Daniel Rosenfeld

• Professor
• Professor (Full) at Hebrew University of Jerusalem

Aerosol interactions with clouds represent a significant uncertainty in our understanding of the Earth system. Deep convective clouds may respond to aerosol perturbations in several ways that have proven difficult to elucidate with observations. Here, we leverage the two busiest maritime shipping lanes in the world, which emit aerosol particles and...

Cloud adiabatic fraction (fad) is an important metric that quantitatively characterizes the impact of atmospheric mixing on cloud thermodynamic properties. Due to the lack of vertical profiling of cloud water, previous studies on the vertical variability of fad within clouds have been confined to single cloud scales. Our prior research achieved a b...

Marine cloud brightening (MCB) geoengineering aims to inject aerosols over oceans to brighten clouds and reflect more sunlight in order to offset the impacts of global warming or to achieve localized climate cooling. The relative contributions of direct and indirect effects in MCB implementations remain uncertain. Here, we quantify both effects by...

Warm rain prevails in clean marine clouds and is one of the most abundant types of precipitation in the world. However, warm rain is rarely observed in urban polluted atmospheric environments due to high number concentrations of aerosols generally suppress the occurrence of warm rain. Three aircraft observation of clouds were used during summer in...

Marine low clouds play a crucial role in cooling the climate, but accurately predicting them remains challenging due to their highly non‐linear response to various factors. Previous studies usually overlook the effects of cloud droplet number concentration (N d ) and the non‐local information of the target grids. To address these challenges, we int...

Marine low clouds tend to organize into larger mesoscale patterns with distinct morphological appearances over the ocean, referred to as mesoscale morphology. While prior studies have mainly examined the fundamental characteristics and shortwave radiative effects of these mesoscale morphologies, their behaviour in the nighttime marine boundary laye...

The uncertainty of climate projection is significantly related to warm cloud feedback, which involves a complex interplay of various mechanisms. However, it is hard to unentangle temperature's impact on a single cloud with experiments, since the cloud dynamics always covary with environmental thermodynamical conditions. In this study, we investigat...

Previous studies have shown that aerosols invigorate deep convective systems (DCS). However, the magnitude or even the existence of aerosol invigoration of DCS remains controversial. Here, we aimed to observationally quantify the full aerosol effects on DCS by tracking their entire lifecycle and spatial extent in tropical regions. We found that fin...

Aerosol interactions with clouds represent a significant uncertainty in our understanding of the Earth system. Deep convective clouds may respond to aerosol perturbations in several ways that have proven difficult to elucidate with observations. Here, we leverage the two busiest maritime shipping lanes in the world, which emit aerosol particles and...

Climate models commonly overestimate warm rain frequency and underestimate its intensity over the ocean, primarily due to insufficient representation of the aerosol effects. This pertains to both fine aerosols (FA) and coarse sea spray aerosols (CSA), where the latter is mostly absent in the models. Here, our observations show that adding CSA enhan...

Marine Cloud Brightening (MCB) geoengineering aims to inject aerosols over oceans to brighten clouds and reflect more sunlight to offset the impacts of global warming or to achieve localized climate cooling. There is still controversy about the contributions of direct and indirect effects of aerosols in implementing MCB and the lack of quantitative...

Clouds can be classified into regimes based on their appearance or meteorological controlling factors. The cloud appearance regimes inherently include adjustments to aerosol effects, such as transitions between closed and open cells. Therefore, calculating cloud susceptibilities to aerosols for each cloud‐appearance regime individually and then agg...

Understanding how aerosols affect cloud cover is critical for reducing the large uncertainty of the aerosol‐cloud interaction (ACI). The 2014 Holuhraun effusive eruption in Iceland resulted in a significant increase in cloud drop number concentration (Nd) relative to the climatological Nd observed during periods of relatively infrequent volcanic ac...

