Temporal variability of winter mixed layer in the mid- to high-latitude North Pacific
Temporal variability of winter mixed layer in the mid- to high-latitude North Pacific
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DOI：
10.1007/s10872-007-0029-2
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发表时间：
2007-04-01
影响因子：
2.3
通讯作者：
Suga, Toshio
中科院分区：
文献类型：
--
作者：
Oka, Eitarou;Talley, Lynne D.;Suga, Toshio
分析了2001 - 2005年北太平洋中高纬Argo剖面浮标的温度和盐度资料，研究了秋季末至春季初混合层深度和密度的时间演变。为了研究从几天到季节的各种时间尺度上的MLD变化，使用相对较小的标准（0.03 kg m（-3）密度和0.2 ℃温度）来确定MLD。我们的分析强调，最大MLD在某些地区发生的时间比预期的要早得多。我们还观察到系统的最大混合层深度和密度之间的时间差异。具体而言，在副热带和中央模态沃茨和白令海的形成区域，冬季混合层很深，MLD在冬末（2月和3月）达到最大值，正如预期的那样。然而，在东亚北极北太平洋，浅，强，永久盐跃层防止混合层加深后，1月初，导致在一系列的时间最大MLD 1月至4月之间。在南亚热带;在北纬20度到30度，冬季混合层相对较浅，MLD在12月到1月达到最大值甚至更早。在每个地区，MLD在短时间尺度上波动，因为它从晚秋到初冬增加。与这种短期变化相对应的是，在所有区域，最大MLD几乎总是比最大混合层密度早0 - 100天出现。
Temperature and salinity data from 2001 through 2005 from Argo profiling floats have been analyzed to examine the time evolution of the mixed layer depth (MLD) and density in the late fall to early spring in mid to high latitudes of the North Pacific. To examine MLD variations on various time scales from several days to seasonal, relatively small criteria (0.03 kg m(-3) in density and 0.2 degrees C in temperature) are used to determine MLD. Our analysis emphasizes that maximum MLD in some regions occurs much earlier than expected. We also observe systematic differences in timing between maximum mixed layer depth and density. Specifically, in the formation regions of the Subtropical and Central Mode Waters and in the Bering Sea, where the winter mixed layer is deep, MLD reaches its maximum in late winter (February and March), as expected. In the eastern subarctic North Pacific, however, the shallow, strong, permanent halocline prevents the mixed layer from deepening after early January, resulting in a range of timings of maximum MLD between January and April. In the southern subtropics; from 20 degrees to 30 degrees N, where the winter mixed layer is relatively shallow, MLD reaches a maximum even earlier in December-January. In each region, MLD fluctuates on short time scales as it increases from late fall through early winter. Corresponding to this short-term variation, maximum MLD almost always occurs 0 to 100 days earlier than maximum mixed layer density in all regions.