Browse Articles
A Positive Cloud‐to‐Ground Flash Caused by a Sequence of Bidirectional Leaders that Served to Form a Ground‐Reaching Branch of a Pre‐Existing Horizontal Channel
-  29 May 2021
Key Points
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Bidirectional leaders developed below a previously formed horizontal channel and served to form a new positive branch that attached to the ground
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Connection of the negative (upper) end of each bidirectional leader to the horizontal channel resulted in abrupt elongation of the positive (lower) end
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Flickering streamer-like filaments (needles) extended sideways from the horizontal channel in response to the injection of negative charge associated with the positive cloud-to-ground flash
Characteristics of the Long‐Lived Concentric Eyewalls in Tropical Cyclones
-  27 May 2021
Key Points
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The occurrences of long-lasting concentric eyewalls are documented in the western North Pacific, eastern Pacific, and Atlantic basins
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The environmental conditions critical for the maintenance of concentric eyewalls are examined, in addition to the internal dynamics
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Most of the triple eyewalls evolves to a concentric eyewall, and belongs to the long-lived category
Wintertime In Situ Cloud Microphysical Properties of Mixed‐Phase Clouds Over the Southern Ocean
-  27 May 2021
Key Points
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Mixed-phase clouds are commonly present in mid-latitude mesoscale shallow convection over the Southern Ocean during the Austral winter
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Secondary ice production, together with warm rain processes, is potentially important in producing ice particles in the supercooled clouds
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Large discrepancies are found in the widely used satellite-based cloud phase products
Size‐dependent Molecular Characteristics and Possible Sources of Organic Aerosols at a Coastal New Particle Formation Hotspot of East China
-  26 May 2021
Key Points
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Fourier transform-ion cyclotron resonance MS analysis revealed size-dependent organic molecular compositions and possible sources at a coastal new particle formation hotspot
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Solid Phase Micro-Extraction (SPME)-GC-MS analysis linked coastal ultrafine organic aerosols with volatile organic compound emission from local intertidal macroalgae
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We observed higher unsaturation degree, carbon oxidation state and aromaticity of organic aerosols in coastal PM2.5 than inland urban PM2.5
High‐Speed Spectroscopy of Lightning‐Like Discharges: Evidence of Molecular Optical Emissions
-  26 May 2021
Key Points
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High speed (down to submicrosecond time scales), high sensitivity lightning-like spectra (380–800 nm) reveal a rich chemistry
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Molecular species like CO, CN, C2, N2, and are detected. This opens the door to find and quantify lightning NO production by spectroscopy
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Electron concentrations and gas temperatures obtained from different methods are compared and discussed
Measurements of Total OH Reactivity During CalNex‐LA
-  25 May 2021
Key Points
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Total OH reactivity measured during the CalNex-LA field campaign was consistently greater than that calculated from measured OH sinks
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An analysis suggests that the missing reactivity is likely due to both unmeasured local emissions and unmeasured oxidation products
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Approximately 50% of the missing OH reactivity may have been due to emissions of unmeasured volatile chemical products
Sahelian Heat Wave Characterization From Observational Data Sets
-  25 May 2021
Key Points
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Observational data sets are used to statistically document processes involved in spring time heat waves in the Sahel
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Nighttime heat waves are linked to an increase in precipitable water as well as a frequent high aerosol load
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Daytime heat waves are generally associated with cleaner skies; more intense events show in addition a higher amount of precipitable water
Simulation of Aerosol Indirect Effects on Cloud Streets Over the Northwestern Pacific Ocean
-  24 May 2021
Key Points
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Twomey effect (cloud albedo increases with increasing aerosol concentration) is substantial in cloud streets
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Cloud thickness decreases in response to increasing aerosol, which is contrary to the Albrecht effect
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Increasing aerosol concentration generally reduces cloud cover, but the trend reverses when substantial drizzle develops
Heterogeneous Reaction of CaCO3 With NO2 at Different Relative Humidities: Kinetics, Mechanisms, and Impacts on Aerosol Hygroscopicity
-  24 May 2021
Key Points
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Heterogeneous reactivity of CaCO3 toward NO2 was limited at <1% relative humidity (RH), with uptake coefficient estimated to be <2 × 10−8
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This reaction was enhanced at elevated RH, and average uptake coefficients were measured to be ∼1.2 × 10−7 at 20%–80% RH
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Heterogeneous reaction with NO2 significantly increased hygroscopicity of CaCO3 particles
Reconstruction of temperature, accumulation rate, and layer thinning from an ice core at South Pole, using a statistical inverse method
-  4 June 2021
Key Points
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An inverse method using a firn model with isotope diffusion provides self-consistent temperature, accumulation rate, and thinning histories.
