atmospheric stability
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2022 ◽  
Vol 14 (2) ◽  
pp. 959
Author(s):  
Yanjiao Zheng ◽  
Lijuan Zhang ◽  
Wenliang Li ◽  
Fan Zhang ◽  
Xinyue Zhong

The amount of black carbon (BC) on snow surface can significantly reduce snow surface albedo in the visible-light range and change the surface radiative forcing effect. Therefore, it is key to study regional and global climate changes to understand the BC concentration on snow. In this study, we simulated the BC concentration on the surface snow of northeast China using an asymptotic radiative transfer model. From 2001 to 2016, the BC concentration showed no significant increase, with an average increase of 82.104 ng/g compared with that in the early 21st century. The concentration of BC in December was the largest (1344.588 ng/g) and decreased in January and February (1248.619 ng/g and 983.635 ng/g, respectively). The high black carbon content centers were concentrated in the eastern and central regions with dense populations and concentrated industries, with a concentration above 1200 ng/g, while the BC concentration in the southwest region with less human activities was the lowest (below 850 ng/g), which indicates that human activities played an important role in snow BC pollution. Notably, Heilongjiang province has the highest concentration, which may be related to its atmospheric stability in winter. These findings suggest that the BC pollution in northeast China has been aggravated from 2001 to 2016. It is estimated that the snow surface albedo will decrease by 16.448% due to the BC pollution of snow in northeast China. The problem of radiative forcing caused by black carbon to snow reflectivity cannot be ignored.


2022 ◽  
Vol 15 (1) ◽  
pp. 61-77
Author(s):  
Sabrina P. Cochrane ◽  
K. Sebastian Schmidt ◽  
Hong Chen ◽  
Peter Pilewskie ◽  
Scott Kittelman ◽  
...  

Abstract. Aerosol heating due to shortwave absorption has implications for local atmospheric stability and regional dynamics. The derivation of heating rate profiles from space-based observations is challenging because it requires the vertical profile of relevant properties such as the aerosol extinction coefficient and single-scattering albedo (SSA). In the southeastern Atlantic, this challenge is amplified by the presence of stratocumulus clouds below the biomass burning plume advected from Africa, since the cloud properties affect the magnitude of the aerosol heating aloft, which may in turn lead to changes in the cloud properties and life cycle. The combination of spaceborne lidar data with passive imagers shows promise for future derivations of heating rate profiles and curtains, but new algorithms require careful testing with data from aircraft experiments where measurements of radiation, aerosol, and cloud parameters are better colocated and readily available. In this study, we derive heating rate profiles and vertical cross sections (curtains) from aircraft measurements during the NASA ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) project in the southeastern Atlantic. Spectrally resolved irradiance measurements and the derived column absorption allow for the separation of total heating rates into aerosol and gas (primarily water vapor) absorption. The nine cases we analyzed capture some of the co-variability of heating rate profiles and their primary drivers, leading to the development of a new concept: the heating rate efficiency (HRE; the heating rate per unit aerosol extinction). HRE, which accounts for the overall aerosol loading as well as vertical distribution of the aerosol layer, varies little with altitude as opposed to the standard heating rate. The large case-to-case variability for ORACLES is significantly reduced after converting from heating rate to HRE, allowing us to quantify its dependence on SSA, cloud albedo, and solar zenith angle.


Atmosphere ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 61
Author(s):  
Nan-Ching Yeh ◽  
Yao-Chung Chuang ◽  
Hsin-Shuo Peng ◽  
Chih-Ying Chen

In Taiwan, the frequency of afternoon convection increases in summer (July and August), and the peak hour of afternoon convection occurs at 1500–1600 local solar time (LST). Afternoon convection events are forecasted based on the atmospheric stability index, as computed from the 0800 LST radiosonde data. However, the temporal and spatial resolution and forecast precision are not satisfactory. This study used the observation data of Aqua satellite overpass near Taiwan around 1–3 h before the occurrence of afternoon convection. Its advantages are that it improves the prediction accuracy and increases the data coverage area, which means that more airports can use results of this research, especially those without radiosondes. In order to determine the availability of Atmospheric Infrared Sounder (AIRS) in Taiwan, 2010–2016 AIRS and radiosonde-sounding data were used to determine the accuracy of AIRS. This study also used 2017–2018 AIRS data to establish K index (KI) and total precipitable water (TPW) thresholds for the occurrence of afternoon convection of four airports in Taiwan. Finally, the KI and TPW were calculated using the independent AIRS atmospheric sounding (2019–2020) to forecast the occurrence of afternoon convection at each airport. The average predictive accuracy rate of the four airports is 84%. Case studies at Hualien Airport show the average predictive accuracy rate of this study is 81.8%, which is 9.1% higher than that of the traditional sounding forecast (72.7%) during the same period. Research results show that using AIRS data to predict afternoon convection in this study could not only increase data coverage area but also improve the accuracy of the prediction effectively.


