New Studies Linking Ice Nucleation and Precipitation

连接冰核和降水的新研究

• 批准号: 1010851
• 负责人: Markus Petters
• 金额: $ 28.23万
• 依托单位: North Carolina State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-02-01 至 2016-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1010851&HistoricalAwards=false
• 关键词: New; Studies; Linking; Ice; Nucleation

Precipitation is the single most important source of freshwater generation on Earth, but our process-level understanding of its formation and evolution at the microphysical level is crude and remains highly uncertain. In particular, the relative roles of ice microphysical processes, from ice initiation and growth to ice splintering are poorly constrained. The goal of this study is to apply a new method that measures the freezing behavior of individual rain and drizzle drops, with the objective to parameterize the susceptibility of rain rate to ice nuclei number concentrations.INTELLECTUAL MERITPrecipitation forms when drops collide and coalesce, rapidly shunting cloud water into drizzle and rain. To initiate this process a small number of larger hydrometeors must be present, usually assumed to be ice crystals in clouds that are cold enough for heterogeneous ice nucleation to occur. Each precipitation particle contains this seed, provided secondary processes such as ice multiplication or drop breakup did not occur. To analyze the relative importance of primary and secondary processes, individual rain drops will be collected in liquid nitrogen and stored in paraffin. Each raindrop will be placed on a cold stage and the temperature at which it freezes will be measured. The distribution of raindrop freezing temperatures for precipitation from convective storms, synoptic scale winter storms, frontal passages, and remnants of tropical cyclones will be analyzed as a function of the evolution of the precipitating system. All data will be analyzed in the larger meteorological and microphysical context, i.e. rain rate, cloud-top temperature, cloud droplet number concentration, and used to constrain the susceptibility of precipitation to ice nucleation for inclusion in numerical weather and climate prediction models.BROADER IMPACTSThe investigation, although fundamental in nature, touches on questions with important societal implications. It is hypothesized that aerosols from anthropogenic activity affect ice processes and in turn modify precipitation. It is surprising that despite its fundamental importance to society, and more than 200 years after Benjamin Franklins? conjecture implicating ice processes in precipitation formation, we still do not understand the relative importance of the microphysical processes involved. The experiments here will help to constrain this question. In addition to the typical dissemination channels (conferences and peer reviewed contributions to the literature), the investigators will host public lectures to engage the non-science community in the Raleigh/Durham area with this topic. A number of undergraduate and graduate students at N.C. State University will work with the principal investigator on this project.

降水是地球上淡水产生的最重要的单一来源，但我们对其形成和演化的过程级理解在微物理水平上是粗糙的，仍然高度不确定。特别是，冰微物理过程的相对作用，从冰的形成和生长到冰的分裂，都没有得到很好的约束。本研究的目的是应用一种新的方法来测量单个雨滴和细雨的冻结行为，目的是参数化降雨率对冰核数浓度的敏感性。雨滴碰撞合并形成降水，迅速将云水分流成毛毛雨和雨。要启动这一过程，必须有少量较大的水成物存在，通常假定它们是云中的冰晶，温度低到足以发生非均质冰核。每个沉淀颗粒都含有这种种子，前提是没有发生二次过程，如冰倍增或水滴破碎。为了分析初级和次级过程的相对重要性，将单个雨滴收集在液氮中并储存在石蜡中。每个雨滴将被放置在一个低温台上，然后测量它结冰的温度。本文将分析对流风暴、天气尺度冬季风暴、锋面通道和热带气旋残余降水的雨滴冻结温度分布与降水系统演变的关系。所有数据将在更大的气象和微物理背景下进行分析，即降雨率、云顶温度、云滴数浓度，并用于约束降水对冰核的敏感性，以便纳入数值天气和气候预测模式。更广泛的影响这项调查虽然本质上是基础性的，但涉及的问题具有重要的社会意义。据推测，来自人类活动的气溶胶影响冰过程，进而改变降水。令人惊讶的是，尽管它对社会至关重要，而且在本杰明·富兰克林？推测暗示冰过程在降水形成，我们仍然不了解所涉及的微物理过程的相对重要性。这里的实验将有助于限制这个问题。除了典型的传播渠道（会议和对文献的同行评议），研究人员还将举办公开讲座，让罗利/达勒姆地区的非科学界参与到这一主题中来。北卡罗来纳州立大学的一些本科生和研究生将与该项目的首席研究员一起工作。