An evaluation of the liquid cloud droplet effective radius derived from MODIS, airborne remote sensing, and in situ measurements from CAMP<sup>2</sup>Ex

Atmospheric chemistry and physics, Journal Year: 2022, Volume and Issue: 22(12), P. 8259 - 8285

Published: June 27, 2022

Abstract. The cloud drop effective radius (Re) of the size distribution derived from passive satellite sensors is a key variable used in climate research. Validation these products has often taken place under stratiform conditions that favor assumption horizontal homogeneity by retrieval techniques. However, many studies have noted concerns with respect to significant biases retrieved Re arising heterogeneity, for example, cumulus fields. Here, we examine data collected during 2019 “Cloud, Aerosol and Monsoon Processes Philippines Experiment” (CAMP2Ex), which, part, targeted objective providing first detailed evaluation across multiple platforms techniques congestus region. Our consists cross-comparisons between Moderate Resolution Imaging Spectroradiometer (MODIS) onboard Terra satellite, Research Scanning Polarimeter (RSP) NASA P-3 aircraft, situ measurements both Learjet aircraft are all close spatiotemporal proximity same A particular advantage our approach lies capability RSP retrieve using bi-spectral MODIS polarimetric approach, which allows retrievals an airborne perspective samples. Averaged over flight segments examined here warm clouds, method, bias-adjusted method Fu et al. (2019) show comparable median (mean ± standard deviation) samples 9.6 (10.2 4.0) µm, 11.0 (13.6 11.3) 10.4 (10.8 3.8) respectively. These values far lower than 15.1 (16.2 5.5) µm 17.2 (17.7 5.7) MODIS, Similar results observed when segregated cloud-top height case studies. clouds sampled CAMP2Ex consist mostly small transect length ∼ 1.4 km) low 1 km), had more numerous trade wind cumuli past field campaigns such as Rain Shallow Cumulus Ocean (RICO) Indian Experiment (INDOEX). overestimates technique compared increased optical depth decreased. Drizzle, bumpiness, solar zenith angle, however, not closely correlated overestimate Re. For shallow dominated liquid cover region period, 3-D radiative transfer particularly optically thin appear be leading cause large positive retrievals. Because this bias varies underlying structure field, caution continues warranted use

Language: Английский

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Evaluating spectral cloud effective radius retrievals from the Enhanced MODIS Airborne Simulator (eMAS) during ORACLES

Atmospheric measurement techniques, Journal Year: 2025, Volume and Issue: 18(4), P. 981 - 1011

Published: Feb. 27, 2025

Abstract. Satellite remote sensing retrievals of cloud effective radius (CER) are widely used for studies aerosol–cloud interactions. Such retrievals, however, rely on forward radiative transfer (RT) calculations using simplified assumptions that can lead to retrieval errors when the real atmosphere deviates from model. Here, coincident airborne and in situ observations obtained during NASA's ObseRvations Aerosols above CLouds their intEractionS (ORACLES) field campaign evaluate CER marine boundary layer stratocumulus clouds explore impacts RT model other confounding factors. Specifically, spectral Enhanced MODIS Airborne Simulator (eMAS) Research Scanning Polarimeter (RSP) compared with polarimetric RSP derived droplet size distributions (DSDs) observed by Phase Doppler Interferometer (PDI) a combination Cloud Aerosol Spectrometer (CAS) Two-Dimensional Stereo Probe (2D-S). The sensitivities eMAS about DSD variance (CEV) liquid water complex index refraction explored. CEV inferred reflectance backscatter glory provide additional context retrievals. agreement is case dependent, updating assumptions, including as constraint, yields mixed results tied differing vertical heterogeneity. Moreover, probes, often benchmark assessments, themselves do not agree, PDI DSDs yielding values 1.3–1.6 µm larger than CAS roughly 50 %–60 % smaller CAS. Implications interpretation discussed.