The complexity of ice particles in the atmosphere makes it difficult to model microphysical growth processes accurately. In this study, we simulated a snowfall case over Northern China Plain using two different microphysics schemes, that is, Thompson and Morrison schemes, in the Advanced Research WRF (Weather Research and Forecasting) model. Both s...

Satellites are required for the global measurement of aerosol cloud-mediated radiative forcing, but satellite retrievals of aerosols and cloud properties still have challenges to overcome.

The quantification of cloud droplet number concentration (Nd) is essential in gaining insights into the aerosol‐cloud interactions (ACI), contributing to the most significant source of anthropogenic climate forcing uncertainty. This study compared the retrieved Nd from Moderate Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imagi...

Plain Language Summary Clouds lose water through evaporation and precipitation. The cloud adiabatic fraction (fad) represents the degree of cloud mixing with the surrounding air. A smaller fad corresponds to a stronger atmospheric mixing, which leads to a decrease in the amount of cloud water and coverage, thereby resulting in less solar radiation...

Atmospheric aerosols affect the Earth's climate in many ways, including acting as the seeds on which cloud droplets form. Since a large fraction of these particles is anthropogenic, the clouds' microphysical and radiative characteristics are influenced by human activity on a global scale leading to important climatic effects. The respective change...

Exceptionally high‐energy lightning strokes >10⁶ J (X1000 stronger than average) in the very low‐frequency band between 5 and 18 kHz, also known as superbolts (SB), occur mostly during winter over the North‐East Atlantic, the Mediterranean Sea, and over the Altiplano in South America. Here we compare the World‐Wide Lightning Location Network databa...

Protecting the population from aerosol pollution relies on forecasts using models with aerosol composition, yet the respective contributions of aerosol components are poorly known. In particular, the contribution of inorganic condensable particulate matter (PM) to aerosols is likely to be underestimated in most models because condensable particulat...

Plain Language Summary Aerosol has been observed and simulated to be directly associated with the development of strong convective storms, termed as Primary Aerosol Convective Invigoration (PAI). However, the current consensus is that meteorology also affects aerosol distribution, that is, there is covariability between meteorology and aerosols, po...

The global methane pledge paves a fresh, critical way toward carbon neutrality. However, it remains largely invisible and highly controversial due to the fact that planet-scale and plant-level methane retrievals have rarely been coordinated. This has never been more essential within the narrow window to reach the Paris target. Here we present a two...

Acting as efficient ice‐nucleating particles, dust particles can affect cirrus cloud properties through heterogeneous nucleation. A dust‐infused baroclinic storm (DIBS) over East Asia in May 2017 was examined using satellite observations and the Weather Research and Forecasting model coupled with chemistry (WRF‐Chem) to study the dust effects on ci...

Plain Language Summary Changes in the cloud fraction (CF) of marine low‐level clouds have a considerable impact on the radiation budget because they reflect solar radiation into space and greatly cool the planet. Past studies have shown that precipitation plays an important role in the transition between different CF regimes, but the relationship b...

Anthropogenic activities have drastically impacted the climate system since the Industrial Revolution. However, to what extent anthropogenic emissions influence the cloud droplet number concentration (Nd), the critical parameter for understanding aerosol‐cloud interactions, is poorly known on the hemispheric scale due to the considerable retrieval...

Nitrogen oxides (NOx ≡ NO + NO2) play a central role in air pollution and are targeted for emission mitigation by environmental protection agencies globally. Unique challenges for mitigation are presented by super-emitters, typically with the potential to dominate localized NOx budgets. Nevertheless, identifying super-emitters still challenges emis...

Accurate tracking of all components (including core, anvil, and cirrus) of deep convective systems (DCSs) throughout their lifecycle is key to quantifying their impacts on radiative forcing, especially of the anvil and cirrus. Here, a new Full‐tracking Algorithm for Convective Thunderstorm System is developed based on geostationary satellite. It su...

