Search

The Mixed Layer Heat Budget (MLHB) is based on energy conservation wherein Mixed Layer Temperature (MLT) tendency equals the sum of Net Surface Heat Flux (NSHF), Horizontal Advection (HA), Vertical Entrainment (VE), Vertical Diffusion (VD), and residual. This study utilizes 25 years (1991–2015) of data from a Regional Ocean Modeling System (ROMS) simulation for quantifying the Relative Importance (RI) of MLHB terms, using Johnson's Relative Weight Analysis (RWA) approach, in the Bay of Bengal (BoB). The RIs obtained from the RWA approach fall within their respective 95% confidence intervals obtained through bootstrapping. The analysis showed that the NSHF, dependent on spatio-temporally varying Mixed Layer Depth (MLD), plays a greater role in modulating the MLT tendency (≈ 50%) over the whole BoB during different seasons. Moreover, HA (≈ 20%) prominently impacts the southern and western BoB, which is related to the boundary current system and the associated thermal gradients. During monsoon, it was found that HA warms the Sri Lanka dome region due to meridional heat transport from around the east coast of India while cooling the southern BoB through cooler south-west monsoon currents. Finally, VE (≈ 20%) and VD (≈ 10%) contribute higher around the Sri Lanka dome due to the presence of a cyclonic eddy during pre-monsoon and monsoon. Also, VE and VD have a higher role during post-monsoon and winter due to the presence of thermal inversion in the northern BoB. Lastly, the residual showed an average RI of about 15%, which is of the same order as HA, VE, and VD. This suggests that the residual is not only composed of errors associated with the MLHB terms but there might also be some unknown physical processes at play that significantly impact MLT. This points toward the need for improvement in the MLHB, which holds a key for a better assessment of the ocean state. [ABSTRACT FROM AUTHOR]

Little is known about the mechanism of climate–vegetation coverage coupled changes in the Tibetan Plateau (TP) region, which is the most climatically sensitive and ecologically fragile region with the highest terrain in the world. This study, using multisource datasets (including satellite data and meteorological observations and reanalysis data) revealed the mutual feedback mechanisms between changes in climate (temperature and precipitation) and vegetation coverage in recent decades in the Hengduan Mountains Area (HMA) of the southeastern TP and their influences on climate in the downstream region, the Sichuan Basin (SCB). There is mutual facilitation between rising air temperature and increasing vegetation coverage in the HMA, which is most significant during winter, and then during spring, but insignificant during summer and autumn. Rising temperature significantly enhances local vegetation coverage, and vegetation greening in turn heats the atmosphere via enhancing net heat flux from the surface to the atmosphere. The atmospheric heating anomaly over the HMA thickens the atmospheric column and increases upper air pressure. The high pressure anomaly disperses downstream via the westerly flow, expands across the SCB, and eventually increases the SCB temperature. This effect lasts from winter to the following spring, which may cause the maximum increasing trend of the SCB temperature and vegetation coverage in spring. These results are helpful for estimating future trends in climate and eco-environmental variations in the HMA and SCB under warming scenarios, as well as seasonal forecasting based on the connection between the HMA eco-environment and SCB climate. [ABSTRACT FROM AUTHOR]

BACKGROUND AND OBJECTIVES: Studying the monthly variations in the surface features of the Bay of Bengal is a complex task that involves numerous large-scale ocean-atmosphere dynamics. This study identified the bay’s changing circulation patterns over recent decades as a crucial study area requiring in-depth research. Understanding the changes in circulation patterns provides valuable insights into the Bay dynamics. It helps identify the potential impacts of climate change, ocean currents, and other factors on the bay’s ecosystem. This study aims to understand the seasonal variability of the Bay of Bengal’s surface circulation features using a high-resolution numerical Coastal and Regional Ocean Community simulations model. METHODS: To conduct the study in the Bay of Bengal, the Coastal and Regional Ocean Community model, a numerical ocean model, was utilized. The high-resolution numerical model for ocean circulation is three-dimensional and uses hydrostatic primitive equations in generalized curvilinear coordinates. Simulations were conducted over 8 years using a grid comprising 256 x 249 horizontal surface points to model a range of ocean-atmospheric parameters. This grid provided an approximate resolution of 10 kilometers.FINDINGS: The findings are based on the model’s enhanced performance compared to previous study results. It was observed that the sea surface temperature remains above 28 degrees Celsius throughout the bay except in winter. During the monsoon season, surface salinity was observed to be reduced in the Bay of Bengal’s northern region and western and eastern boundaries. Surface eddies along the western bay extend to deep waters before the onset of monsoon. The net heat flux in the bay has been determined as positive before monsoon, negative post-monsoon, and mixed during the monsoon season.CONCLUSION: This analysis focuses on the ocean surface layer with more prominent dynamics. Various surface parameters were calculated, and discussions on surface temperature, salinity, D20, D26, and net heat flux across seasons have been presented.

