scholarly journals Seasonality and time scale dependence of the relationship between turbulent surface heat flux and SST

2021 ◽  
Author(s):  
Xiaoshan Sun ◽  
Renguang Wu
Keyword(s):  
Heat Flux ◽  
South China Sea ◽  
Time Scales ◽  
South China ◽  
Surface Heat Flux ◽  
Arabian Sea ◽  
Scale Dependence ◽  
Surface Heat ◽  
Philippine Sea ◽  
The Relationship

AbstractThe present study examined the relationship between turbulent surface heat flux (SHF) and sea surface temperature (SST) variations using daily observational data. The SHF and SST relationship displays notable differences between winter and summer and prominent time-scale dependence in both seasons. In the mid-latitude SST frontal regions, SST has a larger role in driving SHF in winter than in summer. In the subtropical gyre regions, SHF plays a larger role in the SST change in summer than in winter. In winter, SHF has a larger effect on the SST change in the South China Sea than in the Arabian Sea and Bay of Bengal. In summer, the SST effect on SHF is dominant in the Arabian Sea, whereas the SHF impact on SST is dominant in the Philippine Sea. In the Gulf Stream, Kuroshio Extension and Agulhas Return Current, the SST effect extends up to 90-day time scales in winter, the SHF impact is limited to time scales below 20 days and the SST effect is dominant on time scales above 20 days in summer. In winter, the SHF effect extends up to 90-day time scales in the Bay of Bengal, South China Sea, and Philippine Sea, but is limited to time scales below 40 days in the Arabian Sea. In summer, the SST effect extends up to 90-day time scales in the Arabian Sea, whereas the SHF and SST effect is large on time scales shorter and longer than 40 days, respectively, in the Philippine Sea.

scholarly journals Spatial scale dependence of the relationship between turbulent surface heat flux and SST

2021 ◽  
Author(s):  
Xiaoshan Sun ◽  
Renguang Wu
Keyword(s):  
Heat Flux ◽  
Spatial Scale ◽  
Surface Heat Flux ◽  
Arabian Sea ◽  
Scale Dependence ◽  
Surface Heat ◽  
Western Pacific ◽  
Pacific Region ◽  
Atmospheric Forcing ◽  
Western Pacific Region

AbstractThis study investigates the spatial scale dependence of relationship between turbulent surface heat flux (SHF) and sea surface temperature (SST) variations in the mid-latitude frontal zones, subtropical gyres, and tropical Indo-western Pacific region in winter and summer with daily observational data. A comparison of the SHF and SST/SST tendency correlation between 1° and 4° spatial scale displays a decrease of the positive SHF–SST correlation and an increase of the negative SHF–SST tendency correlation as the spatial scale increases in all the above regions. The lead–lag SHF and SST/SST tendency correlation at different spatial scales illustrates an obvious transition from the oceanic forcing to the atmospheric forcing in the western boundary currents (WBCs) and the Agulhas Return Current (ARC) in both winter and summer. The transition length scale is smaller in summer than in winter, around 2.6°–4.5° in winter and around 0.8°–1.3° in summer based on the OAFlux data. In the subtropical gyres and tropical Indo-western Pacific region, atmospheric forcing dominates up to 10° spatial scale with the magnitude of forcing increasing with the spatial scale in both winter and summer except for the Arabian Sea in summer. The Arabian Sea distinguishes from the other tropical regions in that the SST forcing dominates up to more than 10° spatial scale in summer with the magnitude of forcing decreasing slowly with the spatial scale increase.

scholarly journals Decadal variability of heat content in South China Sea inferred from observation data and an ocean data assimilation product

2013 ◽  
Vol 10 (4) ◽  
pp. 1329-1342
Author(s):  
W. Song ◽  
J. Lan ◽  
Q. Liu ◽  
D. Wang
Keyword(s):  
Heat Flux ◽  
Data Assimilation ◽  
South China Sea ◽  
South China ◽  
Surface Heat Flux ◽  
Decadal Variability ◽  
Heat Content ◽  
Surface Heat ◽  
China Sea ◽  
Ocean Data Assimilation

