Marcus L. Büker

Influence of synoptic waves on column ozone during Arctic summer 1997

The influence of synoptic waves on column ozone over Alaska during the summer of 1997 is explored using observations of ozone and meteorological quantities, a nonhydrostatic three-dimensional model, and theory. From early May to early August, column ozone over Fairbanks declined from 450 to 250 Dobson Units, while 300 hPa heights rose from 8500 to 9500 m. Time series of daily column ozone and 300 hPa heights are correlated at -0.78. Week-to-week variations contribute strongly to this anticorrelation, with column ozone increasing as a trough approaches. Case studies of synoptic scale waves show that they disturb the lower stratosphere, stretching and folding tropospheric and stratospheric air during their life cycles. Mesoscale resolution simulations with the University of Wisconsin Nonhydrostatic Modeling System (UW-NMS) were carried out in support of NASAs Photochemistry of Ozone Loss in the Arctic Region in Summer (POLARIS) campaigns. Layered ozone structures in an ER2 stairstep flight are represented fairly well by the UW-NMS. Two ozone fields were transported in the model, with one subject to a sink below the dynamical tropopause. UW-NMS ozone distributions, a simple box model, and a Stokes drift argument support the idea that synoptic waves cause a poleward and downward flow of ozone through the high latitude tropopause throughout the year. Planetary wave transport of ozone from the tropics is much reduced in the summer. Net transport out of the high latitude stratosphere likely contributes to column ozone decline during summer.