Language: Английский

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Machine-Learning Based Analysis of Liquid Water Path Adjustments to Aerosol Perturbations in Marine Boundary Layer Clouds Using Satellite Observations

Atmosphere, Journal Year: 2022, Volume and Issue: 13(4), P. 586 - 586

Published: April 5, 2022

Changes in marine boundary layer cloud (MBLC) radiative properties response to aerosol perturbations are largely responsible for uncertainties future climate predictions. In particular, the relationship between droplet number concentration (Nd, a proxy aerosol) and liquid water path (LWP) remains challenging quantify from observations. this study, satellite observations multiple polar-orbiting platforms 2006–2011 used combination with atmospheric reanalysis data regional machine learning model predict changes LWP MBLCs Southeast Atlantic. The impact of predictor variables on output is analysed using Shapley values as technique explainable learning. Within model, precipitation fraction, top height, Nd identified important state predictors LWP, dynamical proxies sea surface temperature (SST) being most environmental predictors. A positive nonlinear found, weaker sensitivity at high concentrations. This found be dependent other model: Nd–LWP higher precipitating clouds decreases increasing SSTs.

Language: Английский

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Aerosol-Cloud-Precipitation Interactions in a Closed-cell and Non-homogenous MBL Stratocumulus Cloud

Advances in Atmospheric Sciences, Journal Year: 2022, Volume and Issue: 39(12), P. 2107 - 2123

Published: Sept. 22, 2022

Language: Английский

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Intercomparison of airborne and surface-based measurements during the CLARIFY, ORACLES and LASIC field experiments

Atmospheric measurement techniques, Journal Year: 2022, Volume and Issue: 15(21), P. 6329 - 6371

Published: Nov. 3, 2022

Abstract. Data are presented from intercomparisons between two research aircraft, the FAAM BAe-146 and NASA Lockheed P3, surface-based DOE (Department of Energy) ARM (Atmospheric Radiation Measurement) Mobile Facility at Ascension Island (8∘ S, 14.5∘ W; a remote island in mid-Atlantic). These took place 17 August to 5 September 2017, during African biomass burning (BB) season. The primary motivation was give confidence use data multiple platforms with which evaluate numerical climate models. three were involved CLouds–Aerosol–Radiation Interaction Forcing for Year 2017 (CLARIFY-2017), ObseRvations Aerosols above CLouds their intEractionS (ORACLES), Layered Atlantic Smoke Interactions Clouds (LASIC) field experiments. Comparisons flight segments on 6 d where flew alongside facility presented, along comparisons wing-tip-to-wing-tip P3 18 2017. intercomparison sampled relatively clean atmosphere overlying moderately polluted boundary layer, while six fly-bys site both conditions 2–4 km upwind. We compare validate characterisations aerosol physical, chemical optical properties as well atmospheric radiation cloud microphysics platforms. assess performance measurement instrumentation field, under sampling not tightly controlled laboratory measurements calibrations performed. Solar compared enough permit radiative closure studies. Optical absorption coefficient all within uncertainty limits, although absolute magnitudes too low (<10 Mm−1) fully support comparison Ångström exponents. Aerosol airborne more comparable than aircraft-to-ground observations. Scattering observations adequately platforms, but agreement ground-based worse, potentially caused by small differences or actual population over land. Chemical composition followed similar pattern, better Thermodynamics, microphysical generally agreed given uncertainties.

Language: Английский

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Low cloud response to aerosol‐radiation‐cloud interactions: Idealized WRF numerical experiments for EUREC⁴A project

Atmospheric Science Letters, Journal Year: 2024, Volume and Issue: 25(5)

Published: Jan. 11, 2024

Abstract Aerosols significantly affect cloud microphysics and energy budget in different ways. The contribution of the direct, semi‐direct, indirect effects aerosols on radiation are here investigated over North Atlantic tropical ocean under aerosol loadings. Weather Research Forecasting Model is used to perform a set numerical idealized experiments, which forced with prescribed profiles. We evaluate modeled shallow clouds surface radiative budget. results indicate that large loadings associated enhanced cloudiness reduced precipitation. While change rainfall mainly due larger number smaller droplets, attributed absorbing aerosols, dust particles, responsible for rise temperature feeds back onto specific humidity. As boundary layer increase moisture dominates, net effect higher relative humidity, favors formation thin low non‐precipitating clouds. feedback accounts dynamical lower troposphere: shortwave absorption increases at top marine atmospheric boundary‐layer reduces entrainment warm dry air, increasing level content. Despite overall cloudiness, daytime cover reduced. semi‐direct warming surface, opposite effect.

