An assessment of the quality of aerosol retrievals over the Red Sea and evaluation of the climatological cloud-free dust direct radiative effect in the region

Brindley, Helen E.; Osipov, Sergey; Bantges, R.; Smirnov, A.; Banks, Jamie; Levy, Robert C.; Prakash, P. Jish; Stenchikov, Georgiy L.

doi:10.1002/2015jd023282

Cited by 34 publications

(52 citation statements)

References 76 publications

(110 reference statements)

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“…Nevertheless, Brindley et al (2015) (subsequently denoted B15) recently investigated the performance of satellite retrievals over the Red Sea, making use of ship cruise data taken under the framework of the Maritime AERONET Network (Smirnov et al, 2009). They found close agreement between dust aerosol retrievals from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) and the MODerate resolution Imaging Spectroradiometer (MODIS) instruments.…”

Section: Introductionmentioning

confidence: 98%

Satellite retrievals of dust aerosol over the Red Sea and the Persian Gulf (2005–2015)

et al. 2017

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Abstract. The inter-annual variability of the dust aerosol presence over the Red Sea and the Persian Gulf is analysed over the period [2005][2006][2007][2008][2009][2010][2011][2012][2013][2014][2015]. Particular attention is paid to the variation in loading across the Red Sea, which has previously been shown to have a strong, seasonally dependent latitudinal gradient. Over the 11 years considered, the July mean 630 nm aerosol optical depth (AOD) derived from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) varies between 0.48 and 1.45 in the southern half of the Red Sea. In the north, the equivalent variation is between 0.22 and 0.66. The temporal and spatial pattern of variability captured by SEVIRI is also seen in AOD retrievals from the MODerate Imaging Spectroradiometer (MODIS), but there is a systematic offset between the two records. Comparisons of both sets of retrievals with ship-and land-based AERONET measurements show a high degree of correlation with biases of < 0.08. However, these comparisons typically only sample relatively low aerosol loadings. When both records are stratified by AOD retrievals from the Multi-angle Imaging SpectroRadiometer (MISR), opposing behaviour is revealed at high MISR AODs (> 1), with offsets of +0.19 for MODIS and −0.06 for SEVIRI. Similar behaviour is also seen over the Persian Gulf. Analysis of the scattering angles at which retrievals from the SEVIRI and MODIS measurements are typically performed in these regions suggests that assumptions concerning particle sphericity may be responsible for the differences seen.

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Section: Introductionmentioning

confidence: 98%

Satellite retrievals of dust aerosol over the Red Sea and the Persian Gulf (2005–2015)

et al. 2017

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“…However, the temporal development of the Chl-a anomaly is difficult to make out due to the large fraction of missing data, indicated by the white areas. Inspection of the MODIS-Terra and Aqua true color imagery and AOD retrievals for this time period show elevated AOD due to blowing dust, which is persistent in this season [56,57], as well as high clouds and AOD and Chl-a retrieval exclusions due to sun-glint. The eddy appears in the northwestern part of the SCRS on 22 June, as evidenced by a ring of elevated Chl-a.…”

Section: Temporal and Spatial Variations Of Chl-a Concentration-relatmentioning

confidence: 99%

Synergistic Use of Remote Sensing and Modeling to Assess an Anomalously High Chlorophyll-a Event during Summer 2015 in the South Central Red Sea

El-Askary

Manikandan

et al. 2017

Remote Sensing

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An anomalously high chlorophyll-a (Chl-a) event (>2 mg/m 3 ) during June 2015 in the South Central Red Sea (17.5 • to 22 • N, 37 • to 42 • E) was observed using Moderate Resolution Imaging Spectroradiometer (MODIS) data from the Terra and Aqua satellite platforms. This differs from the low Chl-a values (<0.5 mg/m 3 ) usually encountered over the same region during summertime. To assess this anomaly and possible causes, we used a wide range of oceanographical and meteorological datasets, including Chl-a concentrations, sea surface temperature (SST), sea surface height (SSH), mixed layer depth (MLD), ocean current velocity and aerosol optical depth (AOD) obtained from different sensors and models. Findings confirmed this anomalous behavior in the spatial domain using Hovmöller data analysis techniques, while a time series analysis addressed monthly and daily variability. Our analysis suggests that a combination of factors controlling nutrient supply contributed to the anomalous phytoplankton growth. These factors include horizontal transfer of upwelling water through eddy circulation and possible mineral fertilization from atmospheric dust deposition. Coral reefs might have provided extra nutrient supply, yet this is out of the scope of our analysis. We thought that dust deposition from a coastal dust jet event in late June, coinciding with the phytoplankton blooms in the area under investigation, might have also contributed as shown by our AOD findings. However, a lag cross correlation showed a two-month lag between strong dust outbreak and the high Chl-a anomaly. The high Chl-a concentration at the edge of the eddy emphasizes the importance of horizontal advection in fertilizing oligotrophic (nutrient poor) Red Sea waters.

