Evaluation of UT/LS hygrometer accuracy by intercomparison during the NASA MACPEX mission
Evaluation of UT/LS hygrometer accuracy by intercomparison during the NASA MACPEX mission
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DOI：
10.1002/2013jd020817
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发表时间：
2014-02
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通讯作者：
Andrew W. Rollins;Andrew W. Rollins;T. Thornberry;T. Thornberry;R. Gao;Jessica B. Smith;D. Sayres;M. R. Sargent;Cornelius Schiller;Martina Krämer;N. Spelten;D. Hurst;D. Hurst;A. Jordan;A. Jordan;E. Hall;E. Hall;H. Vömel;G. Diskin;J. R. Podolske;L. Christensen;K. Rosenlof;Eric J. Jensen;D. W. Fahey;D. W. Fahey
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文献类型：
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作者：
Andrew W. Rollins;Andrew W. Rollins;T. Thornberry;T. Thornberry;R. Gao;Jessica B. Smith;D. Sayres;M. R. Sargent;Cornelius Schiller;Martina Krämer;N. Spelten;D. Hurst;D. Hurst;A. Jordan;A. Jordan;E. Hall;E. Hall;H. Vömel;G. Diskin;J. R. Podolske;L. Christensen;K. Rosenlof;Eric J. Jensen;D. W. Fahey;D. W. Fahey
在对流层上部和平流层下部（UT/LS）遇到的低混合比（< 10 ppm）下获得准确的水汽测量值已被证明是一项重大的分析挑战，高精度湿度计之间的持续分歧证明了这一点。这些分歧造成了对控制热带对流层顶空气脱水和水进入平流层的物理过程的描述的不确定性，并妨碍了卫星水汽反演的验证。2011年，NASA WB-57 F高空研究飞机和气球上的大量原位湿度计进行了空中比对，这为评估科学界在改进测量一致性方面的进展提供了一个绝佳的机会。在这项工作中，我们相互比较的测量中纬度空中卷云特性实验（MACPEX），并讨论质量的协议。与之前的一些活动相比，仪器报告的值之间的差异有所减少，但不可忽略，约为20%（0.8 ppm）。我们的分析表明，未识别的错误，在量化的仪器背景的一些或所有的湿度计是一个可能的原因。直到这些错误被理解，在这一水平上的差异将继续在一定程度上限制我们的卷云微物理过程和热带对流层顶层脱水的理解。
Acquiring accurate measurements of water vapor at the low mixing ratios (< 10 ppm) encountered in the upper troposphere and lower stratosphere (UT/LS) has proven to be a significant analytical challenge evidenced by persistent disagreements between high‐precision hygrometers. These disagreements have caused uncertainties in the description of the physical processes controlling dehydration of air in the tropical tropopause layer and entry of water into the stratosphere and have hindered validation of satellite water vapor retrievals. A 2011 airborne intercomparison of a large group of in situ hygrometers onboard the NASA WB‐57F high‐altitude research aircraft and balloons has provided an excellent opportunity to evaluate progress in the scientific community toward improved measurement agreement. In this work we intercompare the measurements from the Midlatitude Airborne Cirrus Properties Experiment (MACPEX) and discuss the quality of agreement. Differences between values reported by the instruments were reduced in comparison to some prior campaigns but were nonnegligible and on the order of 20% (0.8 ppm). Our analysis suggests that unrecognized errors in the quantification of instrumental background for some or all of the hygrometers are a likely cause. Until these errors are understood, differences at this level will continue to somewhat limit our understanding of cirrus microphysical processes and dehydration in the tropical tropopause layer.