Vertical Diffusivity In The Lower Stratosphere From Lagrangian Back-trajectory Reconstructions of Ozone Profiles
Abstract
We present a simple stochastic-dynamical approach to estimate the vertical diffusiv- ity (D) in the stratosphere from routinely observed ozone profiles. First, an observed ozone profile is reconstructed using three-dimensional back-trajectories obtained from analyzed winds and initializing the trajectories with ozone values from the output of a chemistry-transport model. Assuming that diffusion in the vertical follows a simple random walk leading to a Gaussian probability distribution for the particle displace- ments, we perform Monte-Carlo simulations with ensembles of particles originating along each point in the vertical profile. By choosing different values of D as input in the calculations, and comparing the observed profile with profiles that are smoothed through diffusion, we can identify that value of D which is in best agreement with the observed profile at an intermediate range of vertical length scales. For northern mid-latitude lower stratospheric conditions during winter over a period of 9 days, the best estimate of D is about 5 K2day-1, which is approximately 0.06 , in one case while the other case of this study suggests a slightly larger value. The present results are discussed in the context of comparable estimations of vertical diffusivity in the literature.
- Publication:
-
EGS General Assembly Conference Abstracts
- Pub Date:
- 2002
- Bibcode:
- 2002EGSGA..27.5861L