Cloud Microphysical Properties based on Airborne In Situ Observations and Evaluation of a Weather Forecasting Model and a Global Climate Model
Cloud Microphysical Properties based on Airborne In Situ Observations and Evaluation of a Weather Forecasting Model and a Global Climate Model
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DOI：
10.31979/etd.7855-fqvh
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发表时间：
2019
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影响因子：
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通讯作者：
J. D’Alessandro
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作者：
J. D’Alessandro
基于机载现场观测的云微物理特性和天气预报模式与全球气候模式的评估全球云覆盖对局部和全球辐射收支有重大影响。在数值天气模式中正确地表示云是提高天气和气候预测的必要条件。本研究评估了云微物理特性的现场空中观测，并将结果与天气研究和预报模型（WRF）和社区大气模型第5版（CAM 5）进行了比较。动力学条件产生的过饱和条件，相对于冰在高海拔地区诊断对流活动进行了探讨，从深对流云和化学（DC 3）运动的观测，结果与模拟数据从WRF进行了比较。WRF分析测试了多种云微物理方案，发现该模型需要更强的上升气流来启动相对于观测的大幅度冰过饱和（ISS）。这主要是由于微物理方案过度预测冰粒子数浓度（Ncice），从而迅速耗尽可用的水蒸气。利用O2/N2比率和CO2空中南大洋研究（ORCAS）的现场空中观测资料，并与CAM 5的模拟数据进行比较，探讨了南大洋上空不同云相的频率和相对湿度（RH）分布。CAM 5模拟在较暖温度（>-20 ° C）的晴空条件下产生了可比较的RH分布。然而，模拟未能捕捉到较冷温度（<-40 ° C）下晴空国际空间站的高频率。此外，CAM 5低估了-40° C至0°C的冰相云内亚饱和条件的频率。
CLOUD MICROPHYSICAL PROPERTIES BASED ON AIRBORNE IN SITU OBSERVATIONS AND EVALUATION OF A WEATHER FORECASTING MODEL AND A GLOBAL CLIMATE MODEL By John D’Alessandro Global cloud coverage has a substantial impact on local and global radiative budgets. It is necessary to correctly represent clouds in numerical weather models to improve both weather and climate predictions. This study evaluates in situ airborne observations of cloud microphysical properties and compares results with the Weather Research and Forecasting model (WRF) and Community Atmosphere Model version 5 (CAM5). Dynamical conditions producing supersaturated conditions with respect to ice at high altitudes in regions diagnosed by convective activity are explored using observations taken from the Deep Convective Clouds and Chemistry (DC3) campaign, and results are compared with simulated data from WRF. The WRF analysis tests multiple cloud microphysics schemes and finds the model requires much stronger updrafts to initiate large magnitudes of ice supersaturation (ISS) relative to observations. This is primarily due to the microphysics schemes over-predicting ice particle number concentrations (Ncice), which rapidly deplete the available water vapor. The frequency of different cloud phases and the distribution of relative humidity (RH) over the Southern Ocean is explored using in situ airborne observations taken from the O2/N2 Ratio and CO2 Airborne Southern Ocean Study (ORCAS) and compared with simulated data from CAM5. The CAM5 simulations produce comparable distributions of RH in clear-sky conditions at warmer temperatures (>-20°C). However, simulations fail to capture high frequencies of clear-sky ISS at colder temperatures (<-40°C). In addition, CAM5 underestimates the frequency of subsaturated conditions within ice phase clouds from -40°‒0°C.