scholarly journals Susceptibility of East Asian Marine Warm Clouds to Aerosols in Winter and Spring from Co-Located A-Train Satellite Observations

2021 ◽  
Vol 13 (24) ◽  
pp. 5179
Author(s):  
Chiao-Wei Chang ◽  
Wei-Ting Chen ◽  
Yi-Chun Chen
Keyword(s):  
East Asia ◽  
Single Layer ◽  
Environmental Parameters ◽  
Moisture Flux ◽  
Liquid Water Path ◽  
Near Surface ◽  
Surface Stability ◽  
Cloud Data ◽  
Warm Cloud ◽  
Precipitating Clouds

We constructed the A-Train co-located aerosol and marine warm cloud data from 2006 to 2010 winter and spring over East Asia and investigated the sensitivities of single-layer warm cloud properties to aerosols under different precipitation statuses and environmental regimes. The near-surface stability (NSS), modulated by cold air on top of a warm surface, and the estimated inversion strength (EIS) controlled by the subsidence are critical environmental parameters affecting the marine warm cloud structure over East Asia and, thus, the aerosols–cloud interactions. Based on our analysis, precipitating clouds revealed higher cloud susceptibility to aerosols as compared to non-precipitating clouds. The cloud liquid water path (LWP) increased with aerosols for precipitating clouds, yet decreased with aerosols for non-precipitating clouds, consistent with previous studies. For precipitating clouds, the cloud LWP and albedo increased more under higher NSS as unstable air promotes more moisture flux from the ocean. Under stronger EIS, the cloud albedo response to aerosols was lower than that under weaker EIS, indicating that stronger subsidence weakens the cloud susceptibility due to more entrainment drying. Our study suggests that the critical environmental factors governing the aerosol–cloud interactions may vary for different oceanic regions, depending on the thermodynamic conditions.

scholarly journals Factors Controlling Rapid Stratocumulus Cloud Thinning

2014 ◽  
Vol 71 (2) ◽  
pp. 655-664 ◽  
Author(s):  
J. J. van der Dussen ◽  
S. R. de Roode ◽  
A. P. Siebesma
Keyword(s):  
Moisture Flux ◽  
Steady State Solution ◽  
Cloud Layer ◽  
Cloud Base ◽  
Liquid Water Path ◽  
Marine Stratocumulus ◽  
Buoyancy Reversal ◽  
Stratocumulus Clouds ◽  
Budget Equation ◽  
Heat And Moisture

Abstract The relationship between the inversion stability and the liquid water path (LWP) tendency of a vertically well-mixed, adiabatic stratocumulus cloud layer is investigated in this study through the analysis of the budget equation for the LWP. The LWP budget is mainly determined by the turbulent fluxes of heat and moisture at the top and the base of the cloud layer, as well as by the source terms due to radiation and precipitation. Through substitution of the inversion stability parameter κ into the budget equation, it immediately follows that the LWP tendency will become negative for increasing values of κ due to the entrainment of increasingly dry air. Large κ values are therefore associated with strong cloud thinning. Using the steady-state solution for the LWP, an equilibrium value κeq is formulated, beyond which the stratocumulus cloud will thin. The Second Dynamics and Chemistry of Marine Stratocumulus field study (DYCOMS-II) is used to illustrate that, depending mainly on the magnitude of the moisture flux at cloud base, stratocumulus clouds can persist well within the buoyancy reversal regime.

scholarly journals Spatial Patterns and Intensity of the Surface Storm Tracks in CMIP5 Models

2017 ◽  
Vol 30 (13) ◽  
pp. 4965-4981 ◽  
Author(s):  
James F. Booth ◽  
Young-Oh Kwon ◽  
Stanley Ko ◽  
R. Justin Small ◽  
Rym Msadek
Keyword(s):  
Storm Track ◽  
Storm Tracks ◽  
Cmip5 Models ◽  
Western Boundary ◽  
Spatial Correlations ◽  
Boundary Current ◽  
Near Surface ◽  
Surface Stability ◽  
The North ◽  
Basin Scale

To improve the understanding of storm tracks and western boundary current (WBC) interactions, surface storm tracks in 12 CMIP5 models are examined against ERA-Interim. All models capture an equatorward displacement toward the WBCs in the locations of the surface storm tracks’ maxima relative to those at 850 hPa. An estimated storm-track metric is developed to analyze the location of the surface storm track. It shows that the equatorward shift is influenced by both the lower-tropospheric instability and the baroclinicity. Basin-scale spatial correlations between models and ERA-Interim for the storm tracks, near-surface stability, SST gradient, and baroclinicity are calculated to test the ability of the GCMs’ match reanalysis. An intermodel comparison of the spatial correlations suggests that differences (relative to ERA-Interim) in the position of the storm track aloft have the strongest influence on differences in the surface storm-track position. However, in the North Atlantic, biases in the surface storm track north of the Gulf Stream are related to biases in the SST. An analysis of the strength of the storm tracks shows that most models generate a weaker storm track at the surface than 850 hPa, consistent with observations, although some outliers are found. A linear relationship exists among the models between storm-track amplitudes at 500 and 850 hPa, but not between 850 hPa and the surface. In total, the work reveals a dual role in forcing the surface storm track from aloft and from the ocean surface in CMIP5 models, with the atmosphere having the larger relative influence.

