scholarly journals Revisiting the relationship between Atlantic dust and tropical cyclone activity using aerosol optical depth reanalyses: 2003–2018

2020 ◽  
Vol 20 (23) ◽  
pp. 15357-15378
Author(s):  
Peng Xian ◽  
Philip J. Klotzbach ◽  
Jason P. Dunion ◽  
Matthew A. Janiga ◽  
Jeffrey S. Reid ◽  
...  
Keyword(s):  
Tropical Cyclone ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
North Atlantic ◽  
Southern Oscillation ◽  
Tropical Atlantic ◽  
African Dust ◽  
Tropical North Atlantic ◽  
The Caribbean ◽  
The Relationship

Abstract. Previous studies have noted a relationship between African dust and Atlantic tropical cyclone (TC) activity. However, due to the limitations of past dust analyses, the strength of this relationship remains uncertain. The emergence of aerosol reanalyses, including the Navy Aerosol Analysis and Prediction System (NAAPS) aerosol optical depth (AOD) reanalysis, NASA Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2), and ECMWF Copernicus Atmosphere Monitoring Service reanalysis (CAMSRA), enables an investigation of the relationship between African dust and TC activity over the tropical Atlantic and Caribbean in a consistent temporal and spatial manner for 2003–2018. Although June–July–August (JJA) 550 nm dust AOD (DAOD) from all three reanalysis products correlates significantly over the tropical Atlantic and Caribbean, the difference in DAOD magnitude between products can be as large as 60 % over the Caribbean and 20 % over the tropical North Atlantic. Based on the three individual reanalyses, we have created an aerosol multi-reanalysis consensus (MRC). The MRC presents overall better root mean square error over the tropical Atlantic and Caribbean compared to individual reanalyses when verified with ground-based AErosol RObotic NETwork (AERONET) AOD measurements. Each of the three individual reanalyses and the MRC have significant negative correlations between JJA Caribbean DAOD and seasonal Atlantic accumulated cyclone energy (ACE), while the correlation between JJA tropical North Atlantic DAOD and seasonal ACE is weaker. Possible reasons for this regional difference are provided. A composite analysis of 3 high-JJA-Caribbean-DAOD years versus 3 low-JJA-Caribbean-DAOD years reveals large differences in overall Atlantic TC activity. We also show that JJA Caribbean DAOD is significantly correlated with large-scale fields associated with variability in interannual Atlantic TC activity including zonal wind shear, mid-level moisture, and sea surface temperature (SST), as well as the El Niño–Southern Oscillation (ENSO) and the Atlantic Meridional Mode (AMM), implying confounding effects of these factors on the dust–TC relationship. We find that seasonal Atlantic DAOD and the AMM, the leading mode of coupled Atlantic variability, are inversely related and intertwined in the dust–TC relationship. Overall, DAOD in both the tropical Atlantic and Caribbean is negatively correlated with Atlantic hurricane frequency and intensity, with stronger correlations in the Caribbean than farther east in the tropical North Atlantic.

scholarly journals Revisiting the Relationship between Atlantic Dust and Tropical Cyclone Activity using Aerosol Optical Depth Reanalyses: 2003–2018

2020 ◽  
Author(s):  
Peng Xian ◽  
Philip J. Klotzbach ◽  
Jason P. Dunion ◽  
Matthew A. Janiga ◽  
Jeffrey S. Reid ◽  
...  
Keyword(s):  
Tropical Cyclone ◽  
Aerosol Optical Depth ◽  
Optical Depth ◽  
North Atlantic ◽  
Large Scale ◽  
Tropical Atlantic ◽  
African Dust ◽  
Tropical North Atlantic ◽  
June July ◽  
The Relationship