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Glacial-interglacial temperature change at the South Pole was 6.7 +/- 1.0 K. The d18O/T sensitivity is 0.99 +/- 0.03 permille/K.
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Reconstruction of ice thinning shows millennial-scale variations in thinning function and decreased thinning at depth compared to 1-D model.
Seasonal characteristics of biogenic secondary organic aerosols over Chichijima Island in the western North Pacific: Impact of biomass burning activity in East Asia
-  3 June 2021
Key Points
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Monoterpene SOA tracers are significant sources for BSOAs, followed by isoprene and β-caryophyllene SOA tracers in Chichijima aerosols
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High-NOx BSOA tracers (2-MGA, 3-HGA, and 3-MBTCA) are influenced by the long-range transport of anthropogenic air masses from East Asia
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Low-NOx BSOA tracers (2-MTLs and C5-alkenetriols) are produced mainly by the oxidation of locally emitted isoprene
Analysis of the daytime urban heat island mechanism in east China
-  3 June 2021
Key Points
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Two attribution methods are applied to offline simulations employed with several land-use datasets to identify the causes of UHIs.
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The urban-rural contrasts of evapotranspiration and heat storage dominate spatial variations of daytime UHIs in summer and winter.
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Disparities in land-use datasets affect the estimation of UHI intensity and its attributing variables, especially for dominant factors.
Role of Heat Wave‐induced Biogenic VOC Enhancements in Persistent Ozone Episodes Formation in Pearl River Delta
-  2 June 2021
Key Points
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A persistent regional ground-level O3 pollution was observed during the HW period over PRD regions.
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Gas-phase chemistry and vertical transport processes affected by meteorological conditions are dominant contributors to O3 formation.
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Intensive BVOC emissions enhance O3 pollution over VOC-limited areas under the northerly wind and sea-land breezes during the HW period.
Influence of Different ENSO Types on Tropical Cyclone Rapid Intensification over the Western North Pacific
-  29 May 2021
Key Points
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Rapid intensification properties show significant responses to different types of ENSO events
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El Niño and La Niña shift the rapid intensification occurrence position westward significantly in late TC season
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Oceanic processes play important roles in shifting the rapid intensification position westward
Seasonal Variation of Wet Deposition of Black Carbon at Ny‐Ålesund, Svalbard
-  28 May 2021
Key Points
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Black carbon (BC) mass in air and hydrometeors at Ny-Ålesund were statistically correlated, being high in winter-spring and low in summer
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Annual BC concentrations in hydrometeors were lower by a factor of 2.8 at Ny-Ålesund than at Barrow, reflecting lower BC in air
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BC size distributions in hydrometeors were stable in the Arctic, due to size-independent wet removal during transport from lower latitudes
Assessment of the meteorological impact on improved PM2.5 air quality over North China during 2016−2019 based on a regional joint atmospheric composition reanalysis dataset
-  28 May 2021
Key Points
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PM2.5 air quality significantly improved in Beijing from 2016 to 2019.
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Heavy pollution episodes are mainly related to the southerly and easterly weather types.
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Meteorological variations also contributed much to improving air quality as the emissions declined yearly.
Empirical insights into the fate of ammonia in western U.S. wildfire smoke plumes
-  27 May 2021
Key Points
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We estimate e-folding loss timescales for ammonia in 8 western U.S. smoke plumes from 24 to 4000 minutes old (median = 55 minutes).
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Ammonium nitrate formation is favorable in fresh, dense plumes injected higher into the troposphere, nitric acid is normally limiting.
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Observed ammonium and nitrate fractions increase with lower temperatures in medium (1 - 3 days) and old ( > 3 days) chemical aged smoke.
The Influence of Stratospheric Soot and Sulfate Aerosols on the Northern Hemisphere Wintertime Atmospheric Circulation
-  27 May 2021
Key Points
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Acceleration of the stratospheric polar vortex occurs due to heated stratospheric aerosols in nuclear war and volcanic eruption simulations.
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A tropospheric mechanism for acceleration of the stratospheric polar vortex is detected in a 150 Tg soot nuclear war scenario.
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Winter warming is simulated after the 1963 Agung, 1982 El Chichón, and 1991 Pinatubo volcanic eruptions when the observed sea surface temperatures, which include an El Niño in each case, are specified.
