Effects of Cloud Liquid‐Phase Microphysical Processes in Mixed‐Phase Cumuli Over the Tibetan Plateau

Abstract. Overprediction of precipitation over the Tibetan Plateau is often found in numerical simulations, which is thought to be related to coarse grid sizes or inaccurate large-scale forcing. In addition to confirming the important role of model grid sizes, this study shows that liquid-phase precipitation parameterization is another key culprit, and underlying physical mechanisms are revealed. A typical summer plateau precipitation event is simulated with the Weather Research and Forecasting (WRF) model by introducing different parameterizations of liquid-phase microphysical processes into the commonly used Morrison scheme, including autoconversion, accretion, and entrainment-mixing mechanisms. All simulations can reproduce the general spatial distribution and temporal variation of precipitation. The precipitation in the high-resolution domain is less overpredicted than in the low-resolution domain. The accretion process plays more important roles than other liquid-phase processes in simulating precipitation. Employing the accretion parameterization considering raindrop size makes the total surface precipitation closest to the observation which is supported by the Heidke skill scores. The physical reason is that this accretion parameterization can suppress fake accretion and liquid-phase precipitation when cloud droplets are too small to initiate precipitation.

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Differences in Cloud Vertical Structures between the Tibetan Plateau and Eastern China Plains during Rainy Season as Measured by CloudSat/CALIPSO

Advances in Meteorology ◽

10.1155/2019/6292930 ◽

2019 ◽

Vol 2019 ◽

pp. 1-11 ◽

Cited By ~ 1

Author(s):

Mingjian Yi

Keyword(s):

Tibetan Plateau ◽

Probability Density ◽

Eastern China ◽

Mixed Phase ◽

The Tibetan Plateau ◽

Cloud Development ◽

Elevated Surface ◽

Using Data ◽

Mixed Phase Clouds ◽

Cloud Thickness

Cloud vertical structures over the Tibetan Plateau (TP) and Eastern China Plains (ECP) were analyzed by using data in rainy seasons from 2006 to 2009, in order to clarify the cloud development over adjacent regions but with distinct topographies. Results indicate that the largest occurrences of cloud top height over the TP are at 7-8 km above mean sea level, which is about 4 km lower than that over the ECP. Mixed-phase clouds dominated more than 30% over the TP, while it is lower than 10% over the ECP. The infrequent mixed-phase clouds over the ECP are attributed to the unique dynamic and moisture situations over the downstream areas of the TP. Ice clouds have similar occurrences over the two regions. The prominent distinctions are manifested by the probability density of cloud thickness. The probability density of cloud thickness around 4–8 km is about 2% higher over the TP than the ECP. However, there is almost no ice cloud thicker than 10 km over the TP, while it is about 1% over the ECP. Compared with those over the ECP, every cloud layer within multilayered clouds is generally higher and thinner over the TP, which is closely related to the elevated surface and the resulting thinner troposphere. The significant differences in cloud vertical structures between the TP and the ECP present in this study emphasize that topographical characteristics and the resulting moisture and circulation conditions have strong impacts on the cloud vertical structures.

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Comparison of mixed-phase clouds over the Arctic and the Tibetan Plateau: seasonality and vertical structure of cloud radiative effects

Climate Dynamics ◽

10.1007/s00382-020-05257-8 ◽

2020 ◽

Vol 54 (11-12) ◽

pp. 4811-4822

Author(s):

Yafei Yan ◽

Xiaolin Liu ◽

Yimin Liu ◽

Jianhua Lu

Keyword(s):

Tibetan Plateau ◽

Vertical Structure ◽

Mixed Phase ◽

The Arctic ◽

The Tibetan Plateau ◽

Radiative Effects ◽

Cloud Radiative Effects ◽

Mixed Phase Clouds

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Effects of Cloud Microphysics on the Vertical Structures of Cloud Radiative Effects over the Tibetan Plateau and the Arctic

Remote Sensing ◽

10.3390/rs13142651 ◽

2021 ◽

Vol 13 (14) ◽

pp. 2651

Author(s):

Yafei Yan ◽

Yimin Liu ◽

Xiaolin Liu ◽

Xiaocong Wang

Keyword(s):

Tibetan Plateau ◽

Cloud Microphysics ◽

Mixed Phase ◽

The Arctic ◽

Radiative Transfer Model ◽

Transfer Model ◽

The Tibetan Plateau ◽

Radiative Effects ◽

Cloud Radiative Effects ◽

Phase Water

The Tibetan Plateau (TP) and the Arctic are both cold, fragile, and sensitive to global warming. However, they have very different cloud radiative effects (CRE) and influences on the climate system. In this study, the effects of cloud microphysics on the vertical structures of CRE over the two regions are analyzed and compared by using CloudSat/CALIPSO satellite data and the Rapid Radiative Transfer Model. Results show there is a greater amount of cloud water particles with larger sizes over the TP than over the Arctic, and the supercooled water is found to be more prone to exist over the former than the latter, making shortwave and longwave CRE, as well as the net CRE, much stronger over the TP. Further investigations indicate that the vertical structures of CRE at high altitudes are primarily dominated by cloud ice water, while those at low altitudes are dominated by cloud liquid and mixed-phase water. The liquid and mixed-phase water results in a strong shallow heating (cooling) layer above the cooling (heating) layer in the shortwave (longwave) CRE profiles, respectively.

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