Abstract. Using an observation dataset of temperature and the Simple Ocean Data Assimilation (SODA), the decadal variability of upper ocean heat content (0–400 m; hereafter, OHC) in the South China Sea (SCS) was investigated for the period from 1958 to 2007. Decadal variability was identified as the dominant mode of upper OHC besides the seasonal cycle. According to deceasing or increasing OHC, four periods were chosen to discuss detailed processes behind OHC variability in the SCS; the four periods are 1958–1968, 1969–1981, 1982–1992, and 1993–2003. Results show that advection was the major factor for decreasing (increasing) OHC during 1958–1968 (1968–1981). During 1982–1992 and 1993–2003, the net surface heat flux was the main contributor to the variability of OHC besides the advection. The OHC, advection and net surface heat flux had significant rising tendencies during 1992–2003. The spatial characteristics of OHC variability and heat budget in the Luzon Strait, west of Luzon Island, and Xisha warm eddy region were also discussed in this paper.

scholarly journals Mixed Layer Heat Variations in the South China Sea Observed by Argo Float and Reanalysis Data during 2012–2015

2019 ◽  
Vol 11 (19) ◽  
pp. 5429 ◽  
Author(s):  
Liang ◽  
Xing ◽  
Wang ◽  
Zeng
Keyword(s):  
Heat Flux ◽  
South China Sea ◽  
Mixed Layer ◽  
South China ◽  
Surface Heat Flux ◽  
Heat Budget ◽  
Surface Heat ◽  
Horizontal Advection ◽  
Net Heat Flux ◽  
Mixed Layer Heat Budget

The atmospheric and oceanic causes of mixed layer heat variations in the South China Sea (SCS) are examined using data from six long-lived Array for Real-time Geostrophic Oceanography (Argo) floats. The mixed layer heat budget along each float trajectory is evaluated based on direct measurements, satellite and reanalysis datasets. Our results suggest that the mixed layer heat balance in the SCS has distinct spatial and seasonal variations. The amplitude of all terms in the mixed layer heat budget equation is significantly larger in the northern SCS than in the southern SCS, especially in winter. In the northern SCS, the mixed layer heat budget is controlled by the local surface heat flux and horizontal advection terms in winter, and the net heat flux term in summer. In the western and southeastern SCS, the mixed layer heat budget is dominated by the net surface heat flux in both winter and summer. Further analysis shows that in the SCS, surface shortwave radiation and geostrophic heat advection are major contributors to net heat flux and horizontal advection, respectively. Unlike the net heat flux and horizontal advection, the vertical entrainment is a sink term in general. The rate of mixed layer deepening is the most important factor in the entrainment rate, and a barrier layer may decrease the temperature difference between the bottom of the mixed layer and the water beneath. Residual analysis suggests that the residual term in the equation is due to the inexact calculation of heat geostrophic advection, other missing terms, and unresolved physical ocean dynamic processes.

scholarly journals Decadal variability of heat content in the South China Sea inferred from observation data and an ocean data assimilation product

Ocean Science ◽  
2014 ◽  
Vol 10 (1) ◽  
pp. 135-139 ◽  
Author(s):  
Wei Song ◽  
Jian Lan ◽  
Qinyan Liu ◽  
Dandan Sui ◽  
Lili Zeng ◽  
...  
Keyword(s):  
Heat Flux ◽  
Data Assimilation ◽  
South China Sea ◽  
South China ◽  
Surface Heat Flux ◽  
Decadal Variability ◽  
Heat Content ◽  
Surface Heat ◽  
Observation Data ◽  
Ocean Data Assimilation

Abstract. Using an observation data set of temperature and the Simple Ocean Data Assimilation (SODA), the decadal variability of upper ocean heat content (0–400 m; hereafter, OHC) in the South China Sea (SCS) was investigated for the period from 1958 to 2007. Decadal variability was identified as the dominant mode of upper OHC besides the seasonal cycle. According to decreasing or increasing OHC, four periods were chosen to discuss detailed processes behind OHC variability in the SCS; the four periods are 1958–1968, 1969–1981, 1982–1992, and 1993–2003. Results show that advection was the major factor for decreasing (increasing) OHC during 1958–1968 (1968–1981). During 1982–1992 and 1993–2003, the net surface heat flux was the main contributor to the variability of OHC besides the advection. The OHC, advection and net surface heat flux had significant positive trends during 1992–2003. The spatial characteristics of OHC variability and heat budget in the Luzon Strait, west of Luzon Island, and in the Xisha warm eddy region are also discussed.

scholarly journals Spatiotemporal Characteristics of the Dominant Modes of Surface Air Temperature Interannual Variations over South China during the Spring-to-Summer Transition

