scholarly journals Influence of ENSO on entry stratospheric water vapor in coupled chemistry-ocean CCMI and CMIP6 models

2020 ◽  
Author(s):  
Chaim Israel Garfinkel ◽  
Ohad Harari ◽  
Shlomi Ziskin ◽  
Jian Rao ◽  
Olaf Morgenstern ◽  
...  
Keyword(s):  
Water Vapor ◽  
Interannual Variability ◽  
El Niño ◽  
El Nino ◽  
Temperature Response ◽  
La Niña ◽  
Stratospheric Water Vapor ◽  
La Nina ◽  
Tropical Troposphere ◽  
Cold Point

Abstract. The connection between the dominant mode of interannual variability in the tropical troposphere, El Nino Southern Oscillation (ENSO), and entry of stratospheric water vapor, is analyzed in a set of the model simulations archived for the Chemistry-Climate Model Initiative (CCMI) project and for phase 6 of the Coupled Model Intercomparison Project. While the models agree on the temperature response to ENSO in the tropical troposphere and lower stratosphere, and all models also agree on the zonal structure of the response in the tropical tropopause layer, the only aspect of the entry water vapor with consensus is that La Nina leads to moistening in winter relative to neutral ENSO. For El Nino and for other seasons there are significant differences among the models. For example, some models find that the enhanced water vapor for La Nina in the winter of the event reverses in spring and summer, other models find that this moistening persists, while some show a nonlinear response with both El Nino and La Nina leading to enhanced water vapor in both winter, spring, and summer. Focusing on Central Pacific ENSO versus East Pacific ENSO, or temperatures in the mid-troposphere as compared to temperatures near the surface, does not narrow the inter-model discrepancies. Despite this diversity in response, the temperature response near the cold point can explain the response of water vapor when each model is considered separately. While the observational record is too short to fully constrain the response to ENSO, it is clear that most models suffer from biases in the magnitude of interannual variability of entry water vapor. This bias could be due to missing forcing processes that contribute to observed variability in cold point temperatures.

scholarly journals Influence of the El Niño–Southern Oscillation on entry stratospheric water vapor in coupled chemistry–ocean CCMI and CMIP6 models

2021 ◽  
Vol 21 (5) ◽  
pp. 3725-3740
Author(s):  
Chaim I. Garfinkel ◽  
Ohad Harari ◽  
Shlomi Ziskin Ziv ◽  
Jian Rao ◽  
Olaf Morgenstern ◽  
...  
Keyword(s):  
Water Vapor ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Temperature Response ◽  
La Niña ◽  
Stratospheric Water Vapor ◽  
La Nina ◽  
Tropical Troposphere ◽  
Cold Point

Abstract. The connection between the dominant mode of interannual variability in the tropical troposphere, the El Niño–Southern Oscillation (ENSO), and the entry of stratospheric water vapor is analyzed in a set of model simulations archived for the Chemistry-Climate Model Initiative (CCMI) project and for Phase 6 of the Coupled Model Intercomparison Project. While the models agree on the temperature response to ENSO in the tropical troposphere and lower stratosphere, and all models and observations also agree on the zonal structure of the temperature response in the tropical tropopause layer, the only aspect of the entry water vapor response with consensus in both models and observations is that La Niña leads to moistening in winter relative to neutral ENSO. For El Niño and for other seasons, there are significant differences among the models. For example, some models find that the enhanced water vapor for La Niña in the winter of the event reverses in spring and summer, some models find that this moistening persists, and some show a nonlinear response, with both El Niño and La Niña leading to enhanced water vapor in both winter, spring, and summer. A moistening in the spring following El Niño events, the signal focused on in much previous work, is simulated by only half of the models. Focusing on Central Pacific ENSO vs. East Pacific ENSO, or temperatures in the mid-troposphere compared with temperatures near the surface, does not narrow the inter-model discrepancies. Despite this diversity in response, the temperature response near the cold point can explain the response of water vapor when each model is considered separately. While the observational record is too short to fully constrain the response to ENSO, it is clear that most models suffer from biases in the magnitude of the interannual variability of entry water vapor. This bias could be due to biased cold-point temperatures in some models, but others appear to be missing forcing processes that contribute to observed variability near the cold point.

