Stratospheric Ozone (IMAGE) NOAA Headquarters Caption The contribution of stratospheric ozone to US surface ozone peaks in the western Rockies during late spring. This map shows mean contribution in parts per billion by volume (ppbv) for May to June. Credit NOAA Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.