Atmosphere ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 65
Author(s):  
Fen Wang ◽  
Yaokun Li ◽  
Jianping Li
Keyword(s):  
Heat Flux ◽  
Air Temperature ◽  
South China ◽  
Surface Heat Flux ◽  
Surface Air Temperature ◽  
Surface Heat ◽  
Shortwave Radiation ◽  
Northerly Wind ◽  
The North ◽  
Land Surfaces

The surface air temperature (SAT) interannual variability during the spring-to-summer transition over South China (SC) has been decomposed into two dominant modes by applying empirical orthogonal function (EOF) analysis. The first EOF mode (EOF1) is characterized by homogenous SAT anomalies over SC, whereas the second EOF mode (EOF2) features a dipole SAT anomaly pattern with opposite anomalies south and north of the Yangtze River. A regression analysis of surface heat flux and advection anomalies on the normalized principle component time series corresponding to EOF1 suggests that surface heat flux anomalies can explain SAT anomalies mainly by modulating cloud-shortwave radiation. Negative cloud anomalies result in positive downward shortwave radiation anomalies through the positive shortwave cloud radiation effect, which favor warm SAT anomalies over most of SC. For EOF2, the distribution of advection anomalies resembles the north–south dipole pattern of SAT anomalies. This suggests that wind-induced advection plays an important role in the SAT anomalies of EOF2. Negative SAT anomalies are favored by cold advection from northerly wind anomalies over land surfaces in high-latitude regions. Positive SAT anomalies are induced by warm advection from southerly wind anomalies over the ocean in low-latitude regions.

Atmospheric and Oceanic Contributions to Irreducible Forecast Uncertainty of Arctic Surface Climate

2015 ◽  
Vol 29 (1) ◽  
pp. 331-346 ◽  
Author(s):  
Steffen Tietsche ◽  
Ed Hawkins ◽  
Jonathan J. Day
Keyword(s):  
Heat Flux ◽  
Sea Ice ◽  
Time Scales ◽  
Surface Heat Flux ◽  
Surface Heat ◽  
Initial State ◽  
Forecast Uncertainty ◽  
Surface Climate ◽  
Oceanic Heat Flux ◽  
Arctic Surface

Abstract Uncertainty of Arctic seasonal to interannual predictions arising from model errors and initial state uncertainty has been widely discussed in the literature, whereas the irreducible forecast uncertainty (IFU) arising from the chaoticity of the climate system has received less attention. However, IFU provides important insights into the mechanisms through which predictability is lost and hence can inform prioritization of model development and observations deployment. Here, the authors characterize how internal oceanic and surface atmospheric heat fluxes contribute to the IFU of Arctic sea ice and upper-ocean heat content in an Earth system model by analyzing a set of idealized ensemble prediction experiments. It is found that atmospheric and oceanic heat flux are often equally important for driving unpredictable Arctic-wide changes in sea ice and surface water temperatures and hence contribute equally to IFU. Atmospheric surface heat flux tends to dominate Arctic-wide changes for lead times of up to a year, whereas oceanic heat flux tends to dominate regionally and on interannual time scales. There is in general a strong negative covariance between surface heat flux and ocean vertical heat flux at depth, and anomalies of lateral ocean heat transport are wind driven, which suggests that the unpredictable oceanic heat flux variability is mainly forced by the atmosphere. These results are qualitatively robust across different initial states, but substantial variations in the amplitude of IFU exist. It is concluded that both atmospheric variability and the initial state of the upper ocean are key ingredients for predictions of Arctic surface climate on seasonal to interannual time scales.

Upper mixed layer temperature anomalies at the North Atlantic storm-track zone

1995 ◽  
Vol 13 (10) ◽  
pp. 1015-1026 ◽  
Author(s):  
S. N. Moshonkin ◽  
N. A. Diansky
Keyword(s):  
Heat Flux ◽  
Time Scales ◽  
Mixed Layer ◽  
Surface Heat Flux ◽  
Surface Heat ◽  
Heat Advection ◽  
Temperature Anomalies ◽  
Mixed Layer Temperature ◽  
Frequency Functions ◽  
Good Agreement

