Fluxes and Budgets of Trace Gases over the Tropical Pacific

 

Steve Oncley and Don Lenschow, NCAR

 

We will attempt to extend the usefulness of the chemical species measurements from the P-3B by estimating fluxes through the bottom and top of both the planetary boundary layer (PBL) and overlying buffer layer (BuL), as well as other variables involved in chemical species budgets. This will require flying specialized flight tracks, including following an air mass and sampling at several heights in both layers, to maximize the number of techniques which can be applied.

Profiles of fluxes within the PBL will be calculated directly using the eddy-correlation method for scalar quantities for which fast-response measurements are available (at least temperature and H2O). We will estimate fluxes in the PBL for species which are measured at lower rates (down to 1/min) using mixed-layer similarity methods. Budget methods also will be used to estimate surface and entrainment fluxes as well as exchange between the PBL and BuL and at the top of the BuL. We also will examine top-down -- bottom-up (TD-BU) formulations that relate mixed-layer gradients and variances to fluxes at the surface (emission or deposition fluxes) and at the top of the PBL (entrainment fluxes). These methods are summarized below.

All of these methods will be tried on as many chemical species as appropriate for each method to check for consistancy. Hybrid methods may be developed in the course of data analysis.