Comment on “Middle atmospheric O3, CO, N2O, HNO3, and temperature profiles during the warm Arctic winter 2001

对 Giovanni Muscari 等人的“2001-2002 年北极温暖冬季期间的中层大气 O3、CO、N2O、HNO3 和温度剖面”的评论。

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2008

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作者：

R. Müller;S. Tilmes

[1]在最近的一篇论文中，Muscari等人[2007年]介绍了2001-2002年北极冬季1月中旬至3月上旬平流层成分的测量结果，这些数据是在格陵兰图勒（北纬76.5度，西经68.7度）使用地基毫米波光谱仪和激光雷达系统获得的。在最近的北极冬季中，2001-2002年的冬季是有记录以来最温暖的冬季之一[例如，Tilmes等人，2004; Manney等人，2005;雷克斯等人，2006年]。Muscari等人[2007年]利用GBMS平流层O3、CO、N2 O和HNO 3测量值以及激光雷达温度观测值，对极北之地上空17-45公里高度范围内的极地平流层进行了表征，重点关注两个问题。首先，他们发现900 K时阿留申高压中的低臭氧浓度与低太阳照射量密切相关，其次，他们量化了平流层下部极地涡旋中的臭氧损失。[2]在这里，我们讨论Muscari等人[2007]关于平流层下部的声明：“使用GBMSO 3和N2 O混合比之间的相关性，在2月初，由于当地臭氧损失，在涡旋内部注意到大量臭氧不足。GBMS O3-N2 O相关性表明，等熵输送也给涡旋边缘附近的区域带来了O3赤字，在那里输送最有可能模仿当地的臭氧损失。[3]我们将首先讨论Muscari等人[2007年]推导化学臭氧损失的方式中可能存在的不确定性，这是将GBMS廓线分为不同涡旋区域的选择标准的结果。然后，考虑到报告的臭氧损失值，我们认为，对于2001-2002年温暖的北极冬季，Muscari等人[2007年]提出的化学臭氧损失程度与目前对北极卤素驱动的化学臭氧破坏的理解不一致[例如，所罗门，1999年;世界气象组织，2007年]。[4]为了区分极涡内部、外部和边缘的数据点，Muscari等人[2007]使用GBMS N2 O测量值，而不是考虑气象场，如位涡梯度和水平风速[例如，Nash等人，1996; Bodeker等人，2001; Tilmes等人，2006 b; Manney等人，2007年]。作者指出，他们“相信GBMS N2 O观测（O3和N2 O测量在总共4到5小时内进行）比时间和空间上更粗糙的位涡数据分析”。事实上，Greenblatt等人[2002]开发了一种技术，可以通过对N2 O等长寿命痕量气体的现场（飞机和气球）测量来准确确定极地涡旋的边缘。他们发现，对于高分辨率的飞机数据，位涡分析可能会错误识别超过400公里的内边缘。然而，GBMS测量的空间和时间分辨率比Greenblatt等人[2002]采用的原位数据要粗糙得多。虽然GBMS的瞬时视场的宽度是10公里，在平流层下部，积分时间的测量（1.5小时的O3，3小时的N2 O）意味着GBMS采样一定的水平范围的空气质量。假设10百帕风速为20-40公里/小时，Muscari等人[2007年]估计有效水平分辨率为90-180公里。考虑到极地平流层下部约480 K的典型风速[例如，Chan等人，1990]在40 km/h（涡核）和180 km/h（朝向涡边缘）之间，我们得到了180 km至810 km的水平分辨率范围的保守估计，该范围包括单一物种GBMS测量的早期估计（约200-300 km [Muscari等人，2002年]）。在北极平流层下部，GBMS的垂直分辨率约为7 km [Muscari等人，2007年]。目前的气象分析达到了更高的空间分辨率，例如在2000年，欧洲中期天气预报中心（ECMWF）引进了一个T511/L 60系统，在对流层上部和平流层下部的水平分辨率约为40 - 40公里，垂直分辨率约为1公里[例如，Jung和Leutbecher，2007年]。[5]一个适当的标准，以确定是否在内部或外部的涡旋测量的轮廓是必不可少的臭氧示踪剂的关系，计算极地臭氧损失的应用，因为空气的涡旋外的特性是非常不同的涡旋空气。一个标准，导致使用混合的轮廓测量的内部和外部的涡流可能会导致化学臭氧损失的涡流被低估[Tilmes等人，2004年]。[6]我们现在将讨论2001-2002年北极冬季的化学臭氧损失。根据《地球物理学报》第113卷D18303号doi：10.1029/2007 JD 009709，2008年的相关性，

