The Airborne Multiangle SpectroPolarimetric Imager (AirMSPI) acquires radiance measurements in eight spectral bands centered at 355, 380, 445, 470*, 555, 660*, 865*, and 935 nm, three of which also measure linear polarization (denoted by asterisks). A two-step retrieval approach is developed to retrieve total precipitable water vapor (PWV) abundance: a) the first step is a fast estimate of water vapor obtained by comparing the ratio of observed radiance in the near-infrared (NIR) bands L_935nm/L_865nm at multiple view angles against pre-calculated lookup table values as a function of PWV abundance, on the assumption of no aerosols and a moderately bright land surface; (b) the second step refines the estimated solution by accounting for aerosol loading, particle properties, and surface reflection, which are retrieved from AirMSPI measurements in its ultraviolet to NIR aerosol bands. Our retrieval is tested using 27 AirMSPI datasets with low to moderately high aerosol loadings and PWV up to about 3.5 cm, acquired during four NASA field campaigns plus one AirMSPI engineering test flight. Comparison of the retrieved total PWV amount against AERONET reference data shows a mean percentage difference 8.6%. The quantities that inform the second step of the PWV retrieval—namely, aerosol optical depth (AOD), aerosol single scattering albedo (SSA), and aerosol effective radius—are also compared to the AERONET reference data. The mean absolute differences (MADs) are less than 0.0253 and less than 0.036 for AOD and SSA in the visible, respectively. The MADs are 0.036 μm and 1.232 μm for the effective radius of fine and coarse mode aerosols, respectively. Comparison to data from the Cloud Physics Lidar places the MAD of aerosol layer height at about 360 m.

机载多角度光谱仪（AirMSPI）在以355、380、445、470 *，555、660 *，865 *和935 nm为中心的八个光谱带中获取辐射测量值，其中三个还测量线性极化（以星号表示） 。两步检索方法进行显影，以检索总水汽（PWV）丰度：a）所述第一个步骤是通过在近红外（NIR）波段观测辐射的比率相比较而获得的水蒸汽快速估计大号_935nm / L _865nm假设没有气溶胶和中等明亮的陆地表面，则相对于预先计算的查找表值，以多个视角作为PWV丰度的函数；（b）第二步，通过考虑从AirMSPI的紫外到NIR气溶胶波段中的气溶胶负载，颗粒特性和表面反射来细化估计的解决方案。我们的检索是使用27个AirMSPI数据集进行测试的，这些数据集的气溶胶负载量低至中度较高，PWV可达3.5厘米，这是在四次NASA野战活动和一次AirMSPI工程测试飞行中获得的。将检索到的总PWV量与AERONET参考数据进行比较，得出平均百分比差异为8.6％。通知PWV检索第二步的数量，即气溶胶光学深度（AOD），气溶胶单散射反照率（SSA），和气溶胶有效半径-也与AERONET参考数据进行了比较。可见光中AOD和SSA的平均绝对差（MAD）分别小于0.0253和小于0.036。精细和粗模式气溶胶的有效半径的MAD分别为0.036μm和1.232μm。与来自Cloud Physics Lidar的数据进行比较，得出的气溶胶层高度的MAD约为360 m。