Introduction In determining the evapotranspiration (ET) of a crop species, factors such as type, crop density, growth stage, climate of the region, physicochemical characteristics and soil fertility, have a significant effect. Therefore, it has a significant complexity. In recent years, new technologies are used to estimate ET, such as surface energy balance algorithm for land (SEBAL), which estimates actual evapotranspiration, using satellite data and some ground data. The purpose of this research is to estimate the actual ET and water requirement of Rosa damascena using SEBAL during three crop growth years in a part of the Shahrekord high plain. Materials and Methods The studied farm with an area of 16.38 ha is located in the Shahrekord plain, Karoun watershed. The remote sensing data included 42 cloud-free images of Landsat 7 and Landsat 8 satellites (2017, 2018, and 2019). The growth period lasted from the beginning of April to the end of November of each crop year. Images were processed in ERDAS Imagine 2015 software for radiometric correction and subsequent calculations using SEBAL algorithm. In order to estimate the actual evapotranspiration, the energy balance equation is used. For this purpose, all energy fluxes such as, Rn: the net incoming radiation flux to the considered surface, H: the sensible heat flux, G0: the soil heat flux and lET: the latent heat flux of evapotranspiration should be taken into account. The first step in the SEBAL process is to calculate the net radiation flux of the Rn. The second, soil heat flux G0 that is the rate of heat capacity in the soil and vegetation resulting from heat conduction or heat energy used to heat or cools the volume of the soil mass. The third is to calculate sensible heat flux (H) is the rate of heat loss to the air by conduction and convection phenomena, which is caused by the thermal difference. In SEBAL process, two "anchor" pixels are used to create boundary conditions for energy balance. These include as "cold (wet)" and "warm (dry)" pixels that are determined in the study area. A cold pixel is selected at the surface of open water or the surface covered by a well-watered alfalfa crop. It is assumed that the temperature of the surface and the temperature of the air near the surface are the same in this pixel. The "warm" pixel is selected in dry agricultural lands and its ET is considered zero. It is necessary for SEBAL model to establishing a linear equation between the surface temperature (Ts) and the air-surface temperature difference (dT) for each pixel using hot (dry) and cold (wet) pixels. Results and Discussion Based on the results of three years of research in a 16.38 hectare Golmohammadi farm in the Shahrekord plain, using the Sabal algorithm and the number of 42 images on the days of Landsat 7 and Landsat 8 satellites passing, as well as using the modified Penman-Mantith-Fao mathematical relationship. It was found that the amount of evaporation and transpiration of hollyhocks in the studied area was on average 1043.8 mm during the growth period. According to the results of other researchers, which have been conducted using lysimeter data and field studies, it necessarily requires higher costs than remote sensing methods. In this research, the ability of the Sabal algorithm (as one of the best remote sensing algorithms) to estimate evaporation And the actual transpiration and determination of the water requirement of the chrysanthemum plant with a low cost and an easy method compared to the results of other researchers, which were done with difficult and expensive lysimetric methods, were proved and it is suitable to be used for other plant species and in other geographical areas. Results showed that actual evapotranspiration value of rose crop (ETC) obtained from the SEBAL during the three years of experiment were 1089.4, 1021.3, and 1020.6 mm per growth period. In the same period, reference crop evapotranspiration (ET0) values were 1214.8, 1100.5, and 1135.5 mm during the growth period, respectively. In other words, average value for ETC was 1043.8 mm in growth period. ConclusionBased on the results of three years of research in a 16.38 hectare Golmohammadi farm in the Shahrekord plain, using the Sabal algorithm and the number of 42 images on the days of Landsat 7 and Landsat 8 satellites passing, as well as using the modified Penman-Mantith-Fao mathematical relationship. It was found that the amount of evaporation and transpiration of hollyhocks in the studied area was on average 1043.8 mm during the growth period. According to the results of other researchers, which have been conducted using lysimeter data and field studies, it necessarily requires higher costs than remote sensing methods. In this research, the ability of the Sabal algorithm (as one of the best remote sensing algorithms) to estimate evaporation And the actual transpiration and determination of the water requirement of the chrysanthemum plant with a low cost and an easy method compared to the results of other researchers, which were done with difficult and expensive lysimetric methods, were proved and it is suitable to be used for other plant species and in other geographical areas.

BACKGROUND AND OBJECTIVES: Studying the monthly variations in the surface features of the Bay of Bengal is a complex task that involves numerous large-scale ocean-atmosphere dynamics. This study identified the bay's changing circulation patterns over recent decades as a crucial study area requiring in-depth research. Understanding the changes in circulation patterns provides valuable insights into the Bay dynamics. It helps identify the potential impacts of climate change, ocean currents, and other factors on the bay's ecosystem. This study aims to understand the seasonal variability of the Bay of Bengal's surface circulation features using a high-resolution numerical Coastal and Regional Ocean Community simulations model. METHODS: To conduct the study in the Bay of Bengal, the Coastal and Regional Ocean Community model, a numerical ocean model, was utilized. The high-resolution numerical model for ocean circulation is three-dimensional and uses hydrostatic primitive equations in generalized curvilinear coordinates. Simulations were conducted over 8 years using a grid comprising 256 x 249 horizontal surface points to model a range of ocean-atmospheric parameters. This grid provided an approximate resolution of 10 kilometers. FINDINGS: The findings are based on the model's enhanced performance compared to previous study results. It was observed that the sea surface temperature remains above 28 degrees Celsius throughout the bay except in winter. During the monsoon season, surface salinity was observed to be reduced in the Bay of Bengal's northern region and western and eastern boundaries. Surface eddies along the western bay extend to deep waters before the onset of monsoon. The net heat flux in the bay has been determined as positive before monsoon, negative post-monsoon, and mixed during the monsoon season. CONCLUSION: This analysis focuses on the ocean surface layer with more prominent dynamics. Various surface parameters were calculated, and discussions on surface temperature, salinity, D20, D26, and net heat flux across seasons have been presented. [ABSTRACT FROM AUTHOR]

