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Publications
Publications (136)
A fast instrument simulator is developed to simulate the observations made in cloudy atmospheres by the Visible Infrared Imaging Radiometer Suite (VIIRS). The correlated k-distribution (CKD) technique is used to compute the transmissivities associated with absorbing atmospheric gases. The bulk scattering properties of ice clouds are based on the ic...
The absorption Ångström exponent (AAE) is an important aerosol optical parameter used for aerosol characterization and apportionment studies. The AAE of black carbon (BC) particles is widely accepted to be 1.0, although observational estimates give quite a wide range of 0.6–1.3. With considerable uncertainties related to observations, a numerical s...
With the development and the improvement of meteorological satellites, different instruments have significantly enhanced the ability to observe clouds over large spatial regions. Recent geostationary satellite radiometers, e.g., Advanced Himawari Imager (AHI) and Advanced Geosynchronous Radiation Imager (AGRI) onboard the Himawari-8 and the Fengyun...
With the increasing use of satellite and ground-based high spectral resolution (HSR) measurements for weather and climate applications, accurate and efficient radiative transfer (RT) models have become essential for accurate atmospheric retrievals, instrument calibration, and to provide benchmark RT solutions. This study develops a spectral data co...
Current satellite cloud products from passive radiometers provide effective single‐layer cloud properties by assuming a homogeneous cloud in a pixel, resulting in inevitable biases when multiple‐layer clouds are present in a vertical column. We devise a novel method to retrieve cloud vertical properties for ice‐over‐water clouds using passive radio...
Color of the sky serves as a direct indicator of haze, while also exerting substantial influence on human physiological and psychological well-being, as well as the overall environmental scenery. However, quantifying color changes is quite challenging. This research develops a quantitative approach for evaluating the influence of atmospheric aeroso...
Plain Language Summary
Black carbon (BC) significantly affects the radiation balance of the globe due to its light‐absorbing capability. The absorption enhancement of BC Eabs $\left({E}_{\mathit{abs}}\right)$ is induced when BC is coated by other components. However, large discrepancies exist between observed and simulated Eabs ${E}_{\mathit{abs}}$...
Sea surface temperature (SST) is a crucial parameter in climate, weather, and ocean sciences due to its decisive role in ocean–atmosphere interactions. Identifying errors in the prognostic scheme used by the current European Centre for Medium-range Weather Forecasts (ECMWF) model for predicting the diurnal variation in ocean skin temperature led to...
Black carbon (BC) radiative impact is significantly influenced by its mixing state. Single-particle soot photometer (SP2) is a widely recognized instrument for quantifying BC mixing state. However, the derivation of BC mixing state from SP2 is quite challenging. Since the SP2 records individual particle signals, it requires complex data processing...
A large portion of cloud scenes over the globe shows multiple layers composed of different phases, in general with ice clouds on the top and liquid water clouds beneath. Such multi‐layer (ML) clouds constitute major challenges in cloud observations and weather and climate modeling. This study improved a threshold algorithm for detecting ice‐over‐wa...
Measurements studies have shown that the absorption of radiation by black carbon (BC) increases as the particles age. However, there are significant discrepancies between the measured and modeled absorption enhancement (Eabs), largely due to the simplifications used in modeling the mixing states and shape diversities. We took advantage of chamber e...
Cloud base height (CBH) is a crucial parameter for cloud radiative effect estimates, climate change simulations, and aviation guidance. However, due to the limited information on cloud vertical structures included in passive satellite radiometer observations, few operational satellite CBH products are currently available. This study presents a new...
Modeling atmospheric black carbon (BC) aerosol optical properties remains largely uncertain due to their complex mixing states, nonsphericity, and heterogeneity of coating distribution. Although there exist numerical models with realistic BC morphologies, these models are mostly limited to particle‐scale studies and have not been coupled to large‐s...
Black carbon (BC) exerts a notable warming effect due to its strong light absorption, largely influenced by its "mixing state". However, due to computational constraints, mixing state is challenging to accurately represent in large-scale models. In this study, we employ a particle-resolved model to simulate the evolution of BC mixing state based on...