Impacts of Continuously Increasing Urbanization Ratios on Warming Rates and Temperature Extremes Observed over the Beijing Area
-  25 May 2021
Key Points
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Each 10% increase in the urbanization ratio with 10 km2 had led to additional annual warming of 0.17±0.08 and 0.30±0.17 °C for Tmean and Tmin.
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Each 10% increase in urbanization ratios with 10 km2 had led to additional changes of 11.6±5.1, 12.7±5.8, and -11.1±5.2 days for hot days, hot nights, and chilly nights.
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The inner-annual urbanization contributions to warming rates and temperature extremes were continuously increasing in Beijing.
Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century
- Journal of Geophysical Research: Atmospheres
-  17 July 2003
Summarizing multiple aspects of model performance in a single diagram
- Journal of Geophysical Research: Atmospheres
-  7183-7192
-  1 April 2001
Radiative transfer for inhomogeneous atmospheres: RRTM, a validated correlated‐k model for the longwave
- Journal of Geophysical Research: Atmospheres
-  16663-16682
-  1 July 1997
Bounding the role of black carbon in the climate system: A scientific assessment
- Journal of Geophysical Research: Atmospheres
-  5380-5552
-  15 January 2013
Radiative forcing by long‐lived greenhouse gases: Calculations with the AER radiative transfer models
- Journal of Geophysical Research: Atmospheres
-  2 July 2008
Global observed changes in daily climate extremes of temperature and precipitation
- Journal of Geophysical Research: Atmospheres
-  15 March 2006
A simple hydrologically based model of land surface water and energy fluxes for general circulation models
- Journal of Geophysical Research: Atmospheres
-  14415-14428
-  20 July 1994
The community Noah land surface model with multiparameterization options (Noah‐MP): 1. Model description and evaluation with local‐scale measurements
- Journal of Geophysical Research: Atmospheres
-  24 June 2011
Key Points
- The paper describes the augmented Noah LSM
- The augmented Noah LSM allows multiphysics options (hence Noah-MP)
- The Noah-MP outperforms the original Noah LSM
Implementation of Noah land surface model advances in the National Centers for Environmental Prediction operational mesoscale Eta model
- Journal of Geophysical Research: Atmospheres
-  29 November 2003
Application of USDM statistics in NLDAS‐2: Optimal blended NLDAS drought index over the continental United States
- Journal of Geophysical Research: Atmospheres
-  2947-2965
-  1 February 2014
Key Points
- To develop an objective approach to blend NLDAS drought indices
- To establish the linkage between USDM statistics and NLDAS drought indices
- To reconstruct long-term OBNDI
Retrieval of the real part of the refractive index of smoke particles from Sun/sky measurements during SCAR‐B
- Journal of Geophysical Research: Atmospheres
-  31893-31902
-  1 December 1998
The Complex Refractive Index of Volcanic Ash Aerosol Retrieved From Spectral Mass Extinction
- Journal of Geophysical Research: Atmospheres
-  1339-1350
-  3 January 2018
Key Points
- The complex refractive indices of eight samples of volcanic ash aerosol were retrieved from measurements of spectral mass extinction and size and showed considerable variability
- Verification retrievals were performed on measurements of high-purity silica aerosol. The Rayleigh CDE scattering model outperformed Mie theory
- Nonspherical scattering effects can have a significant impact on refractive indices derived from extinction spectra
Measurements of the complex refractive index of volcanic ash at 450, 546.7, and 650 nm
- Journal of Geophysical Research: Atmospheres
-  7747-7757
-  24 July 2015
Key Points
- Complex refractive index data for 11 volcanic ash samples
- Explanation of methods used to find complex refractive indices
- Verification of methods through measurement of a calibration material
Determination of index of refraction and size of supermicrometer particles from light scattering measurements at two angles
- Journal of Geophysical Research: Atmospheres
-  23 August 2008
A potential climatic index for total Saharan dust: the Sun insolation
- Journal of Geophysical Research: Atmospheres
-  11 January 2006
A multiproxy index of the El Niño–Southern Oscillation, A.D. 1525–1982
- Journal of Geophysical Research: Atmospheres
-  6 March 2009
Bounding the role of black carbon in the climate system: A scientific assessment
- Journal of Geophysical Research: Atmospheres
-  5380-5552
-  15 January 2013
The local and global effects of Amazon deforestation
- Journal of Geophysical Research: Atmospheres
-  LBA 55-1-LBA 55-8
-  24 October 2002