Net heat flux, sea surface temperature (SST), and sea surface wind in the northern Indian Ocean were investigated using the TropFlux, ERA5, and J-OFURO3 datasets and correlation analysis, power spectrum analysis, and singular value decomposition (SVD) methods, respectively. The relationships between net heat flux, SST, and sea surface winds were determined. The coupled modes of net heat flux and wind have been found to explain the SST variations in the Indian Ocean basin and the generation mechanism of the Indian Ocean Dipole (IOD). The correlation between net heat flux and wind is strongly negative. The SST lags the net heat flux and wind by approximately one month and has strong positive and negative correlations, respectively. The correlation between net heat flux and wind in the northern Indian Ocean is not only seasonal but also regionally dependent on seasonal variations. Using the SVD method, the important role of net heat flux in local sea-air interactions is discussed and identified as the initial perturbation that triggers the SST anomalies in the Southeast Indian Ocean, and the areas with key sea-air interactions and the generation mechanisms of the local sea-air interactions that form the IOD are determined. [ABSTRACT FROM AUTHOR]

Introduction In determining the evapotranspiration (ET) of a crop species, factors such as type, crop density, growth stage, climate of the region, physicochemical characteristics and soil fertility, have a significant effect. Therefore, it has a significant complexity. In recent years, new technologies are used to estimate ET, such as surface energy balance algorithm for land (SEBAL), which estimates actual evapotranspiration, using satellite data and some ground data. The purpose of this research is to estimate the actual ET and water requirement of Rosa damascena using SEBAL during three crop growth years in a part of the Shahrekord high plain. Materials and Methods The studied farm with an area of 16.38 ha is located in the Shahrekord plain, Karoun watershed. The remote sensing data included 42 cloud-free images of Landsat 7 and Landsat 8 satellites (2017, 2018, and 2019). The growth period lasted from the beginning of April to the end of November of each crop year. Images were processed in ERDAS Imagine 2015 software for radiometric correction and subsequent calculations using SEBAL algorithm. In order to estimate the actual evapotranspiration, the energy balance equation is used. For this purpose, all energy fluxes such as, Rn: the net incoming radiation flux to the considered surface, H: the sensible heat flux, G0: the soil heat flux and λET: the latent heat flux of evapotranspiration should be taken into account. The first step in the SEBAL process is to calculate the net radiation flux of the Rn. The second, soil heat flux G0 that is the rate of heat capacity in the soil and vegetation resulting from heat conduction or heat energy used to heat or cools the volume of the soil mass. The third is to calculate sensible heat flux (H) is the rate of heat loss to the air by conduction and convection phenomena, which is caused by the thermal difference. In SEBAL process, two "anchor" pixels are used to create boundary conditions for energy balance. These include as "cold (wet)" and "warm (dry)" pixels that are determined in the study area. A cold pixel is selected at the surface of open water or the surface covered by a well-watered alfalfa crop. It is assumed that the temperature of the surface and the temperature of the air near the surface are the same in this pixel. The "warm" pixel is selected in dry agricultural lands and its ET is considered zero. It is necessary for SEBAL model to establishing a linear equation between the surface temperature (Ts) and the air-surface temperature difference (dT) for each pixel using hot (dry) and cold (wet) pixels. Results and Discussion Based on the results of three years of research in a 16.38 hectare Golmohammadi farm in the Shahrekord plain, using the Sabal algorithm and the number of 42 images on the days of Landsat 7 and Landsat 8 satellites passing, as well as using the modified Penman-Mantith-Fao mathematical relationship. It was found that the amount of evaporation and transpiration of hollyhocks in the studied area was on average 1043.8 mm during the growth period. According to the results of other researchers, which have been conducted using lysimeter data and field studies, it necessarily requires higher costs than remote sensing methods. In this research, the ability of the Sabal algorithm (as one of the best remote sensing algorithms) to estimate evaporation And the actual transpiration and determination of the water requirement of the chrysanthemum plant with a low cost and an easy method compared to the results of other researchers, which were done with difficult and expensive lysimetric methods, were proved and it is suitable to be used for other plant species and in other geographical areas. Results showed that actual evapotranspiration value of rose crop (ETC) obtained from the SEBAL during the three years of experiment were 1089.4, 1021.3, and 1020.6 mm per growth period. In the same period, reference crop evapotranspiration (ET0) values were 1214.8, 1100.5, and 1135.5 mm during the growth period, respectively. In other words, average value for ETC was 1043.8 mm in growth period. Conclusion Based on the results of three years of research in a 16.38 hectare Golmohammadi farm in the Shahrekord plain, using the Sabal algorithm and the number of 42 images on the days of Landsat 7 and Landsat 8 satellites passing, as well as using the modified Penman-Mantith-Fao mathematical relationship. It was found that the amount of evaporation and transpiration of hollyhocks in the studied area was on average 1043.8 mm during the growth period. According to the results of other researchers, which have been conducted using lysimeter data and field studies, it necessarily requires higher costs than remote sensing methods. In this research, the ability of the Sabal algorithm (as one of the best remote sensing algorithms) to estimate evaporation And the actual transpiration and determination of the water requirement of the chrysanthemum plant with a low cost and an easy method compared to the results of other researchers, which were done with difficult and expensive lysimetric methods, were proved and it is suitable to be used for other plant species and in other geographical areas. [ABSTRACT FROM AUTHOR]

