Volcanic Aerosol Impacts on Hawai‘i Island Rainfall

2021 ◽  
Author(s):  
Tianqi Zuo ◽  
Alison D. Nugent ◽  
Gregory Thompson
Keyword(s):  
Air Quality ◽  
Cloud Droplet ◽  
Kilauea Volcano ◽  
Number Concentration ◽  
Volcanic Aerosol ◽  
Aerosol Emission ◽  
Kīlauea Volcano ◽  
Cloud Water Content ◽  
Volcanic Aerosols ◽  
The Impact

AbstractIn recent decades, a significant rainfall decline over the Island of Hawai‘i has been noted, with many hypothesizing that the drying is associated with the volcanic aerosols emitted from the Kīlauea Volcano. While it is clear that volcanic emissions can create hazardous air quality for Hawaiian communities, the impacts on rainfall are less clear. Here we investigate the impact of volcanic aerosol emissions on Hawai‘i Island rainfall. Based on observed daily rainfall and SO2 emissions, it is found that days with high SO2 emissions have on average 8 mm day−1 less rainfall downstream of the Kīlauea Volcano. Sensitivity studies with varying volcanic aerosol emission sources from the Kīlauea vent locations have also been conducted by the Weather Research and Forecasting (WRF) Model in order to examine the detailed physical processes. Consistent with SO2 air quality observations, it is found that the diurnal change in aerosol number concentration is strongly dependent on the diurnal variation of local circulations. The added aerosols are lofted into the orographic convection where they modify the microphysical properties of the warm clouds by increasing the cloud droplet number concentration, decreasing the cloud droplet size, increasing cloud water content and enhancing cloud evaporation. The volcanic aerosols also delay precipitation production and modify the spatial distribution of rainfall on the downstream mountainside. The modification of precipitation on an island has far reaching consequences. For this reason, we work to quantify the sensitivity of the orographic precipitation to volcanic aerosols and move beyond hypothesized relationships towork toward understanding the underlying problem.

scholarly journals Influence of aerosols on the formation and development of radiation fog

2009 ◽  
Vol 9 (5) ◽  
pp. 17963-18019 ◽  
Author(s):  
J. Rangognio ◽  
P. Tulet ◽  
T. Bergot ◽  
L. Gomes ◽  
O. Thouron ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Chemical Properties ◽  
Cloud Droplet ◽  
Critical Value ◽  
Number Concentration ◽  
Cloud Droplets ◽  
Radiation Fog ◽  
Cloud Water Content ◽  
Aerosol Number Concentration ◽  
The Impact

Abstract. This paper assesses the impact of aerosol properties on the formation and the development of radiation fog. Simulations were performed using the Meso-NH meteorological model including the ORILAM aerosol scheme coupled with a two-moment microphysical cloud scheme (number concentration of cloud droplets and cloud water content). The activation scheme used was taken from the work of Abdul-Razzak and Ghan (2004). "Off-line" sensitivity analysis of CCN (Cloud Condensation Nuclei) activation was performed on number, median diameter and chemical compounds of aerosols. During this "off-line" study, the interactions with the other physical processes (e.g. radiative) were not taken into account since the cooling rate was imposed. Different regimes of CCN activation and a critical value of aerosol number concentration were found. This critical aerosol number corresponds to the maximum of activated cloud droplets for a given cooling rate and given aerosol chemical properties. As long as the aerosol number concentration is below this critical value, the cloud droplet number increases when the aerosol number increases. But when the aerosol number concentration exceeds this critical value, the cloud droplet number decreases when aerosol number increases. A sensitivity study on aerosol chemical composition showed that the CCN activation was limited in the case of hydrophilic aerosol composed of material with a solubility in the 10% range. An event observed during the ParisFOG field experiment was simulated. This case took place in the polluted sub-urban area of Paris (France) characterized by particle concentrations of 17 000 aerosols per cm3. 1D simulations successfully reproduced the observed temporal evolution of the fog layer. Beyond the initial fog formation at the surface, cloud droplet formation occurred at the top of the fog layer where the cooling rate was maximum, reaching more than −10 K h−1. These simulations confirm that the aerosol particle number concentration is a key parameter for the accurate prediction of the microphysical properties of a fog layer and also influences the vertical development of fog. The important of the interaction between microphysical and radiative processes is illustrated, showing how the life cycle of a fog layer is determined by the CCN number concentration and chemical properties.

