Marine atmospheric boundary layer and low-level cloud responses to the Kuroshio Extension front in the early summer of 2012: three-vessel simultaneous observations and numerical simulations
Marine atmospheric boundary layer and low-level cloud responses to the Kuroshio Extension front in the early summer of 2012: three-vessel simultaneous observations and numerical simulations
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DOI：
10.1007/s10872-014-0266-0
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发表时间：
2015-10
影响因子：
2.3
通讯作者：
Y. Kawai;T. Miyama;S. Iizuka;A. Manda;M. Yoshioka;S. Katagiri;Y. Tachibana;H. Nakamura
中科院分区：
文献类型：
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作者：
Y. Kawai;T. Miyama;S. Iizuka;A. Manda;M. Yoshioka;S. Katagiri;Y. Tachibana;H. Nakamura
2012年初夏，5艘考察船在黑潮延伸区的海表面温度锋上进行了密集的大气观测，以确定海表温度锋对海洋大气边界层的热结构和云形成的影响。7月2-6日，三艘船沿143°E子午线排列在一起，纬度间隔小至30‘或45’，穿过SST锋面来回进行现场观测。海温锋面相当尖锐，在3天的时间里向北移动了约50公里，这在客观分析的海温数据集中并没有很好地反映出来。观测捕捉到了横跨SST锋面的中尺度MABL结构的快速变化，这在表面的云底高度和向下的长波辐射(DLR)方面尤为明显。在较暖的海面上观测到的较高的低层云基数是由于MABL中更强的湍流混合造成的，这种混合在北风下变得突出。最频繁测量的DLR值在海温锋面以南比向北大20W/m−2。在有和没有锋面海温梯度的情况下进行的高分辨率大气模式试验证实了海温梯度对MABL结构和低层云的关键作用。模式中模拟的这些海温锋面印记对模式下界的海温资料很敏感。
Intensive atmospheric observations were carried out with five research vessels in total across the sea surface temperature (SST) front along the Kuroshio Extension in the early summer of 2012, to identify the effects of the front on the thermal structure and cloud formation in the marine atmospheric boundary layer (MABL). Three of the vessels were aligned together along the 143°E meridian with latitudinal separation of as small as 30′ or 45′, going back and forth across the SST front for in situ observations during 2–6 July. The SST front was quite sharp and moved northward by about 50 km in 3 days, which was not well represented in objectively analyzed SST data sets. The observations captured rapid changes of the mesoscale MABL structure across the SST front, which were particularly evident in cloud base height and downward longwave radiation (DLR) at the surface. The higher base of low-level clouds observed over the warmer water resulted from stronger turbulent mixing in the MABL, which became prominent under the northerlies. The most frequently measured DLR value was greater by 20 W m−2to the south of the SST front than to the north. High-resolution atmospheric model experiments conducted with and without the frontal SST gradient have confirmed its critical importance for the MABL structure and low-level clouds. These imprints of the SST front simulated in the models are sensitive to SST data assigned at the lower boundary of the model.