Black carbon (BC) exerts significant impacts on both climate and environment. BC aging process alters its hygroscopicity and light absorption properties. Current models, like the Weather Research and Forecasting – Community Multiscale Air Quality (WRF-CMAQ) two-way coupled model, inadequately characterize these alterations. In this study, we accoun...
Cloud base height (CBH) is a crucial parameter for cloud radiative effect estimates, climate change simulations, and aviation guidance. However, due to the limited information on cloud vertical structures included in passive satellite radiometer observations, few operational satellite CBH products are currently available. This study presents a new...
Fire hazard is a crucial issue in urban arears. Fire plumes have large buoyancy forces and can significantly change the flow pattern around buildings. However, the interaction of these plumes with buildings under atmospheric boundary flow conditions has rarely been studied, and the effect on the wake characteristics of the buildings remains unclear...
Understanding the flow and flame dynamics is important due to its relevance in wildfires, which become severe in recent years. The flow and flame dynamics of wildfire have been extensively studied on flat and inclined surface but are rarely studied under rough surface, such as the condition of a ridge or a hill, which is relevant for many of the wi...
Atmospheric radiation is a major branch of atmospheric physics that encompasses the fundamental theories of atmospheric absorption, particle scattering (aerosols and clouds), and radiative transfer. Specifically, the simulations of atmospheric gaseous absorption and scattering properties of particles are the essential components of atmospheric radi...
The subject of “atmospheric radiation” includes not only fundamental theories on atmospheric gaseous absorption and the scattering and radiative transfer of particles (molecules, cloud, and aerosols), but also their applications in weather, climate, and atmospheric remote sensing, and is an essential part of the atmospheric sciences. This review in...
Brown carbon (BrC) is an organic carbon component with noticeable absorption in the ultraviolet and short visible wavelengths, which influences the global radiative balance. However, assessing BrC radiative effects remains a challenging task owing to the scarcity of direct BrC observations and the uncertainties regarding their chemical and optical...
Sea surface temperature (SST) is a pivotal parameter in climate, weather, and ocean sciences because it plays a decisive role in ocean-atmosphere interactions. Identifying deficiencies in the ERA5 reanalysis of ocean skin temperature, we revisited the ocean mixed layer (OML) model used at ECMWF and identified errors in the model, and revised it acc...
While a variety of methods have been developed for estimating single-layer cloud base height (CBH), few studies have been introduced for retrieving overlapping CBH. To enhance the characterization of the vertical structure of overlapping clouds, which account for approximately a quarter of global clouds, this study presents an extrapolation algorit...
Cloud liquid water path (LWP) quantifies liquid water amount within the atmosphere and is closely related to water cycle, weather, and climate. Passive microwave (MW) observations are powerful tools for retrieving LWP. An empirical relationship between the LWPs and brightness temperatures (BTs) can be obtained for conventional retrievals, which con...
The discrete dipole approximation (DDA) simulates optical properties of particles with any given shape based on the volume discretization. These calculations cost a large amount of time and memory to achieve high accuracy, especially for particles with large sizes and complex geometric structures, such as mixed black-carbon aerosol particles. We sy...
Brown carbon (BrC) is an organic carbon component with noticeable absorption in the ultraviolet and short visible wavelengths, which influences the global radiative balance. However, the assessment of BrC radiative effects remains a challenging task because of the scarcity of direct BrC observations and uncertainties in their chemical and optical p...
Atmospheric black carbon (BC) aerosols have been long‐lasting uncertain components in environmental and climate studies. Global climate models (GCMs) potentially overestimate BC absorption efficiency due to a lack of consideration of complex BC microphysical and mixing properties. We extract multiple BC properties from observations and develop an a...
In this study, a thermal infrared (TIR) based convolutional neural network (TIR-CNN), originally designed for retrieving cloud optical properties from TIR radiometry, is further developed to obtain global cloud base height (CBH) and cloud thermodynamic phase during both daytime and nighttime. It employs TIR radiances, cloud optical properties retri...
