scholarly journals Vertical Distributions of Aerosol and Cloud Microphysical Properties and the Aerosol Impact on a Continental Cumulus Cloud Based on Aircraft Measurements From the Loess Plateau of China

2022 ◽  
Vol 9 ◽  
Author(s):  
Zhaoxin Cai ◽  
Zhanqing Li ◽  
Peiren Li ◽  
Junxia Li ◽  
Hongping Sun ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Water Content ◽  
Loess Plateau ◽  
Cloud Droplet ◽  
Vertical Profiles ◽  
Aircraft Measurements ◽  
Cumulus Cloud ◽  
The Loess Plateau ◽  
Cumulus Clouds ◽  
Microphysical Properties

Based on aircraft measurements of aerosols and continental cumulus clouds made over the Loess Plateau of China (Xinzhou, Shanxi Province) on 30 July 2020, this study focuses on the vertical profiles of microphysical properties of aerosols and cumulus clouds, and use them to study aerosol-cloud interactions. During the study period, the boundary layer was stable with a height ∼1,500 m above sea level. Aerosols in the boundary layer mainly came from local emissions, while aerosols above this layer were mostly dust aerosols transported over long distances. Vertical profiles of aerosols and cloud condensation nuclei were obtained, and aerosol activation ratios at different supersaturation (SS) levels ranged from 0.16 to 0.32 at 0.2% SS and 0.70 to 0.85 at 0.8% SS. A thick cumulus cloud in the development stage was observed from the bottom to the top with the horizontal dimension of 10 km by 7 km, the cloud-base height of 2,450 m (15.8°C), and the cloud-top height of 5,400 m (−3°C). The maximum updraft velocity near the cloud top was 13.45 m s−1, and the maximum downdraft velocity occuring in the upper-middle part of the cloud was 4.44 ms−1. The temperature inside the cloud was higher than the outside, with their difference being positively correlated with the cloud water content. The temperature lapse rate inside the cloud was about −6.5°C km−1. The liquid water content and droplet effective radius (Re) increased with increasing height. The cloud droplet number concentration (Nc) increased first then decreased, peaking in the middle and lower part of the cloud, the average values of Nc and Re were 767.9 cm−3 and 5.17 μm, respectively. The cloud droplet spectrum had a multi-peak distribution, with the first appearing at ∼4.5 μm. SS in the cloud first increased then decreased with height. The maximum SS is ∼0.7% appearing at ∼3,800 m. The conversion rate of intra-cloud aerosols to cloud droplets was between 0.2 and 0.54, with the ratio increasing gradually with increasing height. The cloud droplet spectral dispersion and Nc were positively correlated. The aerosol indirect effect (AIE) was estimated to be 0.245 and 0.16, based on Nc and Re, respectively. The cloud droplet dispersion mainly attenuated the AIE, up to ∼34.7%.

scholarly journals Numerical Simulations of Local Circulation and Cumulus Generation over the Loess Plateau, China

2009 ◽  
Vol 48 (4) ◽  
pp. 849-862 ◽  
Author(s):  
Masanori Nishikawa ◽  
Tetsuya Hiyama ◽  
Kazuhisa Tsuboki ◽  
Yoshihiro Fukushima
Keyword(s):  
Numerical Simulations ◽  
Loess Plateau ◽  
Cumulus Cloud ◽  
The Loess Plateau ◽  
Local Circulation ◽  
Cumulus Clouds ◽  
Thermal Generation ◽  
The Real ◽  
Flat Terrain ◽  
Vertical Scales

Abstract The Loess Plateau of China consists of dissected flat tablelands with steep gullies. To evaluate the effect of topography on local circulation and cumulus generation over the Loess Plateau, numerical simulations of atmospheric boundary layer (ABL) development were conducted using a cloud-resolving nonhydrostatic model. Two types of numerical simulation were carried out under two sets of bottom boundary conditions: real terrain and flat terrain. The differences in ABL development and cumulus generation between the flat- and real-terrain conditions are described and the local circulation structures induced by ABL development are illustrated. More cumulus clouds were generated over the real terrain than over the flat terrain. In the real-terrain case, large amounts of cumulus cloud were generated on the windward slopes and on the edge of the tableland, with updrafts caused by thermal generation and a local circulation developing with horizontal and vertical scales of several kilometers. Cumulus clouds clearly developed at the top of the ABL because the water vapor is nonhomogeneously lifted by the local circulation on windward slopes and on edge of the tableland. Thus, the topography of the Loess Plateau plays an important role in cumulus generation.

