scholarly journals Aerosol vertical distribution and interactions with land/sea breezes over the eastern coast of the Red Sea from lidar data and high-resolution WRF-Chem simulations

2020 ◽  
Vol 20 (24) ◽  
pp. 16089-16116
Author(s):  
Sagar P. Parajuli ◽  
Georgiy L. Stenchikov ◽  
Alexander Ukhov ◽  
Illia Shevchenko ◽  
Oleg Dubovik ◽  
...  
Keyword(s):  
Red Sea ◽  
Large Scale ◽  
Eastern Coast ◽  
Size Distributions ◽  
Vertical Profiles ◽  
Dust Event ◽  
Breeze Circulation ◽  
Sea Breezes ◽  
Dust Aerosols ◽  
Different Seasons

Abstract. With advances in modeling approaches and the application of satellite and ground-based data in dust-related research, our understanding of the dust cycle has significantly improved in recent decades. However, two aspects of the dust cycle, namely the vertical profiles and diurnal cycles, are not yet adequately understood, mainly due to the sparsity of direct observations. Measurements of backscattering caused by atmospheric aerosols have been ongoing since 2014 at the King Abdullah University of Science and Technology (KAUST) campus using a micro-pulse lidar (MPL) with a high temporal resolution. KAUST is located on the eastern coast of the Red Sea and currently hosts the only operating lidar system in the Arabian Peninsula. We use the data from the MPL together with other collocated observations and high-resolution simulations (with 1.33 km grid spacing) from the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) to study the following three aspects of dust over the Red Sea coastal plains. Firstly, we compare the model-simulated surface winds, aerosol optical depth (AOD), and aerosol size distributions with observations and evaluate the model performance in representing a typical large-scale dust event over the study site. Secondly, we investigate the vertical profiles of aerosol extinction and concentration in terms of their seasonal and diurnal variability. Thirdly, we explore the interactions between dust aerosols and land/sea breezes, which are the most influential components of the local diurnal circulation in the region. The WRF-Chem model successfully reproduced the diurnal profile of surface wind speed, AOD, and dust size distributions over the study area compared to observations. The model also captured the onset, demise, and height of a large-scale dust event that occurred in 2015, as compared to the lidar data. The vertical profiles of aerosol extinction in different seasons were largely consistent between the MPL data and WRF-Chem simulations along with key observations and reanalyses used in this study. We found a substantial variation in the vertical profile of aerosols in different seasons and between daytime and nighttime, as revealed by the MPL data. The MPL data also identified a prominent dust layer at ∼5–7 km during the nighttime, which likely represents the long-range transported dust brought to the site by the easterly flow from remote inland deserts. The sea breeze circulation was much deeper (∼2 km) than the land breeze circulation (∼1 km), but both breeze systems prominently affected the distribution of dust aerosols over the study site. We observed that sea breezes push the dust aerosols upwards along the western slope of the Sarawat Mountains. These sea breezes eventually collide with the dust-laden northeasterly trade winds coming from nearby inland deserts, thus causing elevated dust maxima at a height of ∼1.5 km above sea level over the mountains. Moreover, the sea and land breezes intensify dust emissions from the coastal region during the daytime and nighttime, respectively. Our study, although focused on a particular region, has broader environmental implications as it highlights how aerosols and dust emissions from the coastal plains can affect the Red Sea climate and marine habitats.

scholarly journals Interaction of Dust Aerosols with Land/Sea Breezes over the Eastern Coast of the Red Sea from LIDAR Data and High-resolution WRF-Chem Simulations

2020 ◽  
Author(s):  
Sagar P. Parajuli ◽  
Georgiy L. Stenchikov ◽  
Alexander Ukhov ◽  
Illia Shevchenko ◽  
Oleg Dubovik ◽  
...  
Keyword(s):  
Red Sea ◽  
Lidar Data ◽  
Aerosol Extinction ◽  
Vertical Profiles ◽  
Coastal Plains ◽  
Breeze Circulation ◽  
Sea Breezes ◽  
Dust Emissions ◽  
Dust Aerosols ◽  
Different Seasons