Abstract. Previous studies have noted a relationship between African dust and Atlantic tropical cyclone (TC) activity. However, due to the limitations of past dust analyses, the strength of this relationship remains uncertain. The emergence of aerosol reanalyses, including the Navy Aerosol Analysis and Prediction System (NAAPS) Aerosol Optical Depth (AOD) reanalysis, NASA Modern-Era Retrospective analysis for Research and Applications, Version-2 (MERRA-2) and ECMWF Copernicus Atmosphere Monitoring Service reanalysis (CAMSRA) enable an investigation of the relationship between African dust and TC activity over the tropical Atlantic and Caribbean in a consistent temporal and spatial manner for 2003–2018. Although June-July-August (JJA) 550 nm dust AOD (DAOD) from all three reanalysis products correlate significantly over the tropical Atlantic and Caribbean, the difference in DAOD magnitude between products can be as large as 60 % over the Caribbean and 20 % over the tropical North Atlantic. Based on the three individual reanalyses, we have created an aerosol multi-reanalysis-consensus (MRC). The MRC presents overall better root mean square error over the tropical Atlantic and Caribbean compared to individual reanalyses when verified with ground-based AErosol RObotic NETwork (AERONET) AOD measurements. Each of the three individual reanalyses and the MRC have significant negative correlations between JJA Caribbean DAOD and seasonal Atlantic Accumulated Cyclone Energy (ACE), while the correlation between JJA tropical North Atlantic DAOD and seasonal ACE is weaker. Possible reasons for this regional difference are provided. A composite analysis of three high versus three low JJA Caribbean DAOD years reveals large differences in overall Atlantic TC activity. We also show that JJA Caribbean DAOD is significantly correlated with large-scale fields associated with variability in interannual Atlantic TC activity including zonal wind shear, mid-level moisture and SST, as well as ENSO and the Atlantic Meridional Mode (AMM), implying confounding effects of these factors on the dust-TC relationship. Further analysis indicates that seasonal Atlantic DAOD and the AMM, the leading mode of coupled Atlantic variability, are inversely related and intertwined in the dust-TC relationship.

scholarly journals Moisture and Precipitation Evolution during Tropical Cyclone Formation as Revealed by the SSM/I–SSMIS Retrievals

2016 ◽  
Vol 73 (7) ◽  
pp. 2773-2781 ◽  
Author(s):  
Zhuo Wang ◽  
Isaac Hankes
Keyword(s):  
Water Vapor ◽  
Tropical Cyclone ◽  
North Atlantic ◽  
Deep Convection ◽  
Exponential Rate ◽  
Tropical Cyclone Formation ◽  
Time Period ◽  
Tropical North Atlantic ◽  
The Relationship ◽  
High Column

Abstract The simultaneous precipitation and column water vapor retrievals from the SSM/I and SSMIS passive microwave instruments were used to examine the convective and moisture evolution during tropical cyclone formation. Using a wave-pouch-track dataset, composites of precipitation and column water vapor were constructed with more than 2000 satellite overpasses for a 3-day time period prior to genesis. It was found that high column water vapor occurs near the pouch center and starts to increase about 42 h prior to genesis while a substantial increase in precipitation occurs within 24 h prior to genesis. These features are consistent with a recently proposed two-stage conceptual model for tropical cyclone formation, in which gradual moisture preconditioning precedes an abrupt transition to sustained deep convection leading up to genesis. The relationship between precipitation and saturation fraction (SF) is examined for the developing waves and compared with the general tropical North Atlantic. Precipitation rate is found to increase at the same exponential rate above the same critical point of SF in the two groups, but convection in the developing waves has a higher probability of occurrence near and above criticality. This can be attributed to the positive feedback between convection and the low-level moisture convergence, which counteracts the negative feedback of convection on water vapor and makes convection in a developing tropical cyclone more sustainable.