A method to derive the 3D cloud envelope and the cloud development velocity from high spatial and temporal resolution satellite imagery is presented. The CLOUD instrument of the recently proposed C3IEL mission lends itself well to observing at high spatial and temporal resolutions the development of convective cells. Space-borne visible cameras sim...

We investigated the relationship between the number concentration of cloud droplets (Nd) in ice‐free convective clouds and of particles large enough to act as cloud condensation nuclei (CCN) measured at the lateral boundaries of cloud elements. The data were collected during the ACRIDICON‐CHUVA aircraft campaign over the Amazon Basin. The results i...

Fine aerosols, by acting as cloud condensation nuclei, suppress rainfall and enhance the albedo and coverage of marine warm clouds, thereby partly counteracting the greenhouse-induced warming. While this is relatively well documented, the co-existing opposite effects of giant cloud condensation nuclei from coarse sea spray aerosols are poorly quant...

Representing subgrid variability of cloud properties has always been a challenge in global climate models (GCMs). In many cloud microphysics schemes, the warm rain non‐linear process rates calculated based on grid‐mean cloud properties are usually scaled by an enhancement factor (EF) to account for the effects of subgrid cloud variability. In our s...

Condensable particulate matter (CPM) emitted from stationary combustion and mobile sources exhibits high emissions and a large proportion of organic components. However, CPM is not generally measured when conducting emission surveys of PM in most countries, including China. Consequently, previous emission inventories have not included emission rate...

Aerosols significantly affect the Earth–atmosphere energy balance and climate change by acting as cloud condensation nuclei. Specifically, the susceptibility of cloud and precipitation to aerosols is stronger when aerosols are faint but tends to be saturated in polluted conditions. However, previous methodologies generally miss these faint aerosols...

The known effects of thermodynamics and aerosols can well explain the thunderstorm activity over land, but fail over oceans. Here, tracking the full lifecycle of tropical deep convective cloud clusters shows that adding fine aerosols significantly increases the lightning density for a given rainfall amount over both ocean and land. In contrast, add...

The microphysical characteristics of wintertime cold clouds in North China were investigated from 22 aircraft observation flights from 2014 to 2017, 2020, and 2021. The clouds were generated by mesoscale weather systems with little orographic component. Over the mixed-phase temperature range (−10°C to 0°C), the average fraction of liquid, mixed-pha...

The global methane pledge paves a fresh, critical way toward Carbon Neutrality. However, it remains largely invisible and highly controversial due to the fact that planet-scale and plant-level methane retrievals have rarely been coordinated. This has never been more essential within a narrow window to reach the Paris target. Here we present a versa...

Light-duty gasoline vehicles (LDGVs) have made up >90 % of vehicle fleets in China since 2019, moreover, with a high annual growth rate (> 10 %) since 2017. Hence, accurate estimates of air pollutant emissions of these fast-changing LDGVs are vital for air quality management, human healthcare, and ecological protection. However, this issue is poorl...

We present a new approach of analyzing and interpreting vertical profiles of cloud microstructure obtained by satellite remote sensing. The method is based on a spectral bin microphysics adiabatic parcel model and aims to elucidate the effects of aerosols on the evolution of convective clouds and related microphysical processes, including the activ...

Increasing severe and persistent ozone pollution in China has resulted in serious harm to human health in recent years, yet the precise pollution sources are poorly known because there is few knowledge on large-scale extreme ozone episodes. Here, we studied the formation of the historical orange-alert regional ozone episode in eastern China on 6 Ju...

Condensable particulate matter (CPM) emitted from stationary combustion and mobile sources exhibits high emissions and a large proportion of organic components. However, CPM is not generally measured when conducting emission surveys of PM in most countries, including China. Consequently, previous emission inventories have not included emission rate...

This review presents how the boreal and the tropical forests affect the atmosphere, its chemical composition, its function, and further how that affects the climate and, in return, the ecosystems through feedback processes. Observations from key tower sites standing out due to their long-term comprehensive observations: The Amazon Tall Tower Observ...