scholarly journals MBL drizzle properties and their impact on cloud property retrievals

2015 ◽  
Vol 8 (4) ◽  
pp. 4307-4323
Author(s):  
P. Wu ◽  
X. Dong ◽  
B. Xi
Keyword(s):  
Liquid Water ◽  
Cloud Droplet ◽  
Number Concentration ◽  
Effective Radius ◽  
Liquid Water Path ◽  
Water Path ◽  
Cloud Property ◽  
Annual Means ◽  
Mean Differences ◽  
The Impact

Abstract. In this study, we retrieve and document drizzle properties, and investigate the impact of drizzle on cloud property retrievals from ground-based measurements at the ARM Azores site from June 2009 to December 2010. For the selected cloud and drizzle samples, the drizzle occurrence is 42.6% with a maximum of 55.8% in winter and a minimum of 35.6% in summer. The annual means of drizzle liquid water path LWPd, effective radius rd, and number concentration Nd for the rain (virga) samples are 5.48 (1.29) g m−2, 68.7 (39.5) μm, and 0.14 (0.38) cm−3. The seasonal mean LWPd values are less than 4% of the MWR-retrieved LWP values. The annual mean differences in cloud-droplet effective radius with and without drizzle are 0.12 and 0.38 μm, respectively, for the virga and rain samples. Therefore, we conclude that the impact of drizzle on cloud property retrievals is insignificant at the ARM Azores site.

scholarly journals The impact of sampling strategy on the cloud droplet number concentration estimated from satellite data

2021 ◽  
Author(s):  
Edward Gryspeerdt ◽  
Daniel T. McCoy ◽  
Ewan Crosbie ◽  
Richard H. Moore ◽  
Graeme J. Nott ◽  
...  
Keyword(s):  
Satellite Data ◽  
Radiative Forcing ◽  
Sampling Strategy ◽  
Cloud Droplet ◽  
Number Concentration ◽  
Cloud Properties ◽  
Systematic Biases ◽  
Cloud Droplet Number Concentration ◽  
Aerosol Cloud Interactions ◽  
The Impact

Abstract. Cloud droplet number concentration (Nd) is of central importance to observation-based estimates of aerosol indirect effects, being used to quantify both the cloud sensitivity to aerosol and the base state of the cloud. However, the derivation of Nd from satellite data depends on a number of assumptions about the cloud and the accuracy of the retrievals of the cloud properties from which it is derived, making it prone to systematic biases. A number of sampling strategies have been proposed to address these biases by selecting the most accurate Nd retrievals in the satellite data. This work compares the impact of these strategies on the accuracy of the satellite retrieved Nd, using a selection of insitu measurements. In stratocumulus regions, the MODIS Nd retrieval is able to achieve a high precision (r2 of 0.5–0.8). This is lower in other cloud regimes, but can be increased by appropriate sampling choices. Although the Nd sampling can have significant effects on the Nd climatology, it produces only a 20 % variation in the implied radiative forcing from aerosol-cloud interactions, with the choice of aerosol proxy driving the overall uncertainty. The results are summarised into recommendations for using MODIS Nd products and appropriate sampling.

scholarly journals The Influence of Remote Aerosol Forcing from Industrialized Economies on the Future Evolution of East and West African Rainfall

2019 ◽  
Vol 32 (23) ◽  
pp. 8335-8354 ◽  
Author(s):  
Claire Scannell ◽  
Ben B. B. Booth ◽  
Nick J. Dunstone ◽  
David P. Rowell ◽  
Dan J. Bernie ◽  
...  
Keyword(s):  
Air Quality ◽  
Climate Adaptation ◽  
Climate Projections ◽  
Rcp Scenarios ◽  
Future Evolution ◽  
African Rainfall ◽  
Aerosol Emission ◽  
Near Term ◽  
Aerosol Emissions ◽  
The Impact