Seasonal radiogenic isotopic variability of the African dust outflow to the tropical Atlantic Ocean and across to the Caribbean

2018 ◽  
Vol 487 ◽  
pp. 94-105 ◽  
Author(s):  
Ashwini Kumar ◽  
W. Abouchami ◽  
S.J.G. Galer ◽  
Satinder Pal Singh ◽  
K.W. Fomba ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Tropical Atlantic ◽  
Tropical Atlantic Ocean ◽  
African Dust ◽  
The Caribbean

Non-linearity in the pathway of El Niño-Southern Oscillation to the tropical North Atlantic

2021 ◽  
pp. 1-54
Author(s):  
Jake W. Casselman ◽  
Andréa S. Taschetto ◽  
Daniela I.V. Domeisen
Keyword(s):  
North Atlantic ◽  
El Niño ◽  
Climate Model ◽  
El Nino ◽  
Southern Oscillation ◽  
Static Stability ◽  
Reanalysis Data ◽  
El Niño Southern Oscillation ◽  
El Nino Southern Oscillation ◽  
Tropical North Atlantic

AbstractEl Niño-Southern Oscillation can influence the Tropical North Atlantic (TNA), leading to anomalous sea surface temperatures (SST) at a lag of several months. Several mechanisms have been proposed to explain this teleconnection. These mechanisms include both tropical and extratropical pathways, contributing to anomalous trade winds and static stability over the TNA region. The TNA SST response to ENSO has been suggested to be nonlinear. Yet the overall linearity of the ENSO-TNA teleconnection via the two pathways remains unclear. Here we use reanalysis data to confirm that the SST anomaly (SSTA) in the TNA is nonlinear with respect to the strength of the SST forcing in the tropical Pacific, as further increases in El Niño magnitudes cease to create further increases of the TNA SSTA. We further show that the tropical pathway is more linear than the extratropical pathway by sub-dividing the inter-basin connection into extratropical and tropical pathways. This is confirmed by a climate model participating in the CMIP5. The extratropical pathway is modulated by the North Atlantic Oscillation (NAO) and the location of the SSTA in the Pacific, but this modulation insufficiently explains the nonlinearity in TNA SSTA. As neither extratropical nor tropical pathways can explain the nonlinearity, this suggests that external factors are at play. Further analysis shows that the TNA SSTA is highly influenced by the preconditioning of the tropical Atlantic SST. This preconditioning is found to be associated with the NAO through SST-tripole patterns.

scholarly journals Checklist of the salps (Tunicata, Thaliacea) from the Western Caribbean Sea with a key for their identification and comments on other North Atlantic salps

Zootaxa ◽  
2012 ◽  
Vol 3210 (1) ◽  
pp. 50 ◽  
Author(s):  
CLARA MARÍA HEREU ◽  
EDUARDO SUÁREZ-MORALES
Keyword(s):  
North Atlantic ◽  
Caribbean Sea ◽  
Depth Range ◽  
Tropical Atlantic ◽  
The North ◽  
New Information ◽  
Plankton Biomass ◽  
Western Caribbean ◽  
The Caribbean

In waters of the Northwestern Atlantic pelagic tunicates may contribute significantly to the plankton biomass; however, theregional information on the salp fauna is scarce and limited to restricted sectors. In the Caribbean Sea (CS) and the Gulf ofMexico (GOM) the composition of the salpid fauna is still poorly known and this group remains among the less studiedzooplankton taxa in the Northwestern Tropical Atlantic. A revised checklist of the salp species recorded in the North At-lantic (NA, 0–40° N) is provided herein, including new information from the Western Caribbean. Zooplankton sampleswere collected during two cruises (March 2006, January 2007) within a depth range of 0–941 m. A total of 14 species wererecorded in our samples, including new records for the CS and GOM area (Cyclosalpa bakeri Ritter 1905), for the CS (Cy-closalpa affinis (Chamisso, 1819)), and for the Western Caribbean (Salpa maxima Forskål, 1774). The number of speciesof salps known from the CS and GOM rose to 18. A key for the identification of the species recorded in the region is provided. Studies on the ecological role of salps in several sectors of the NA are scarce and deserve further attention.