A method to derive the 3D cloud envelope and the cloud development velocity from high spatial and temporal resolution satellite imagery is presented. The CLOUD instrument of the recently proposed C3IEL mission lends itself well to observing at high spatial and temporal resolutions the development of convective cells. Space-borne visible cameras sim...

Aerosols significantly affect the Earth-atmosphere energy balance and climate change by acting as cloud condensation nuclei. Particularly, the susceptibility of clouds to aerosols is more pronounced when the aerosols are faint. However, previous methodologies generally miss these faint aerosols and their climate effect based on instantaneous observ...

The regime-dependence of aerosol-cloud interaction has recently been highlighted and explored using idealized cloud-resolving models in previous studies. We further utilized synergistic observations from satellites and LiDARs to reinforce understandings of this interaction, and then examined and clarified the regime dependence of aerosol indirect e...

Clouds play a major role in Earth's energy budget and hydrological cycle. Clouds dynamical structure and mixing with the ambient air have a large impact on their vertical mass and energy fluxes and on precipitation. Most of the cloud evolution and mixing occurs at scales smaller than presently observable from geostationary orbit, which is less than...

Aerosol–cloud interactions (ACIs) are considered to be the most uncertain driver of present-day radiative forcing due to human activities. The nonlinearity of cloud-state changes to aerosol perturbations make it challenging to attribute causality in observed relationships of aerosol radiative forcing. Using correlations to infer causality can be ch...

In-time and accurate assessments of on-road vehicle emissions play a central role in urban air quality and health policymaking. However, official insight is hampered by the Inspection/Maintenance (I/M) procedure conducted in the laboratory annually. It not only has a large gap to real-world situations (e.g., meteorological conditions) but also is i...

Boreal forest acts as a carbon sink and contributes to the formation of secondary organic aerosols via emission of aerosol precursor compounds. However, these influences on the climate system are poorly quantified. Here we show direct observational evidence that aerosol emissions from the boreal forest biosphere influence warm cloud microphysics an...

Aerosol–cloud interactions contribute to the large uncertainties in current estimates of climate forcing. We investigated the effect of aerosol particles on cloud droplet formation by model calculations and aircraft measurements over the Amazon and over the western tropical Atlantic during the ACRIDICON–CHUVA campaign in September 2014. On the HALO...

Urban on-road vehicle emissions affect air quality and human health locally and globally. Given uneven sources, they typically exhibit distinct spatial heterogeneity, varying sharply over short distances (10 m–1 km). However, all-around observational constraints on the emission sources are limited in much of the world. Consequently, traditional emi...

Low clouds play a key role in the Earth-atmosphere energy balance and influence agricultural production and solar-power generation. Smoke aloft has been found to enhance marine stratocumulus through aerosol-cloud interactions, but its role in regions with strong human activities and complex monsoon circulation remains unclear. Here we show that bio...

We explore the decoupling physics of a stratocumulus-topped boundary layer (STBL) moving over cooler water, a situation mimicking warm-air advection (WADV). We simulate an initially well-mixed STBL over a doubly periodic domain with the sea surface temperature decreasing linearly over time using the System for Atmospheric Modeling large-eddy model....

In this study, the variability of the spectral dispersion of droplet size distributions (DSDs) in convective clouds is investigated. Analyses are based on aircraft measurements of growing cumuli near the Amazon basin, and on numerical simulations of an idealized ice‐free cumulus. In cleaner clouds, the relative dispersion ϵ, defined as the ratio of...

Plain Language Summary Marine low‐lying clouds cool by emitting thermal radiation. The cooling is known as cloud top radiative cooling (CTRC). A change in CTRC can influence the properties of marine clouds via many avenues, ranging from altering the vertical motions of the clouds to changing the clouds' ability to reflect sunlight. Despite the impo...

