Influence of the North American Dipole on the Atlantic Warm Pool

2021 ◽  
Author(s):  
Jinghua Chao ◽  
Guangzhou Fan ◽  
Ruiqiang Ding ◽  
Quanjia Zhong ◽  
Zhenchao Wang
Keyword(s):  
Air Temperature ◽  
North Atlantic ◽  
North American ◽  
Southern Oscillation ◽  
Warm Pool ◽  
Atmospheric Forcing ◽  
The North ◽  
Remote Forcing ◽  
Atlantic Warm Pool ◽  
Tropical North Atlantic

Abstract The Atlantic warm pool(AWP) of water having a temperature above 28.5°C encompasses the Gulf of Mexico, the Caribbean, and the western tropical North Atlantic, influencing the regional and global climate. Much of the AWP interannual variabillity has been thought to be an outcome of external remote forcing by climate variability outside the tropical Atlantic, such as the El Niño-Southern Oscillation (ENSO) or the North Atlantic Oscillation (NAO). This study indicates that the North American dipole (NAD), exemplified by a north-south seesaw in sea level pressure anomalies over the western tropical North Atlantic and northeastern North America, may provide another integral remote forcing source to influence the AWP. Both observational and model data prove that a strong positive (negative) phase of the winter NAD tends to inhibit (favor) the development of AWP in its area and depth in subsequent months. As opposed to the NAO, the NAD plays a more pivotal role in influencing the AWP due to its effectiveness in forcing the TNA SST variability, which means that AWP variability may be more of a lagging response to NAD atmospheric forcing than a lagging response to NAO atmospheric forcing. Additional analysis indicates that the winter NAD-like atmospheric signal may be stored in the following AWP, thus markedly influencing the TNA precipitation and air temperature in summer. It is speculated that the AWP may act as a bridge linking winter NAD to the following summer precipitation and air temperature in the TNA region.

scholarly journals Impact of the Atlantic Warm Pool on the Summer Climate of the Western Hemisphere

2007 ◽  
Vol 20 (20) ◽  
pp. 5021-5040 ◽  
Author(s):  
Chunzai Wang ◽  
Sang-ki Lee ◽  
David B. Enfield
Keyword(s):  
North Atlantic ◽  
Moisture Transport ◽  
Caribbean Sea ◽  
Warm Pool ◽  
Western Hemisphere ◽  
Trade Winds ◽  
The North ◽  
Atlantic Warm Pool ◽  
Tropical North Atlantic ◽  
The Caribbean

Abstract The Atlantic warm pool (AWP) is a large body of warm water that comprises the Gulf of Mexico, the Caribbean Sea, and the western tropical North Atlantic. Located to its northeastern side is the North Atlantic subtropical high (NASH), which produces the tropical easterly trade winds. The easterly trade winds carry moisture from the tropical North Atlantic into the Caribbean Sea, where the flow intensifies, forming the Caribbean low-level jet (CLLJ). The CLLJ then splits into two branches: one turning northward and connecting with the Great Plains low-level jet (GPLLJ), and the other continuing westward across Central America into the eastern North Pacific. The easterly CLLJ and its westward moisture transport are maximized in the summer and winter, whereas they are minimized in the fall and spring. This semiannual feature results from the semiannual variation of sea level pressure in the Caribbean region owing to the westward extension and eastward retreat of the NASH. The NCAR Community Atmospheric Model and observational data are used to investigate the impact of the climatological annual mean AWP on the summer climate of the Western Hemisphere. Two groups of the model ensemble runs with and without the AWP are performed and compared. The model results show that the effect of the AWP is to weaken the summertime NASH, especially at its southwestern edge. The AWP also strengthens the summertime continental low over the North American monsoon region. In response to these pressure changes, the CLLJ and its moisture transport are weakened, but its semiannual feature does not disappear. The weakening of the easterly CLLJ increases (decreases) moisture convergence to its upstream (downstream) and thus enhances (suppresses) rainfall in the Caribbean Sea (in the far eastern Pacific west of Central America). Model runs show that the AWP’s effect is to always weaken the southerly GPLLJ. However, the AWP strengthens the GPLLJ’s northward moisture transport in the summer because the AWP-induced increase of specific humidity overcomes the weakening of southerly wind, and vice versa in the fall. Finally, the AWP reduces the tropospheric vertical wind shear in the main development region that favors hurricane formation and development during August–October.

scholarly journals The Role of Tropical Cyclones on the Total Precipitation in Cuba during the Hurricane Season from 1980 to 2016

