# Dependence of Convective Cloud Properties and Their Transport on Cloud Fraction and GCM Resolution Diagnosed from a Cloud-Resolving Model Simulation

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## Abstract

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## 1. Introduction

## 2. Simulation Data and Analysis Method

^{2}, 4

^{3}, 4

^{4}, 4

^{5}, 4

^{6}, 4

^{7}subdomains for 256, 128, 64, 32, 16, 8 and 4 km subdomain sizes, respectively. Hereafter, we will use “subdomain size” and “GCM resolution” interchangeably. Within each subdomain, a convective updraft grid point is identified by the following criteria: (1) vertical velocity w > 1 m/s and total hydrometeor mixing ratio ${\mathrm{q}}_{\mathrm{t}}>1\times {10}^{-6}$ kg/kg or (2) w > 2 m/s. Similarly, a convective downdraft is determined by (1) w < −1 m/s and ${\mathrm{q}}_{\mathrm{t}}>1\times {10}^{-6}$ kg/kg or (2) w < −2 m/s. Each subdomain can contain any of updrafts, downdrafts, and environment. In [8] and subsequent applications of their scale-aware convective parameterization approach [9,10,11], only updrafts are considered for convective cloud fraction and associated transport. However, convective downdrafts play an important role in the interaction between convection and its large-scale environment [18,19,20,21]. Therefore, in this study we will examine cloud properties and their transport by first considering updrafts only and then considering both updrafts and downdrafts.

## 3. Results

#### 3.1. Dependence on Subdomain Size

#### 3.2. Cloud Fraction Dependence without Considering Downdrafts

#### 3.3. Cloud Fraction Dependence Considering Downdrafts

## 4. Discussion

## 5. Conclusions

## Author Contributions

## Funding

## Data Availability Statement

## Acknowledgments

## Conflicts of Interest

## References

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**Figure 1.**Snapshot of (

**a**) vertical velocity (m/s) at 500 hPa and (

**b**) surface precipitation (mm/h) at 0100 UTC May 24. Precipitation is a 6-min averaged, the model output interval, converted to mm/h. Warm colors in (

**a**) are for upward motion and cold colors are for downward motion.

**Figure 2.**Profiles of (

**a**) cloud fraction and (

**b**) convective mass flux for different subdomain sizes. The solid lines in (

**a**) consider updrafts only, the dashed lines consider both updrafts and downdrafts.

**Figure 3.**Vertical profiles of total and eddy transport of (

**a**) moist static energy (normalized by $1/{C}_{p}$) and (

**b**) water vapor mixing ratio (normalized by $L/{C}_{p}$ ) for different subdomain sizes.

**Figure 4.**Vertical velocity in (

**a**) updrafts, (

**b**) environment, and (

**c**) their difference as functions of cloud fraction and subdomain size at the 500 hPa height.

**Figure 5.**Moist static energy (top panel) and specific humidity (bottom panel) in (

**a**,

**d**) updrafts, (

**b**,

**e**) environment, and (

**c**,

**f**) their difference as functions of cloud fraction and subdomain size at the 500 hPa height. h and q are deviations of moist static energy and specific humidity from their time averages. h is normalized by $1/{C}_{p}$ and q is normalized by $L/{C}_{p}$ so that both have the units of Kelvin.

**Figure 6.**(

**a**) $\left({w}_{u}-{w}_{e}\right)\left({h}_{u}-{h}_{e}\right)$ and (

**b**) $\left({w}_{u}-{w}_{e}\right)\left({q}_{u}-{q}_{e}\right)$ $\mathrm{m}/\mathrm{s}\xb7\mathrm{K}$ as functions of cloud fraction and subdomain size at 500 hPa.

**Figure 7.**Subdomain size and convective cloud fraction dependency of eddy transport ($\mathrm{m}/\mathrm{s}\xb7\mathrm{K}$) of moist static energy from (

**a**) Equation (3) and (

**b**) Equation (5) at 500 hPa.

**Figure 8.**Vertical velocity for (

**a**) downdraft; (

**b**) environment; (

**c**) the difference between updraft and environment; and (

**d**) the difference between downdraft and environment as functions of cloud fraction and subdomain size at 500 hPa.

**Figure 9.**Moist static energy and specific humidity (K) in (

**a**,

**d**) downdrafts, (

**b**,

**e**) environment, and (

**c**,

**f**) their difference as functions of downdraft cloud fraction and subdomain size at the 500 hPa height.

**Figure 10.**Cloud fraction and subdomain size dependence of (

**a**) $\left({w}_{d}-{w}_{e}\right)\left({h}_{d}-{h}_{e}\right)$, (

**b**) $\left({w}_{d}-{w}_{e}\right)\left({q}_{d}-{q}_{e}\right)$, and (

**c**) eddy transport of MSE from Equation (6) at 500 hPa. Units are in ($\mathrm{m}/\mathrm{s}\text{}\mathrm{K}$).

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**MDPI and ACS Style**

Zhang, Z.; Zhang, G.J.
Dependence of Convective Cloud Properties and Their Transport on Cloud Fraction and GCM Resolution Diagnosed from a Cloud-Resolving Model Simulation. *J. Mar. Sci. Eng.* **2022**, *10*, 1318.
https://doi.org/10.3390/jmse10091318

**AMA Style**

Zhang Z, Zhang GJ.
Dependence of Convective Cloud Properties and Their Transport on Cloud Fraction and GCM Resolution Diagnosed from a Cloud-Resolving Model Simulation. *Journal of Marine Science and Engineering*. 2022; 10(9):1318.
https://doi.org/10.3390/jmse10091318

**Chicago/Turabian Style**

Zhang, Zhanjie, and Guang J. Zhang.
2022. "Dependence of Convective Cloud Properties and Their Transport on Cloud Fraction and GCM Resolution Diagnosed from a Cloud-Resolving Model Simulation" *Journal of Marine Science and Engineering* 10, no. 9: 1318.
https://doi.org/10.3390/jmse10091318