Meridional variations in stratospheric acetylene and ethane in the southern hemisphere of the saturnian atmosphere as determined from Cassini/CIRS measurements
Meridional variations in stratospheric acetylene and ethane in the southern hemisphere of the saturnian atmosphere as determined from Cassini/CIRS measurements
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DOI：
10.1016/j.icarus.2007.03.009
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发表时间：
2007-10
期刊：
影响因子：
3.2
通讯作者：
C. Howett;P. Irwin;N. Teanby;A. Simon-Miller;S. Calcutt;L. Fletcher;R. Kok
中科院分区：
文献类型：
--
作者：
C. Howett;P. Irwin;N. Teanby;A. Simon-Miller;S. Calcutt;L. Fletcher;R. Kok
这些是从土星南半球的卡西尼/CIRS数据平流层乙炔和乙烷丰度的纬向变化的最低点研究的第一个结果。使用了2004年6月至11月三个数据集的高分辨率0.5 cm−1 CIRS数据，并将其分成2°宽的纬度带，以提高信噪比。对流层和平流层温度最初检索，以确定每个纬度箱的温度分布。从9° S到68° S，2毫巴时平流层温度升高了14 K，包括60° S到68° S之间的4 K急剧升高。对流层温度的纬向变化明显大于平流层温度，其位置与纬向急流的位置密切相关。平流层乙炔丰度从30 ° S到68° S稳定下降，在2.0毫巴时下降1.8倍。在18°和30° S之间，乙炔丰度在2.0毫巴下增加。乙炔的总体值在2.0 mbar时为（1.9±0.19）×10− 7，在1.6 mbar时为（2.6±0.27）×10− 7，在1.4 mbar时为（3.1±0.32）×10− 7。乙烷在0.5 mbar和1.0 mbar时的总浓度分别为（1.6±0.25）×10− 5和（1.4±0.19）×10− 5。在2.0毫巴下，平流层中乙烷的丰度向南极方向增加2.5倍。平流层乙烷的增加在2.0毫巴下向南纬60°的方向尤为明显。平流层乙烷向南极方向的增加支持了土星平流层中纬向风系统的存在。
These are the first results from nadir studies of meridional variations in the abundance of stratospheric acetylene and ethane from Cassini/CIRS data in the southern hemisphere of Saturn. High resolution, 0.5 cm−1, CIRS data was used from three data sets taken in June–November 2004 and binned into 2° wide latitudinal strips to increase the signal-to-noise ratio. Tropospheric and stratospheric temperatures were initially retrieved to determine the temperature profile for each latitude bin. The stratospheric temperature at 2 mbar increased by 14 K from 9° to 68° S, including a steep 4 K rise between 60° and 68° S. The tropospheric temperatures showed significantly more meridional variation than the stratospheric ones, the locations of which are strongly correlated to that of the zonal jets. Stratospheric acetylene abundance decreases steadily from 30 to 68° S, by a factor of 1.8 at 2.0 mbar. Between 18° and 30° S the acetylene abundance increases at 2.0 mbar. Global values for acetylene have been calculated as (1.9±0.19)×10−7at 2.0 mbar, (2.6±0.27)×10−7at 1.6 mbar and (3.1±0.32)×10−7at 1.4 mbar. Global values for ethane are also determined and found to be (1.6±0.25)×10−5at 0.5 mbar and (1.4±0.19)×10−5at 1.0 mbar. Ethane abundance in the stratosphere increases towards the south pole by a factor of 2.5 at 2.0 mbar. The increase in stratospheric ethane is especially pronounced polewards of 60° S at 2.0 mbar. The increase of stratospheric ethane towards the south pole supports the presence of a meridional wind system in the stratosphere of Saturn.