The significant multi-decadal mode (MDM) of the Indian summer monsoon rainfall (ISMR) during the past two millennia provides a basis for decadal predictability of the ISMR and has a strong association with the North-Atlantic (NA) variability with the Atlantic Multi-decadal Oscillation (AMO) as a potential external driver. It is also known that the annual cycles and interannual variability of ISMR and sea surface temperatures (SST) over the tropical Indian Ocean (IO) are strongly coupled. However, the role of local air–sea interactions in maintaining or modifying the ISMR MDM remains unknown. A related puzzle we identify is that the IO SST has an increasing trend during two opposite phases of the ISMR MDM, namely during an increasing phase of ISMR (1901–1957) as well as a decreasing phase of ISMR (1958–2007). Here, using a twentieth-century reanalysis (20CR), we examine the role of air-sea interactions in maintaining two opposite phases of the ISMR MDM and unravel that the Bjerknes feedback is at the heart of maintaining the ISMR MDM but cannot explain the increasing trend of SST in the tropical IO during the opposite phases. Large-scale low-level vorticity influence on SST and net heat flux changes through circulation and cloudiness changes associated with the two phases of the ISMR MDM together contribute to the SST trends. The decreasing trend of low-level wind convergence during the period between 1958 and 2007 is a determining factor for the decreasing trend of ISMR in the backdrop of an increasing trend of atmospheric moisture content. Consistent with the lead of the AMO with respect to ISMR by about a decade, the AMO drives the transition from one phase of ISMR MDM to another by changing its phase first and setting up low-level equatorial zonal winds conducive for the transition. [ABSTRACT FROM AUTHOR]

In this study, a deep learning model called Four Dimensional Residual Network (4D-ResNet) was proposed, which can capture both temporal and spatial information. Temperatures at various depths were predicted for the next 40 days using the last month's sea surface variables, and a spatio-temporal prediction of the thermocline was achieved. In addition to the satellite-observed sea surface parameters: sea surface temperature (SST), sea level anomaly (SLA), and sea surface wind (SSW), net heat flux (Q net) was also included in the model input. Q net can alter the density of the upper water, resulting in convection or improved stratification stability. The results indicate that the additional input of Q net improves the model's accuracy, especially at the depth of the thermocline, where the RMSE reduced by up to 13.7%. The 4D-ResNet model has much lower estimation error compared to other models and successfully captures the seasonal characteristics of the thermocline. • The 4D-ResNet model was used to achieve spatio-temporal prediction from sea surface variables to thermocline. • The additional input of net heat flux improves the accuracy of the model at the depth of the thermocline. • An analysis was conducted on the evolutionary patterns of the thermocline in the South China Sea. • The physical mechanisms by which net heat flux affectschanges in the thermocline. [ABSTRACT FROM AUTHOR]

Coastal fronts play vital roles in local biogeochemical environment. An abrupt change of Zhejiang-Fujian coastal front (ZFCF) during early spring was well captured by multi-source satellite-retrieved sea surface temperature images. Here in this study, we investigated the mechanism of the abrupt decay with a combination of satellite observation and numerical simulation. Correlation analysis of long-term reanalysis data indicates that the variability of wind, heat flux and the Zhejiang-Fujian coastal current (ZFCC) have significant relationships with the variation of ZFCF in winter. Following heat budget analysis points out that net heat flux and horizontal advection are important in determining the net temperature tendency difference between two water masses of ZFCF during this process. To further explore the intrinsic physical roles of different dynamic factors, a comprehensive numerical investigation was conducted. Compared with the observations, the model reproduced the abrupt change process of the ZFCF satisfyingly. Sensitive experiments reveal that the weakening of the ZFCC, caused by the relaxation of the monsoon, contributes to the abrupt decay of ZFCF in the first half period, and heating effect of the Kuroshio Intrusion (KI) water gives rise to the following half period of the decay under the recovered monsoon. Further, with the impact of the KI water after the change, the ZFCF can be maintained even if the ZFCC is weak, whereas in January, the contribution of the KI water to the formation of the ZFCF seems to be limited under the prevailing monsoon. Besides, the riverine discharge and the tidal forcing can also modulate the spatiotemporal variation of ZFCF, the decrease of the river input also intensifies that decay, while tides fix the front at a specific depth.