Abstract Past changes in global industrial aerosol emissions have played a significant role in historical shifts in African rainfall, and yet assessment of the impact on African rainfall of near-term (10–40 yr) potential aerosol emission pathways remains largely unexplored. While existing literature links future aerosol declines to a northward shift of Sahel rainfall, existing climate projections rely on RCP scenarios that do not explore the range of air quality drivers. Here we present projections from two emission scenarios that better envelop the range of potential aerosol emissions. More aggressive emission cuts result in northward shifts of the tropical rainbands whose signal can emerge from expected internal variability on short, 10–20-yr time horizons. We also show for the first time that this northward shift also impacts East Africa, with evidence of delays to both onset and withdrawal of the short rains. However, comparisons of rainfall impacts across models suggest that only certain aspects of both the West and East African model responses may be robust, given model uncertainties. This work motivates the need for wider exploration of air quality scenarios in the climate science community to assess the robustness of these projected changes and to provide evidence to underpin climate adaptation in Africa. In particular, revised estimates of emission impacts of legislated measures every 5–10 years would have a value in providing near-term climate adaptation information for African stakeholders.

scholarly journals Droplet number uncertainties associated with CCN: an assessment using observations and a global model adjoint

2013 ◽  
Vol 13 (8) ◽  
pp. 4235-4251 ◽  
Author(s):  
R. H. Moore ◽  
V. A. Karydis ◽  
S. L. Capps ◽  
T. L. Lathem ◽  
A. Nenes
Keyword(s):  
Large Scale ◽  
Transport Model ◽  
Cloud Droplet ◽  
Number Concentration ◽  
Chemical Transport Model ◽  
Anthropogenic Aerosol ◽  
Cloud Properties ◽  
Stratiform Clouds ◽  
The Impact ◽  
Indirect Forcing

Abstract. We use the Global Modelling Initiative (GMI) chemical transport model with a cloud droplet parameterisation adjoint to quantify the sensitivity of cloud droplet number concentration to uncertainties in predicting CCN concentrations. Published CCN closure uncertainties for six different sets of simplifying compositional and mixing state assumptions are used as proxies for modelled CCN uncertainty arising from application of those scenarios. It is found that cloud droplet number concentrations (Nd) are fairly insensitive to the number concentration (Na) of aerosol which act as CCN over the continents (∂lnNd/∂lnNa ~10–30%), but the sensitivities exceed 70% in pristine regions such as the Alaskan Arctic and remote oceans. This means that CCN concentration uncertainties of 4–71% translate into only 1–23% uncertainty in cloud droplet number, on average. Since most of the anthropogenic indirect forcing is concentrated over the continents, this work shows that the application of Köhler theory and attendant simplifying assumptions in models is not a major source of uncertainty in predicting cloud droplet number or anthropogenic aerosol indirect forcing for the liquid, stratiform clouds simulated in these models. However, it does highlight the sensitivity of some remote areas to pollution brought into the region via long-range transport (e.g., biomass burning) or from seasonal biogenic sources (e.g., phytoplankton as a source of dimethylsulfide in the southern oceans). Since these transient processes are not captured well by the climatological emissions inventories employed by current large-scale models, the uncertainties in aerosol-cloud interactions during these events could be much larger than those uncovered here. This finding motivates additional measurements in these pristine regions, for which few observations exist, to quantify the impact (and associated uncertainty) of transient aerosol processes on cloud properties.

scholarly journals The impact of degassing on the oxidation state of basaltic magmas: A case study of Kīlauea volcano

2016 ◽  
Vol 450 ◽  
pp. 317-325 ◽  
Author(s):  
Yves Moussallam ◽  
Marie Edmonds ◽  
Bruno Scaillet ◽  
Nial Peters ◽  
Emanuela Gennaro ◽  
...  
Keyword(s):  
Oxidation State ◽  
Kilauea Volcano ◽  
Kīlauea Volcano ◽  
Basaltic Magmas ◽  
The Impact

scholarly journals Is a more physical representation of aerosol activation needed for simulations of fog?