Abstract. With advances in modeling approaches and the application of satellite and ground-based data in dust-related research, our understanding of the dust cycle has significantly improved in recent decades. However, two aspects of the dust cycle, namely the vertical profiles and diurnal cycles, are not yet adequately understood, mainly due to the sparsity of direct observations. Measurements of backscattering caused by atmospheric aerosols have been ongoing since 2014 at the King Abdullah University of Science and Technology (KAUST) campus using a micro-pulse LIDAR with a high temporal resolution. KAUST is located on the east coast of the Red Sea (22.3° N, 39.1° E), and currently hosts the only operating LIDAR system in the Arabian Peninsula. We use the data from this LIDAR together with other collocated observations and high-resolution WRF-Chem model simulations to study the following aspects of aerosols, with a focus on dust over the Red Sea Arabian coastal plains. Firstly, we investigate the vertical profiles of aerosol extinction and concentration in terms of their seasonal and diurnal variability. Secondly, we evaluate how well the WRF-Chem model performs in representing the vertical distribution of aerosols over the study site. Thirdly, we explore the interactions between dust aerosols and land/sea breezes, which are the most influential components of the local diurnal circulation in the region. We found a substantial variation in the vertical profile of aerosols in different seasons. We also discovered a marked difference in the daytime and nighttime vertical distribution of aerosols at the study site, as revealed by the LIDAR data. The LIDAR data also identified a prominent dust layer at ∼5–7 km during the nighttime, which represented the long-range transported dust brought to the site by the easterly flow from remote inland deserts. The vertical profiles of aerosol extinction in different seasons were largely consistent between the LIDAR, MERRA-2 reanalysis, and CALIOP data, as well as in the WRF-Chem simulations. The sea breeze circulation was much deeper (∼2 km) than the land breeze circulation (∼1 km), but both breeze systems prominently affected the distribution of dust aerosols over the study site. We observed that sea breezes push the dust aerosols upwards along the western slope of the Sarawat Mountains, which eventually collide with the dust-laden northeasterly trade winds coming from nearby inland deserts, causing elevated dust maxima at a height of ∼1.5 km above sea level over the mountains. Moreover, the sea and land breezes intensified dust emissions from the coastal region during the daytime and nighttime, respectively. The WRF-Chem model successfully captured the onset, demise, and height of a large-scale dust event that occurred in 2015, compared to LIDAR data. Our study, although focused on a particular region, has broader environmental implications as it highlights how aerosols and dust emissions from the coastal plains can affect the Red Sea climate and marine habitats.

Interaction of the Vertical Profile of Dust Aerosols with Land/sea Breezes over the Eastern Coast of the Red Sea from LIDAR and High-resolution WRF-Chem Simulations

2020 ◽  
Author(s):  
Sagar Parajuli ◽  
Georgiy Stenchikov ◽  
Alexander Ukhov ◽  
Illia Shevchenko
Keyword(s):  
High Resolution ◽  
Red Sea ◽  
Vertical Profile ◽  
Lidar Data ◽  
Aerosol Extinction ◽  
Vertical Profiles ◽  
Sea Breezes ◽  
Dust Emissions ◽  
Dust Aerosols ◽  
Land Breezes

<p>With the advances in modeling approaches, and the application of satellite and ground-based data in dust-related research, our understanding of the dust cycle is significantly improved in recent decades. However, two aspects of the dust cycle, the vertical profiles and diurnal cycles of dust aerosols have not been understood adequately, mainly due to the sparsity of observations. A micro-pulse LIDAR has been operating at the King Abdullah University of Science and Technology (KAUST) campus located on the east coast of the Red Sea (22.3N, 39.1E), measuring the backscattering from atmospheric aerosols at a high temporal resolution for several years since 2015. It is the only operating LIDAR system over the Arabian Peninsula. We use this LIDAR data together with other collocated observations and high-resolution WRF-Chem model simulations to study the 3-d structure of aerosols, with a focus on dust over the Red Sea Arabian coastal plains. </p><p>Firstly, we investigate the vertical profiles of aerosol extinction and concentration in terms of their seasonal and diurnal variability. Secondly, using the hourly model output and observations, we study the diurnal cycle of aerosols over the site. Thirdly, we explore the interactions between dust aerosols and land/sea breezes, which are the critical components of the local diurnal circulation in the region. </p><p>We found a substantial variation in the vertical profile of aerosols in different seasons. There is also a marked difference in the daytime and nighttime vertical distribution of aerosols in the study site, as shown by LIDAR data. A prominent dust layer is observed at ~5-7km at night in the LIDAR data, corresponding to the long-range transported dust of non-local origin. The vertical profiles of aerosol extinction are consistently reproduced in LIDAR, MERRA-2 reanalysis, and CALIOP data, as well as in WRF-Chem simulations in all seasons. Our results show that the sea breezes are much deeper (~1km) than the land breezes (~200m), and both of them prominently affect the distribution of dust aerosols over the study site. Sea breezes mainly trap the dust aerosols near the coast, brought by the northeasterly trade winds from inland deserts, causing elevated dust maxima at the height of ~1.5km. Also, sea and land breezes intensify dust emissions from the coastal region in daytime and nighttime, respectively. Such dust emissions caused by sea breezes and land breezes are most active in spring and winter. Finally, WRF-Chem successfully captures the onset, demise, and the height of some large-scale dust events as compared to LIDAR data qualitatively. </p>