The recent increase in atmospheric pollutants (aerosols) over the northern Indian Ocean due to an increase in industrial activity in South and Southeast Asia decreased air temperature (AT) leading to the strengthening of winter convective mixing and promotion of phytoplankton blooms in the northern Arabian Sea (AS). To test this hypothesis, the variability in meteorological and surface ocean properties was analyzed for a period of 4 decades (1979–2018) in the northern AS. The total and anthropogenic aerosol optical depth (AOD) increased at a rate of 0.05 and 0.07 per decade respectively in the recent decades associated with a decrease in AT over the northern AS during winter. The estimated decrease in AT due to increasing AOD accounts for 0.18°C over the AS and it is close to that of the mean decrease in AT from 1994 to 2018 of 0.25°C. This increased the difference in temperature between the sea surface and atmosphere and enhanced specific humidity in the atmosphere resulting in the strengthening of convective mixing in the northern AS as evidenced by the deepening of the depth of 20°C isotherm in the recent decades during winter. Enhanced nutrient concentration and phytoplankton biomass were observed in the photic zone during winter further confirming that convective mixing strengthened in the recent decades in the northern AS than hitherto hypothesized as weakening due to the warming of the Eurasian landmass. The enhanced nutrients supported diatoms blooms, which are prey for Noctiluca scintillans to initiate the bloom in the AS in the recent decades. Plain Language Summary: Atmospheric pollution is ever‐increasing over the northern Indian Ocean leading to decreasing solar radiation resulting in a decrease in atmospheric temperature. This led to an increase in temperature difference between sea surface and atmosphere which triggers convective mixing and supply of nutrients to the surface. The enhanced nutrients support the formation of phytoplankton blooms and a decrease in oxygen concentrations in the subsurface waters. This work suggests that atmospheric pollution modifies oceanic mixing patterns and increases food for heterotrophs in the northern Arabian Sea. Key Points: Enhanced atmospheric pollution in the recent decades decreased atmospheric temperature over northern Arabian Sea (AS)Increase in sea to air temperature and specific humidity increased winter convective mixing in the recent decadesEnhanced convective mixing increased nutrient inputs leading to formation of phytoplankton blooms in the northern AS [ABSTRACT FROM AUTHOR]

Abstract The Indonesian sea is the only low-latitude pathway connecting two tropical oceans, which plays an important role in the coupled ocean-atmosphere mode in the Indo-Pacific sector. A small change in the sea surface temperature (SST) in the Indonesian sea has a significant influence on the precipitation and air-sea heat flux. During the past 33 years, the SST in the Indonesian sea has indicated a warming trend on the average of 0.19 ± 0.04 decade−1, which is larger than global SST warming trend. Moreover, the warming trend indicates seasonal variations, in which maximum trend occurred during boreal summer season. Investigation on the potential driver for this warming trend, namely, the net surface heat flux, resulted in an opposite trend (cooling trend), while the Ekman pumping and the wind mixing only play a minor role on the SST warming. Here, we proposed the upper layer process associated with an increasing trend in precipitation and decreasing trend in mixed layer depth (MLD) for the SST warming within the Indonesian seas. Shoaling of MLD gives a favorable condition for the surface heat flux to warm the surface ocean. However, shoaling of MLD could not solely explain the total SST warming within the Indonesian seas. The seasonal dependence in the warming trend, highest during boreal summer, was significantly related to the Indo-Pacific climate modes, namely the negative Indian Ocean Dipole (IOD) and La Niña events. Higher warming trend observed in the south of Makassar Strait and in the eastern Indonesian seas, in the vicinity of the Maluku Sea and the northeastern part of the Banda Sea, was significantly associated with the La Niña event. Meanwhile, strong warming trend observed in the Karimata Strait and Java Sea, and in the Flores Sea south of Sulawesi Island seems to be enhanced by the negative IOD event. Our rough quantitative estimate of the possible mechanism leading to the SST warming suggests that other mechanism might be at work in warming the SST within the Indonesian seas. Horizontal heat advection associated with an increasing trend of the heat transport from the Pacific into the Indian Ocean by the Indonesian Throughflow (ITF) might play a role in causing the warming trend within the Indonesian seas. However, to what extend this heat advection could modulate the SST warming is still unresolved in the present study. Further study based on realistic model output as well as long-term observational records is necessary to describe the dynamics underlying the warming trend within the Indonesian seas.

