Three Dimensional Simulations of Polar Stratospheric Cloud Formation

 

Research Staff: Eric Jensen

Clouds composed of water ice and nitric acid form in the stratosphere over the Antarctic and Arctic during wintertime. These clouds have been definitively linked to ozone destruction due to heterogeneous chemical reactions on the particle surfaces. This process leads to the ozone hole over the Antarctic, and several studies have suggested the relatively minor ozone loss over the Arctic may worsen in the future.

Over the past year, we have developed a three-dimensional (3D) model for simulation of these polar stratospheric clouds (PSCs). With this model, we can calculate the PSC properties and their effects over the entire hemisphere. The model is driven by measured wind fields and temperatures. Microphysical processes are explicitly calculated, with 20 size bins for sulfate aerosols and cloud particles. The figure shows a snapshot of PSCs simulated during the Arctic winter of 1999/2000 during the NASA SAGE III Ozone Loss and Validation Experiment (SOLVE). We are validating the simulations using aircraft and satellite measurements made during SOLVE. We are using the 3D simulations to calculate the vertical redistribution of nitric acid over the entire Arctic.

Preliminary modeling results suggest that the net removal of nitric acid is relatively insensitive to the threshold conditions for PSC formation assumed. The 3D model is also useful for providing a large-scale context for the localized in situ aircraft measurements. We expect this modeling tool will be very useful for analysis and interpretation of future satellite measurements of PSCs.

 

Point of Contact: Eric Jensen, 650/604-4392, ejensen@sky.arc.nasa.gov

 

[3D Simulation of Arctic PSCs]

Results from a three dimensional simulation of Arctic polar stratospheric clouds (PSCs) during the winter of 1999/2000. Condensed nitric acid mixing ratio (color shading, parts per billion by volume) and temperature (red contours) are shown on the 32mbar pressure level, on December 23. The model indicates a large PSC extending from eastern Greenland over northern Russia.