Polar stratospheric cloud observations by MIPAS on ENVISAT: detection method, validation and analysis of the northern hemisphere winter 2002/2003
Polar stratospheric cloud observations by MIPAS on ENVISAT: detection method, validation and analysis of the northern hemisphere winter 2002/2003
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MIPAS在ENVISAT上的极地平流层云观测：2002/2003年北半球冬季的探测方法、验证和分析
DOI：
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发表时间：
2004
期刊：
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通讯作者：
P. Konopka
中科院分区：
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作者：
R. Spang;John Remedios;L. Kramer;L. Poole;M. Fromm;M. Müller;Gerd Baumgarten;P. Konopka
抽象。2002/2003年冬季，ENVISAT卫星上的迈克尔逊被动大气探测干涉仪（MIPAS）对北方极地平流层云（PSC）进行了广泛的测量。PSC检测方法的基础上的辐射率（云指数）的MIPAS已经实施，并在这项研究中验证地面激光雷达和星载掩星测量。一个很好的对应关系，在PSC瞄准和云高度之间的MIPAS检测和其他仪器被发现云指数值小于4。与平流层气溶胶和气体实验（SAGE）III的数据进行比较，进一步表明MIPAS检测方法对云指数阈值的灵敏度大约相当于1022 nm处10- 3 km-1的消光极限，该波长是用于太阳掩星实验的波长。随后，MIPAS云指数数据首次被用于以任何技术检查几乎每天在北极极地涡旋直至北纬90°附近的PSC演变。我们发现，2002/2003年冬季的特点是三个阶段的非常不同的PSC活动。首先，12月前三周的异常寒冷阶段导致PSC发生率很高。接下来是第二阶段，从1月5日至13日只有中等强度的PSC活动，与第一阶段分开的是一次轻微的变暖事件。最后，从2月到3月底是第三个阶段，只发生零星的、大多是微弱的和平、安全与合作事件。在冬季期间的PSC的组成也进行了检查，特别是利用红外光谱特征，这可能是NAT的特性。MIPAS观测显示，这些粒子的存在在一些场合在12月，但很少在1月。从MIPAS的PSC类型分化表明，未来的PSC观测与微物理和反硝化模型的比较可能会揭示固体颗粒的存在和位置方面。
Abstract. The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on ENVISAT has made extensive measurements of polar stratospheric clouds (PSCs) in the northern hemisphere winter 2002/2003. A PSC detection method based on a ratio of radiances (the cloud index) has been implemented for MIPAS and is validated in this study with respect to ground-based lidar and space borne occultation measurements. A very good correspondence in PSC sighting and cloud altitude between MIPAS detections and those of other instruments is found for cloud index values of less than four. Comparisons with data from the Stratospheric Aerosol and Gas Experiment (SAGE) III are used to further show that the sensitivity of the MIPAS detection method for this threshold value of cloud index is approximately equivalent to an extinction limit of 10-3km-1 at 1022nm, a wavelength used by solar occultation experiments. The MIPAS cloud index data are subsequently used to examine, for the first time with any technique, the evolution of PSCs throughout the Arctic polar vortex up to a latitude close to 90° north on a near-daily basis. We find that the winter of 2002/2003 is characterised by three phases of very different PSC activity. First, an unusual, extremely cold phase in the first three weeks of December resulted in high PSC occurrence rates. This was followed by a second phase of only moderate PSC activity from 5-13 January, separated from the first phase by a minor warming event. Finally there was a third phase from February to the end of March where only sporadic and mostly weak PSC events took place. The composition of PSCs during the winter period has also been examined, exploiting in particular an infra-red spectral signature which is probably characteristic of NAT. The MIPAS observations show the presence of these particles on a number of occasions in December but very rarely in January. The PSC type differentiation from MIPAS indicates that future comparisons of PSC observations with microphysical and denitrification models might be revealing about aspects of solid particle existence and location.