Atmosphere ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 27
Author(s):  
Lidiane de Oliveira Lemos ◽  
Antonio Carlos Oscar Júnior ◽  
Francisco Mendonça

This study aims to evaluate the thermal field of the central business district (CBD) of Rio de Janeiro during summer from land surface temperature (LST) and the thermal characteristics of the urban canopy layer (UCL) of the urban canyon in Avenida Rio Branco. In order to conduct this evaluation, two methods were employed: (1) TIRS Landsat-8 sensor for data selection and processing (latest generation, 2011–2020); (2) a field survey using nine sampling points—seven along two mobile transects, one fixed point, and one vertical measurement point, which required the use of an RPA (remotely piloted aircraft). Three categories of analysis were established for the field survey based on the prevailing synoptic situations: stability, instability, and post-instability. The CBD is characterized by extensive areas with surface heat islands, in which temperatures were higher than 38.9 °C; the areas with milder LSTs were Campo do Santana, Avenida Rio Branco, and one of the mixed-use zones (Praça Mauá). With respect to Rio Branco Avenue, the LST niches of lowest elevation were derived through building shadowing; however, due to the nature of the data, the orbital data diverged from the observation data of the 10 field-study days. In situ data revealed that the characteristics urban morphology of Avenida Rio Branco, by contrast with the LST result, is susceptible to the formation of atmospheric heat islands, presenting heat islands of very strong magnitude (over 6.1 °C) in atmospheric stability, strong magnitude (4.1–6.0 °C) in atmospheric instability, and moderate magnitude (2.1–4.0 °C) in post-atmospheric instability. Despite the synoptic situation, thermal cores were concentrated at 1 p.m. The intersection between Avenida Rio Branco, Rua do Ouvidor, and Praça Mauá stored most of the solar energy received during the day due to the greater sky obstruction caused by the verticalization. Finally, vertical analysis demonstrated the formation of a thermal inversion on the night of the highest mean air temperature (29.5 °C), probably due to the roughness and number of buildings in the urban canyon.


Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8483
Author(s):  
Tomasz Węsierski ◽  
Robert Piec ◽  
Małgorzata Majder-Łopatka ◽  
Bernard Król ◽  
Wiktor Gawroński ◽  
...  

The publication presents the results of a field test of 2–4 min releases of 96% LNG from a road tanker designed to carry the gas. The release was performed at a pressure of 5.9–6.1 atm at a discharge rate of 1.67–1.78 kg/s from a height of 0.75 m under class B conditions of atmospheric stability. Comparison of the obtained experimental results of the maximum concentrations and the simulation carried out with the EFFECS (11.2.0) software showed that the Gaussian gas model better describes the gas cloud propagation at most control points at this release intensity than the dense gas model. The dense gas model gave only slightly better results along the cloud propagation axis at close distances, not exceeding 25/30 m at ground level. It is shown that concentrations between 71% and 110% LEL are observed at the cloud visibility limit. The maximum value of the temperature drop, in the release axis, at a distance of 4 m amounts to ∆Tmax = 93.3 °C. This indicates that the cloud of the released LNG is almost entirely in the vapour state already in the short distance from the point of release, due to the turbulent outflow of the pressurised gas.


Atmosphere ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1619
Author(s):  
Yingsai Ma ◽  
Xianhong Meng ◽  
Yinhuan Ao ◽  
Ye Yu ◽  
Guangwei Li ◽  
...  

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.


Urban Climate ◽  
2021 ◽  
Vol 40 ◽  
pp. 101008
Author(s):  
Jia-li Feng ◽  
Xiao-ming Cai ◽  
Lee Chapman ◽  
Qi-lin Wan ◽  
Xin Xia ◽  
...  

MAUSAM ◽  
2021 ◽  
Vol 58 (2) ◽  
pp. 251-260
Author(s):  
JAGADISH SINGH ◽  
R. K. GIRI ◽  
SURYA KANT

The intense, long-spell and synoptic scale fog over north India has been studied using Very High Resolution Radiometer (V.H.R.R.) visible imageries of INSAT-1D and Kalpana Geo-Stationary satellites. The intensity, coverage and characteristics of fog seen in satellite imageries are found to be in conformity with the ground –based surface meteorological observations. The unusually long spell fog formations have been explained using maximum temperature and relative humidity anomalies of I.G.I Airport, New Delhi, Amousi Airport, Lucknow, Babatpur Airport, Varanasi and Rajasansi Airport, Amritsar. Atmospheric stability of very high order was seen in the lower part of the atmosphere at Delhi creating favourable condition for the formation of intense and long-spell fog. The relation between Wetness Index derived based on Basist study (1998) using 19, 37 and 85 GHz frequency channels of Special Sensor Microwave/Imager (SSM/I) onboard Defense Meteorological Satellite Programme (DMSP) satellite and fog duration were studied.  


MAUSAM ◽  
2021 ◽  
Vol 59 (1) ◽  
pp. 69-76
Author(s):  
M. EL-NOUBY ADAM ◽  
SAYED M. EL SHAZLY

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