Intercomparison of integrated IASI and AATSR calibrated radiances at 11 and 12 μm
Intercomparison of integrated IASI and AATSR calibrated radiances at 11 and 12 μm
复制标题
11 和 12 μm 处集成 IASI 和 AATSR 校准辐射率的相互比较
DOI：
10.5194/acp-9-6677-2009
复制
发表时间：
2009
影响因子：
6.3
通讯作者：
R. Parker
中科院分区：
文献类型：
--
作者：
S. Illingworth;J. Remedios;R. Parker
抽象的。红外大气探测干涉仪 (IASI) 的任务目标是由数值天气预报 (NWP) 和气候监测界的需求驱动的。这些目标依赖于 IASI 仪器能够准确测量大气层顶部的辐射率。本文介绍了一种技术和初步结果，用于验证 IASI 辐射率的辐射校准，使用高级沿轨扫描辐射计 (AATSR) 的交叉校准。 AATSR 能够以 30 mK 的精度测量亮度温度 (BT)，并且通过将 AATSR 光谱滤波器功能应用于 IASI 测量的辐射率，我们能够比较 AATSR 和 IASI 亮度温度。通过选择海上和晴空条件下的重合数据点，得出同质性阈值。结果发现，在这些均匀条件下，IASI BT 与 AATSR 测量的结果一致在 0.3 K 以内，不确定性为 0.1 K 量级。在 11 μm 处，一致性特别好，差异小于 0.1 K。这些初步结果表明 IASI 正在达到 0.5 K 精度的目标。据信，AATSR 光谱滤波器函数的改进将有望对 IASI 数据的质量进行更严格的误差限制，从而进一步评估辐射的气候质量。
Abstract. The mission objectives of the Infrared Atmospheric Sounding Interferometer (IASI) are driven by the needs of the Numerical Weather Prediction (NWP) and climate monitoring communities. These objectives rely upon the IASI instrument being able to measure top of atmosphere radiances accurately. This paper presents a technique and first results for the validation of the radiometric calibration of radiances for IASI, using a cross-calibration with the Advanced Along Track Scanning Radiometer (AATSR). The AATSR is able to measure Brightness Temperature (BT) to an accuracy of 30 mK, and by applying the AATSR spectral filter functions to the IASI measured radiances we are able to compare AATSR and IASI Brightness Temperatures. By choosing coincident data points that are over the sea and in clear sky conditions, a threshold of homogeneity is derived. It is found that in these homogenous conditions, the IASI BTs agree with those measured by the AATSR to within 0.3 K, with an uncertainty of order 0.1 K. The agreement is particularly good at 11 μm where the difference is less than 0.1 K. These first results indicate that IASI is meeting its target objective of 0.5 K accuracy. It is believed that a refinement of the AATSR spectral filter functions will hopefully permit a tighter error constraint on the quality of the IASI data and hence further assessment of the climate quality of the radiances.