Role of ocean dynamics in the evolution of mixed-layer temperature in the Bay of Bengal during the summer monsoon

2021 ◽  
pp. 101895
Author(s):  
Vineet Jain ◽  
D. Shankar ◽  
P.N. Vinayachandran ◽  
A. Mukherjee ◽  
P. Amol
Keyword(s):  
Summer Monsoon ◽  
Mixed Layer ◽  
Bay Of Bengal ◽  
Ocean Dynamics ◽  
Mixed Layer Temperature

scholarly journals Mixed Layer Temperature Budget for the Northward Propagating Summer Monsoon Intraseasonal Oscillation (MISO) in the Central Bay of Bengal

2017 ◽  
Vol 122 (11) ◽  
pp. 8841-8854 ◽  
Author(s):  
M. S. Girishkumar ◽  
J. Joseph ◽  
V. P. Thangaprakash ◽  
V. Pottapinjara ◽  
M. J. McPhaden
Keyword(s):  
Summer Monsoon ◽  
Mixed Layer ◽  
Bay Of Bengal ◽  
Intraseasonal Oscillation ◽  
Mixed Layer Temperature

Quantifying the Role of Ocean Dynamics in Ocean Mixed-Layer Temperature Variability

2021 ◽  
pp. 1-63
Author(s):  
Casey R. Patrizio ◽  
David W.J. Thompson
Keyword(s):  
Mixed Layer ◽  
Temperature Variability ◽  
Ocean Dynamics ◽  
Western Boundary ◽  
Ocean Mixed Layer ◽  
Low Frequencies ◽  
Mixed Layer Temperature ◽  
Equatorial Upwelling ◽  
Key Aspects

AbstractUnderstanding the role of the ocean in climate variability requires first understanding the role of ocean dynamics in ocean mixed layer and thus sea surface temperature variability. However, key aspects of the spatially and temporally varying contributions of ocean dynamics to such variability remain unclear. Here, the authors quantify the contributions of ocean-dynamical processes to mixed layer temperature variability on monthly to multiannual timescales across the globe. To do so, they use two complementary but distinct methods: 1) a method in which ocean heat transport is estimated directly from a state-of-the-art ocean state estimate spanning 1992-2015; and 2) a method in which it is estimated indirectly from observations between 1980-2017 and the energy budget of the mixed layer. The results extend previous studies by providing quantitative estimates of the role of ocean dynamics in mixed layer temperature variability throughout the globe, across a range of timescales, in a range of available measurements, and using two different methods. Consistent with previous studies, both methods indicate that the ocean-dynamical contribution to mixed layer temperature variance is largest over western boundary currents, their eastward extensions, and regions of equatorial upwelling. In contrast to previous studies, the results suggest that ocean dynamics reduce the variance of Northern Hemisphere mixed layer temperatures on timescales longer than a few years. Hence, in the global-mean, the fractional contribution of ocean dynamics to mixed layer temperature variability decreases at increasingly low-frequencies. Differences in the magnitude of the ocean-dynamical contribution based on the two methods highlight the critical need for improved and continuous observations of the ocean mixed layer.

scholarly journals Mixing in the Transition Layer during Two Storm Events

2011 ◽  
Vol 41 (1) ◽  
pp. 42-66 ◽  
Author(s):  
Kathleen Dohan ◽  
Russ E. Davis
Keyword(s):  
Mixed Layer ◽  
Transition Layer ◽  
Wavelet Transforms ◽  
Ocean Dynamics ◽  
Small Scale ◽  
Storm Events ◽  
Inertial Waves ◽  
Space Time Structure ◽  
Inertial Energy

Abstract Upper-ocean dynamics analyzed from mooring-array observations are contrasted between two storms of comparable magnitude. Particular emphasis is put on the role of the transition layer, the strongly stratified layer between the well-mixed upper layer, and the deeper more weakly stratified region. The midlatitude autumn storms occurred within 20 days of each other and were measured at five moorings. In the first storm, the mixed layer follows a classical slab-layer response, with a steady deepening during the course of the storm and little mixing of the thermocline beneath. In the second storm, rather than deepening, the mixed layer shoals while intense near-inertial waves are resonantly excited within the mixed layer. These create a large shear throughout the transition layer, generating turbulence that broadens the transition layer. Details of the space–time structure of the frequencies in both short waves and near-inertial waves are presented. Small-scale waves are excited within the transition layer. Their frequencies change with time and there are no clear peaks at harmonics of inertial or tidal frequencies. Wavelet transforms of the inertial oscillations show the evolution as a spreading in frequency, a deepening of the core into the transition layer, and a shift off the inertial frequency. A second near-inertial energy core appears below the transition layer at all moorings coincident with a rapid decay of mixed layer currents. An overall result is that direct wind-generated motions extend to the depth of the transition layer. The transition layer is a location of enhanced wave activity and enhanced shear-driven mixing.

