The High Altitude Ice Crystals – High Ice Water Content?(HAIC-HIWC) joint field campaign produced aircraft retrievals of total condensed water content?(TWC), hydrometeor particle size distributions?(PSDs), and vertical velocity?(iw/i) in high ice water content regions of mature and decaying tropical mesoscale convective systems?(MCSs). The resulting dataset is used here to explore causes of the commonly documented high bias in radar reflectivity within cloud-resolving simulations of deep convection. This bias has been linked to overly strong simulated convective updrafts lofting excessive condensate mass but is also modulated by parameterizations of hydrometeor size distributions, single particle properties, species separation, and microphysical processes. Observations are compared with three Weather Research and Forecasting model simulations of an observed MCS using different microphysics parameterizations while controlling for?iw/i, TWC, and temperature. Two popular bulk microphysics schemes (Thompson and Morrison) and one bin microphysics scheme (fast spectral bin microphysics) are compared. For temperatures between ?10?and ?40?°C and TWC??&??1?g?msup?3/sup, all microphysics schemes produce median mass diameters?(MMDs) that are generally larger than observed, and the precipitating ice species that controls this size bias varies by scheme, temperature, and iw/i. Despite a much greater number of samples, all simulations fail to reproduce observed high-TWC conditions (?&??2?g?msup?3/sup) between ?20?and ?40?°C in which only a small fraction of condensate mass is found in relatively large particle sizes greater than 1?mm in diameter. Although more mass is distributed to large particle sizes relative to those observed across all schemes when controlling for temperature, iw/i, and TWC, differences with observations are significantly variable between the schemes tested. As a result, this bias is hypothesized to partly result from errors in parameterized hydrometeor PSD and single particle properties, but because it is present in all schemes, it may also partly result from errors in parameterized microphysical processes present in all schemes. Because of these ubiquitous ice size biases, the frequently used microphysical parameterizations evaluated in this study inherently produce a high bias in convective reflectivity for a wide range of temperatures, vertical velocities, and TWCs.
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机译：高空冰晶＆ndash;高冰水含量（HAIC-HIWC）联合野战活动产生了飞机总冷凝水含量（TWC），水凝液颗粒尺寸分布（PSDs）和垂直速度（ w ）的飞机反演。热带中尺度对流系统的成熟和衰变的高冰水含量区域？这里使用结果数据集来探讨深对流云解析模拟中雷达反射率普遍记录的原因。该偏差与过高的模拟对流上升气流有关，该对流上升气流引起过多的凝结水质量，但也受到水凝物尺寸分布，单颗粒性质，物种分离和微物理过程参数化的调节。在控制温度，TWC和温度的同时，将观测值与使用不同微物理参数化的三个观测到的MCS的天气研究和预报模型模拟进行比较。比较了两种流行的整体微观物理学方案（Thompson和Morrison）和一种箱微观物理学方案（快速光谱箱微观物理学）。当温度在10到40摄氏度之间，TWC≥1克g·m ≥3时，所有的微观物理学方案都会产生中值质量直径（MMD），通常更大比观测到的要多，控制该尺寸偏差的沉淀冰种随方案，温度和 w 的不同而变化。尽管有大量的样本，但所有模拟都无法重现在20°C和40°C之间的观察到的高TWC条件（α>Δ22 ggmm Δ3）。仅在直径大于1？mm的较大颗粒中发现冷凝物的一小部分。尽管与控制温度， i和TWC时在所有方案中观察到的相比，大颗粒尺寸的质量分布更大，但在所测试方案之间观察值的差异明显不同。结果，假设该偏差部分是由于参数化水凝物PSD和单个粒子属性中的错误所致，但由于它存在于所有方案中，因此也可能部分是由于所有方案中存在的参数化微物理过程中的错误所致。由于存在这些普遍存在的冰尺寸偏差，因此在本研究中评估的常用微物理参数化对温度，垂直速度和TWC的宽范围内的对流反射率固有地产生高偏差。
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