Measuring the elusive particles that form ice in clouds

摘要和目的云中冰的形成是地球气候系统中最不为人所知的方面之一。特殊的气溶胶粒子，称为成冰粒子，需要用来触发冰的形成，但它们的来源、特征和在全球的分布情况却很不清楚。一旦冰晶形成，可能会有一系列过程导致降雨量、卷云覆盖率和云反射率的变化。所有这些变化对气候变化都很重要。这一领域的一个主要限制是缺乏可用于在半自主基础上测量INP浓度的仪器。作为利兹大学、卡尔斯鲁厄理工学院(KIT)和Bilinger Noell GmbH合作的一部分，我们开发了一种新的概念仪器，用于量化大气中的冰核粒子。这种新的仪器，便携式冰核粒子测量膨胀室(PINE)，已经被开发为在与混合相云条件相关的条件下工作，并正在商业化过程中。该博士项目的目的是将松树室的使用范围扩大到与卷云相关的温度和条件。该项目将涉及与CASE合作伙伴(Bilinger Noell GmbH)以及卡尔斯鲁厄理工学院密切合作。这在很大程度上将是一个以实验室为基础的项目，包括对德国的长期访问。因此，它提供了一个在不同国家的学术和工业环境中工作的绝佳机会。所获得的经验将使你处于令人羡慕的地位，在未来的工业或学术部门就业。目标该项目将涉及：i)改造松木室，使其在低于水饱和的卷云相关温度下运行。这将包括首先学习如何在利兹的当前配置下使用该仪器，然后才能使其适应较低的温度和卷云条件。您将与比尔芬格诺埃尔的Boffo博士密切合作，使密封舱适应低温使用。然后你将在卡尔斯鲁厄理工学院工作，在那里你将使用成熟的AIDA云模拟室来校准松树室中饱和水条件下的冰晶产量。二)在一系列实验室实验中研究与卷云有关的条件下尘埃气溶胶老化的影响。这将在利兹进行，在那里气溶胶将在一个小室中产生，以一种受控的方式处理以模拟大气老化，然后采样到松树小室。三)在大气中的卷云条件下进行一些INP的首次长期测量。我们刚刚开始制作与混合相云相关的INP浓度的第一个长期(长达数月)的数据集。你将在卷云条件下进行可能是有史以来第一次长期测量。为此，您将利用新的利兹大气观测站，它位于利兹以东的乡村。

Summary and aimThe formation of ice in clouds is one of the least well understood aspects of the planet's climate system. Special aerosol particles, known as ice-nucleating particles, are needed to trigger ice formation but their sources, characteristics and distribution around the globe are very poorly defined. Once ice crystals form, there can be a cascade of processes leading to changes in precipitation, cirrus cloud coverage and cloud reflectivity. All of these changes are important for climate change. A major limitation in this field is the lack of instrumentation which can be used to measure INP concentrations on a semi-autonomous basis. In this project you will play a direct role in breaking this deadlock and revolutionising the field.As part of a collaboration between Leeds, Karlsruhe Institute of Technology (KIT) and Bilfinger Noell GmbH, a new concept instrument for quantifying atmospheric ice nucleating particles has been developed. This new instrument, the Portable expansion chamber for Ice Nucleating particles mEasurement (PINE), has been developed to work at conditions relevant for mixed-phase cloud conditions and is in the process of commercialization. The aim of this PhD project is expand the use of the PINE chamber to temperatures and conditions relevant for cirrus clouds. This will involve taking a working instrument and adapting it for use at lower temperatures.The project will involve working closely with the CASE partner (Bilfinger Noell GmbH) as well as Karlsruhe Institute of Technology. It will largely be a lab based project involving extended visits to Germany. Hence, it offers a fantastic opportunity to work in both academic and industrial settings in different countries. The experience gained will place you in an enviable position for future employment in either the industrial or academic sectors.ObjectivesThe project will involve:i) Adapting the PINE chamber to operate at cirrus relevant temperatures below water saturation. This will involve first learning how to use the instrument in its current configuration in Leeds before adapting it to work at lower temperatures and cirrus conditions. You will work closely with Dr Boffo at Bilfinger Noel to adapt the chamber for use at low temperatures. You will then work at Karlsruhe institute of technology where you will use the well-established AIDA cloud simulation chamber to calibrate the production of ice crystals in the PINE chamber below water saturation. ii) Studying the effects of aging of dust aerosol under conditions relevant for cirrus in a set of laboratory experiments. This will be conducted in Leeds where aerosol will be generated in a chamber, processed in a controlled way to mimic atmospheric aging, and then sampled into the PINE chamber. iii) Conducting some of the first long-term measurements of INP under cirrus conditions in the atmosphere. We are just starting to produce the first long-term (months long) datasets for INP concentrations relevant for mixed-phase clouds. You will make what might be the first ever long term measurements under cirrus conditions. For this, you will make use of the new Leeds Atmospheric Observatory, which is located in the countryside east of Leeds.