Airborne Measurements of CO2 Column Concentration and Range Using a Pulsed Direct- Detection IPDA Lidar
Airborne Measurements of CO2 Column Concentration and Range Using a Pulsed Direct- Detection IPDA Lidar
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DOI：
10.3390/rs6010443
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发表时间：
2014-01-01
期刊：
影响因子：
5
通讯作者：
Browell, Edward V.
中科院分区：
文献类型：
--
作者：
Abshire, James B.;Ramanathan, Anand;Browell, Edward V.
我们之前已经演示了脉冲直接探测IPDA激光雷达，用于测量大气中二氧化碳的距离和柱浓度。激光雷达测量大气后向散射分布，并采样1,572.33 nm二氧化碳吸收线的形状。我们在2011年8月参加了NASA DC-8飞机上的Ascends科学飞行，并在这里报告了在美国附近各种地表和云条件下进行的四次飞行的激光雷达测量。它们包括太平洋上空的层状云层，内华达州被群山环绕的干燥湖床，有燃煤发电厂的沙漠地区，以及从落基山脉到爱荷华州的积云和卷云。大多数航班的飞行高度为12公里，有5-6个高度阶梯。分析表明，激光雷达距离、CO2柱吸收和CO2混合比在高度和反射率快速变化的地形上、通过薄云、积云之间和层状云顶测量时效果良好。检索显示，由于在爱荷华州农田上空生长的植被，以及一座燃煤发电厂附近二氧化碳浓度的突然增加，二氧化碳柱的减少。对于二氧化碳浓度相对恒定的地区，测得的二氧化碳吸收线形(平均为50 S)与预测形状匹配，均方根误差优于1%。对于10个S平均值，反演中的散射通常是2-3ppm，并且受到接收信号光子计数的限制。使用来自大气模型的大气参数和来自飞机的现场温度和压力进行检索。检索没有自由参数，没有使用经验调整，70%的测量结果通过了筛选并用于分析。激光雷达测量的二氧化碳柱浓度与现场测量的平均二氧化碳浓度之间的差异为6公里。
We have previously demonstrated a pulsed direct detection IPDA lidar to measure range and the column concentration of atmospheric CO2. The lidar measures the atmospheric backscatter profiles and samples the shape of the 1,572.33 nm CO2 absorption line. We participated in the ASCENDS science flights on the NASA DC-8 aircraft during August 2011 and report here lidar measurements made on four flights over a variety of surface and cloud conditions near the US. These included over a stratus cloud deck over the Pacific Ocean, to a dry lake bed surrounded by mountains in Nevada, to a desert area with a coal-fired power plant, and from the Rocky Mountains to Iowa, with segments with both cumulus and cirrus clouds. Most flights were to altitudes >12 km and had 5-6 altitude steps. Analyses show the retrievals of lidar range, CO2 column absorption, and CO2 mixing ratio worked well when measuring over topography with rapidly changing height and reflectivity, through thin clouds, between cumulus clouds, and to stratus cloud tops. The retrievals shows the decrease in column CO2 due to growing vegetation when flying over Iowa cropland as well as a sudden increase in CO2 concentration near a coal-fired power plant. For regions where the CO2 concentration was relatively constant, the measured CO2 absorption lineshape (averaged for 50 s) matched the predicted shapes to better than 1% RMS error. For 10 s averaging, the scatter in the retrievals was typically 2-3 ppm and was limited by the received signal photon count. Retrievals were made using atmospheric parameters from both an atmospheric model and from in situ temperature and pressure from the aircraft. The retrievals had no free parameters and did not use empirical adjustments, and >70% of the measurements passed screening and were used in analysis. The differences between the lidar-measured retrievals and in situ measured average CO2 column concentrations were 6 km.