Atmosphere ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1156
Author(s):  
José C. Fernández–Alvarez ◽  
Rogert Sorí ◽  
Albenis Pérez–Alarcón ◽  
Raquel Nieto ◽  
Luis Gimeno
Keyword(s):  
Tropical Cyclones ◽  
Southern Oscillation ◽  
Warm Pool ◽  
Total Precipitation ◽  
Data Set ◽  
The North ◽  
Atlantic Warm Pool ◽  
Significant Difference ◽  
Great Heterogeneity ◽  
Del Rio

This study quantifies the amount of rainfall supplied by tropical cyclones (TCs) to Cuba. It uses the long–term global gridded Multi–Source Weighted–Ensemble Precipitation (MSWEP) v2 data set, with a resolution of 0.1° in latitude and longitude, and a temporal resolution of 3 h during the hurricane seasons from 1980–2016. During this study period, 146 TCs were identified within a 500–km radius of Cuba. The contribution of TCs to the total precipitation over Cuba during the cyclonic season was ~11%. The maximum contribution occurs in October and November, representing 18% and 28% of the total precipitation, respectively. The interannual precipitation contribution shows a positive correlation (~0.74) with the number of TCs, but without a significant trend for the period. A climatological spatial analysis of the rainfall associated with TCs revealed great heterogeneity, although the major contribution was observed along the southern coast of the eastern and central provinces of Cuba, and in the western province of Pinar del Río. No significant difference was observed between the number of TCs that affected Cuba and their rainfall contribution under the positive and negative phases of the El Niño Southern Oscillation. However, the negative phase of the NAO led to an increase in the genesis of TCs that later affected Cuba, which led to a greater contribution to precipitation compared to that obtained from TCs during the positive phase of this oscillation. Our results also confirm that anomalous warmth of the tropical Atlantic Ocean, revealed through the Atlantic Meridional Mode, and enlargement of the Atlantic Warm Pool, enhances the genesis in the North Atlantic Basin of the TCs that affect Cuba, which was associated with an increase of the rainfall contribution to the total precipitation compared to that calculated for TCs formed during the opposite phases.

scholarly journals Combined Influences on North American Winter Air Temperature Variability from North Pacific Blocking and the North Atlantic Oscillation: Subseasonal and Interannual Time Scales

2020 ◽  
Vol 33 (16) ◽  
pp. 7101-7123 ◽  
Author(s):  
Binhe Luo ◽  
Dehai Luo ◽  
Aiguo Dai ◽  
I. Simmonds ◽  
Lixin Wu
Keyword(s):  
North America ◽  
Air Temperature ◽  
North Atlantic ◽  
North American ◽  
North Pacific ◽  
Eastern North America ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation ◽  
The North Pacific

AbstractWinter surface air temperature (SAT) over North America exhibits pronounced variability on subseasonal, interannual, decadal, and interdecadal time scales. Here, reanalysis data from 1950–2017 are analyzed to investigate the atmospheric and surface ocean conditions associated with its subseasonal to interannual variability. Detrended daily SAT data reveal a known warm west/cold east (WWCE) dipole over midlatitude North America and a cold north/warm south (CNWS) dipole over eastern North America. It is found that while the North Pacific blocking (PB) is important for the WWCE and CNWS dipoles, they also depend on the phase of the North Atlantic Oscillation (NAO). When a negative-phase NAO (NAO−) coincides with PB, the WWCE dipole is enhanced (compared with the PB alone case) and it also leads to a warm north/cold south dipole anomaly in eastern North America; but when PB occurs with a positive-phase NAO (NAO+), the WWCE dipole weakens and the CNWS dipole is enhanced. The PB events concurrent with the NAO− (NAO+) and SAT WWCE (CNWS) dipole are favored by the Pacific El Niño–like (La Niña–like) sea surface temperature mode and the positive (negative) North Pacific mode. The PB-NAO+ has a larger component projecting onto the SAT WWCE dipole during the La Niña winter than during the El Niño winter because a more zonal wave train is formed. Strong North American SAT WWCE dipoles and enhanced projections of PB-NAO+ events onto the SAT WWCE dipole component are also readily seen for the positive North Pacific mode. The North Pacific mode seems to play a bigger role in the North American SAT variability than ENSO.

Atlantic Warm Pool: climate variability, thermal ocean-atmosphere interactions and remote response to ENSO and NAO.