Wildfires emit large amounts of black carbon and light-absorbing organic carbon, known as brown carbon, into the atmosphere. These particles perturb Earth’s radiation budget through absorption of incoming shortwave radiation. It is generally thought that brown carbon loses its absorptivity after emission in the atmosphere due to sunlight-driven pho...
Cloud base heights (CBHs) play an important role in weather and climate studies, but remain one of the most challenging properties to be inferred using passive satellite spectral instruments. This is because spectral signals detected from space are mainly from cloud tops and contain minimal information on cloud vertical structures owing to limited...
Mingyue Su Chao Liu Di Di- [...]
B.J. Sohn
Forward radiative transfer (RT) models are essential for atmospheric applications such as remote sensing and weather and climate models, where computational efficiency becomes equally as important as accuracy for high-resolution hyperspectral measurements that need rigorous RT simulations for thousands of channels. This study introduces a fast and...
Data assimilation of satellite microwave measurements is one of the important keys to improving weather forecasting over the Arctic region. However, the use of surface‐sensitive microwave‐sounding channel measurements for data assimilation or retrieval has been limited, especially during winter, due to the poorly constrained sea ice emissivity. In...
Black carbon (BC) plays an important role in the climate system because of its strong warming effect, yet the magnitude of this effect is highly uncertain owing to the complex mixing state of aerosols. Here we build a unified theoretical framework to describe BC’s mixing states, linking dynamic processes to BC coating thickness distribution, and sh...
The flyby of the New Horizons spacecraft in 2015 July revealed an unexpected cold atmosphere of Pluto and confirmed the existence of its atmospheric haze. The observed and simulated vertical profiles of chemical species and microphysical processes suggest that the haze particles in Pluto’s middle and lower atmosphere may contain organic ice condens...
Radiative calibration of satellite spectral radiometers is essential for their downstream applications. The Medium Resolution Spectral Imager (MERSI-II) is a key instrument of the Chinese polar orbit Fengyun-3D (FY-3D) satellite. However, its calibration performance has not been sufficiently studied, which limits its broad application. This study r...
In the above article
[1]
, a difference in the definitions of our simulated reflectance (with respect to instantaneous TOA radiance) and the operational MERSI-II L1 reflectance (with respect to solar constant) causes errors in their direct comparisons.
In this study, a deep learning algorithm is developed to consistently retrieve the daytime and nighttime cloud properties from passive satellite observations without auxiliary atmospheric parameters. The algorithm involves the thermal infrared (TIR) radiances, viewing geometry, and altitude into a convolutional neural network (denoted as TIR-CNN),...
Black carbon (BC) plays an important role in the climate system due to its strong warming effect, yet the magnitude of this effect is highly uncertain due to the complex mixing state of aerosols. Here we build a unified theoretical framework to describe BC’s mixing states, linking dynamic processes to BC coating thickness distribution, and show its...
You Zhao Chao Liu Di Di- [...]
Shihao Tang
Typhoon-related precipitation over land can result in severe disasters such as floods and landslides, and satellites are a valuable tool for estimating surface precipitation with high spatial-temporal resolutions. Accordingly, this study develops a surface precipitation integration framework to combine high-resolution observations from the radiomet...
Airborne aerosols reduce surface solar radiation through light scattering and absorption (aerosol direct effects, ADEs), influence regional meteorology, and further affect atmospheric chemical reactions and aerosol concentrations. The inhibition of turbulence and the strengthened atmospheric stability induced by ADEs increases surface primary aeros...
Cloud top properties (CTPs) are important satellite products. However, the failures of CTPs derived from the Advanced Geostationary Radiation Imager of FengYun-4A (FY-4A/AGRI) have been occasionally reported by users. To this end, the feasibility of the operational CTP algorithm has been reviewed. First, this study reveals the slight differences in...
Plain Language Summary
Supercooled water clouds (SWCs) are clouds with temperatures under the freezing point but still containing liquid water droplets. The detection of SWCs is crucial for aviation safety as aviation accidents are frequently caused by the accumulation of supercooled water droplets on airplanes. Detecting SWCs is also critical for...
