iii) characteristics of cloud-radiative forcing in the Arctic. The clouds not only significantly reduce the peak summer radiative heating of the surface but also reduce the wintertime radiative cooling at the surface in　higher latitudes. The downward longwave fluxes dominates the incident radiative fluxes in the Arctic during most of the year. Incoming shortwave fluxes are negligible during late fall, winter and early spring, and even during the midsummer the incoming shortwave fluxes are only slightly greater than the downward longwave fluxes. The total net surface radiative flux is negative for most of the year and only positive during midsummer in the Arctic. The global net cloud-radiative forcing is negative, but the cloud-radiative forcing is positive in the Arctic, showing a warming effect, except for a short period in mid-summer. Positive cloud-radiative forcing in the Arctic is attributed　to the presence of snow and ice with high albedo and the absence of solar radiation during the polar night.  相似文献   

复杂地形城市冬季边界层对气溶胶辐射效应的响应   总被引：9，自引：3，他引：6  

郑飞  张镭  朱江 《大气科学》2006,30(1):171-179

作者着眼于城市气溶胶辐射效应与大气边界层的相互作用问题,针对地形复杂的兰州市及周边地区,开发应用了WRF(Weather Research and Forecasting,天气研究和预报)模式,使之与包含了大气气溶胶辐射效应和气溶胶粒子扩散的综合大气边界层数值模式嵌套起来.通过个例分析,揭示了冬季气溶胶辐射效应对边界层结构的定量影响.主要特征为夜间气溶胶的长波辐射效应使地面附近的气温增高,增温幅度为0.1～0.3 K/h,使低空(25～300 m)大气层冷却,降温幅度为0.08～0.15 K/h,风速在150 m以下减小;白天气溶胶的短波辐射效应使地面层内明显增温,1 h内升温约0.5 K,增温最大值在混合层顶500～600 m高度.受增温影响,垂直风场和水平风场随之调整,风速在450 m以下增大约0.1 m/s左右,而在450 m以上风速减小0.1 m/s左右.  相似文献   

Radiative Forcing of SO2 and NOx： A Case Study in Beijing     

孙治安  王晓云  曾宪宁 《大气科学进展》2006,23(2):317-322

A case study was performed in Beijing in 2000 to observe concentrations of SO2 and NOx in the atmosphere and to evaluate their radiative impact. It was found that the concentrations of these gases are usually high in the morning due to a temperature inversion in the boundary layer. The average concentrations obtained from the observations are much higher than those used in the McClatchey reference atmosphere. The radiative impacts of these gases are calculated using a line-by-line radiative transfer model. The results show that the radiative forcing at the surface due to SO2 is 0.0576 W m-2 and that due to NOx is 0.0032 W m-2. These figures are almost compatible with that due to CFC11.  相似文献   

被动微波遥感数据反演地表温度研究进展   总被引：7，自引：1，他引：6  

贾媛媛  李召良 《地理科学进展》2006,25(3):96-105

被动微波遥感具有穿透云层( 甚至雨区) 获取地表辐射信息的能力, 在处理云的问题上, 明 显优于可见光、红外遥感, 可更好地服务于相关领域研究。由于微波信号受多种因素的影响, 目前 被动微波反演地表温度的算法还不成熟。根据建模手段和方法的不同, 从经验反演模型和物理反 演模型两方面入手, 系统回顾国内外被动微波数据反演地表温度的算法并加以评述, 指出今后应 加强尺度转换、物理机理以及多数据源结合方面的研究。  相似文献   

星载红外辐射计海上辐射校正方法研究   总被引：1，自引：0，他引：1  

董仁杰  李铜基  陈清莲  任洪启 《海洋技术学报》2006,25(2):73-77

以FY-1D卫星的热红外通道为例,利用2003年黄东海海上试验站点及其周围海域对辐射校正原理进行了分析研究,包括对现场辐亮度的测量、星地光谱匹配、大气辐射传输计算、辐射校正系数获取等方面的研究。  相似文献   

气溶胶光学特性的反演方法研究   总被引：1，自引：0，他引：1  

韩冰  高飞  李铜基 《海洋技术学报》2006,25(3):55-60

气溶胶是大气重要组成部分,其对地球的辐射收支平衡以及气候变化均有非常重要的贡献。文中根据非线性辐射传输理论,研究了从自动观测太阳光度计(CE 318)多角度的天空扫描数据获取气溶胶粒子谱分布、散射相函数等光学特性的反演方法,并对2000年10月27日、30日南海试验的观测数据进行了分析,取得了较好效果。  相似文献   

The bulk kinetic power of the jets of GRS 1915+105     

M. Gliozzi  G. Bodo  G. Ghisellini 《Monthly notices of the Royal Astronomical Society》1999,303(3):L37-L40

  相似文献