This paper presents the release of LTRANS-Zlev, which is a new version of the off-line Lagrangian ocean particle-tracking model LTRANS v.2b that is compatible with a Z-coordinate (constant-depth layers) discretization of the hydrodynamic equations. The model capitalizes on and massively extends the capabilities of the original code LTRANS, which is already quite popular but can be used only adopting a sigma-coordinate (terrain-following layers) discretization. Among the additional features included in LTRANS-Zlev, there are the backward-in-time particle-tracking algorithm and some new customizable larval behaviour options. The new version also includes the OILTRANS-module for oil spill simulations. The new implementations were validated by using the output of the Z-coordinate Massachusetts Institute of Technology general circulation model (MITgcm) for an idealized case study describing a cyclonic gyre in a mid-latitude closed basin. Another test-case in which larval dispersal is modelled in the northern Adriatic Sea illustrates some of the new features of LTRANS-Zlev.

本文介绍了LTRANS-Zlev的发布，它是离线拉格朗日海洋粒子跟踪模型LTRANS v.2b的新版本，它与流体力学方程的Z坐标（恒定深度层）离散化兼容。该模型利用并大量扩展了原始代码LTRANS的功能，该代码已经非常流行，但是只能通过使用sigma坐标（地形跟随层）离散化来使用。LTRANS-Zlev包含的其他功能中，还有实时粒子追踪算法和一些新的可自定义的幼虫行为选项。新版本还包括用于漏油模拟的OILTRANS模块。通过使用Z坐标麻省理工学院普通循环模型（MITgcm）的输出对描述中纬度封闭盆地旋风回旋的理想案例研究进行了验证，从而验证了新的实施方案。在亚得里亚海北部模拟幼虫扩散的另一个测试案例说明了LTRANS-Zlev的一些新功能。