Abstract Net heat flux (Qnet) and its components from four reanalysis (NCEP‐2, CFSR, ERA5, and MERRA) and two blended products (OAFlux & TropFlux) are compared with in situ observation (two Research Moored Array for African‐Asian‐Australian Monsoon Analysis and Prediction buoys and one Woods Hole Oceanographic Institution buoy) over the north Indian Ocean to quantify their uncertainties in daily, seasonal, and annual scales. These comparisons provide the present status of Qnet error in most state of the art reanalysis/blended products. The root‐mean‐square error (RMSE) remains similar to the RMSE a decade earlier, despite more observation and improved models and reanalysis methods. However, there is a clear separation of flux quality from the older generation of reanalysis (NCEP‐2) to the newer production of reanalysis (MERRA, CFSR, and ERA5). While individually ERA5 provides the best estimate, the ensemble mean (i.e., average of ERA5, CFSR, MERRA, TropFlux, and OAFlux) is very close to ERA5 both in terms of correlations and RMSE and provides the most reliable estimate by virtue of removal of some of the uncertainties in estimation of flux by each of the flux products. A significant reduction of RMSE in Qnet estimates from 100 W/m2 (in NCEP‐2) to 45 W/m2 (in the ensemble mean) is considerable progress. It is noteworthy that all the recent flux products estimate the increasing trend of Qnet in the north Bay of Bengal and subseasonal fluctuations with significant fidelity. Also, in the south of equator location vigorous subseasonal fluctuations in boreal winter are well captured. We believe that this is significant progress in the estimation of Qnet over the Indian Ocean.

This study focuses on the intercomparisons of 22 net heat flux (NHF) data sets in terms of mean, linear trend, and interannual variability during 1993–2007 over the western North Pacific and its surrounding waters. The data sets can be categorized into the dominant group that shares common interannual variabilities and the outcasts that exhibit exceptional variability. Based on our analysis, we provide guidelines for users to choose reliable NHF data sets in the study regions. In addition, many NHF data sets tend to represent similar interannual variabilities in the marginal sea regions, whereas the opposite is true in open oceans where interannual variability is weak. Also, we find an evidence showing the mean biases of the NHF are mainly due to the difference in calculation of the latent heat flux. The aforementioned information will be useful for a wide community of scientists who are interested in using heat flux data. [ABSTRACT FROM AUTHOR]

Net heat flux (Qnet) and its components from four reanalysis (NCEP‐2, CFSR, ERA5, and MERRA) and two blended products (OAFlux & TropFlux) are compared with in situ observation (two Research Moored Array for African‐Asian‐Australian Monsoon Analysis and Prediction buoys and one Woods Hole Oceanographic Institution buoy) over the north Indian Ocean to quantify their uncertainties in daily, seasonal, and annual scales. These comparisons provide the present status of Qnet error in most state of the art reanalysis/blended products. The root‐mean‐square error (RMSE) remains similar to the RMSE a decade earlier, despite more observation and improved models and reanalysis methods. However, there is a clear separation of flux quality from the older generation of reanalysis (NCEP‐2) to the newer production of reanalysis (MERRA, CFSR, and ERA5). While individually ERA5 provides the best estimate, the ensemble mean (i.e., average of ERA5, CFSR, MERRA, TropFlux, and OAFlux) is very close to ERA5 both in terms of correlations and RMSE and provides the most reliable estimate by virtue of removal of some of the uncertainties in estimation of flux by each of the flux products. A significant reduction of RMSE in Qnet estimates from 100 W/m2 (in NCEP‐2) to 45 W/m2 (in the ensemble mean) is considerable progress. It is noteworthy that all the recent flux products estimate the increasing trend of Qnet in the north Bay of Bengal and subseasonal fluctuations with significant fidelity. Also, in the south of equator location vigorous subseasonal fluctuations in boreal winter are well captured. We believe that this is significant progress in the estimation of Qnet over the Indian Ocean. Key Points: Surface net heat flux is compared in recent reanalysis and blended productsThe flux quality has improved significantly as compared to older generation reanalysisEnsemble mean net heat flux is the new data much better than individual flux data with least RMSE and almost comparable correlations [ABSTRACT FROM AUTHOR]