scholarly journals Hydrochemical Characterisation of High-Fluoride Groundwater and Development of a Conceptual Groundwater Flow Model Using a Combined Hydrogeological and Hydrochemical Approach on an Active Volcano: Mount Meru, Northern Tanzania

Water ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2159
Author(s):  
George Bennett ◽  
Jill Van Reybrouck ◽  
Ceven Shemsanga ◽  
Mary Kisaka ◽  
Ines Tomašek ◽  
...  
Keyword(s):  
Drinking Water ◽  
Large Scale ◽  
Active Volcano ◽  
Aquifer System ◽  
Groundwater Samples ◽  
Northern Tanzania ◽  
Different Seasons ◽  
High Fluoride ◽  
Arusha National Park ◽  
The Impact

This study characterises high-fluoride groundwater in the aquifer system on the flanks of Mount Meru, focusing on parts of the flanks that were only partially or not at all covered by previous research. Additionally, we analyse the impact of rainwater recharge on groundwater chemistry by monitoring spring discharges during water sampling. The results show that the main groundwater type in the study area is NaHCO3 alkaline groundwater (average pH = 7.8). High F− values were recorded: in 175 groundwater samples, the concentrations range from 0.15 to 301 mg/L (mean: 21.89 mg/L, median: 9.67 mg/L), with 91% of the samples containing F− values above the WHO health-based guideline for drinking water (1.5 mg/L), whereas 39% of the samples have Na+ concentrations above the WHO taste-based guideline of 200 mg/L. The temporal variability in F− concentrations between different seasons is due to the impact of the local groundwater recharge. We recommend that a detailed ecohydrological study should be carried out for the low-fluoride springs from the high-altitude recharge areas on the eastern and northwestern flanks of Mount Meru inside Arusha National Park. These springs are extracted for drinking purposes. An ecohydrological study is required for the management of these springs and their potential enhanced exploitation to ensure the sustainability of this water extraction practice. Another strategy for obtaining safe drinking water could be to use a large-scale filtering system to remove F− from the groundwater.

scholarly journals Remote sensing of aerosols by synergy of caliop and modis

2018 ◽  
Vol 176 ◽  
pp. 08012
Author(s):  
Rei Kudo ◽  
Tomoaki Nishizawa ◽  
Akiko Higurashi ◽  
Eiji Oikawa
Keyword(s):  
Remote Sensing ◽  
Biomass Burning ◽  
Sea Salt ◽  
Water Soluble ◽  
Dust Particles ◽  
Vertical Profiles ◽  
Dust Event ◽  
Carbonaceous Particles ◽  
The Individual ◽  
Better Than

For the monitoring of the global 3-D distribution of aerosol components, we developed the method to retrieve the vertical profiles of water-soluble, light absorbing carbonaceous, dust, and sea salt particles by the synergy of CALIOP and MODIS data. The aerosol product from the synergistic method is expected to be better than the individual products of CALIOP and MODIS. We applied the method to the biomass-burning event in Africa and the dust event in West Asia. The reasonable results were obtained; the much amount of the water-soluble and light absorbing carbonaceous particles were estimated in the biomass-burning event, and the dust particles were estimated in the dust event.

Air recirculation and ventilation in the coastal regions of the Black Sea

2013 ◽  
Vol 5 (2) ◽  
Author(s):  
Galina Surkova
Keyword(s):  
Black Sea ◽  
Eastern Coast ◽  
The Black Sea ◽  
Additional Risk Factor ◽  
Additional Risk ◽  
Sea Breezes ◽  
North Eastern ◽  
Favorable Conditions ◽  
Parameter Values

AbstractAn initial investigation of recirculation is carried out for the coast of the Black Sea. The local mesoscale circulations (land-sea breezes, mountain and valley winds) in coastal areas are shown to be an additional risk factor in creating favorable conditions for air stagnation and accumulation of air pollutants in the surface atmosphere layer. Two types of annual recirculation patterns are revealed for northern and north-eastern coast of the Black Sea. Long-term changes in recirculation are investigated. It is shown that the recirculation parameter values remained quasistable until the mid-1970s. Since 1976–1977, steady intensification of recirculation in both winter and summer is identified.