2020 ◽  
Author(s):  
Craig Poku ◽  
Andrew N. Ross ◽  
Adrian A. Hill ◽  
Alan M. Blyth ◽  
Ben Shipway
Keyword(s):  
Climate Models ◽  
Thick Layer ◽  
Cloud Droplet ◽  
Droplet Formation ◽  
Number Concentration ◽  
Radiation Fog ◽  
Simple Method ◽  
Physically Based ◽  
Aerosol Activation ◽  
The Impact

Abstract. Aerosols play a crucial role in the fog life cycle, as they determine the droplet number concentration, and hence droplet size, which in turn controls both the fog's optical thickness and life span. Detailed aerosol-microphysics schemes which accurately represent droplet formation and growth are unsuitable for weather forecasting and climate models, as the computational power required to calculate droplet formation would dominate the treatment of the rest of the physics in the model. A simple method to account for droplet formation is the use of an aerosol activation scheme, which parameterises the droplet number concentration based on a change in supersaturation at a given time. Traditionally, aerosol activation parameterisation schemes were designed for convective clouds and assume that supersaturation is reached through adiabatic lifting, with many imposing a minimum vertical velocity (e.g. 0.1 m/s) to account for unresolved sub-grid ascent. In radiation fog, the measured updrafts during initial formation are often insignificant, with radiative cooling being the dominant process leading to saturation. As a result, there is a risk that many aerosol activation schemes will overpredict the initial fog number concentration, which in turn may result in the fog transitioning to an optically thick layer too rapidly. This paper presents a more physically-based aerosol activation scheme that can account for a change in saturation due to non-adiabatic processes. Using an offline model, our results show that the minimum updraft velocity threshold assumption can overpredict the droplet number by up to 70 % in comparison to a cooling rate found in fog formation. The new scheme has been implemented in the Met Office Natural Environment Research Council (NERC) Cloud (MONC) LES model, and tested using observations of a radiation fog case study based in Cardington, UK. The results in this work show that using a more physically-based method of aerosol activation leads to the calculation of a more appropriate cloud droplet number. As a result, there is a slower transition to an optically thick (well-mixed) fog that is more in-line with observations. The results shown in this paper demonstrate the importance of aerosol activation representation in fog modelling, and the impact that the cloud droplet number has on processes linked to the formation and development of radiation fog. Unlike the previous parameterisation for aerosol activation, the revised scheme is suitable to simulate aerosol activation in both fog and convective cloud regimes.

scholarly journals Seasonal variation of ozone and black carbon observed at Paknajol, an urban site in the Kathmandu Valley, Nepal

2015 ◽  
Vol 15 (16) ◽  
pp. 22527-22566 ◽  
Author(s):  
D. Putero ◽  
P. Cristofanelli ◽  
A. Marinoni ◽  
B. Adhikary ◽  
R. Duchi ◽  
...  
Keyword(s):  
Air Pollution ◽  
Air Quality ◽  
Black Carbon ◽  
Regional Scale ◽  
Number Concentration ◽  
Urban Site ◽  
Kathmandu Valley ◽  
Rapid Urbanization ◽  
Aerosol Number Concentration ◽  
The Impact

Abstract. The Kathmandu Valley in South Asia is considered as one of the global "hot spots" in terms of urban air pollution. It is facing severe air quality problems as a result of rapid urbanization and land use change, socioeconomic transformation and high population growth. In this paper, we present the first full year (February 2013–January 2014) analysis of simultaneous measurements of two short-lived climate forcers/pollutants (SLCF/P), i.e. ozone (O3) and equivalent black carbon (hereinafter noted as BC) and aerosol number concentration at Paknajol, in the center of the Kathmandu metropolitan city. The diurnal behavior of equivalent black carbon (BC) and aerosol number concentration indicated that local pollution sources represent the major contributions to air pollution in this city. In addition to photochemistry, the planetary boundary layer (PBL) and wind play important roles in determining O3 variability, as suggested by the analysis of seasonal diurnal cycle and correlation with meteorological parameters and aerosol properties. Especially during pre-monsoon, high values of O3 were found during the afternoon/evening; this could be related to mixing and entrainment processes between upper residual layers and the PBL. The high O3 concentrations, in particular during pre-monsoon, appeared well related to the impact of major open vegetation fires occurring at regional scale. On a synoptic-scale perspective, westerly and regional atmospheric circulations appeared to be especially conducive for the occurrence of the high BC and O3 values. The very high values of SLCF/P, detected during the whole measurement period, indicated persisting adverse air quality conditions, dangerous for the health of over 3 million residents of the Kathmandu Valley, and the environment. Consequently, all of this information may be useful for implementing control measures to mitigate the occurrence of acute pollution levels in the Kathmandu Valley and surrounding area.

Sign in / Sign up

Export Citation Format

Share Document