Near‐cloud aerosols in monsoon environment and its impact on radiative forcing

Konwar, Mahen; Panicker, A. S.; Axisa, Duncan; Prabha, Thara V.

doi:10.1002/2014jd022420

Cited by 11 publications

(7 citation statements)

References 56 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The appearance of higher σ in the highly diluted cloud edge region of monsoon cloud could be caused by collision‐coalescence of the larger droplets (Devenish et al , ) which are not present in pre‐monsoon clouds (Prabha et al , ). As the environment is moist and aerosols near clouds are pre‐moistened as illustrated by (Konwar et al , ), there is partial evaporation of droplets, which broaden the spectra in downdrafts and may activate in cloud updrafts. The presence of collision‐coalescence in monsoon deep convective cloud is reported by Prabha et al () and Khain et al ().…”

Section: Resultsmentioning

confidence: 99%

Entrainment and droplet spectral characteristics in convective clouds during transition to monsoon

Bera

Pandithurai

Prabha

2016

Atmospheric Science Letters

View full text Add to dashboard Cite

In situ observations in growing deep cumulus in polluted and clean environments during the transition to monsoon over Indian peninsula are used to investigate entrainment effects on droplet size distribution and the width of possible cloud cores. Pre-monsoon clouds indicate reduction in spectral width in the diluted cloud volumes due to lateral entrainment whereas monsoon cloud has higher spectral width. Relative dispersion is observed to increase with the distance from cloud core of monsoon cloud while for pre-monsoon clouds it remained almost constant. Enhanced entrainment in polluted pre-monsoon clouds is responsible for narrow cloud core compared to monsoon cloud.

show abstract

Section: Resultsmentioning

confidence: 99%

Entrainment and droplet spectral characteristics in convective clouds during transition to monsoon

Bera

Pandithurai

Prabha

2016

Atmospheric Science Letters

View full text Add to dashboard Cite

show abstract

“…A cloud flag was formulated and activated to in‐cloud 20 s before and 20 s after each of the aircraft trajectory data points that show either liquid water content above 0.02 g/m 3 or a total FSSP particle concentration above 25 cm −3 . In addition to cloud filtering, this also excluded the near‐cloud areas, where high relative humidity values might contribute to aerosol hygroscopic growth and, thus, bias the measurements (Konwar et al, ). Regardless, we found that in most cases, the major contribution to column‐integrated PSD was made by the cloud‐free planetary boundary layer (PBL) segments of the flight, where relative humidity remained well below 80%.…”

Section: Model and Datamentioning

confidence: 99%

Observations and Cloud‐Resolving Modeling of Haboob Dust Storms Over the Arabian Peninsula

et al. 2018

View full text Add to dashboard Cite

Strong mesoscale haboob dust storms in April 2007 in the central Arabian Peninsula were studied using the cloud-resolving Weather Research and Forecasting-Chemistry (WRF-Chem) modeling system and observations collected during an intensive atmospheric field campaign. The field campaign provided the valuable aircraft and Doppler weather radar measurements. Active convection persisted for several days during the study period. Dust generation was caused by both strong large-scale winds and locally produced density currents. Because of insufficient spatial resolution, the event was not resolved accurately by the conventional reanalyses. However, the WRF-Chem model did successfully capture the primary features of the convection, its location, and precipitation patterns. Although the amount of rainfall in the model was slightly underestimated compared to the satellite measurements, it was approximately double the rainfall in the reanalysis. The convection-associated dust outbreaks were simulated well, with the aerosols optical depth magnitude and the temporal variability being in good agreement with both the ground-based and satellite aerosol retrievals. The model captured the major dust generation patterns, transport pathways, and several of the largest haboobs identified from the satellite observations. About 25 Tg of dust was emitted in the Arabian Peninsula during the 10-day period. Approximately 40% of the locally deposited dust was subject to wet removal processes. During periods of high local dust production, the WRF-Chem model underestimated the PM 10 mass concentration (associated mostly with dust particles larger than 3 μm in diameter) by nearly a factor of 2. This suggests that the current dust parameterizations, which prescribe the size distribution of the emitted dust, underestimate the number of large particles that increases at strong wind conditions.Plain Language Summary In this study, we use a sophisticated numerical model of atmospheric circulation with an aerosol component to simulate a series of local-scale haboob dust storms that occurred in the central Arabian Peninsula during April 2007. This type of dust storm is associated with a cold air outflow from thunderstorms and is specific to the wet spring season in this region. We compare the model results with the data obtained from aircraft and meteorological radar during a field campaign conducted at that time. The high-resolution model produces good results that capture the atmospheric convection, rainfall features, and major dust outbreaks recorded at a ground station in Riyadh. We demonstrate that it performs better than other global reanalysis products. However, our results show that the aerosol component of the numerical model needs to be improved, as the model underestimates the concentration of coarse dust particles. This is caused by the uncertainties introduced when prescribing the physical properties of dust aerosols generated from the surface.

show abstract

“…Since the advent of observational techniques for monitoring these variations from surface, air and space, the diversity of sensors with improved precision and accuracy has increased and corresponding innovative methods have been developed [8][9][10][11]. Aircraft measurements are becoming increasingly important for model validation studies because they can document aerosol variations in remote regions where access to ground-based observations is difficult or unavailable, and offer observations with higher temporal resolution than can typically be attained with satellites [12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Airborne Aerosol in Situ Measurements during TCAP: A Closure Study of Total Scattering

et al. 2015

View full text Add to dashboard Cite

We present a framework for calculating the total scattering of both non-absorbing and absorbing aerosol at ambient conditions from aircraft data. Our framework is developed emphasizing the explicit use of chemical composition data for estimating the complex refractive index (RI) of particles, and thus obtaining improved ambient size spectra derived from Optical Particle Counter (OPC) measurements. The feasibility of our framework for improved calculations of total scattering is demonstrated using three types of data collected by the U.S. Department of Energy's (DOE) aircraft during the Two-Column Aerosol Project (TCAP). Namely, these data types are: (1) size distributions measured by a suite of OPC's; (2) chemical composition data measured by an Aerosol Mass Spectrometer and a Single Particle Soot Photometer; and (3) the dry total scattering coefficient measured by a integrating nephelometer and scattering enhancement factor measured with a humidification system. We demonstrate that good agreement (~10%) between the observed and calculated scattering can be obtained under ambient conditions (RH < 80%) by applying chemical composition data for the RI-based correction OPEN ACCESSAtmosphere 2015, 6 1070 of the OPC-derived size spectra. We also demonstrate that ignoring the RI-based correction or using non-representative RI values can cause a substantial underestimation (~40%) or overestimation (~35%) of the calculated scattering, respectively.

show abstract

Near‐cloud aerosols in monsoon environment and its impact on radiative forcing

Cited by 11 publications

References 56 publications

Entrainment and droplet spectral characteristics in convective clouds during transition to monsoon

Entrainment and droplet spectral characteristics in convective clouds during transition to monsoon

Observations and Cloud‐Resolving Modeling of Haboob Dust Storms Over the Arabian Peninsula

Airborne Aerosol in Situ Measurements during TCAP: A Closure Study of Total Scattering

Contact Info

Product

Resources

About