scholarly journals Heat Balance and Soil Water Content for Bare Soil Surfaces in the Loess Plateau, China

2005 ◽  
Vol 60 (5) ◽  
pp. 1013-1016
Author(s):  
Reiji KIMURA ◽  
Yuanbo LIU ◽  
Naru TAKAYAMA ◽  
Makio KAMICHIKA ◽  
Nobuhiro MATSUOKA ◽  
...  
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Loess Plateau ◽  
Heat Balance ◽  
Bare Soil ◽  
The Loess Plateau

scholarly journals Soil Moisture-Boundary Layer Feedbacks on the Loess Plateau in China Using Radiosonde Data with 1-D Atmospheric Boundary Layer Model

Atmosphere ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1619
Author(s):  
Yingsai Ma ◽  
Xianhong Meng ◽  
Yinhuan Ao ◽  
Ye Yu ◽  
Guangwei Li ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Soil Moisture ◽  
Atmospheric Boundary Layer ◽  
Loess Plateau ◽  
Atmospheric Stability ◽  
Heat Fluxes ◽  
Radiosonde Data ◽  
Atmospheric Conditions ◽  
The Loess Plateau ◽  
The Impact

The Loess Plateau is one land-atmosphere coupling hotspot. Soil moisture has an influence on atmospheric boundary layer development under specific early-morning atmospheric thermodynamic structures. This paper investigates the sensitivity of atmospheric convection to soil moisture conditions over the Loess Plateau in China by using the convective triggering potential (CTP)—humidity index (HIlow) framework. The CTP indicates atmospheric stability and the HIlow indicates atmospheric humidity in the low-level atmosphere. By comparing the model outcomes with the observations, the one-dimensional model achieves realistic daily behavior of the radiation and surface heat fluxes and the mixed layer properties with appropriate modifications. New CTP-HIlow thresholds for soil moisture-atmosphere feedbacks are found in the Loess Plateau area. By applying the new thresholds with long-time scales sounding data, we conclude that negative feedback is dominant in the north and west portion of the Loess Plateau; positive feedback is predominant in the south and east portion. In general, this framework has predictive significance for the impact of soil moisture on precipitation. By using this new CTP-HIlow framework, we can determine under what atmospheric conditions soil moisture can affect the triggering of precipitation and under what atmospheric conditions soil moisture has no influence on the triggering of precipitation.

Coupling model of ecohydrology and simulation of typical shrub ecosystems on the Loess Plateau

2020 ◽  
Author(s):  
Yu Zhang ◽  
Xiaoyan Li ◽  
Wei Li ◽  
Weiwei Fang ◽  
Fangzhong Shi
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Loess Plateau ◽  
Field Experiments ◽  
Annual Precipitation ◽  
The Loess Plateau ◽  
Rainfall Interception ◽  
Area Index ◽  
Caragana Korshinskii

<p>Shrub is the main vegetation type for vegetation restoration in the Loess Plateau, which plays an important role in the regional ecosystem restoration. Study on the relationships between vegetation and soil water of typical shrub ecosystems are significant for the restoration and reconstruction of ecosystems in the Loess Plateau. Three typical shrub (<em>Hippophae rhamnoides</em> Linn., <em>Spiraea pubescens</em> Turcz., and <em>Caragana korshinskii</em> Kom.) ecosystems were chosen in the Loess Plateau. Field experiments were conducted to investigate the factors that influencing the processes of rainfall interception and root uptake of typical shrubs. S-Biome-BGC model was established based on the Biome-BGC model by developing the rainfall interception and soil water movement sub-models. The model was calibrated and verified using field data. The calibrated S-Biome-BGC model was used to simulate the characteristics of leaf area index (<em>LAI</em>), net primary productivity (<em>NPP</em>), soil water content and the interactions among them for the shrub ecosystems along the precipitation gradients in the Loess Plateau, respectively. The results showed that the predictions of the S-Biome-BGC model for soil water content and<em> LAI</em> of typical shrub ecosystems in Loess Plateau were significantly more accurate than that of Biome-BGC model. The simulated <em>RMSE</em> of soil water content decreased from 0.040~0.130 cm<sup>3</sup> cm<sup>-3</sup> to 0.026~0.035 cm<sup>3</sup> cm<sup>-3</sup>, and the simulated <em>RMSE</em> of<em> LAI</em> decreased from 0.37~0.70 m<sup>2</sup> m<sup>-2</sup> to 0.35~0.37 m<sup>2</sup> m<sup>-2</sup>. Therefore, the S-Biome-BGC model can reflect the interaction between plant growth and soil water content in the shrub ecosystems of the Loess Plateau. The S-Biome-BGC model simulation for <em>LAI</em>,<em> NPP</em> and soil water content of the three typical shrubs were significantly different along the precipitation gradients, and increased with annual precipitation together. However, different <em>LAI</em>, <em>NPP</em> and soil water correlations were found under different precipitation gradients.<em> LAI</em> and<em> NPP</em> have significant positive correlations with soil water content in the areas where the annual precipitation is above 460~500 mm that could afford the shrubs growth. The results of the study provide a re-vegetation threshold to guide future re-vegetation activities in the Loess Plateau.</p>

