Cohen J E
Rockefeller University, New York, New York 10021-6399, USA.
Nature. 1995 Dec 7;378(6557):610-2. doi: 10.1038/378610a0.
Because water has a higher heat capacity than air, large bodies of water fluctuate in temperature more slowly than does the atmosphere. Marine temperature time series are 'redder' than atmospheric temperature time series by analogy to light: in red light, low-frequency variability has greater amplitude than high-frequency variability, whereas in white light all frequencies have the same amplitude. Differences in the relative importance of high-and low-frequency variability in different habitats affect the population dynamics of individual species and the structure of ecological communities. Population dynamics of individual species are thought to be dominated by low-frequency fluctuations, that is, to display reddened fluctuations. Here I report, however, that in eight nonlinear, iterative, deterministic, autonomous, discrete-time population models, some of which have been used to model real biological populations, the power spectral densities of chaotic trajectories are neither white nor reddened but are notably blue, with increasing power at higher frequencies.
由于水的比热容比空气高，大片水域的温度波动比大气温度波动更为缓慢。海洋温度时间序列与大气温度时间序列相比，类似于光的情况，呈现出“更红”的特征：在红光中，低频变化的幅度比高频变化的幅度更大，而在白光中，所有频率的幅度相同。不同栖息地中高频和低频变化的相对重要性差异会影响单个物种的种群动态以及生态群落的结构。人们认为单个物种的种群动态主要由低频波动主导，即呈现出变红的波动。然而，在此我报告，在八个非线性、迭代、确定性、自治、离散时间的种群模型中，其中一些模型已被用于模拟实际生物种群，混沌轨迹的功率谱密度既非白色也非变红，而是显著变蓝，高频处功率增加。
