Abstract
Abstract. Tropospheric ozone profiles have been retrieved from the new ground-based National Aeronautics and Space Administration (NASA) Goddard Space Flight Center TROPospheric OZone DIfferential Absorption Lidar (GSFC TROPOZ DIAL) in Greenbelt, MD (38.99° N, 76.84° W, 57 m a.s.l.), from 400 m to 12 km a.g.l. Current atmospheric satellite instruments cannot peer through the optically thick stratospheric ozone layer to remotely sense boundary layer tropospheric ozone. In order to monitor this lower ozone more effectively, the Tropospheric Ozone Lidar Network (TOLNet) has been developed, which currently consists of five stations across the US. The GSFC TROPOZ DIAL is based on the DIAL technique, which currently detects two wavelengths, 289 and 299 nm, with multiple receivers. The transmitted wavelengths are generated by focusing the output of a quadrupled Nd:YAG laser beam (266 nm) into a pair of Raman cells, filled with high-pressure hydrogen and deuterium, using helium as buffer gas. With the knowledge of the ozone absorption coefficient at these two wavelengths, the range-resolved number density can be derived. An interesting atmospheric case study involving the stratospheric–tropospheric exchange (STE) of ozone is shown, to emphasize the regional importance of this instrument as well as to assess the validation and calibration of data. There was a low amount of aerosol aloft, and an iterative aerosol correction has been performed on the retrieved data, which resulted in less than a 3 ppb correction to the final ozone concentration. The retrieval yields an uncertainty of 16–19% from 0 to 1.5 km, 10–18% from 1.5 to 3 km, and 11–25% from 3 to 12 km according to the relevant aerosol concentration aloft. There are currently surface ozone measurements hourly and ozonesonde launches occasionally, but this system will be the first to make routine tropospheric ozone profile measurements in the Baltimore–Washington, D.C. area.
Highlights
Tropospheric ozone above the ground level has been historically difficult to measure directly due to its relatively short lifetime and nonlinear formation (Stevenson et al, 2013)
TROPOZ DIfferential Absorption Lidar (DIAL)) has been developed in a transportable trailer to take routine measurements of tropospheric ozone near the Baltimore–Washington, D.C. area (Greenbelt, MD 38.99◦ N, 76.84◦ W, 57 m a.s.l.) and various campaign locations. This instrument has been developed as part of the ground-based Tropospheric Ozone Lidar NETwork (TOLNet), which currently consists of five stations across the United States
This paper investigates the steps necessary to construct the GSFC TROPOZ DIAL in order to retrieve and better characterize the vertical distribution of tropospheric ozone in the Baltimore–Washington, D.C. area, in which a regionally important validation test case of an unusually low tropopause – resulting in the exchange of high amounts of ozone between the stratosphere and the lower free troposphere, or stratospheric–tropospheric exchange (STE) – is presented and analyzed
Summary
Tropospheric ozone above the ground level has been historically difficult to measure directly due to its relatively short lifetime and nonlinear formation (Stevenson et al, 2013). TROPOZ DIAL) has been developed in a transportable trailer to take routine measurements of tropospheric ozone near the Baltimore–Washington, D.C. area (Greenbelt, MD 38.99◦ N, 76.84◦ W, 57 m a.s.l.) and various campaign locations This instrument has been developed as part of the ground-based Tropospheric Ozone Lidar NETwork (TOLNet), which currently consists of five stations across the United States (http://www-air.larc.nasa.gov/missions/ TOLNet/). This paper investigates the steps necessary to construct the GSFC TROPOZ DIAL in order to retrieve and better characterize the vertical distribution of tropospheric ozone in the Baltimore–Washington, D.C. area, in which a regionally important validation test case of an unusually low tropopause – resulting in the exchange of high amounts of ozone between the stratosphere and the lower free troposphere, or STE – is presented and analyzed. With the knowledge of the ozone absorption coefficient at these two wavelengths, the rangeresolved ozone number density can be derived with the DIAL equation
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