Aggravated water deficit in the Loess Plateau of China as indicated by the soil available water content

2020 ◽  
Author(s):  
Xiao Zhang ◽  
Wenwu Zhao ◽  
Paulo Pereira
Keyword(s):  
Land Cover ◽  
Water Content ◽  
Soil Water ◽  
Water Deficit ◽  
Loess Plateau ◽  
Characteristic Curve ◽  
The Loess Plateau ◽  
Land Cover Types ◽  
Soil Water Characteristic Curve ◽  
Available Water Content

<p>The soil available water content (AWC) has a strong ability to indicate the soil water conditions under different land cover types. Although the AWC has long been calculated, soil water characteristic curve estimation models and the distribution of AWC, as well as the impact factors, have rarely been evaluated in the Loess Plateau of China. In this study, four typical land cover types were selected: introduced shrubland, introduced grassland, natural restored shrubland and natural restored grassland. Four widely used models were compared with the van Genuchten (VG) model, including the Arya and Paris (AP) model, Mohammadi and Vanclooster (MV) model, Tyler and Wheatcraft (TW) model, and linear fitting (LF) model to estimate the wilting point. The distribution of AWC and the relationships with environmental factors were measured and analyzed. The results showed the following: (1) the MV model was the most suitable model to estimate the soil water characteristic curve in the Loess Plateau; (2) the factors impacting the AWC varied under different precipitation gradients, and the area with a mean annual precipitation of 440-510 mm was the most sensitive zone to environmental and vegetation factors; and (3) the soil water deficit was more severe when considering AWC than when considering soil water content (SWC), and the water deficits were different under introduced grassland and introduced shrubland. Consequently, the construction of vegetation restoration should be more cautious and consider the trade-off between soil conservation and water conservation. During restoration, policy makers should focus on the AWC in addition to the SWC to better assess the soil moisture status.</p>

Survey of microphysical properties of marine boundary-layer clouds in the Western North Atlantic 

2021 ◽  
Author(s):  
Simon Kirschler ◽  
Christiane Voigt ◽  
Andrew S. Ackerman ◽  
Bruce Anderson ◽  
Gao Chen ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Water Content ◽  
North Atlantic ◽  
Radiation Budget ◽  
Late Winter ◽  
Western Atlantic ◽  
Low Level ◽  
Aerosol Cloud ◽  
Microphysical Properties ◽  
Cloud Properties

<p>Oceanic low level clouds strongly affect the atmospheric radiation budget. Uncertainties in their microphysical properties and cover currently limit the accuracy of climate predictions. Further, studies quantifying the relative importance of aerosol and dynamics on cloud properties in specific meteorological regimes are poorly constrained by observations in the Western North Atlantic boundary layer.</p><p>Low level clouds were measured during the Aerosol Cloud meTereology Interactions oVer the western ATlantic Experiment (ACTIVATE) campaign in winter and summer 2020. The two NASA LaRC research aircraft HU-25 Falcon and UC-12 B-200 King Air conducted 35 simultaneous flights to investigate aerosol-cloud interactions of maritime clouds and their impact on radiation. Number concentration, liquid water content, ice water content, and particle size distribution in the size range of 3 µm to 1460 µm in diameter were measured with the fast forward scattering cloud probe (FCDP) and 2-dimensional optical array imaging probe (2D-S) onboard the Falcon. Here, we present an overview of late winter (February-March) and late summer (August-September) oceanic cloud properties in the region 65°W to 80°W and 30°N to 40°N. We compare cloud properties in these two seasons and investigate their dependence on meteorological parameters and aerosol abundance. In a case study, we present cloud observations in a cold air outbreak event on 1 March 2020 with a specific focus on mixed-phase clouds.</p>

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