scholarly journals Saharan dust, lightning and tropical cyclones in the eastern tropical Atlantic during NAMMA-06

2008 ◽  
Vol 35 (12) ◽  
pp. n/a-n/a ◽  
Author(s):  
Gregory S. Jenkins ◽  
Aaron Pratt
Keyword(s):  
Tropical Cyclones ◽  
Saharan Dust ◽  
Tropical Atlantic

scholarly journals Influence of Saharan dust on Atlantic tropical cyclones

2020 ◽  
Author(s):  
Zhenxi Zhang ◽  
Wen Zhou
Keyword(s):  
Tropical Cyclones ◽  
North Atlantic ◽  
Radiative Forcing ◽  
Saharan Dust ◽  
Tropical Atlantic ◽  
Atmospheric Moisture ◽  
The North ◽  
The North Atlantic ◽  
Atlantic Itcz ◽  
Atlantic Tropical Cyclone

Abstract. The influence of Saharan dust outbreaks on summertime Atlantic tropical cyclone (TC) activity is explored using continuous atmospheric reanalysis products and TC track data from 1980 to 2019. Analyses reveal that the Saharan dust plume over the tropical Atlantic can affect TC activity by affecting the atmospheric hydrology and radiation absorbed by the earth's surface, which can be classified into three mechanisms. (1) A strong Saharan dust plume indirectly induces the reduction of atmospheric moisture, which further suppresses TC track, number of TC days, and intensity, with the influence covering the whole tropical Atlantic. (2) A strong Saharan dust plume enhances atmospheric moisture just along the North Atlantic ITCZ through the dust microphysical effect, which further promotes TC activity along 10º N latitude in June. (3) The climatological influence of dust on TC activity is caused by the strong radiative forcing of Saharan dust over the eastern tropical Atlantic in June, which produces an evident reduction in SST and lessens the duration and intensity of regional TC activity in June, according to the 40-yr average from 1980 to 2019.

The Track Integrated Kinetic Energy of Atlantic Tropical Cyclones

2013 ◽  
Vol 141 (7) ◽  
pp. 2383-2389 ◽  
Author(s):  
V. Misra ◽  
S. DiNapoli ◽  
M. Powell
Keyword(s):  
Tropical Cyclone ◽  
Kinetic Energy ◽  
Tropical Cyclones ◽  
Warm Pool ◽  
Equatorial Pacific ◽  
Interannual Variations ◽  
Tropical Atlantic ◽  
Cyclone Activity ◽  
Atlantic Warm Pool ◽  
Atlantic Tropical Cyclone

Abstract In this paper the concept of track integrated kinetic energy (TIKE) is introduced as a measure of seasonal Atlantic tropical cyclone activity and applied to seasonal variability in the Atlantic. It is similar in concept to the more commonly used accumulated cyclone energy (ACE) with an important difference that in TIKE the integrated kinetic energy (IKE) is accumulated for the life span of the Atlantic tropical cyclone. The IKE is, however, computed by volume integrating the 10-m level sustained winds of tropical strength or higher quadrant by quadrant, while ACE uses the maximum sustained winds only without accounting for the structure of the storm. In effect TIKE accounts for the intensity, duration, and size of the tropical cyclones. In this research, the authors have examined the seasonality and the interannual variations of the seasonal Atlantic TIKE over a period of 22 yr from 1990 to 2011. It is found that the Atlantic TIKE climatologically peaks in the month of September and the frequency of storms with the largest TIKE are highest in the eastern tropical Atlantic. The interannual variations of the Atlantic TIKE reveal that it is likely influenced by SST variations in the equatorial Pacific and in the Atlantic Oceans. The SST variations in the central equatorial Pacific are negatively correlated with the contemporaneous seasonal (June–November) TIKE. The size of the Atlantic warm pool (AWP) is positively correlated with seasonal TIKE.

scholarly journals An additional low layer transport of Sahelian and Saharan dust over the north-eastern Tropical Atlantic

1995 ◽  
Vol 22 (23) ◽  
pp. 3191-3194 ◽  
Author(s):  
I. Chiapello ◽  
G. Bergametti ◽  
L. Gomes ◽  
B. Chatenet ◽  
F. Dulac ◽  
...  
Keyword(s):  
Saharan Dust ◽  
Tropical Atlantic ◽  
The North ◽  
North Eastern

scholarly journals Profiling of Saharan dust from the Caribbean to western Africa – Part 2: Shipborne lidar measurements versus forecasts