scholarly journals The effect of ENSO activity on lower stratospheric water vapor

2011 ◽  
Vol 11 (2) ◽  
pp. 4141-4166 ◽  
Author(s):  
F. Xie ◽  
W. Tian ◽  
J. Austin ◽  
J. Li ◽  
H. Tian ◽  
...  
Keyword(s):  
Water Vapor ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
El Niño ◽  
Lower Stratosphere ◽  
El Nino ◽  
La Niña ◽  
Stratospheric Water Vapor ◽  
La Nina ◽  
El Niño Events

Abstract. Using the ECMWF/NCEP reanalysis data, satellite observations from AURA MLS and UARS HALOE, and Oceanic Niño Index (ONI) data, the effects of El Niño and La Niña events on the stratospheric water vapor changes are investigated. Overall, El Niño events tend to moisten the lower stratosphere but dry the middle stratosphere. La Niña events are likely to dry the lower stratosphere over a narrow band of tropics (5° S–5° N) but have a moistening effect on the whole stratosphere when averaged over a broader region of tropics between 25° S–25° N. The moistening effect of La Niña events mainly occurs in lower stratosphere in the Southern Hemisphere tropics where a significant 20% increase in the tropical upwelling is caused by La Niña events. El Niño events have a more significant effect on the tropical upwelling in the Northern Hemisphere extratropics than in Southern Hemisphere extratropics. The net effect of ENSO activities on the lower stratospheric water vapor is stronger in the Southern Hemisphere tropics than in the Northern Hemisphere tropics.

scholarly journals Three-Dimensional Structure and Interannual Variability of the Kuroshio Loop Current in the Northeastern South China Sea

2020 ◽  
Vol 50 (9) ◽  
pp. 2437-2455 ◽  
Author(s):  
Zhongbin Sun ◽  
Zhiwei Zhang ◽  
Bo Qiu ◽  
Xincheng Zhang ◽  
Chun Zhou ◽  
...  
Keyword(s):  
Interannual Variability ◽  
El Niño ◽  
El Nino ◽  
Three Dimensional ◽  
La Niña ◽  
Dimensional Structure ◽  
Northeast Monsoon ◽  
Loop Current ◽  
La Nina ◽  
The Kuroshio

AbstractBased on long-term mooring-array and satellite observations, three-dimensional structure and interannual variability of the Kuroshio Loop Current (KLC) in the northeastern South China Sea (SCS) were investigated. The 3-yr moored data between 2014 and 2017 revealed that the KLC mainly occurred in winter and it exhibited significant interannual variability with moderate, weak, and strong strengths in the winters of 2014/15, 2015/16, and 2016/17, respectively. Spatially, the KLC structure was initially confined to the upper 500 m near the Luzon Strait, but it became more barotropic, with kinetic energy transferring from the baroclinic mode to the barotropic mode when it extended into the SCS interior. Through analyzing the historical altimeter data between 1993 and 2019, it is found that the KLC event in 2016/17 winter is the strongest one since 1993. Moored-data-based energetics analysis suggested that the growth of this KLC event was primarily fed by the strong wind work associated with the strengthened northeast monsoon in that La Niña–year winter. By examining all of the historical KLC events, it is found that the strength of KLC is significantly modulated by El Niño–Southern Oscillation, being stronger in La Niña and weaker in El Niño years. This interannual modulation could be explained by the strengthened (weakened) northeast monsoon associated with the anomalous atmospheric cyclone (anticyclone) in the western North Pacific during La Niña (El Niño) years, which inputs more (less) energy and negative vorticity southwest of Taiwan that is favorable (unfavorable) for the development of KLC.

scholarly journals Characteristics of the Onset, Withdrawal, and Breaks of the Western North Pacific Summer Monsoon in the 1949–2014 Period

2020 ◽  
Vol 33 (17) ◽  
pp. 7371-7389
Author(s):  
Inmaculada Vega ◽  
Pedro Ribera ◽  
David Gallego
Keyword(s):  
Interannual Variability ◽  
Summer Monsoon ◽  
El Niño ◽  
North Pacific ◽  
Western North Pacific ◽  
El Nino ◽  
La Niña ◽  
Onset Date ◽  
Central Pacific ◽  
La Nina