Relationship between MODIS based Aerosol Optical Depth and PM10 over Croatia

2014 ◽  
Vol 6 (1) ◽  
Author(s):  
Sanja Grgurić ◽  
Josip Križan ◽  
Goran Gašparac ◽  
Oleg Antonić ◽  
Zdravko Špirić ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Mass Concentration ◽  
Meteorological Data ◽  
Neural Network Approach ◽  
Data Set ◽  
Independent Variables ◽  
Data Variability ◽  
Modis Aod ◽  
The Relationship

AbstractThis study analyzes the relationship between Aerosol Optical Depth (AOD) obtained from Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) and ground-based PM10 mass concentration distribution over a period of 5 years (2008–2012), and investigates the applicability of satellite AOD data for ground PM10 mapping for the Croatian territory. Many studies have shown that satellite AOD data are correlated to ground-based PM mass concentration. However, the relationship between AOD and PM is not explicit and there are unknowns that cause uncertainties in this relationship.The relationship between MODIS AOD and ground-based PM10 has been studied on the basis of a large data set where daily averaged PM10 data from the 12 air quality stations across Croatia over the 5 year period are correlated with AODs retrieved from MODIS Terra and Aqua. A database was developed to associate coincident MODIS AOD (independent) and PM10 data (dependent variable). Additional tested independent variables (predictors, estimators) included season, cloud fraction, and meteorological parameters — including temperature, air pressure, relative humidity, wind speed, wind direction, as well as planetary boundary layer height — using meteorological data from WRF (Weather Research and Forecast) model.It has been found that 1) a univariate linear regression model fails at explaining the data variability well which suggests nonlinearity of the AOD-PM10 relationship, and 2) explanation of data variability can be improved with multivariate linear modeling and a neural network approach, using additional independent variables.

scholarly journals Improved MODIS Dark Target aerosol optical depth algorithm over land: angular effect correction

2016 ◽  
Vol 9 (11) ◽  
pp. 5575-5589 ◽  
Author(s):  
Yerong Wu ◽  
Martin de Graaf ◽  
Massimo Menenti
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Vegetation Index ◽  
Surface Reflectance ◽  
Infrared Band ◽  
Surface Reflection ◽  
Global Land ◽  
Bidirectional Reflectance Factor ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
The Relationship

Abstract. Aerosol optical depth (AOD) product retrieved from MODerate Resolution Imaging Spectroradiometer (MODIS) measurements has greatly benefited scientific research in climate change and air quality due to its high quality and large coverage over the globe. However, the current product (e.g., Collection 6) over land needs to be further improved. The is because AOD retrieval still suffers large uncertainty from the surface reflectance (e.g., anisotropic reflection) although the impacts of the surface reflectance have been largely reduced using the Dark Target (DT) algorithm. It has been shown that the AOD retrieval over dark surface can be improved by considering surface bidirectional distribution reflectance function (BRDF) effects in previous study. However, the relationship of the surface reflectance between visible and shortwave infrared band that applied in the previous study can lead to an angular dependence of the AOD retrieval. This has at least two reasons. The relationship based on the assumption of isotropic reflection or Lambertian surface is not suitable for the surface bidirectional reflectance factor (BRF). However, although the relationship varies with the surface cover type by considering the vegetation index NDVISWIR, this index itself has a directional effect and affects the estimation of the surface reflection, and it can lead to some errors in the AOD retrieval. To improve this situation, we derived a new relationship for the spectral surface BRF in this study, using 3 years of data from AERONET-based Surface Reflectance Validation Network (ASRVN). To test the performance of the new algorithm, two case studies were used: 2 years of data from North America and 4 months of data from the global land. The results show that the angular effects of the AOD retrieval are largely reduced in most cases, including fewer occurrences of negative retrievals. Particularly, for the global land case, the AOD retrieval was improved by the new algorithm compared to the previous study and MODIS Collection 6 DT algorithm, with the increase of 2.0 and 4.5 % AOD retrievals falling within the expected accuracy envelope ±(0.05 + 15 %), respectively. This implies that the users can get more accurate data without angular bias, i.e., more meaningful AOD data.

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