The Role of Bay of Bengal Convection in the Onset of the 1998 South China Sea Summer Monsoon

2002 ◽  
Vol 130 (11) ◽  
pp. 2731-2744 ◽  
Author(s):  
Yimin Liu ◽  
Johnny C. L. Chan ◽  
Jiangyu Mao ◽  
Guoxiong Wu
Keyword(s):  
South China Sea ◽  
Summer Monsoon ◽  
South China ◽  
Bay Of Bengal ◽  
China Sea

scholarly journals Possible role of pre-monsoon sea surface warming in driving the summer monsoon onset over the Bay of Bengal

2015 ◽  
Vol 47 (3-4) ◽  
pp. 753-763 ◽  
Author(s):  
Kuiping Li ◽  
Yanliang Liu ◽  
Yang Yang ◽  
Zhi Li ◽  
Baochao Liu ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
Bay Of Bengal ◽  
Monsoon Onset ◽  
Sea Surface ◽  
Surface Warming ◽  
Summer Monsoon Onset

Genesis of Indian Ocean Mixed Layer Temperature Anomalies: A Heat Budget Analysis

2010 ◽  
Vol 23 (20) ◽  
pp. 5375-5403 ◽  
Author(s):  
Agus Santoso ◽  
Alexander Sen Gupta ◽  
Matthew H. England
Keyword(s):  
Indian Ocean ◽  
Time Scales ◽  
Mixed Layer ◽  
Heat Budget ◽  
Heat Fluxes ◽  
Temperature Anomalies ◽  
Mixed Layer Temperature ◽  
The Indian Ocean ◽  
The Tropics

Abstract The genesis of mixed layer temperature anomalies across the Indian Ocean are analyzed in terms of the underlying heat budget components. Observational data, for which a seasonal budget can be computed, and a climate model output, which provides improved spatial and temporal coverage for longer time scales, are examined. The seasonal climatology of the model heat budget is broadly consistent with the observational reconstruction, thus providing certain confidence in extending the model analysis to interannual time scales. To identify the dominant heat budget components, covariance analysis is applied based on the heat budget equation. In addition, the role of the heat budget terms on the generation and decay of temperature anomalies is revealed via a novel temperature variance budget approach. The seasonal evolution of the mixed layer temperature is found to be largely controlled by air–sea heat fluxes, except in the tropics where advection and entrainment are important. A distinct shift in the importance and role of certain heat budget components is shown to be apparent in moving from seasonal to interannual time scales. On these longer time scales, advection gains importance in generating and sustaining anomalies over extensive regions, including the trade wind and midlatitude wind regimes. On the other hand, air–sea heat fluxes tend to drive the evolution of thermal anomalies over subtropical regions including off northwestern Australia. In the tropics, however, they limit the growth of anomalies. Entrainment plays a role in the generation and maintenance of interannual anomalies over localized regions, particularly off Sumatra and over the Seychelles–Chagos Thermocline Ridge. It is further shown that the spatial distribution of the role and importance of these terms is related to oceanographic features of the Indian Ocean. Mixed layer depth effects and the influence of model biases are discussed.

scholarly journals Numerical Study on the Variability of Mixed Layer Temperature in the North Pacific

2009 ◽  
Vol 39 (3) ◽  
pp. 737-752 ◽  
Author(s):  
Shin’ichiro Kako ◽  
Masahisa Kubota
Keyword(s):  
Mixed Layer ◽  
North Pacific ◽  
Interannual Variation ◽  
Ocean Dynamics ◽  
Positive Temperature ◽  
Thermal Forcing ◽  
The North ◽  
Mixed Layer Temperature ◽  
Temperature Tendency ◽  
The North Pacific

Abstract Physical processes important for the interannual variability in mixed layer temperature (MLT) in the North Pacific have been examined by using a three-dimensional bulk mixed layer model. This model was forced by the momentum, heat, and freshwater flux data derived from the NCEP–NCAR reanalysis and geostrophic flow data included in Japanese Ocean Flux datasets with Use of Remote Sensing Observations. The interannual variation in MLT was hindcasted over the course of 11 years from January 1993 to December 2003. The interannual variation in the modeled MLT favorably agreed with that of the available in situ and satellite sea surface temperature (SST) observational data. This agreement depended crucially on whether horizontal heat advection was considered a part of the model dynamics. Although both atmospheric and oceanic processes were required to explain the observed interannual MLT variability, the physical process most important for determining this variability was likely to differ year by year. For example, in the Kuroshio Extension region, it was found that the positive temperature tendency peak in 1997 was attributed to the positive surface thermal forcing, while the temperature tendency in 1998 and 1999 continued to increase in spite of the negative surface thermal forcing. Thus, the abnormal heat loss from the ocean to the atmosphere (hence, the atmospheric circulation change) in 1998–99 was considered to be excited by the ocean dynamics related to the warmer SST. Likewise, it was found that the rapid decrease in SST during 2001–03 was mainly caused by the effect of lateral flux.

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