Rahul P, Prasanna K, Ghosh Prosenjit, Anilkumar N, Yoshimura Kei
Divecha Centre for Climate Change, Indian Institute of Science, Bangalore, India.
Centre for Earth Sciences, Indian Institute of Science, Bangalore, India.
Sci Rep. 2018 May 15;8(1):7552. doi: 10.1038/s41598-018-25522-5.
Stable Hydrogen and Oxygen isotopic composition of water vapor, rainwater and surface seawater show a distinct trend across the latitude over the Southern Indian Ocean. Our observations on isotopic composition of surface seawater, water vapor and rainwater across a transect covering the tropical Indian Ocean to the regions of the Southern Ocean showed a strong latitudinal dependency; characterized by the zonal process of evaporation and precipitation. The sampling points were spread across diverse zones of SST, wind speed and rainfall regimes. The observed physical parameters such as sea surface temperature, wind speed and relative humidity over the oceanic regions were used in a box model calculation across the latitudes to predict the isotopic composition of water vapor under equilibrium and kinetic conditions, and compared with results from isotope enabled global spectral model. Further, we obtained the average fraction of recycled moisture across the oceanic transect latitudes as 13.4 ± 7.7%. The values of recycled fraction were maximum at the vicinity of the Inter Tropical Convergence Zone (ITCZ), while the minimum values were recorded over the region of subsidence and evaporation, at the Northern and Southern latitudes of the ITCZ. These estimates are consistent with the earlier reported recyling values.
印度洋南部上空水汽、雨水和表层海水的稳定氢氧同位素组成随纬度呈现出明显的变化趋势。我们对横跨热带印度洋至南大洋区域的一个断面的表层海水、水汽和雨水的同位素组成进行了观测，结果显示出强烈的纬度依赖性；其特征为蒸发和降水的纬向过程。采样点分布在不同的海表温度、风速和降雨状况区域。利用海洋区域观测到的诸如海表温度、风速和相对湿度等物理参数，通过一个箱式模型对不同纬度进行计算，以预测平衡和动力学条件下水汽的同位素组成，并与同位素驱动的全球谱模式结果进行比较。此外，我们得出整个海洋断面纬度上再循环水汽的平均占比为13.4 ± 7.7%。再循环占比在热带辐合带（ITCZ）附近最大，而在ITCZ南北纬度的下沉和蒸发区域记录到最小值。这些估算结果与先前报道的再循环值一致。