ABSTRACTThe western North Pacific summer monsoon (WNPSM) onset and withdrawal dates as well as its breaks have been determined throughout the 1949–2014 period by defining the monsoon daily directional index (MDDI). This index, developed exclusively with wind direction observations, is an upgrade of the monthly western North Pacific directional index. The onset date shows a high interannual variability, varying between early May and early August, whereas the WNPSM withdrawal shows a lower interannual variability, occurring between October and mid-November. The MDDI reflects the multibreak character of the WNPSM. Breaks, which tend to last a few weeks, are more likely to happen from mid-August to early September and from late June to mid-July. This bimodal distribution shows decadal variability. In addition, the monsoon dates determined by the MDDI show very good agreement with relationships previously described in literature, such as the influence of tropical Pacific SST on the monsoon onset/withdrawal and changes in tropical cyclone (TC) tracks related to monsoon breaks. The WNPSM tends to start earlier (later) and finish later (earlier) under eastern Pacific (EP) La Niña (El Niño) conditions, especially from the 1980s on. Central Pacific (CP) ENSO is also associated with the monsoon withdrawal, which is advanced (delayed) under CP El Niño (La Niña). TCs tend to move from the Philippine Sea to the South China Sea during active monsoon days whereas they tend to reach higher latitudes during inactive monsoon days, especially in August and July.

scholarly journals Interannual variability in contributions of the Equatorial Undercurrent (EUC) to Peruvian upwelling source water

Ocean Science ◽  
2021 ◽  
Vol 17 (5) ◽  
pp. 1385-1402
Author(s):  
Gandy Maria Rosales Quintana ◽  
Robert Marsh ◽  
Luis Alfredo Icochea Salas
Keyword(s):  
Interannual Variability ◽  
El Niño ◽  
El Nino ◽  
La Niña ◽  
Depth Range ◽  
Equatorial Undercurrent ◽  
La Nina ◽  
Key Species ◽  
Wide Range ◽  
Northern Peru

Abstract. Time-varying sources of upwelling waters off the coast of northern Peru are analyzed in a Lagrangian framework, tracking virtual particles backwards in time for 12 months. Particle trajectories are calculated with temperature, salinity and velocity fields from a hindcast spanning 1988–2007, obtained with an eddy-resolving (1/12∘) global configuration of the Nucleus for European Modelling of the Ocean (NEMO) ocean model. At 30 and 100 m, where coastal upwelling rates exceed 50 m month−1, particles are seeded at monthly intervals in proportion to the upwelling rate. Ensemble maps of particle concentration, age, depth, temperature, salinity and density reveal that a substantial but variable fraction of the particles upwelling off Peru arrives via the Equatorial Undercurrent (EUC). Particles follow the EUC core within the depth range 125–175 m, characterized by temperatures <17 ∘C, salinities in the range 34.9–35.2 and densities of σθ=25.5–26.5. Additional inflows are via two slightly deeper branches further south from the main system, at around ≈3 and ≈8∘ S. Averaged across the hindcast, annual-mean percentages of particles upwelling at 30 m (100 m) associated with the EUC vary from 57.4 % (52 %) at 92∘ W to 19.2 % (17.9 %) at 165∘ W. Considerable interannual variability in these percentages reveals that more of the Peruvian upwelling can be traced back to the EUC during warm events, such as El Niño. In contrast, upwelling waters are of more local origin during cold events such as La Niña. Despite weaker EUC transport during El Niño, relative flattening of the equatorial thermocline brings the EUC upwelling waters much closer to the Peruvian coast than under neutral or La Niña conditions. Annually averaging EUC transport at specific longitudes, a notable negative-to-positive transition is evident during the major El Niño/La Niña events of 1997/99. On short timescales, a degree of longitudinal coherence is evident in EUC transport, with transport anomalies at 160∘ W evident at the Galápagos Islands (92∘ W) around 30–35 d later. It is concluded that the Peruvian upwelling system is subject to a variable EUC influence, on a wide range of timescales, most notably the interannual timescale of El Niño–Southern Oscillation (ENSO). Identifying this variability as a driver of shifts in population and catch data for several key species, during the study period, these new findings might inform sustainable management of commercially important fisheries off northern Peru.

