Analysis and modeling of scale-invariance in plankton abundance
| dc.creator | Pelletier, Jon D. | |
| dc.date | 1996-05-31 | |
| dc.date.accessioned | 2026-07-07T09:07:28Z | |
| dc.date.available | 2026-07-07T09:07:28Z | |
| dc.description | The power spectrum, $S$, of horizontal transects of plankton abundance are often observed to have a power-law dependence on wavenumber, $k$, with exponent close to -2: $S(k)\propto k^{-2}$ over a wide range of scales. I present power spectral analyses of aircraft lidar measurements of phytoplankton abundance from scales of 1 to 100 km. A power spectrum $S(k)\propto k^{-2}$ is obtained. As a model for this observation, I consider a stochastic growth equation where the rate of change of plankton abundance is determined by turbulent mixing, modeled as a diffusion process in two dimensions, and exponential growth with a stochastically variable net growth rate representing a fluctuating environment. The model predicts a lognormal distribution of abundance and a power spectrum of horizontal transects $S(k)\propto k^{-1.8}$, close to the observed spectrum. The model equation predicts that the power spectrum of variations in abundance in time at a point in space is $S(f)\propto f^{-1.5}$ (where $f$ is the frequency). Time series analysis of local variations of phytoplankton and zooplankton yield a power-law power spectrum with exponents -1.3 and -1.2, respectively from time scales of one hour to one year. These values are roughly consistent with the model prediction of -1.5. The distribution of abundances is nearly lognormal as predicted. The model may be more generally applicable than for the spatial distribution of plankton. I relate the model predictions to observations of spatial patchiness in vegetation. | |
| dc.description | latex file, 11 pages, 2 of 3 figures (Figure 2 was judged to be too large (3 Megs) for submission but is available by request) | |
| dc.identifier | https://arxiv.org/abs/ao-sci/9605002 | |
| dc.identifier | http://arxiv.org/abs/ao-sci/9605002 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/150384 | |
| dc.subject | Atmospheric and Oceanic Physics | |
| dc.subject | Condensed Matter | |
| dc.title | Analysis and modeling of scale-invariance in plankton abundance | |
| dc.type | text |