scholarly journals Carbon dioxide and methane fluxes at the air–sea interface of Red Sea mangroves

2018 ◽  
Vol 15 (17) ◽  
pp. 5365-5375 ◽  
Author(s):  
Mallory A. Sea ◽  
Neus Garcias-Bonet ◽  
Vincent Saderne ◽  
Carlos M. Duarte
Keyword(s):  
Carbon Dioxide ◽  
Organic Matter ◽  
Red Sea ◽  
Ghg Emissions ◽  
Eastern Coast ◽  
Relative Role ◽  
Emission Rates ◽  
Mangrove Forests ◽  
Ch4 Production

Abstract. Mangrove forests are highly productive tropical and subtropical coastal systems that provide a variety of ecosystem services, including the sequestration of carbon. While mangroves are reported to be the most intense carbon sinks among all forests, they can also support large emissions of greenhouse gases (GHGs), such as carbon dioxide (CO2) and methane (CH4), to the atmosphere. However, data derived from arid mangrove systems like the Red Sea are lacking. Here, we report net emission rates of CO2 and CH4 from mangroves along the eastern coast of the Red Sea and assess the relative role of these two gases in supporting total GHG emissions to the atmosphere. Diel CO2 and CH4 emission rates ranged from −3452 to 7500 µmol CO2 m−2 d−1 and from 0.9 to 13.3 µmol CH4 m−2 d−1 respectively. The rates reported here fall within previously reported ranges for both CO2 and CH4, but maximum CO2 and CH4 flux rates in the Red Sea are 10- to 100-fold below those previously reported for mangroves elsewhere. Based on the isotopic composition of the CO2 and CH4 produced, we identified potential origins of the organic matter that support GHG emissions. In all but one mangrove stand, GHG emissions appear to be supported by organic matter from mixed sources, potentially reducing CO2 fluxes and instead enhancing CH4 production, a finding that highlights the importance of determining the origin of organic matter in GHG emissions. Methane was the main source of CO2 equivalents despite the comparatively low emission rates in most of the sampled mangroves and therefore deserves careful monitoring in this region. By further resolving GHG fluxes in arid mangroves, we will better ascertain the role of these forests in global carbon budgets.

scholarly journals High biogeographic and latitudinal variability in gastropod drilling predation on molluscs along the eastern Indian coast: Implications on the history of fossil record of drillholes

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0256685
Author(s):  
Subhronil Mondal ◽  
Hindolita Chakraborty ◽  
Sandip Saha ◽  
Sahana Dey ◽  
Deepjay Sarkar
Keyword(s):  
Spatial Variability ◽  
Large Scale ◽  
Abiotic Factors ◽  
Eastern Coast ◽  
Detailed Knowledge ◽  
Biogeographic Pattern ◽  
Drilling Predation ◽  
History Of ◽  
Latitudinal Patterns ◽  
Consecutive Time

Studies on the large-scale latitudinal patterns of gastropod drilling predation reveal that predation pressure may decrease or increase with increasing latitude, or even show no trend, questioning the generality of any large-scale latitudinal or biogeographic pattern. Here, we analyze the nature of spatio-environmental and latitudinal variation in gastropod drilling along the Indian eastern coast by using 76 samples collected from 39 locations, covering ~2500 km, incorporating several ecoregions, and ~15° latitudinal extents. We find no environmental or latitudinal gradient. In fact, drilling intensity varies highly within the same latitudinal bin, or oceanic sub-basins, or even the same ecoregions. Moreover, different ecoregions with their distinctive biotic and abiotic environmental variables show similar predation intensities. However, one pattern is prevalent: some small infaunal prey taxa, living in the sandy-muddy substrate—which are preferred by the naticid gastropods—are always attacked more frequently over others, indicating taxon and size selectivity by the predators. The result suggests that the biotic and abiotic factors, known to influence drilling predation, determine only the local predation pattern. In the present case, the nature of substrate and prey composition determines the local predation intensity: soft substrate habitats host dominantly small, infaunal prey. Since the degree of spatial variability in drilling intensity within any time bin can be extremely high, sometimes greater than the variability across consecutive time bins, temporal patterns in drilling predation can never be interpreted without having detailed knowledge of the nature of this spatial variability within a time bin.

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