Due to rapid urbanization and intense human activities, the urban heat island (UHI) effect has become a more concerning climatic and environmental issue. A high-spatial-resolution canopy UHI monitoring method would help better understand the urban thermal environment. Taking the city of Nanjing in China as an example, we propose a method for evalua...
Satellite remote sensing is an important method for forest phenological studies at continental or global scales. Sentinel-1 (S1), a polar orbit satellite with a spatial resolution of 10 m, provides an opportunity to observe high-resolution forest phenology. The sensitivities of S1 C-band backscatter measurements to vegetation phenology, such as cro...
You Zhao Chao Liu Di Di- [...]
Shihao Tang
Typhoon-related precipitation over land can result in severe disasters such as floods and landslides, and satellites are a valuable tool to estimate surface precipitation with high spatial-temporal resolutions. This study develops a high-resolution surface precipitation integration framework to combine observations from geostationary Fengyun-4A/ Hi...
Pluto, Titan, and Triton make up a unique class of solar system bodies, with icy surfaces and chemically reducing atmospheres rich in organic photochemistry and haze formation. Hazes play important roles in these atmospheres, with physical and chemical processes highly dependent on particle sizes, but the haze size distribution in reducing atmosphe...
This paper compiles indices for the El Niño—Southern Oscillation (ENSO) and seven unforced decadal-to-multidecadal climate modes (Interdecadal Pacific Oscillation (IPO), Tripole Pacific Index (TPI), Pacific Decadal Oscillation focused over North Pacific (PDO) and South Pacific (SPDO), North Atlantic Multidecadal Oscillation (AMO), South Atlantic Mu...
Under the assumption that clouds are homogeneous and single-layered (SL), most current operational cloud top height (CTH) products derived from passive radiometers may largely underestimate the CTH of overlapping clouds. This article proposes a statistics-based extrapolation algorithm for retrieving the CTHs of overlapping clouds using only existin...
The result of Aethalometer model to black carbon (BC) source apportionment is highly determined by the absorption Ångström exponent ( α ) of aerosols from fossil fuel combustion ( α ff ) and wood burning ( α wb ). A method using hourly measured potassium to calculate the α ff and α wb values was developed in this study. Results showed that the opti...
Direct Aerosol Radiative Forcing (DARF) characterizes aerosol influences on the radiative energy budget due to scattering and absorption of solar radiation, while clear uncertainties remain in both global and regional DARF estimations due to differences on aerosol properties and time periods considered. Through a multi-source strategy, this study s...
Deriving large-scale and high-quality precipitation products from satellite remote-sensing spectral data is always challenging in quantitative precipitation estimation (QPE), and limited studies have been conducted even using China's latest Fengyun-4A (FY-4A) geostationary satellite. Taking three rainstorm events over South China as examples, a mac...
Due to rapid urbanization and intense human activities, the urban heat island (UHI) effect has become a more concerning climatic and environmental issue. A high spatial resolution canopy UHI monitoring method would help better understand the urban thermal environment. Taking the city of Nanjing in China as an example, we propose a method for evalua...
The paper presents a systematic description about the observation scheme analysis and practical observation of artificially triggered lightning with a ground-based microwave radiometer together with other discharging observation instruments at Guangzhou Field Experiment Site for Lightning research and testing in Conghua, Guangdong in the thundersto...
Data assimilation of Short-Wave (SW, ≤ 4μm) satellite radiance in cloudy regions could potentially improve cloud forecasts. Operational SW observation operators neglect cloud 3D radiative effects, which may cause nonnegligible errors in some circumstances, for example, with large solar zenith angles or for broken clouds. This study introduced a mac...
Deriving large-scale and high-quality precipitation products from satellite remote sensing spectral data is always challenging in quantitative precipitation estimation (QPE), and limited studies have been conducted even using the China’s latest Fengyun-4A (FY-4A) geostationary satellite. Taking three rainstorm events over South China as examples, a...
Cloud Masking is one of the most essential products for satellite remote sensing and downstream applications. This study develops machine learning-based (ML-based) cloud detection algorithms using spectral observations for the Advanced Himawari Imager (AHI) onboard the Himawari-8 geostationary satellite. Collocated active observations from Cloud-Ae...