The Indonesian sea is the only low-latitude pathway connecting two tropical oceans, which plays an important role in the coupled ocean-atmosphere mode in the Indo-Pacific sector. A small change in the sea surface temperature (SST) in the Indonesian sea has a significant influence on the precipitation and air-sea heat flux. During the past 33 years, the SST in the Indonesian sea has indicated a warming trend on the average of 0.19 ± 0.04 decade−1, which is larger than global SST warming trend. Moreover, the warming trend indicates seasonal variations, in which maximum trend occurred during boreal summer season. Investigation on the potential driver for this warming trend, namely, the net surface heat flux, resulted in an opposite trend (cooling trend), while the Ekman pumping and the wind mixing only play a minor role on the SST warming. Here, we proposed the upper layer process associated with an increasing trend in precipitation and decreasing trend in mixed layer depth (MLD) for the SST warming within the Indonesian seas. Shoaling of MLD gives a favorable condition for the surface heat flux to warm the surface ocean. However, shoaling of MLD could not solely explain the total SST warming within the Indonesian seas. The seasonal dependence in the warming trend, highest during boreal summer, was significantly related to the Indo-Pacific climate modes, namely the negative Indian Ocean Dipole (IOD) and La Niña events. Higher warming trend observed in the south of Makassar Strait and in the eastern Indonesian seas, in the vicinity of the Maluku Sea and the northeastern part of the Banda Sea, was significantly associated with the La Niña event. Meanwhile, strong warming trend observed in the Karimata Strait and Java Sea, and in the Flores Sea south of Sulawesi Island seems to be enhanced by the negative IOD event. Our rough quantitative estimate of the possible mechanism leading to the SST warming suggests that other mechanism might be at work in warming the SST within the Indonesian seas. Horizontal heat advection associated with an increasing trend of the heat transport from the Pacific into the Indian Ocean by the Indonesian Throughflow (ITF) might play a role in causing the warming trend within the Indonesian seas. However, to what extend this heat advection could modulate the SST warming is still unresolved in the present study. Further study based on realistic model output as well as long-term observational records is necessary to describe the dynamics underlying the warming trend within the Indonesian seas. [ABSTRACT FROM AUTHOR]

The Weddell Sea is susceptible to the ongoing climate change and experiences a reduction in an overall increase in the sea-ice extent (SIE). The nature of sea-ice in the Weddell Sea is largely associated with its geographical setup that determines the seasonal and decadal sea-ice variability. The study analysed long-term sea ice-ocean-atmosphere variability and trends (1979–2019) based on satellite and reanalysis measurements. The result shows the expansion of yearly SIE is 2.5 ± 3.5 × 10 ^3 km ^2 yr ^−1 with a significant increase in the austral summer (12.4 ± 4.6 × 10 ^3 km ^2 yr ^−1 ), whereas a decrease in the spring SIE (−4.8 ± 5.0 × 10 ^3 km ^2 yr ^−1 ) over the last four decades. Seasonal sea-ice concentration (SIC) variations in the Weddell Sea are associated with latitudinal thermal differences and westerlies intensification, culminating in the weakening or strengthening of the Weddell Gyre. The SIC recorded significant positive trends in the western and eastern parts of the Weddell Sea during the austral summer and autumn, respectively. These changes are consistent with the prevailing wind patterns and Weddell Gyre intensification in the respective seasons. During the austral winter and spring, significant negative SIC trends (north of 65° S) were recorded due to the easterlies intensification and weakening of the Weddell Gyre. While, the significant positive trends observed along the coast are linked with the easterlies intensification and sea-ice advection. Composite analysis reveals that the SIC variability is related to the sea surface temperature (SST) during austral summer and spring, whereas SST and net heat flux both regulate the SIC in the Weddell Sea during the austral winter and autumn. The positive Southern Annular Mode is associated with an increase in sea-ice during austral summer, while sea-ice decreases during the winter in the Weddell Sea. The present study reveals a strong relationship between the sea-ice variability and ocean-atmospheric forcings, but these relationships are not constant over time; therefore, continuous monitoring is required.

Abstract This paper is focused on the development and verification of a heat attitude model (HAM) for satellite attitude determination. Within this context, the Sun and the Earth are considered as the main external sources of radiation that could effect the satellite surface temperature changes. Assuming that the satellite orbital position (navigational data) is known, the proposed HAM provides the satellite surface temperature with acceptable accuracy and also relates the net heat flux (NHF) of three orthogonal satellite surfaces to its attitude via the inertial to satellite transformation matrix. The proposed HAM simulation results are verified through comparison with commercial thermal analysis tools. The proposed HAM has been successfully utilized in some researches for attitude estimation, and further studies for practical implementations are still ongoing. [ABSTRACT FROM AUTHOR]

A study of the inter-annual variability of the warming of the southeastern Arabian Sea (SEAS) during the spring transition months was carried out from 2013 to 2015 based on in situ data from moored buoys. An attempt was made to identify the roles of the different variables in the warming of the SEAS (e.g., net heat flux, advection, entrainment, and thickness of the barrier layer during the previous northeast monsoon season). The intense freshening of the SEAS (approximately 2 PSU) occurring in each December, together with the presence of a downwelling Rossby wave, supports the formation of a thick barrier layer during the northeast monsoon season. It is known that the barrier layer thickness, varying each year, plays a major role in the spring warming of the SEAS. Interestingly, an anomalously thick barrier layer occurred during the northeast monsoon season of 2012-2013. However, the highest sea surface temperature (31 °C) was recorded during the last week of April 2015, while the lowest sea surface temperature (29.7 °C) was recorded during the last week of May 2013. The mixed layer heat budget analysis during the spring transition months proved that the intense warming has been mainly supported by the net heat flux, not by other factors like advection and entrainment. The inter-annual variability analysis of the net heat flux and its components, averaged over a box region of the SEAS, showed a substantial latent heat flux release and a reduction in net shortwave radiation in 2013. Both factors contributed to the negative net heat flux. Strong breaks in the warming were also observed in May due to the entrainment of cold sub-surface waters. These events are associated with the cyclonic eddy persisting over the SEAS during the same time. The entrainment term, favoring the cooling, was stronger in 2015 than that in 2013 and 2014. The surface temperatures measured in 2013 were lower than those in 2014 and 2015 despite the presence of a thick barrier layer. The substantial decrease in net heat flux along with entrainment cooling has been identified as causes for this behavior. [ABSTRACT FROM AUTHOR]