Language: Английский

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Precipitation prediction in several Chinese regions using machine learning methods

International Journal of Dynamics and Control, Journal Year: 2023, Volume and Issue: 12(4), P. 1180 - 1196

Published: July 12, 2023

Language: Английский

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In situ and satellite-based estimates of cloud properties and aerosol–cloud interactions over the southeast Atlantic Ocean

Atmospheric chemistry and physics, Journal Year: 2022, Volume and Issue: 22(19), P. 12923 - 12943

Published: Oct. 7, 2022

Abstract. In situ cloud probe data from the NASA ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) field campaign were used to estimate effective radius (Re), optical thickness (τ), droplet concentration (Nc) for marine stratocumulus over southeast Atlantic Ocean. The in Re, τ, Nc compared with co-located Moderate Resolution Imaging Spectroradiometer (MODIS) retrievals Re τ MODIS-derived Nc. For 145 profiles, a MODIS retrieval was time gap less than 1 h. On average, (11.3 µm 11.7) 1.6 2.3 higher Pearson's correlation coefficients (R) 0.77 0.73, respectively. average (151.5 cm−3) within cm−3 an R 0.90. profiles classified into 67 contact where aerosol (Na) greater 500 sampled 100 m tops 78 separated Na up tops. Contact had (by 88 cm−3), 2.5), lower 2.2 µm) profiles. These differences associated aerosol–cloud interactions (ACI), estimates 5 cm−3, 0.5, 0.2 when Re>15 or τ>25 removed. agreement between changes ACI driven by small biases properties relative measurements across different regimes. Thus, combined location concentration, can be study larger domains longer timescales possible using data.

Language: Английский

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Multi-campaign ship and aircraft observations of marine cloud condensation nuclei and droplet concentrations

Scientific Data, Journal Year: 2023, Volume and Issue: 10(1)

Published: July 20, 2023

Abstract In-situ marine cloud droplet number concentrations (CDNCs), condensation nuclei (CCN), and CCN proxies, based on particle sizes optical properties, are accumulated from seven field campaigns: ACTIVATE; NAAMES; CAMP 2 EX; ORACLES; SOCRATES; MARCUS; CAPRICORN2. Each campaign involves aircraft measurements, ship-based or both. Measurements collected over the North Central Atlantic, Indo-Pacific, Southern Oceans, represent a range of clean to polluted conditions in various climate regimes. With extensive environmental sampled, this data collection is ideal for testing satellite remote detection methods CDNC environments. Remote measurement vital expanding available these difficult-to-reach regions Earth improving our understanding aerosol-cloud interactions. The includes composition continental tracers identify potential contributing sources. Several campaigns include High Spectral Resolution Lidar (HSRL) polarimetric imaging measurements retrievals that will be basis next generation space-based sensors and, thus, can utilized as surrogates.

Language: Английский

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Distinctive aerosol–cloud–precipitation interactions in marine boundary layer clouds from the ACE-ENA and SOCRATES aircraft field campaigns

Atmospheric chemistry and physics, Journal Year: 2024, Volume and Issue: 24(18), P. 10323 - 10347

Published: Sept. 18, 2024

Abstract. The aerosol–cloud–precipitation interactions within the cloud-topped marine boundary layer (MBL) are examined using aircraft in situ measurements from Aerosol and Cloud Experiments Eastern North Atlantic (ACE-ENA) Southern Ocean Clouds, Radiation, Transport Experimental Study (SOCRATES) field campaigns. SOCRATES clouds exhibit a larger number concentration smaller cloud droplet effective radius (148.3 cm−3 8.0 µm) compared to ACE-ENA summertime (89.4 9.0 wintertime (70.6 9.8 µm). clouds, especially during winter, feature stronger drizzle formation via growth through enhanced collision–coalescence that is attributed relatively cleaner environment deeper layer. Furthermore, aerosol–cloud interaction (ACI) indices two campaigns distinct sensitivities, indicating different microphysical responses aerosols. winter season features fewer aerosols, which more likely activated into droplets under conditions of sufficient water vapor availability strong turbulence. enriched aerosol loading summer generally leads competing for limited exhibiting ACI. Notably, precipitation susceptibilities than in-cloud behavior significantly alters sub-cloud condensation nuclei (CCN) budgets coalescence-scavenging effect and, turn, impacts ACI assessments. results this study can enhance understanding aid future model simulation assessment interaction.

Language: Английский

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