Abstract. Synoptic sea surface temperature anomalies (SSTAs) were determined as a result of separation of time scales smaller than 183 days. The SSTAs were investigated using daily data of ocean weather station "C" (52.75°N; 35.5°W) from 1 January 1976 to 31 December 1980 (1827 days). There were 47 positive and 50 negative significant SSTAs (lifetime longer than 3 days, absolute value greater than 0.10 °C) with four main intervals of the lifetime repetitions: 1. 4–7 days (45% of all cases), 2. 9–13 days (20–25%), 3. 14–18 days (10–15%), and 4. 21–30 days (10–15%) and with a magnitude 1.5–2.0 °C. An upper layer balance model based on equations for temperature, salinity, mechanical energy (with advanced parametrization), state (density), and drift currents was used to simulate SSTA. The original method of modelling taking into account the mean observed temperature profiles proved to be very stable. The model SSTAs are in a good agreement with the observed amplitudes and phases of synoptic SSTAs during all 5 years. Surface heat flux anomalies are the main source of SSTAs. The influence of anomalous drift heat advection is about 30–50% of the SSTA, and the influence of salinity anomalies is about 10–25% and less. The influence of a large-scale ocean front was isolated only once in February-April 1978 during all 5 years. Synoptic SSTAs develop just in the upper half of the homogeneous layer at each winter. We suggest that there are two main causes of such active sublayer formation: 1. surface heat flux in the warm sectors of cyclones and 2. predominant heat transport by ocean currents from the south. All frequency functions of the ocean temperature synoptic response to heat and momentum surface fluxes are of integral character (red noise), though there is strong resonance with 20-days period of wind-driven horizontal heat advection with mixed layer temperature; there are some other peculiarities on the time scales from 5.5 to 13 days. Observed and modelled frequency functions seem to be in good agreement.

scholarly journals Air–Sea Relationship Associated with Precipitation Anomaly Changes and Mean Precipitation Anomaly over the South China Sea and the Arabian Sea during the Spring to Summer Transition

2015 ◽  
Vol 28 (18) ◽  
pp. 7161-7181 ◽  
Author(s):  
Renguang Wu ◽  
Wenting Hu
Keyword(s):  
South China Sea ◽  
South China ◽  
Arabian Sea ◽  
Precipitation Anomaly ◽  
Surface Heat ◽  
Heat Fluxes ◽  
The South China Sea ◽  
The South ◽  
China Sea ◽  
Precipitation Anomalies

Abstract The period from April to June is the time of transition from spring to summer over the north Indian Ocean and the South China Sea. Analysis shows that precipitation anomaly changes from April to June may indicate summer (June–August) mean precipitation anomalies over the South China Sea and the Arabian Sea. This study documents and compares the evolution of precipitation, surface wind, and sea surface temperature (SST) anomalies during the spring to summer transition corresponding to April–June precipitation anomaly changes and April–June mean precipitation anomalies over the South China Sea and the Arabian Sea. Over the South China Sea, a clear signal of local air–sea interaction is identified corresponding to the precipitation anomaly change, as indicated by a sequence of less precipitation, higher SST, more precipitation, and lower SST. In contrast, the mean precipitation anomaly features a response to remote SST forcing and a local forcing of atmosphere on the ocean. The evolution of surface heat flux anomalies supports the air–sea interaction over the South China Sea during the transition season. Over the Arabian Sea, local SST forcing contributes to both precipitation anomaly changes and mean precipitation anomalies through modulating atmospheric stability. A local negative feedback of atmosphere on SST is observed in the Arabian Sea as in the South China Sea. The surface heat fluxes make a large contribution to local SST change before May in the South China Sea but a small one in the Arabian Sea. Surface heat fluxes are important for local SST change after May in both the South China Sea and the Arabian Sea.

Analysis of significant measures for thermal conductivity

2020 ◽  
pp. 35-42
Author(s):  
Yuri P. Zarichnyak ◽  
Vyacheslav P. Khodunkov
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Surface Heat Flux ◽  
Heat Flux Density ◽  
Measurement Method ◽  
Conductivity Measurement ◽  
Surface Heat ◽  
Measuring Instrument ◽  
New Class ◽  
Achievable Accuracy

The analysis of a new class of measuring instrument for heat quantities based on the use of multi-valued measures of heat conductivity of solids. For example, measuring thermal conductivity of solids shown the fallacy of the proposed approach and the illegality of the use of the principle of ambiguity to intensive thermal quantities. As a proof of the error of the approach, the relations for the thermal conductivities of the component elements of a heat pump that implements a multi-valued measure of thermal conductivity are given, and the limiting cases are considered. In two ways, it is established that the thermal conductivity of the specified measure does not depend on the value of the supplied heat flow. It is shown that the declared accuracy of the thermal conductivity measurement method does not correspond to the actual achievable accuracy values and the standard for the unit of surface heat flux density GET 172-2016. The estimation of the currently achievable accuracy of measuring the thermal conductivity of solids is given. The directions of further research and possible solutions to the problem are given.

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