2020 ◽  
Author(s):  
Yoania Povea Perez
Keyword(s):  
Climate Variability ◽  
Gulf Of Mexico ◽  
North Atlantic ◽  
Southern Oscillation ◽  
Caribbean Sea ◽  
Warm Pool ◽  
Empirical Orthogonal Functions ◽  
Thermal Component ◽  
Atlantic Warm Pool ◽  
Ocean Atmosphere

<p>The Atlantic Warm Pool (AWP) is a big body of warm water with SST greater or equal to 28.5◦ C, that appears in the Gulf of Mexico, the Caribbean and the western tropical North Atlantic and it is a key element of the climate system. Previous studies have focused on climate variability within the AWP, but did not take into account the distinctive properties of AWP sub-regions. In other cases, obtained results had not been tested against selected databases. This work will try to deal systematically with these limitations. Ocean reanalysis databases have been used in order to detect AWP climate variability, mechanisms through which thermal component of ocean-atmosphere interactions operates and the effect of remote phenomena such as El Niño-Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO).  Empirical Orthogonal Functions, spectral analysis, linear correlation and composites analysis techniques have been used. A large portion of AWP variability comes from Caribbean Sea and Gulf of Mexico while North tropical Atlantic contains a large internal variability. The thermal component of ocean-atmosphere interactions appears partitioned in Gulf of Mexico and Atlantic from Caribbean Sea. SST/latent heat feedback mechanism operates not globally in the AWP but stronger in the open Atlantic sub-region. ENSO+ enhances AWP development, while ENSO- is opposite to both development and decay of AWP. NAO effect is stronger in its negative phase by enhancing the AWP decay.</p>

scholarly journals Revisiting the ENSO Teleconnection to the Tropical North Atlantic

2017 ◽  
Vol 30 (17) ◽  
pp. 6945-6957 ◽  
Author(s):  
Javier García-Serrano ◽  
Christophe Cassou ◽  
Hervé Douville ◽  
Alessandra Giannini ◽  
Francisco J. Doblas-Reyes
Keyword(s):  
Heat Flux ◽  
North Atlantic ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Mixed Layer Depth ◽  
Sensible Heat Flux ◽  
Atmospheric Forcing ◽  
Tropical North Atlantic ◽  
Sst Anomalies

One of the most robust remote impacts of El Niño–Southern Oscillation (ENSO) is the teleconnection to tropical North Atlantic (TNA) sea surface temperature (SST) in boreal spring. However, important questions still remain open. In particular, the timing of the ENSO–TNA relationship lacks understanding. The three previously proposed mechanisms rely on teleconnection dynamics involving a time lag of one season with respect to the ENSO mature phase in winter, but recent results have shown that the persistence of ENSO into spring is necessary for the development of the TNA SST anomalies. Likewise, the identification of the effective atmospheric forcing in the deep TNA to drive the regional air–sea interaction is also lacking. In this manuscript a new dynamical framework to understand the ENSO–TNA teleconnection is proposed, in which a continuous atmospheric forcing is present throughout the ENSO decaying phase. Observational datasets in the satellite era, which include reliable estimates over the ocean, are used to illustrate the mechanism at play. The dynamics rely on the remote Gill-type response to the ENSO zonally compensated heat source over the Amazon basin, associated with perturbations in the Walker circulation. For El Niño conditions, the anomalous diabatic heating in the tropical Pacific is compensated by anomalous diabatic cooling, in association with negative rainfall anomalies and descending motion over northern South America. A pair of anomalous cyclonic circulations is established at upper-tropospheric levels in the tropical Atlantic straddling the equator, displaying a characteristic baroclinic structure with height. In the TNA region, the mirrored anomalous anticyclonic circulation at lower-tropospheric levels weakens the northeasterly trade winds, leading to a reduction in evaporation and of the ocean mixed layer depth, hence to positive SST anomalies. Apart from the dominance of latent heat flux anomalies in the remote response, sensible heat flux and shortwave radiation anomalies also appear to contribute. The “lagged” relationship between mature ENSO in winter and peaking TNA SSTs in spring seems to be phase locked with the seasonal cycle in both the location of the mechanism’s centers of action and regional SST variance.

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

2021 ◽  
Author(s):  
Jake W. Casselman ◽  
Andréa S. Taschetto ◽  
Daniela I.V. Domeisen
Keyword(s):  
North Atlantic ◽  
Southern Oscillation ◽  
Static Stability ◽  
Reanalysis Data ◽  
Trade Winds ◽  
The North ◽  
The Pacific ◽  
Tropical North Atlantic ◽  
Sst Anomaly ◽  
The North Atlantic Oscillation

<p>El 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. 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.</p>

scholarly journals Response of Freshwater Flux and Sea Surface Salinity to Variability of the Atlantic Warm Pool

2013 ◽  
Vol 26 (4) ◽  
pp. 1249-1267 ◽  
Author(s):  
Chunzai Wang ◽  
Liping Zhang ◽  
Sang-Ki Lee
Keyword(s):  
Central America ◽  
North Atlantic ◽  
Warm Pool ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Freshwater Flux ◽  
Surface Salinity ◽  
Atlantic Warm Pool ◽  
Mean Circulation ◽  
Circulation Dynamics

