Photochemical and Dynamical Contributions to the Seasonal Variation of Total Ozone Amount over Japan

Abstract

The latitudinal and seasonal variations of ozone photochemical process are analyzed using the monthly means of ozone density observed by ozonesondes at Sapporo, Tateno and Kagoshima.The estimated photochemical change rate (creation minus destruction) and observed ozone density variation are used to evaluate the divergence of ozone.The seasonal variation of total ozone amount at Kagoshima is mainly due to the density variation in the quasi steady region, where the photochemical change rate of ozone density is effectively balanced with its divergence.On the other hand, the variation at Sapporo is dominated by the dynamical process in the non-steady region.In this case, the primary effect in the dynamical process is the seasonal variation of tropopause height and the secondary one is the accumulation in the lower stratosphere due to the meridional circulation in winter.The former tends to set the time of maximum of total ozone amount in mid-winter and the latter shifts it to early spring. Especially, the continuous increase in the total ozone amount during winter is an evidence that the distribution of ozone remains at a transient state for the winter circulation.Such a remarkable difference between the mechanisms of the seasonal variation of total ozone amount in the two stations is originated from the variation of tropopause structure.The major tropopause that effectively separates the stratospheric air mass from the tropospheric one is the tropical tropopause through all seasons over Kagoshima, but it is the tropical one in summer and the polar one in winter over Sapporo.Finally, from the view point of the longitudinal dependence, the ozone distribution over Japan is discussed.

A Parameterization Scheme of Orographic Gravity Wave Drag with Two Different Vertical Partitionings

“…As is wellknown, total ozone amounts (vertically integrated ozone mass) are much larger on the polar side of the subtropical jet stream than on the equatorial side, reflecting the difference in the tropopause height. Iwasaki and Kaneto (1984) showed that the altitude of the tropopause primarily determines the seasonal variation of total ozone amounts in midlatitudes. In the control run without GWD schemes, the tropopause height in mid-latitudes (northern side of the subtropical jet stream) cannot be maintained realistically, but it becomes higher with the forecast period because cooling biases in the lower stratosphere reduce static stability just above the tropopause.…”

The Role of Quasi-Stationary Waves in Annual Cycle in Mid-Latitude Stratospheric and Mesospheric Ozone in 2011-2020

“…This AO evolution in the NH mid-latitude lower stratosphere is determined by the QSW structure in Fig. 3a (see also [23,32,35]). The two months later (September-October), annual minimum is observed in region of zonal minimum and in zonal mean (Fig.…”

“…6r is evidence of the QSW structure influence. The specificity of AO here depends on the relationship between the rates of the processes of dynamical ozone accumulation (the larger effect of meridional circulation in autumn-winter) and photochemical relaxation (spring-summer) in the region of the quasi-stationary maximum of total ozone [2,23,32,35]. As a result, the AO extrema in the Longfengshan domain appear 2-3 months earlier than in the region of the zonal TOC minimum: April and October-November, respectively [24].…”

“…4d and 4f). Generally, this difference can be explained by the relationship between a rate of the process of photochemical ozone relaxation during late spring-summer following by dynamical ozone accumulation since late autumn and during winter- [22,28,32].…”

“…Most previous works, where the ozone seasonality was determined, used zonal mean [22,[25][26][27][28][29], local [24,30,31] or regional [23,24,32,33] ozone data. The monthlongitude dependence of total ozone in zone 50-60°N has been presented by Zou et al [34] (their Fig.…”