Observed and Projected Frontal Activities in East Asia

2021 ◽  
pp. 1-46
Author(s):  
Chia-Chi Wang ◽  
Huang-Hsiung Hsu ◽  
Ying-Ting Chen
Keyword(s):  
East Asia ◽  
Climate Model ◽  
Southern China ◽  
Model Performance ◽  
Moisture Flux ◽  
Central China ◽  
Cmip5 Models ◽  
The South ◽  
Front Detection ◽  
Local Moisture

AbstractAn objective front detection method is applied to ERA5, CMIP5 historical, and RCP8.5 simulations to evaluate climate model performance in simulating front frequency and understand future projections of seasonal front activities. The study area is East Asia for two natural seasons, defined as winter (December 2nd –February 14th) and spring (February 15th –May 15th), in accordance with regional circulation and precipitation patterns. Seasonal means of atmospheric circulation and thermal structures are analyzed to understand possible factors responsible for future front changes.The front location and frequency in CMIP5 historical simulations are captured reasonably. Frontal precipitation accounts for more than 30% of total precipitation over subtropical regions. Projections suggest that winter fronts will decrease over East Asia, especially over southern China. Frontal precipitation is projected to decrease for 10-30%. Front frequency increases in the South China Sea and tropical western Pacific because of more tropical moisture supply, which enhances local moisture contrasts. During spring, southern China and Taiwan will experience fewer fronts and less frontal precipitation while central China, Korea, and Japan may experience more fronts and more frontal precipitation due to moisture flux from the south that enhances 𝜽𝒘 gradients.Consensus among CMIP5 models in front frequency tendency is evaluated. The models exhibit relatively high consensus in the decreasing trend over polar and subtropical frontal zone in winter and over southern China and Taiwan in spring that may prolong the dry season. Spring front activities are crucial for water resource and risk management in the southern China and Taiwan.

scholarly journals Relative Role of Turbulent and Radiative Flux on the Near-Surface Temperature in a Single-Layer Urban Canopy Model over Houston

2017 ◽  
Vol 56 (8) ◽  
pp. 2173-2187 ◽  
Author(s):  
James Brownlee ◽  
Pallav Ray ◽  
Mukul Tewari ◽  
Haochen Tan
Keyword(s):  
Heat Flux ◽  
Surface Temperature ◽  
Single Layer ◽  
Urban Canopy ◽  
Heat Fluxes ◽  
Radiative Flux ◽  
Hydrological Processes ◽  
Urban Canopy Model ◽  
Near Surface ◽  
Canopy Model

AbstractNumerical simulations without hydrological processes tend to overestimate the near-surface temperatures over urban areas. This is presumably due to underestimation of surface latent heat flux. To test this hypothesis, the existing single-layer urban canopy model (SLUCM) within the Weather Research and Forecasting Model is evaluated over Houston, Texas. Three simulations were conducted during 24–26 August 2000. The simulations include the use of the default “BULK” urban scheme, the SLUCM without hydrological processes, and the SLUCM with hydrological processes. The results show that the BULK scheme was least accurate, and it overestimated the near-surface temperatures and winds over the urban regions. In the presence of urban hydrological processes, the SLUCM underestimates these parameters. An analysis of the surface heat fluxes suggests that the error in the BULK scheme is due to a lack of moisture at the urban surface, whereas the error in the SLUCM with hydrological processes is due to increases in moisture at the urban surface. These results confirm earlier studies in which changes in near-surface temperature were primarily due to the changes in the turbulent (latent and sensible heat) fluxes in the presence of hydrological processes. The contribution from radiative flux was about one-third of that from turbulent flux. In the absence of hydrological processes, however, the results indicate that the changes in radiative flux contribute more to the near-surface temperature changes than the turbulent heat flux. The implications of these results are discussed.

scholarly journals The interdependence of continental warm cloud properties derived from unexploited solar background signals in ground-based lidar measurements