In-time and accurate assessments of on-road vehicle emissions play a central role in urban air quality and health policymaking. However, official insight is hampered by the Inspection/Maintenance (I/M) procedure conducted in the laboratory annually. It not only has a large gap to real-world situations (e.g., meteorological conditions) but also is i...

Quantifying the precipitation within clouds is a crucial challenge to improve our current understanding of the Earth's hydrological cycle. We have investigated the relationship between the effective radius of droplets and ice particles (re) and precipitation water content (PWC) measured by cloud probes near the top of growing convective cumuli. The...

Aerosol-cloud interactions (ACI) are considered to be the most uncertain driver of present-day radiative forcing due to human activities. The non-linearity of cloud-state changes to aerosol perturbations make it challenging to attribute causality in observed relationships of aerosol radiative forcing. Using correlations to infer causality can also...

Urban on-road vehicle emissions affect air quality and human health locally and globally. Such emissions typically exhibit distinct spatial heterogeneity, varying sharply over short distances (10 m ~ 1 km). However, all-around observational constraints on the emission sources are limited in much of the world. Consequently, traditional emission inve...

Satellite-based cloud base and top height (CBH and CTH) and cloud geometrical thickness (CGT) are validated against ground-based lidar measurements and provide new scientific insights. The satellite measurements are done by the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO). The retrieval methodology is built on the 333...

This chapter assesses multiple lines of evidence to evaluate past, present and future changes in the global water cycle. It complements material in Chapters 2, 3, and 4 on observed and projected changes in the water cycle, and Chapters 10 and 11 on regional climate change and extreme events. The assessment includes the physical basis for water cycl...

The current Geostationary Operational Environmental Satellites (GOES-16 and 17) cloud-top phase classification algorithm is based primarily on empirical thresholds at multiple wavelengths that have varying absorption capabilities for water and ice. The performance of current GOES-16 cloud-top phase product largely depends on the accuracy of the sel...

Rising air pollution by surface ozone (O3) in China has induced extensive efforts to control ozone generation in major urban and industrial areas, yet mechanisms ruling the ozone production and loss are not well understood. In particular, ozone levels are strongly influenced by meteorological factors such as relative humidity, but this has been exp...

Transportation contributes to around one-fifth of global greenhouse gas emissions, while also causing severe air pollution. The conversion to electric vehicles (EVs) represents a major path to decarbonize the transport sector, with potentially significant co-benefits for human health. However, the scale of such co-benefits largely remains an empiri...

Monitoring cloud droplet effective radius (re) is of great significance for studying aerosol-cloud interactions (ACI). Passive satellite retrieval, e.g., MODIS (Moderate Resolution Imaging Spectroradiometer), requires sunlight. This requirement prompted developing re retrieval using active sensors, e.g., CALIOP (Cloud-Aerosol Lidar with Orthogonal...

In this study, we present and validate a methodology for satellite retrievals of cloud condensation nuclei (CCN) in shallow marine boundary layer clouds. In our approach, supersaturation (S) is calculated by the retrieved cloud base drop concentration (Nd) and updrafts (Wb). Nd is the activated CCN concentration in clouds at a given S. We validate...

Operational cloud seeding has been implemented to alleviate local precipitation shortages in China for over half a century. Here, we present quantitative evidence for the effect of AgI seeding on supercooled layer clouds with a top cloud temperature of −15°C in China, as documented for the first time by a combination of radar, satellite, and disdro...

Aerosols affect cloud microstructure, dynamics, and precipitation by acting as cloud condensation nuclei (CCN) and ice nuclei with a large uncertainty for deep convective clouds (DCCs). Here, we quantify the relationships between aerosols and DCC properties after isolating aerosol impacts from meteorology based on the METEOSAT geostationary satelli...

Convective clouds are common and play a major role in Earth's water cycle and energy balance; they may even develop into storms and cause severe rainfall events. To understand the convective cloud development process, this study investigates the impact of aerosols on convective clouds by considering the influence of both topography and diurnal vari...