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Titan's atmosphere exhibits variations in composition as it progresses through its seasons. Past observations have shown a substantial enrichment in short-lived molecules in the winter stratosphere above 100 km. Seasonal variations in Titan's stratospheric dynamics also lead to a transient detached haze layer (DHL) above 400 km. The seasonal variations in aerosol opacity and molecular abundance lead to varying radiative heating rates in both the shortwave and longwave spectral regions. In this paper, we report on the effects of a new dataset for aerosol opacity and trace gas abundance derived from Cassini observations on simulations of Titan's stratospheric dynamics with the Titan Atmospheric Model (TAM). We find that including seasonally varying radiative species (SVRS) decreases the autumn and winter polar stratopause temperature by up to 10 K poleward of 60°. We also find a similar increased seasonality in the zonal winds with the early autumn polar jet strengthening by 60 m s−1, while the mid winter jet is unaffected. While including the observationally derived SVRS dataset increases the strength of the seasonal variations of the polar jet, it does not substantially affect the timing of the onset or dissipation of the jet or other seasonal phenomena. • We present a dataset of Titan's seasonally varying radiative species (SVRS). • SVRS includes haze and molecular seasonal changes derived from Cassini observations. • Radiative heating from SVRS strengthens the winter stratospheric polar jet. • SVRS heating resolves some differences between prior TAM simulations and observations. [ABSTRACT FROM AUTHOR]

Abstract: Atmospheric circulation and rainfall are important factors controlling the deposition of atmospheric pollutants. This paper aims to quantify the role of these factors in the deposition of sulphur and nitrogen compounds, using case studies in the United Kingdom and Poland. The FRAME model has been applied to calculate deposition for the base year (2005), dry and wet years (2003 and 2000 for the UK and 2003 and 1974 for Poland, respectively), and for years with contrasting annual wind patterns (1986 and 1996 for the UK, and 1998 and 1996 for Poland). Variation in annual wind and rainfall resulted in statistically significant changes in spatial patterns of deposition and the national deposition budget of sulphur and nitrogen compounds in both countries. The deposition budgets of S and N are 5% lower than for the reference year if the dry year is considered in both countries. For the wet year, there is an increase in country total deposition by up to 17%. Years with an increased frequency of eastern winds are associated with an increase in deposition of up to 14% in Poland and 8% in the UK. The national deposition budget is below the average for the years with high frequencies of W winds, especially for the UK (up to 13%). Wet deposition varies due to meteorological factors to a larger extent than dry deposition. In Poland, the changes in national deposition budget due to meteorological factors exceed the changes resulting from emission abatements in years 2000–2009 for nitrogen compounds. In the UK, emission abatements influence the national deposition budget to a larger extent than meteorological changes (except for NH x ). The findings are important in relation to future climate changes, especially considering the potential increase in annual precipitation. This may lead to an increase in deposition over mountainous areas with sensitive ecosystems, where annual rainfall brings significant load of S and N. Changes in annual wind speed and frequency can modify the spatial pattern of deposition. An increased frequency of W winds will benefit both countries through reduced S and N deposition. NW areas of Poland and the UK will suffer from above-average deposition during years with enhanced easterly flow, and this may result in critical loads for acid and nitrogen deposition being exceeded over the areas that are at present sufficiently protected from acidification and eutrophication, despite the ongoing emission abatements. [Copyright &y& Elsevier]