Precipitation and Temperature Variations on the Interannual Time Scale: Assessing the Impact of ENSO and Volcanic Eruptions
Precipitation and Temperature Variations on the Interannual Time Scale: Assessing the Impact of ENSO and Volcanic Eruptions
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DOI：
10.1175/2010jcli3727.1
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发表时间：
2011-05-01
影响因子：
4.9
通讯作者：
Adler, Robert F.
中科院分区：
文献类型：
--
作者：
Gu, Guojun;Adler, Robert F.
利用各种基于卫星和台站的降水、温度（地面和大气）和对流层水汽含量观测资料，研究了1979-2008年期间ENSO和两次大型热带火山爆发（1982年3月的El Chichon和1991年6月的Mt. Pinatubo）的影响。通过关注陆地、海洋以及陆地和海洋组合的热带和全球平均时间序列的响应，作者打算提供以尼诺-3.4和热带平均平流层气溶胶光学厚度（tau）分别为代表的这两种现象如何影响降水、温度和水蒸气变化的观测比较。在过去的研究中发现，强烈的同符号ENSO信号出现在陆地和海洋的热带和全球平均温度（地表和对流层）中。然而，ENSO对热带和全球平均（陆地+海洋）降水的影响非常微弱，尽管在陆地或海洋平均降水的时间序列中很容易看到强烈的异常。相比之下，两个火山不仅降低了热带和全球平均地表和对流层温度，而且降低了热带和全球平均（陆地+海洋）降水。因此，对ENSO和火山爆发的响应之间的差异可以通过滞后相关分析进一步研究。与enso相关的海洋降水和海表温度（SST）峰值响应在热带（全球）均值上与Nino-3.4具有相同的滞后时间，滞后时间为2(4)个月。热带和全球海洋（和陆地）上空的平均对流层水汽通常随地表温度变化。然而，陆地降水对ENSO的响应要比温度快得多，表明在ENSO相关环流和降水异常之后，陆地地表能量调整需要一定的时间。进一步发现了热带和全球平均对流层中下层大气（干）静态不稳定的弱ENSO信号，这与热带和全球平均（陆地+海洋）降水的弱ENSO响应趋于一致。对于火山爆发，海洋或陆地上的热带和全球平均降水的响应速度快于同一地区的平均温度（地表和大气）和对流层水汽，这表明降水对火山相关的太阳强迫更为敏感。火山相关降水变化进一步表明与对流层中下层大气（干）不稳定性的变化有关。
The effects of ENSO and two large tropical volcanic eruptions (El Chichon, March 1982; Mt. Pinatubo, June 1991) are examined for the period of 1979-2008 using various satellite- and station-based observations of precipitation, temperature (surface and atmospheric), and tropospheric water vapor content. By focusing on the responses in the time series of tropical and global means over land, ocean, and land and ocean combined, the authors intend to provide an observational comparison of how these two phenomena, represented by Nino-3.4 and the tropical mean stratospheric aerosol optical thickness (tau), respectively, influence precipitation, temperature, and water vapor variations.As discovered in past studies, strong same-sign ENSO signals appear in tropical and global mean temperature (surface and tropospheric) over both land and ocean. However, ENSO only has very weak impact on tropical and global mean (land + ocean) precipitation, though intense anomalies are readily seen in the time series of precipitation averaged over either land or ocean. In contrast, the two volcanoes decreased not only tropical and global mean surface and tropospheric temperature but also tropical and global mean (land + ocean) precipitation. The differences between the responses to ENSO and volcanic eruptions are thus further examined by means of lag-correlation analyses. The ENSO-related peak responses in oceanic precipitation and sea surface temperature (SST) have the same time lags with Nino-3.4, 2 (4) months for the tropical (global) means. Tropical and global mean tropospheric water vapor over ocean (and land) generally follows surface temperature. However, land precipitation responds to ENSO much faster than temperature, suggesting a certain time needed for surface energy adjustment there following ENSO-related circulation and precipitation anomalies. Weak ENSO signals in the tropical and global mean mid- to lower-tropospheric atmospheric (dry) static instability are further discovered, which tend to be consistent with weak ENSO responses in the tropical and global mean (land + ocean) precipitation. For volcanic eruptions, tropical and global mean precipitation over either ocean or land responds faster than temperature (surface and atmospheric) and tropospheric water vapor averaged over the same areas, suggesting that precipitation tends to be more sensitive to volcanic-related solar forcing. The volcanic-related precipitation variations are further shown to be related to the changes in the mid- to lower-tropospheric atmospheric (dry) instability.