[1] In a recent paper, Muscari et al. [2007] presented measurements of stratospheric constituents in Arctic winter 2001–2002 from mid-January to early March that were obtained using the ground-based millimeter-wave spectrometer (GBMS) and a Lidar system at Thule, Greenland (76.5 N, 68.7 W). Among the recent Arctic winters, winter 2001–2002 is one of the warmest winters on record [e.g., Tilmes et al., 2004; Manney et al., 2005; Rex et al., 2006]. Using the GBMS stratospheric O3, CO, N2O, and HNO3 measurements together with Lidar temperature observations, Muscari et al. [2007] characterized the polar stratosphere over Thule in the altitude range between 17–45 km focusing on two issues. First, they found low ozone concentrations in the Aleutian high at 900 K to be well correlated with low solar exposure and, secondly, they quantified ozone loss in the polar vortex in the lower stratosphere. [2] Here, we discuss statements by Muscari et al. [2007] with regard to the lower stratosphere: ‘‘using correlations between GBMSO3 and N2O mixing ratios, in early February a large ozone deficiency owing to local ozone loss is noted inside the vortex. GBMS O3-N2O correlations suggest that isentropic transport brought a O3 deficit also to regions near the vortex edge, where transport most likely mimicked local ozone loss’’. [3] We will first discuss possible uncertainties in the way that the chemical ozone loss was derived by Muscari et al. [2007] as a result of the selection criteria used to sort GBMS profiles into different vortex regions. Then, considering the reported ozone loss values, we argue that, for the warm Arctic winter 2001–2002, chemical ozone loss to the extent suggested by Muscari et al. [2007] cannot be reconciled with the current understanding of halogen-driven chemical ozone destruction in the Arctic [e.g., Solomon, 1999; World Meteorological Organization, 2007]. [4] To distinguish between data points inside, outside, and at the edge of the polar vortex, Muscari et al. [2007] used GBMS N2O measurements instead of considering meteorological fields such as potential vorticity gradients and horizontal wind speed [e.g., Nash et al., 1996; Bodeker et al., 2001; Tilmes et al., 2006b; Manney et al., 2007]. The authors state that they ‘‘trust the GBMS N2O observations (O3 and N2O measurements were carried out within a total of 4 to 5 h) more than the temporally and spatially coarser Potential Vorticity data analysis’’. Indeed, Greenblatt et al. [2002] developed a technique to accurately determine the edge of the polar vortex from in situ (aircraft and balloon) measurements of a long-lived trace gas like N2O. They found that for high-resolution aircraft data, a potential vorticity analysis may misidentify the inner edge by more than 400 km. However, GBMS measurements have a much coarser spatial and temporal resolution than the in situ data employed by Greenblatt et al. [2002]. Although the width of the instantaneous field of view of the GBMS is 10 km in the lower stratosphere, the integration time of the measurements ( 1.5 h for O3, 3 h for N2O) means that the GBMS samples an air mass of a certain horizontal extent. Assuming wind speeds of 20–40 km/h at 10 hPa, Muscari et al. [2007] estimated an effective horizontal resolution of 90–180 km. Considering typical wind speeds for the lower polar stratosphere at approximately 480 K [e.g., Chan et al., 1990] between 40 km/h (vortex core) and 180 km/h (toward the vortex edge), we obtain a conservative estimate of the range of horizontal resolution of 180 km to 810 km, a range that includes earlier estimates for GBMS measurements of a single species (about 200–300 km [Muscari et al., 2002]). The vertical resolution of the GBMS is about 7 km in the Arctic lower stratosphere [Muscari et al., 2007]. Current meteorological analyses reach higher spatial resolutions, for example in 2000 the European Centre for Medium-Range Weather Forecasts (ECMWF) introduced a T511/L60 system with a horizontal resolution of about 40 40 km and a vertical resolution of about 1 km in the upper troposphere and lower stratosphere [e.g., Jung and Leutbecher, 2007]. [5] An appropriate criterion to determine whether profiles are measured inside or outside the vortex is essential for the application of ozone-tracer relations to calculate polar ozone loss because the characteristics of air outside the vortex are very different to those of vortex air. A criterion that leads to using a mixture of profiles measured inside and outside of the vortex could cause the chemical ozone loss in the vortex to be underestimated [Tilmes et al., 2004]. [6] We will now discuss the chemical ozone loss in Arctic winter 2001–2002. On the basis of correlations between JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 113, D18303, doi:10.1029/2007JD009709, 2008

Comment on “Middle atmospheric O3, CO, N2O, HNO3, and temperature profiles during the warm Arctic winter 2001–2002” by Giovanni Muscari et al.

对 Giovanni Muscari 等人的“2001-2002 年北极温暖冬季期间的中层大气 O3、CO、N2O、HNO3 和温度剖面”的评论。

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