2017 ◽  
Vol 17 (24) ◽  
pp. 14987-15006 ◽  
Author(s):  
Albert Ansmann ◽  
Franziska Rittmeister ◽  
Ronny Engelmann ◽  
Sara Basart ◽  
Oriol Jorba ◽  
...  
Keyword(s):  
Mass Concentration ◽  
Dust Emission ◽  
Saharan Dust ◽  
Light Extinction ◽  
Tropical Atlantic ◽  
Fine Dust ◽  
Anthropogenic Aerosol ◽  
Dust Transport ◽  
Western Africa ◽  
Dust Sources

Abstract. A unique 4-week ship cruise from Guadeloupe to Cabo Verde in April–May 2013 see part 1, Rittmeister et al. (2017) is used for an in-depth comparison of dust profiles observed with a polarization/Raman lidar aboard the German research vessel Meteor over the remote tropical Atlantic and respective dust forecasts of a regional (SKIRON) and two global atmospheric (dust) transport models (NMMB/BSC-Dust, MACC/CAMS). New options of model–observation comparisons are presented. We analyze how well the modeled fine dust (submicrometer particles) and coarse dust contributions to light extinction and mass concentration match respective lidar observations, and to what extent models, adjusted to aerosol optical thickness observations, are able to reproduce the observed layering and mixing of dust and non-dust (mostly marine) aerosol components over the remote tropical Atlantic. Based on the coherent set of dust profiles at well-defined distances from Africa (without any disturbance by anthropogenic aerosol sources over the ocean), we investigate how accurately the models handle dust removal at distances of 1500 km to more than 5000 km west of the Saharan dust source regions. It was found that (a) dust predictions are of acceptable quality for the first several days after dust emission up to 2000 km west of the African continent, (b) the removal of dust from the atmosphere is too strong for large transport paths in the global models, and (c) the simulated fine-to-coarse dust ratio (in terms of mass concentration and light extinction) is too high in the models compared to the observations. This deviation occurs initially close to the dust sources and then increases with distance from Africa and thus points to an overestimation of fine dust emission in the models.

scholarly journals Impacts of Saharan Dust on Atlantic Regional Climate and Implications for Tropical Cyclones

2018 ◽  
Vol 31 (18) ◽  
pp. 7621-7644 ◽  
Author(s):  
Bowen Pan ◽  
Yuan Wang ◽  
Jiaxi Hu ◽  
Yun Lin ◽  
Jen-Shan Hsieh ◽  
...  
Keyword(s):  
Tropical Cyclones ◽  
Wind Shear ◽  
Large Scale ◽  
Hydrological Cycle ◽  
Regional Climate ◽  
Vertical Wind Shear ◽  
Saharan Dust ◽  
Specific Humidity ◽  
Shortwave Radiation ◽  
Cloud Formation

The radiative and microphysical properties of Saharan dust are believed to impact the Atlantic regional climate and tropical cyclones (TCs), but the detailed mechanism remains uncertain. In this study, atmosphere-only simulations are performed from 2002 to 2006 using the Community Atmospheric Model, version 5.1, with and without dust emission from the Sahara Desert. The Saharan dust exhibits noticeable impacts on the regional longwave and shortwave radiation, cloud formation, and the convective systems over West Africa and the tropical Atlantic. The African easterly jet and West African monsoon are modulated by dust, leading to northward shifts of the intertropical convergence zone and the TC genesis region. The dust events induce positive midlevel moisture and entropy deficit anomalies, enhancing the TC genesis. On the other hand, the increased vertical wind shear and decreased low-level vorticity and potential intensity by dust inhibit TC formation in the genesis region. The ventilation index shows a decrease in the intensification region and an increase in the genesis region by dust, corresponding to favorable and unfavorable TC activities, respectively. The comparison of nondust scenarios in 2005 and 2006 shows more favorable TC conditions in 2005 characterized by higher specific humidity and potential intensity, but lower ventilation index, wind shear, and entropy deficit. Those are attributable to the observed warmer sea surface temperature (SST) in 2005, in which dust effects can be embedded. Our results imply significant dust perturbations on the radiative budget, hydrological cycle, and large-scale environments relevant to TC activity over the Atlantic.

scholarly journals When Does the Saharan Air Layer Impede the Intensification of Tropical Cyclones?

