scholarly journals Observational evidence for the vertical redistribution and scavenging of Saharan dust by tropical cyclones

2017 ◽  
Vol 44 (12) ◽  
pp. 6421-6430 ◽  
Author(s):  
Kathryn Sauter ◽  
Tristan S. L'Ecuyer
Keyword(s):  
Tropical Cyclones ◽  
Observational Evidence ◽  
Saharan Dust

Observational evidence for an ocean heat pump induced by tropical cyclones

Nature ◽  
2007 ◽  
Vol 447 (7144) ◽  
pp. 577-580 ◽  
Author(s):  
Ryan L. Sriver ◽  
Matthew Huber
Keyword(s):  
Tropical Cyclones ◽  
Heat Pump ◽  
Observational Evidence

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 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

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.

scholarly journals Tropical cyclone motion in a changing climate

2020 ◽  
Vol 6 (17) ◽  
pp. eaaz7610 ◽  
Author(s):  
Gan Zhang ◽  
Hiroyuki Murakami ◽  
Thomas R. Knutson ◽  
Ryo Mizuta ◽  
Kohei Yoshida
Keyword(s):  
North America ◽  
Tropical Cyclone ◽  
Tropical Cyclones ◽  
21St Century ◽  
Climate Models ◽  
Observational Evidence ◽  
Accumulated Damage ◽  
Ensemble Simulations ◽  
Poleward Shift ◽  
Anthropogenic Forcings

The locally accumulated damage by tropical cyclones (TCs) can intensify substantially when these cyclones move more slowly. While some observational evidence suggests that TC motion might have slowed significantly since the mid-20th century (1), the robustness of the observed trend and its relation to anthropogenic warming have not been firmly established (2–4). Using large-ensemble simulations that directly simulate TC activity, we show that future anthropogenic warming can lead to a robust slowing of TC motion, particularly in the midlatitudes. The slowdown there is related to a poleward shift of the midlatitude westerlies, which has been projected by various climate models. Although the model’s simulation of historical TC motion trends suggests that the attribution of the observed trends of TC motion to anthropogenic forcings remains uncertain, our findings suggest that 21st-century anthropogenic warming could decelerate TC motion near populated midlatitude regions in Asia and North America, potentially compounding future TC-related damages.

scholarly journals The Evolution and Role of the Saharan Air Layer during Hurricane Helene (2006)

2013 ◽  
Vol 141 (12) ◽  
pp. 4269-4295 ◽  
Author(s):  
Scott A. Braun ◽  
Jason A. Sippel ◽  
Chung-Lin Shie ◽  
Ryan A. Boller
Keyword(s):  
Tropical Cyclones ◽  
Satellite Remote Sensing ◽  
Substantial Reduction ◽  
Remote Sensing Data ◽  
Negative Influence ◽  
Sea Surface ◽  
Saharan Dust ◽  
Forward Motion ◽  
Saharan Air Layer

Abstract The Saharan air layer (SAL) has received considerable attention in recent years as a potential negative influence on the formation and development of Atlantic tropical cyclones. Observations of substantial Saharan dust in the near environment of Hurricane Helene (2006) during the National Aeronautics and Space Administration (NASA) African Monsoon Multidisciplinary Activities (AMMA) Experiment (NAMMA) field campaign led to suggestions about the suppressing influence of the SAL in this case. In this study, a suite of satellite remote sensing data, global meteorological analyses, and airborne data are used to characterize the evolution of the SAL in the environment of Helene and assess its possible impact on the intensity of the storm. The influence of the SAL on Helene appears to be limited to the earliest stages of development, although the magnitude of that impact is difficult to determine observationally. Saharan dust was observed on the periphery of the storm during the first two days of development after genesis when intensification was slow. Much of the dust was observed to move well westward of the storm thereafter, with little SAL air present during the remainder of the storm's lifetime and with the storm gradually becoming a category-3 strength storm four days later. Dry air observed to wrap around the periphery of Helene was diagnosed to be primarily non-Saharan in origin (the result of subsidence) and appeared to have little impact on storm intensity. The eventual weakening of the storm is suggested to result from an eyewall replacement cycle and substantial reduction of the sea surface temperatures beneath the hurricane as its forward motion decreased.

Sign in / Sign up

Export Citation Format

Share Document