scholarly journals Nonlinear response of tropical lower stratospheric temperature and water vapor to ENSO

2017 ◽  
Author(s):  
Chaim I. Garfinkel ◽  
Amit Gordon ◽  
Luke D. Oman ◽  
Feng Li ◽  
Sean Davis ◽  
...  
Keyword(s):  
Water Vapor ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
La Niña ◽  
Stratospheric Temperature ◽  
La Nina ◽  
El Niño Events ◽  
The Impact ◽  
El Nino Events

Abstract. A series of simulations using the NASA Goddard Earth Observing System Chemistry-Climate Model are analyzed in order to assess interannual and sub-decadal variability in tropical lower stratospheric temperature and water vapor over the past 35 years. The impact of El Niño-Southern Oscillation in this region is nonlinear. While moderate El Niño events lead to cooling in this region, strong El Niño events appear to lead to warming, even as the response of the large scale Brewer Dobson Circulation appears to scale nearly linearly with El Niño. The tropospheric warming associated with strong El Niño events extends into the tropical tropopause layer and up to the cold point, where it allows for more water vapor to enter the stratosphere. The net effect is that both strong La Niña and strong El Niño events lead to enhanced entry water vapor and stratospheric moistening. These results lead to the following interpretation of the millennial drop in water vapor in 2001: the very strong El Niño event in 1997/1998 followed by more than two consecutive years of La Niña led to enhanced lower stratospheric water vapor. As this period ended in early 2001, entry water vapor concentrations declined. The net effect is that sea surface temperature variability led to a decrease in water vapor of 0.14 ppmv after 2001, which accounts for approximately 23&amp;thinsp.% of the observed drop.

Influence of ENSO on entry stratospheric water vapor in coupled chemistry-ocean CCMI and CMIP6 models

2021 ◽  
Author(s):  
Ohad Harari ◽  
Chaim garfinkel ◽  
Shlomi Ziskin
Keyword(s):  
Water Vapor ◽  
Climate Model ◽  
Temperature Response ◽  
Coupled Model ◽  
Dominant Mode ◽  
Central Pacific ◽  
Stratospheric Water Vapor ◽  
Tropical Tropopause ◽  
Tropical Troposphere ◽  
Cold Point

&lt;p&gt;The connection between the dominant mode of interannual variability in the tropical troposphere, El Ni&amp;#241;o Southern&lt;br&gt;Oscillation (ENSO), and entry of stratospheric water vapor, is analyzed in a set of the model simulations archived for the&lt;br&gt;Chemistry-Climate Model Initiative (CCMI) project and for phase 6 of the Coupled Model Intercomparison Project. While the&lt;br&gt;models agree on the temperature response to ENSO in the tropical troposphere and lower stratosphere, and all models also agree&lt;br&gt;&amp;#160;on the zonal structure of the response in the tropical tropopause layer, the only aspect of the entry water vapor with consensus&lt;br&gt;is that La Ni&amp;#241;a leads to moistening in winter relative to neutral ENSO. For El Ni&amp;#241;o and for other seasons there are significant&lt;br&gt;differences among the models. For example, some models find that the enhanced water vapor for La Ni&amp;#241;a in the winter of the&lt;br&gt;event reverses in spring and summer, other models find that this moistening persists, while some show a nonlinear response&lt;br&gt;with both El Ni&amp;#241;o and La Ni&amp;#241;a leading to enhanced water vapor in both winter, spring, and summer. A moistening in the spring&lt;br&gt;&amp;#160;following El Ni&amp;#241;o events, perhaps the strongest signal in observations, is simulated by only half of the models. Focusing on&lt;br&gt;Central Pacific ENSO versus East Pacific ENSO, or temperatures in the mid-troposphere as compared to temperatures near the&lt;br&gt;surface, does not narrow the inter-model discrepancies. Despite this diversity in response, the temperature response near the&lt;br&gt;cold point can explain the response of water vapor when each model is considered separately. While the observational record is&lt;br&gt;too short to fully constrain the response to ENSO, it is clear that most models suffer from biases in the magnitude of interannual&lt;br&gt;variability of entry water vapor. This bias could be due to biased cold point temperatures in some models, but others appear to&lt;br&gt;be missing forcing processes that contribute to observed variability near the cold point&lt;/p&gt;

scholarly journals ENSO Effect on Interannual Variability of Spring Aerosols over East Asia

