Citation:

Alapaty, Kiran, B. Cheng, J. Bash, w. Munger, JohnT Walker, AND S. Arunachalam. Introducing Turbulence Kinetic Energy to Dry Deposition Modeling. American Geophysical Union Fall Meeting, New Orleans, On-Line/Everywhere, December 13 - 17, 2021.

Impact/Purpose:

Atmospheric chaotic motions (i.e., turbulence) control the amount of dry deposition of pollutants to the surface that can impact ecosystems and human health. Existing dry deposition equations use adjustmnent methods to account for turbulence in the atmosphere for different conditions and these methods in part can be sources of errors in estimating pollutant deposition. To avoid using such methods, we (1) proposed and evaluated a new velocity parameter derived from using atmospheric turbulence energy, which is estimated using routinely measured other atmospheric parameters. Then, we validated the new velocity parameter using a sophisticated instrument measurements of turbulent motions. Further, we imagined and proved that a constant fraction of that new velocity parameter can be used to avoid adjustment methods and yet accurately describe atmospheric turbulence. Finally, we used it in developing new equations that estimate dry deposition of ozone via various routes exist in the atmosphere. We used a modeling tool to validate new equations using decadal mesaurements of ozone fluidities at the Harvard Forest (MA) site. Results indicate that our new equations work very well estimating pollutant deposition. This research has a potential to manifest a community science package for use in mathematical models at local to global scales.

Description:

Several stability functions are in use to account for turbulence in the atmospheric boundary layer for different stability regimes. These functions are one of the sources for differences among different atmospheric models’ predictions and associated biases. To address this issue with dry deposition, firstly we take advantage of three-dimensional (3-D) aspects of turbulence in estimating resistances by proposing and validating a 3-D turbulence velocity scale that is representative of different stability regimes of atmospheric boundary layer and does not use stability correction functions. Secondly, we hypothesize and prove that 3-D sonic anemometer measured friction velocity, used in several resistances in 0-D and 1-D models, can be effectively replaced by the new turbulence velocity scale multiplied by the von Karman constant.  Finally, we (1) evaluate a set of resistance formulations for ozone (O3), based on the 3-D turbulence velocity scale; and (2) intercompare estimations of such resistances with those obtained using the existing formulations and also evaluate simulated O3 fluxes using a single-point dry deposition model against long-term observations of O3 fluxes at the Harvard Forest site. Results indicate that the new resistance formulations work very well in simulating surface latent heat and O3 fluxes when compared to respective simulations using traditional formulations as well as measurements at decadal time scale. Findings from this research may help to improve the capability of dry deposition schemes for better estimation of dry deposition fluxes and creates opportunities for the development of a community dry deposition model for use in regional/global air quality models.

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