Assessment of some parameterizations of heterogeneous ice nucleation in cloud and climate models
Assessment of some parameterizations of heterogeneous ice nucleation in cloud and climate models
复制标题
云和气候模型中异质冰核的一些参数化评估
DOI：
10.5194/acp-12-1151-2012
复制
发表时间：
2010
影响因子：
6.3
通讯作者：
V. Khvorostyanov
中科院分区：
文献类型：
--
作者：
J. Curry;V. Khvorostyanov
摘要。在过去几十年中，为云和气候模型开发了几种不同类型的异质冰核形成参数化方案，从经验推导的表达式到源自理论的冰晶成核速率参数化，包括作者开发的同时依赖温度和饱和度比的参数化方案（以下简称KC）。本文在热力学约束、实验室测量以及近期实地测量的背景下，对解决潮解 - 异质冻结（DHetF）（结合了凝结冻结和浸没冻结模式）的参数化方案进行了评估。研究表明，仅依赖冰饱和度比或仅依赖温度的经验方案可以产生合理的冰晶浓度，但在温度 - 饱和度比相空间的某些区域，冰晶成核在热力学上是被禁止的。一些近期的经验参数化方案产生的云在低至 -35°C的温度下几乎完全是液态的，这与云气候学不符。通过与近期几次实地考察的大量数据、实验室数据以及云相态气候学数据进行比较，证明了KC冰核形成方案的合理性能。文中描述并纠正了近期文献中出现的KC参数化方案的几种错误应用。在此强调，正确应用KC方案需要对代表具有特定冰核形成特性的环境气溶胶的一部分或几部分的冰核测量尺寸谱上的单个成核速率进行积分。这些部分中的浓度可能远小于总气溶胶浓度，但大于实验装置所测量的冰晶浓度。采用与温度相关的活性位点面积或具有不同特性的几个冰核部分进行模拟表明，KC方案中的冰核形成发生在10 - 20°C的较宽温度范围内，这取决于冰核特性。利用光谱箱模型进行模拟以及正确应用KC方案，能够充分描述通过DHetF模式的冰核形成，并得出与在混合相北极云实验（MPACE）中观测到的单层层积云中所测量的接近的冰晶浓度和相态。文中还对当前气块建模方法和云室观测中的一些不足及其对参数化开发和评估的影响进行了评估。
Abstract. Several different types of parameterization of heterogeneous ice nucleation for cloud and climate models have been developed over the past decades, ranging from empirically-derived expressions to parameterizations of ice crystal nucleation rates derived from theory, including the parameterization developed by the authors that includes simultaneous dependence on the temperature and saturation ratio, hereafter referred to as KC. Parameterizations schemes that address the deliquescence-heterogeneous-freezing (DHetF), which combines the modes of condensation freezing and immersion freezing, are assessed here in the context of thermodynamic constraints, laboratory measurements, and recent field measurements. It is shown that empirical schemes depending only on the ice saturation ratio or only on temperature can produce reasonable crystal concentrations, but ice crystal nucleation is thermodynamically prohibited in certain regions of the temperature-saturation ratio phase space. Some recent empirical parameterizations yield clouds that are almost entire liquid at temperatures as low as −35 °C in contrast to cloud climatology. Reasonable performance of the KC ice nucleation scheme is demonstrated by comparison with numerous data from several recent field campaigns, laboratory data, climatology of cloud phase-state. Several mis-applications of the KC parameterization that appeared recently in the literature are described and corrected. It is emphasized here that a correct application of the KC scheme requires integration of the individual nucleation rates over the measured size spectrum of ice nuclei that represent a fraction or several fractions of the environmental aerosol with specific ice nucleation properties. The concentration in these fractions can be substantially smaller than that of the total aerosol, but greater than the crystal concentration measured by an experimental device. Simulations with temperature-dependent active site area or with several IN fractions having different properties show that ice nucleation in the KC scheme occurs in a wide temperature range of 10–20 °C, which depends on IN properties. Simulation with a spectral bin model and correct application of KC scheme adequately describes ice nucleation via the DHetF mode and yields crystal concentrations and phase state close to those measured in the single-layer stratocumulus cloud observed in the Mixed Phase Arctic Cloud Experiment (MPACE). An assessment of some deficiencies in current parcel modeling methods and cloud chamber observations and their impact on parameterization development and evaluation is provided.