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“…As was pointed out by Yu et al (2013) the differences between the deposition and AOD time series can in part be attributed to modifications of the natural dust aerosol by anthropogenic activities, including petrochemical and other large industries along the Red Sea coast, as well as by entrainment of construction and road dust. However, the substantial contamination of dust by anthropogenic species and sea salt is not likely in this area, as was suggested by both observational Brindley et al, 2015) and modeling studies (Kalenderski and Stenchikov, 2016). To further test whether the non-dust fine aerosols (or remotely transported fine dust) significantly contribute to the interrelation between AOD and deposition rates, we followed two additional approaches.…”

Section: Aeronet and Visibility Measurementsmentioning

confidence: 99%

“…The Red Sea, being enveloped by the Arabian and African deserts, is strongly impacted by windborne mineral dust. Along with profound influence on the surface energy budget over land and the Red Sea (Kalenderski et al, 2013;Osipov et al, 2015;Brindley et al, 2015), dust is an important source of nutrients, more so for the oligotrophic northern Red Sea waters (Acosta et al, 2013). From preliminary assessments it is estimated that five to six major dust storms per year impact the Red Sea region, depositing about 6 Mt of mineral dust into the Red Sea (Jish .…”

Section: Previous Dust Studies In the Regionmentioning

confidence: 99%

Physical and chemical properties of deposited airborne particulates over the Arabian Red Sea coastal plain

et al. 2017

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Abstract. Mineral dust is the most abundant aerosol, having a profound impact on the global energy budget. This research continues our previous studies performed on surface soils in the Arabian Peninsula, focusing on the mineralogical, physical and chemical composition of dust deposits from the atmosphere at the Arabian Red Sea coast. For this purpose, aerosols deposited from the atmosphere are collected during 2015 at six sites on the campus of the King Abdullah University of Science and Technology (KAUST) situated on the Red Sea coastal plain of Saudi Arabia and subjected to the same chemical and mineralogical analysis we conducted on soil samples. Frisbee deposition samplers with foam inserts were used to collect dust and other deposits, for the period December 2014 to December 2015. The average deposition rate measured at KAUST for this period was 14 g m −2 per month, with lowest values in winter and increased deposition rates in August to October. The particle size distributions provide assessments of < 10 and < 2.5 µm dust deposition rates, and it is suggested that these represent proxies for PM 10 (coarse) and PM 2.5 (fine) particle size fractions in the dust deposits.X-ray diffraction (XRD) analysis of a subset of samples confirms variable amounts of quartz, feldspars, micas, and halite, with lesser amounts of gypsum, calcite, dolomite, hematite, and amphibole. Freeze-dried samples were resuspended onto the Teflon ® filters for elemental analysis by X-ray fluorescence (XRF), while splits from each sample were analyzed for water-soluble cations and anions by ion chromatography. The dust deposits along the Red Sea coast are considered to be a mixture of dust emissions from local soils and soils imported from distal dust sources. Airborne mineral concentrations are greatest at or close to dust sources, compared to those through medium-and long-range transport. It is not possible to identify the exact origin of deposition samples from the mineralogical and chemical results alone. These aerosol data are the first of their kind from the Red Sea region. They will help assess their potential nutrient input into the Red Sea, as well the impact on human health, industry, and solar panel efficiency. These data will also support dust modeling in this important dust belt source area by better quantifying dust mass balance and optical properties of airborne dust particles.

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An assessment of the quality of aerosol retrievals over the Red Sea and evaluation of the climatological cloud-free dust direct radiative effect in the region

Cited by 34 publications

References 76 publications

Satellite retrievals of dust aerosol over the Red Sea and the Persian Gulf (2005–2015)

Satellite retrievals of dust aerosol over the Red Sea and the Persian Gulf (2005–2015)

Synergistic Use of Remote Sensing and Modeling to Assess an Anomalously High Chlorophyll-a Event during Summer 2015 in the South Central Red Sea

Physical and chemical properties of deposited airborne particulates over the Arabian Red Sea coastal plain

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