Abstract The response of freshwater flux and sea surface salinity (SSS) to the Atlantic warm pool (AWP) variations from seasonal to multidecadal time scales is investigated by using various reanalysis products and observations. All of the datasets show a consistent response for all time scales: A large (small) AWP is associated with a local freshwater gain (loss) to the ocean, less (more) moisture transport across Central America, and a local low (high) SSS. The moisture budget analysis demonstrates that the freshwater change is dominated by the atmospheric mean circulation dynamics, while the effect of thermodynamics is of secondary importance. Further decomposition points out that the contribution of the mean circulation dynamics primarily arises from its divergent part, which mainly reflects the wind divergent change in the low level as a result of SST change. In association with a large (small) AWP, warmer (colder) than normal SST over the tropical North Atlantic can induce anomalous low-level convergence (divergence), which favors anomalous ascent (decent) and thus generates more (less) precipitation. On the other hand, a large (small) AWP weakens (strengthens) the trade wind and its associated westward moisture transport to the eastern North Pacific across Central America, which also favors more (less) moisture residing in the Atlantic and hence more (less) precipitation. The results imply that variability of freshwater flux and ocean salinity in the North Atlantic associated with the AWP may have the potential to affect the Atlantic meridional overturning circulation.

scholarly journals Contrastive Influence of ENSO and PNA on Variability and Predictability of North American Winter Precipitation

2019 ◽  
Vol 32 (19) ◽  
pp. 6271-6284 ◽  
Author(s):  
Xiaofan Li ◽  
Zeng-Zhen Hu ◽  
Ping Liang ◽  
Jieshun Zhu
Keyword(s):  
North America ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
North American ◽  
North Pacific ◽  
Winter Precipitation ◽  
Sea Surface ◽  
The North ◽  
Remote Forcing ◽  
The North Pacific

Abstract In this work, the roles of El Niño–Southern Oscillation (ENSO) in the variability and predictability of the Pacific–North American (PNA) pattern and precipitation in North America in winter are examined. It is noted that statistically about 29% of the variance of PNA is linearly linked to ENSO, while the remaining 71% of the variance of PNA might be explained by other processes, including atmospheric internal dynamics and sea surface temperature variations in the North Pacific. The ENSO impact is mainly meridional from the tropics to the mid–high latitudes, while a major fraction of the non-ENSO variability associated with PNA is confined in the zonal direction from the North Pacific to the North American continent. Such interferential connection on PNA as well as on North American climate variability may reflect a competition between local internal dynamical processes (unpredictable fraction) and remote forcing (predictable fraction). Model responses to observed sea surface temperature and model forecasts confirm that the remote forcing is mainly associated with ENSO and it is the major source of predictability of PNA and winter precipitation in North America.

scholarly journals Trends in compound extremes of air temperature and precipitation in Eastern Europe

2021 ◽  
Author(s):  
Elena Vyshkvarkova ◽  
Olga Sukhonos
Keyword(s):  
Eastern Europe ◽  
North Atlantic Oscillation ◽  
Air Temperature ◽  
North Atlantic ◽  
Large Scale ◽  
The North ◽  
Temperature And Precipitation ◽  
Atmosphere System ◽  
Daily Data ◽  
The North Atlantic Oscillation

Abstract The spatial distribution of compound extremes of air temperature and precipitation was studied over the territory of Eastern Europe for the period 1950–2018 during winter and spring. Using daily data on air temperature and precipitation, we calculated the frequency and trends of the four indices – cold/dry, cold/wet, warm/dry and warm/wet. Also, we studying the connection between these indices and large-scale processes in the ocean-atmosphere system such as North Atlantic Oscillation, East Atlantic Oscillation and Scandinavian Oscillation. The results have shown that positive trends in the region are typical of the combinations with the temperatures above the 75th percentile, i.e., the warm extremes in winter and spring. Negative trends were obtained for the cold extremes. Statistically significant increase in the number of days with warm extremes was observed in the northern parts of the region in winter and spring. The analysis of the impacts of the large-scale processes in oceans-atmosphere system showed that the North Atlantic Oscillation index has a strong positive and statistically significant correlation with the warm indices of compound extremes in the northern part of Eastern Europe in winter, while the Scandinavian Oscillation shows the opposite picture.

scholarly journals The North Pacific blob acts to increase the predictability of the Atlantic warm pool

2021 ◽  
Author(s):  
Yusen Liu ◽  
Cheng Sun ◽  
Fred Kucharski ◽  
Jianping Li ◽  
Chunzai Wang ◽  
...  
Keyword(s):  
North Pacific ◽  
Warm Pool ◽  
The North ◽  
Atlantic Warm Pool ◽  
The North Pacific
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