2020 ◽  
Author(s):  
Anbao Zhu ◽  
Haiming Xu ◽  
Jiechun Deng ◽  
Jing Ma ◽  
Shuhui Li
Keyword(s):  
East Asia ◽  
Interannual Variability ◽  
El Niño ◽  
El Nino ◽  
Transport Processes ◽  
La Niña ◽  
Carbonaceous Aerosol ◽  
Indochina Peninsula ◽  
Central Pacific ◽  
La Nina

Abstract. Effects of the El Niño/Southern Oscillation (ENSO) on the interannual variability of spring aerosols over East Asia are investigated using the Modern Era Retrospective analysis for Research and Applications Version 2 (MERRA-2) reanalysis aerosol data. Results show that the ENSO has a crucial effect on the spring aerosols over the Indochina Peninsula, southern China and the ocean south of Japan. The above-normal (below-normal) aerosols are found over these regions during the El Niño (La Niña) ensuing spring. In contrast to the local aerosol diffusion in winter, the ENSO affects East Asian aerosols in the following spring mainly via modulating upstream aerosol generation and transport processes. The underlying physical mechanism is that during the El Niño (La Niña) ensuing spring, the dry (wet) air and less (more) precipitation are beneficial for the increase (reduction) of biomass burning activities over the northern Indochina Peninsula, resulting in more (less) carbonaceous aerosol emissions. On the other hand, the anomalous anticyclone (cyclone) over the western North Pacific (WNP) associated with El Niño (La Niña) enhances (weakens) the low-level southwesterly wind from the northern Indochina Peninsula to southern Japan, which transports more (less) carbonaceous aerosol downstream. Anomalous precipitation plays a role in reducing aerosols over the source region, but its washout effect over the downstream region is limited. The ENSO’s impact on the ensuing spring aerosols is mainly attributed to the eastern Pacific ENSO rather than the central Pacific ENSO.

scholarly journals Impact of El Niño/La Niña on the Seasonality of Oceanic Water Vapor: A Proposed Scheme for Determining the ITCZ

2005 ◽  
Vol 133 (10) ◽  
pp. 2940-2946 ◽  
Author(s):  
Ge Chen ◽  
Hui Lin
Keyword(s):  
Water Vapor ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
La Niña ◽  
Empirical Modeling ◽  
Oceanic Water ◽  
Alternative Scheme ◽  
La Nina ◽  
The Impact

Abstract Previous research has shown that oceanic water vapor (OWV) is a useful quantity for studying the low-frequency variability of the atmosphere–ocean system. In this work, 10 years (1993–2002) of high-quality OWV data derived from the Ocean Topography Experiment (TOPEX) microwave radiometer are used to investigate the impact of El Niño/La Niña on the amplitude and phase of the annual cycle. These results suggest that El Niños (La Niñas) can weaken (strengthen) the seasonality of OWV by decreasing (increasing) the annual amplitude. The change of amplitude is usually slight but significant, especially for the five most dynamic seasonal belts across the major continents at midlatitudes. The El Niño–Southern Oscillation (ENSO) impact on the annual phase of OWV is seen to be fairly systematic and geographically correlated. The most striking feature is a large-scale advancing/delay of about 10 days (as estimated through empirical modeling) for the midlatitude oceans of the Northern Hemisphere in reaching their summer maxima during the El Niño/La Niña years. In addition, an alternative scheme for estimating the mean position of the intertropical convergence zone (ITCZ) based on the annual phase map of OWV is proposed. This ITCZ climatology favors 4°N in mean latitude, and agrees with existing results in that its position meanders from 2°S to 8°N oceanwide, and stays constantly north of the equator over the Atlantic and eastern Pacific.

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