2014 ◽  
Vol 14 (16) ◽  
pp. 8389-8401 ◽  
Author(s):  
J. C. Chiu ◽  
J. A. Holmes ◽  
R. J. Hogan ◽  
E. J. O'Connor
Keyword(s):  
Optical Depth ◽  
Effective Radius ◽  
Liquid Water Path ◽  
Cloud Optical Depth ◽  
Cloud Properties ◽  
Warm Cloud ◽  
Lidar Measurements ◽  
Atmospheric Radiation Measurement ◽  
Ground Based Lidar ◽  
Geometric Thickness

Abstract. We have extensively analysed the interdependence between cloud optical depth, droplet effective radius, liquid water path (LWP) and geometric thickness for stratiform warm clouds using ground-based observations. In particular, this analysis uses cloud optical depths retrieved from untapped solar background signals that are previously unwanted and need to be removed in most lidar applications. Combining these new optical depth retrievals with radar and microwave observations at the Atmospheric Radiation Measurement (ARM) Climate Research Facility in Oklahoma during 2005–2007, we have found that LWP and geometric thickness increase and follow a power-law relationship with cloud optical depth regardless of the presence of drizzle; LWP and geometric thickness in drizzling clouds can be generally 20–40% and at least 10% higher than those in non-drizzling clouds, respectively. In contrast, droplet effective radius shows a negative correlation with optical depth in drizzling clouds and a positive correlation in non-drizzling clouds, where, for large optical depths, it asymptotes to 10 μm. This asymptotic behaviour in non-drizzling clouds is found in both the droplet effective radius and optical depth, making it possible to use simple thresholds of optical depth, droplet size, or a combination of these two variables for drizzle delineation. This paper demonstrates a new way to enhance ground-based cloud observations and drizzle delineations using existing lidar networks.

scholarly journals Investigating the role of dust in ice nucleation within clouds and further effects on the regional weather system over East Asia – Part II: modification of the weather system

2017 ◽  
Author(s):  
Lin Su ◽  
Jimmy C.H. Fung
Keyword(s):  
Surface Temperature ◽  
East Asia ◽  
South China ◽  
Indirect Effects ◽  
Convective Precipitation ◽  
Wave Radiation ◽  
Direct And Indirect Effects ◽  
Weather System ◽  
Near Surface ◽  
Atmospheric Instability

Abstract. An updated version of the Weather Research and Forecast model coupled with Chemistry (WRF-Chem) was applied to quantify and discuss the full effects of dust on the meteorological field over East Asia during March and April 2012. The performances of the model in simulating the short-wave and long-wave radiation, surface temperature, and precipitation over East Asia are improved by incorporating the effects of dust in the simulations. The radiative forcing induced by the dust-enhanced cloud radiative effect is over one order of magnitude larger than that induced by the direct effect of dust. The semi-direct and indirect effects of dust result in a substantial increase in mid- to high clouds, and a significant reduction in low clouds, leading to a decrease of near-surface temperature and an increase of temperature at the mid- to upper troposphere over East Asia. The spatial redistribution of atmospheric water vapor and modification of the vertical temperature profile over East Asia lead to an inhibition of atmospheric instability over most land areas, but an enhancement of atmospheric instability over South China and the ocean, resulting in a significant inhibition of convective precipitation in areas from central to East China, and a substantial enhancement of convective precipitation over South China. Meanwhile, non-convective precipitation is also reduced significantly over East Asia, as cloud droplets are hindered from growing large enough to form rain droplets, due to the semi-direct and indirect effects of dust. The total precipitation can be reduced or increased by up to 20 % or more.

scholarly journals Characteristics of Oceanic Warm Cloud Layers within Multilevel Cloud Systems Derived by Satellite Measurements

Atmosphere ◽  
2019 ◽  
Vol 10 (8) ◽  
pp. 465 ◽  
Author(s):  
Yuhao Ding ◽  
Qi Liu ◽  
Ping Lao
Keyword(s):  
Double Layer ◽  
Lower Layer ◽  
Single Layer ◽  
Distribution Patterns ◽  
Radar Data ◽  
Multilayered Structures ◽  
Layer System ◽  
Cloud Systems ◽  
Warm Cloud ◽  
Double Layer System

Low-level warm clouds are a major component in multilayered cloud systems and they are generally hidden from the top-down view of satellites with passive measurements. This study conducts an investigation on oceanic warm clouds embedded in multilayered structures by using spaceborne radar data with fine vertical resolution. The occurrences of warm cloud overlapping and the geometric features of several kinds of warm cloud layers are examined. It is found that there are three main types of cloud systems that involve warm cloud layers, including warm single layer clouds, cold-warm double layer clouds, and warm-warm double layer clouds. The two types of double layer clouds account for 23% and in the double layer occurrences warm-warm double layer subsets contribute about 13%. The global distribution patterns of these three types differ from each other. Single-layer warm clouds and the lower warm clouds in the cold-warm double layer system they have nearly identical geometric parameters, while the upper and lower layer warm clouds in the warm-warm double layer system are distinct from the previous two forms of warm cloud layers. In contrast to the independence of the two cloud layers in cold-warm double layer system, the two kinds of warm cloud layers in the warm-warm double layer system may be coupled. The distance between the two layers in the warm-warm double layer system is weakly dependent on cloud thickness. Given the upper and lower cloud layer with moderate thickness of around 1 km, the cloudless gap reaches its maximum when exceeding 600 m. The cloudless gap decreases in thickness as the two cloud layers become even thinner or thicker.

