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Hans R. Schneider, Malcolm K. W. Ko, Nien Dak Sze, Guang-Yu Shi, and Wei-Chyung Wang

Abstract

The effect of eddy diffusion in an interactive two-dimensional model of the stratosphere is reexamined. The model consists of a primitive equation dynamics module, a simplified HOx ozone model and a full radiative transfer scheme. The diabatic/residual circulation in the model stratosphere is maintained by the following processes: 1) nonlocal forcing resulting from dissipation in the parameterized model troposphere and frictional drag at mesospheric levels, 2) mechanical damping within the stratosphere itself, and 3) potential vorticity flux due to large scale waves. The net effect of each process is discussed in terms of the efficiency of the induced circulation in transporting ozone from the equatorial lower stratosphere to high latitude regions. The same eddy diffusion coefficients are used to parameterize the flux of quasi-geostrophic potential vorticity and diffusion in the tracer transport equation. It is shown that the ozone distributions generated with the interactive two-dimensional model are very sensitive to the choice of values for the friction and the eddy diffusion coefficients. The strength of the circulation increases with the mechanical damping and Kyy. At the same time, larger diffusion in the tracer transport equation reduces the equator to pole transport (Holton 1986). Depending on the amount of friction assumed in the stratosphere, increasing eddy diffusion can lead to an increase as well as a decrease in the net transport. It is shown that reasonable latitudinal gradients of ozone can be obtained by using small values for the mechanical damping [≈1/(100 days)] and Kyy (order 104 m2 s−1) for the mid- and high-latitude stratosphere.

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Guang-Yu Shi, Tadahiro Hayasaka, Atsumu Ohmura, Zhi-Hua Chen, Biao Wang, Jian-Qi Zhao, Hui-Zheng Che, and Li Xu

Abstract

Solar radiation is one of the most important factors affecting climate and the environment. Routine measurements of irradiance are valuable for climate change research because of long time series and areal coverage. In this study, a set of quality assessment (QA) algorithms is used to test the quality of daily solar global, direct, and diffuse radiation measurements taken at 122 observatories in China during 1957–2000. The QA algorithms include a physical threshold test (QA1), a global radiation sunshine duration test (QA2), and a standard deviation test applied to time series of annually averaged solar global radiation (QA3). The results show that the percentages of global, direct, and diffuse solar radiation data that fail to pass QA1 are 3.07%, 0.01%, and 2.52%, respectively; the percentages of global solar radiation data that fail to pass the QA2 and QA3 are 0.77% and 0.49%, respectively. The method implemented by the Global Energy Balance Archive is also applied to check the data quality of solar radiation in China. Of the 84 stations with a time series longer that 20 yr, suspect data at 35 of the sites were found. Based on data that passed the QA tests, trends in ground solar radiation and the effect of the data quality assessment on the trends are analyzed. There is a decrease in ground solar global and direct radiation in China over the years under study. Although the quality assessment process has significant effects on the data from individual stations and/or time periods, it does not affect the long-term trends in the data.

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