Atmospheric ice-nucleating particles (INPs) play an important role in determining the phase of clouds, which affects their albedo and lifetime. A lack of data on the spatial and temporal variation of INPs around the globe limits our predictive capacity and understanding of clouds containing ice. Automated instrumentation that can robustly measure INP concentrations across the full range of tropospheric temperatures is needed in order to address this knowledge gap. In this study, we demonstrate the functionality and capacity of the new Portable Ice Nucleation Experiment (PINE) to study ice nucleation processes and to measure INP concentrations under conditions pertinent for mixed-phase clouds, with temperatures from about −10 to about −40 ^∘C. PINE is a cloud expansion chamber which avoids frost formation on the cold walls and thereby omits frost fragmentation and related background ice signals during the operation. The development, working principle and treatment of data for the PINE instrument is discussed in detail. We present laboratory-based tests where PINE measurements were compared with those from the established AIDA (Aerosol Interaction and Dynamics in the Atmosphere) cloud chamber. Within experimental uncertainties, PINE agreed with AIDA for homogeneous freezing of pure water droplets and the immersion freezing activity of mineral aerosols. Results from a first field campaign conducted at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) observatory in Oklahoma, USA, from 1 October to 14 November 2019 with the latest PINE design (a commercially available PINE chamber) are also shown, demonstrating PINE's ability to make automated field measurements of INP concentrations at a time resolution of about 8 min with continuous temperature scans for INP measurements between −10 and −30 ^∘C. During this field campaign, PINE was continuously operated for 45 d in a fully automated and semi-autonomous way, demonstrating the capability of this new instrument to also be used for longer-term field measurements and INP monitoring activities in observatories.

中文翻译：

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便携式冰核实验（PINE）：一种用于实验室研究和冰核颗粒的自动长期野外观测的新型在线仪器

大气冰核颗粒（INPs）在确定云的相位方面起着重要作用，这会影响其反照率和寿命。缺乏关于全球INP时空变化的数据，限制了我们的预测能力和对含冰云的理解。为了解决这一知识鸿沟，需要一种能够在整个对流层温度范围内稳健地测量INP浓度的自动化仪器。在这项研究中，我们证明了新的便携式冰核实验（松树）的功能性和能力，以研究冰核过程和条件下对有关混合相云，温度从约测量INP浓度-10至约-40  ^∘C. PINE是一个云膨胀室，可避免在冷壁上结霜，从而在操作过程中省去了结霜和相关的背景冰信号。详细讨论了PINE仪器的开发，工作原理和数据处理。我们介绍了基于实验室的测试，其中将PINE测量值与已建立的AIDA（大气中的气溶胶相互作用和动力学）云室的测量值进行了比较。在实验不确定性的范围内，PINE与AIDA同意将纯净水滴均匀冻结，并将矿物气溶胶浸没冻结。在美国俄克拉荷马州的大气辐射测量（ARM）南部大平原（SGP）天文台进行的首次野外活动的结果，−10和−30  ^° C。在此野外试验期间，PINE以全自动和半自主方式连续运行了45天，证明了该新仪器也可用于长期野外测量和INP监测天文台的活动。