2020 ◽  
Vol 33 (24) ◽  
pp. 10609-10626
Author(s):  
W. T. K. Huang ◽  
C. Schnadt Poberaj ◽  
B. Enz ◽  
C. Horat ◽  
U. Lohmann
Keyword(s):  
Tropical Cyclones ◽  
North Atlantic Ocean ◽  
Negative Impact ◽  
Saharan Dust ◽  
Air Masses ◽  
Saharan Air Layer ◽  
The North ◽  
Weak Negative Correlation ◽  
Central Atlantic ◽  
Hurricane Tracking

AbstractWe investigate the circumstances under which the Saharan air layer (SAL) has a negative impact on the intensification of tropical cyclones (TCs) over the North Atlantic Ocean. Using hurricane tracking, aerosol optical depth (AOD) data, and meteorological analyses, we analyze the interaction of the SAL with 52 named TCs that formed over the east and central Atlantic south of the Cape Verde islands between 2004 and 2017. Following the categorization of negative SAL influences on TC intensification by Dunion and Velden, only 21% of the investigated storms can be classified (28% of all storms that encountered the SAL), and 21% of the storms continue to intensify despite the presence of the SAL. We show that among TCs that encounter the SAL, there is evidence supporting a weak negative correlation between the magnitude of TC intensification and the ambient AOD. However, above-average Saharan dust abundance in the vicinity of TCs is not a good independent indicator for storm nonintensification. To better understand the specific processes involved, a composite study is carried out, contrasting storms that intensify in the presence of the SAL against those that do not. We find that sheared air masses on the north side and drier air from the northeast of the storm early on during its lifetime, in addition to higher AOD, are associated with TC nonintensification in proximity to the SAL.

scholarly journals Profiling of Saharan dust from the Caribbean to West Africa, Part 2: Shipborne lidar measurements versus forecasts

2017 ◽  
Author(s):  
Albert Ansmann ◽  
Franziska Rittmeister ◽  
Ronny Engelmann ◽  
Sara Basart ◽  
Angela Benedetti ◽  
...  
Keyword(s):  
Mass Concentration ◽  
Dust Emission ◽  
Saharan Dust ◽  
Light Extinction ◽  
Tropical Atlantic ◽  
Anthropogenic Aerosol ◽  
Dust Transport ◽  
Source Regions ◽  
Dust Sources ◽  
Lidar Measurements

Abstract. A unique 4-week ship cruise from Guadeloupe to Cabo Verde in April–May 2013 (see part 1, Rittmeister et al., 2017) is used for an in-depth comparison of dust profiles observed with a polarization/Raman lidar aboard the German research vessel Meteor over the remote tropical Atlantic and respective dust forecasts of a regional (SKIRON) and two global atmospheric (dust) transport models (NMMB/BSC-Dust, MACC/CAMS). New options of model-observation comparisons are presented. We analyze how well the modeled fine dust (submicrometer particles) and coarse dust contributions to light extinction and mass concentration match respective lidar observations, and to what extent models, adjusted to aerosol optical thickness observations, are able to reproduce the observed layering and mixing of dust and non-dust (mostly marine) aerosol components over the remote tropical Atlantic. Based on the coherent set of dust profiles at well defined distances from Africa (without any disturbance by anthropogenic aerosol sources over the ocean) we investigate how accurately the models handle dust removal at distances of 1500 km to more than 5000 km west of the Saharan dust source regions. It was found that (a) dust predictions are of acceptable quality for the first several days after dust emission up to 2000 km west of the African continent, (b) the removal of dust from the atmosphere is too strong for large transport paths in the global models, and (c) the simulated fine-to-coarse dust ratio (in terms of mass concentration and light extinction) is too high in the models compared to the observations. This deviation is already given close to the dust sources and then increases with distance from Africa.

scholarly journals The Climatological Effect of Saharan Dust on Global Tropical Cyclones in a Fully Coupled GCM

2018 ◽  
Vol 123 (10) ◽  
pp. 5538-5559 ◽  
Author(s):  
Jeffrey D. O. Strong ◽  
Gabriel A. Vecchi ◽  
Paul Ginoux
Keyword(s):  
Tropical Cyclones ◽  
Saharan Dust ◽  
Coupled Gcm ◽  
Fully Coupled
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