Accession Number:

AD1100155

Title:

Extraction of Wind and Temperature Information from Hybrid 4D-Var Assimilation of Stratospheric Ozone Using NAVGEM

Descriptive Note:

Journal Article - Open Access

Corporate Author:

NAVAL RESEARCH LAB WASHINGTON DC WASHINGTON United States

Report Date:

2018-03-02

Pagination or Media Count:

28.0

Abstract:

Extraction of wind and temperature information from stratospheric ozone assimilation is examined within the context of the Navy Global Environmental Model NAVGEM hybrid 4-D variational assimilation 4D-Var data assimilation DA system. Ozone can improve the wind and temperature through two different DA mechanisms 1 through the flow-of-the-day ensemble background error covariance that is blended together with the static background error covariance and 2 via the ozone continuity equation in the tangent linear model and adjoint used for minimizing the cost function. All experiments assimilate actual conventional data in order to maintain a similar realistic troposphere. In the stratosphere, the experiments assimilate simulated ozone andor radiance observations in various combinations. The simulated observations are constructed for a case study based on a 16-day cycling truth experiment TE, which is an analysis with no stratospheric observations. The impact of ozone on the analysis is evaluated by comparing the experiments to the TE for the last 6 days, allowing for a 10-day spin-up. Ozone assimilation benefits the wind and temperature when data are of sufficient quality and frequency. For example, assimilation of perfect no applied error global hourly ozone data constrains the stratospheric wind and temperature to within similar to 2 m s-1 and similar to 1 K. This demonstrates that there is dynamical information in the ozone distribution that can potentially be used to improve the stratosphere. This is particularly important for the tropics, where radiance observations have difficulty constraining wind due to breakdown of geostrophic balance

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Distribution Statement:

APPROVED FOR PUBLIC RELEASE