scholarly journals Determination of the united quality latent index of adaptability (UQLIA) and contribution of some environmental parameters to it for Deschampsia antarctica populations, Galindez island (Maritime Antarctic) season 2017/2018

2019 ◽  
Vol 16 (2) ◽  
pp. 190-202
Author(s):  
I. Y. Parnikoza ◽  
N. Y. Miryuta ◽  
V. Y. Ivanets ◽  
E. O. Dykyi
Keyword(s):  
Surface Temperature ◽  
Pairwise Comparison ◽  
Environmental Parameters ◽  
Soil Surface ◽  
Deschampsia Antarctica ◽  
Near Surface ◽  
Soil Surface Temperature ◽  
Experimental Populations ◽  
The Individual

The purpose of our work has been to determine the indicator of complex adaptability — the United Quality Latent Index of Adaptability (UQLIA) for the experimental populations of Deschampsia antarctica É. Desv. and study the contribution to it of some environmental factors such as the near soil surface temperature and organogens content. Materials and methods. The determination of UQLIA was based on a pairwise comparison of the differences between investigated parameters of populations by mathematical regression techniques. The soil surface temperature was measured by loggers installed near plants in each locus during April 2017 – April 2018. Results and conclusions. Temperature fluctuations were described during December 2017 – February 2018 for twelve experimental populations of D. antarctica and one control fragment of moss turf subformation from Galindez Island. Significant variations in average daily near surface temperature were observed during the study period between populations, especially in December and January. The UQLIA of D. antarctica for this season was calculated on the basis of the projective cover, biometric indices of generative plants and the content of protective and reserve proteins in seeds for the eleven populations. The values of the United Soil Surface Temperature Influence Index (UTII) for the season summer months and the United Organogens Content in Soil Influence Index (UOCSII) have been calculated for the individual parameters of D. antarctica plants adaptability. The reliable contribution of UTII to ULIA has been shown for December and January, at the moment of the greatest variation of soil surface temperature. UOCSII provided a reliable contribution to the ULIA only in the amount of UTII. Keywords: Deschampsia antarctica, United Quality Latent Index of Adaptability (UQLIA), contribution of soil surface temperature and organogens content to complex adaptability.

scholarly journals Evaluation of a Regional Reanalysis and ERA-Interim over East Asia Using In Situ Observations during 2013–14

2017 ◽  
Vol 56 (10) ◽  
pp. 2821-2844 ◽  
Author(s):  
Eun-Gyeong Yang ◽  
Hyun Mee Kim
Keyword(s):  
Relative Humidity ◽  
East Asia ◽  
Geopotential Height ◽  
Spatial Scales ◽  
Weather Prediction ◽  
Surface Wind ◽  
Lower Troposphere ◽  
Near Surface ◽  
Skill Scores ◽  
Regional Reanalysis

AbstractIn this study, the East Asia Regional Reanalysis (EARR) is developed for the period 2013–14 and characteristics of the EARR are examined in comparison with ERA-Interim (ERA-I) reanalysis. The EARR is based on the Unified Model with 12-km horizontal resolution, which has been an operational numerical weather prediction model at the Korea Meteorological Administration since being adopted from the Met Office in 2011. Relative to the ERA-I, in terms of skill scores, the EARR performance for wind, temperature, relative humidity, and geopotential height improves except for mean sea level pressure, the lower-troposphere geopotential height, and the upper-air relative humidity. In a similar way, RMSEs of the EARR are smaller than those of ERA-I for wind, temperature, and relative humidity, except for the upper-air meridional wind and the upper-air relative humidity in January. With respect to the near-surface variables, the triple collocation analysis and the correlation coefficients confirm that EARR provides a much improved representation when compared with ERA-I. In addition, EARR reproduces the finescale features of near-surface variables in greater detail than ERA-I does, and the kinetic energy (KE) spectra of EARR agree more with the canonical atmospheric KE spectra than do the ERA-I KE spectra. On the basis of the fractions skill score, the near-surface wind of EARR is statistically significantly better simulated than that of ERA-I for all thresholds, except for the higher threshold at smaller spatial scales. Therefore, although special care needs to be taken when using the upper-air relative humidity from EARR, the near-surface variables of the EARR that were developed are found to be more accurate than those of ERA-I.

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