Experiments were carried out to study the dripping behavior of vertical burning thermally thin poly(methyl methacrylate) (PMMA) with different spacings between the wall and PMMA. The dripping behavior was studied by infrared video image analysis with spacings of 7, 10, 13, 16, 19, 22, and 25 mm. As the spacing increased, the dripping time and mass and burnout growth distance first increased and then decreased. The critical value was observed at the 13 mm case. The dripping behavior is assumed to correspond to the net heat flux to the surface, extensional viscosity, and gravitational force of melting PMMA. After the dripping, the pyrolysis and burnout spread rates become asymptotically equal.In this study, the effects of spacing between the wall and fuels on the dripping behavior were investigated for the first time using uniform PMMA samples with 200 mm height, 50 mm width, and 2 mm thickness. [ABSTRACT FROM AUTHOR]

The typhoon Wind-Pump induced upwelling and cold eddy often promote the significant growth of phytoplankton after the typhoon. However, the importance of eddy-pumping and wind-driven upwelling on the sea surface chlorophyll a concentration (Chl-a) during the typhoon are still not clearly distinguished. In addition, the air−sea heat flux exchange is closely related to the upper ocean processes, but few studies have discussed its role in the sea surface Chl-a variations under typhoon conditions. Based on the cruise data, remote sensing data, and model data, this paper analyzes the contribution of the vertical motion caused by the eddy-pumping upwelling and Ekman pumping upwelling on the surface Chl-a, and quantitatively analyzes the influence of air−sea heat exchange on the surface Chl-a after the typhoon Linfa over the northeastern South China Sea (NSCS) in 2009. The results reveal the Wind Pump impacts on upper ocean processes: (1) The euphotic layer-integrated Chl-a increased after the typhoon, and the increasing of the surface Chl-a was not only the uplift of the deeper waters with high Chl-a but also the growth of the phytoplankton; (2) The Net Heat Flux (air−sea heat exchange) played a major role in controlling the upper ocean physical processes through cooling the SST and indirectly increased the surface Chl-a until two weeks after the typhoon; (3) the typhoon-induced cyclonic eddy was the most important physical process in increasing the surface Chl-a rather than the Ekman pumping and wind-stirring mixing after typhoon; (4) the spatial shift between the surface Chl-a blooms and the typhoon-induced cyclonic eddy could be due to the Ekman transport; (5) nutrients uplifting and adequate light were two major biochemical elements supplying for the growth of surface phytoplankton.

This paper presents a novel heat based measurement model for attitude determination (AD) using temperature data via two filtering techniques. Within the space environment, the Sun and Earth are considered as the major sources of external radiation that affect satellite surface temperature. In order to perform the required AD task, the satellite surface temperatures are related to its attitude via a proposed heat model (HM), assuming that the satellite navigational data is available. The proposed HM relates the net heat flux of three satellite orthogonal surfaces to its attitude. Filtering implementation of the proposed HM using the Unscented Kalman Filter (UKF) for AD is the key contribution of this paper, while the results are compared with those of the Extended Kalman Filter (EKF) for performance assessment. The results demonstrate the positive applicability of the proposed HM for AD via filtering, while performance evaluation of both filtering techniques is performed using a Monte Carlo simulation. In addition, threshold boundaries for the satellite initial attitude and rates error for which the proposed HM is able to produce acceptable AD results are outlined. The study is completed with a pertinent conclusion and future research directives. [ABSTRACT FROM AUTHOR]

Attitude Determination (AD) is one of the key requirements of many current and emerging remote sensing missions. As such AD has been traditionally accomplished through a variety of algorithms and measurement models pertinent to sensing mechanisms. The current paper addresses conceptual validation and utility of a novel radiation based heat (measurement) model for space application. The proposed new Heat Attitude (HA) model utilizes temperature data to relate the Satellite Surfaces’ (SS) Net Heat Flux (NHF) to attitude assuming that the satellite navigational data are available. As Sun and the Earth are considered the main external sources of radiation, their effects are modeled for the SS temperature changes via a novel measurement model and sensing mechanism. In this respect and in order to experimentally validate the capability of the proposed HA model, a Cubic Laboratory Satellite (CLS) with three orthogonal copper coated surface plates is constructed. Next, Non-Contact Thermopiles (NCT) are installed to measure the SS radiative temperatures in a vacuum chamber equipped with a Sun simulator. Subsequently, the CLS is tested under static and dynamic scenarios where the temperature data are used for error analysis and model validation via an Extended Kaman Filter (EKF). Comparison of the CLS true and HA model EKF estimated attitudes demonstrate a good accuracy. In this sense, the proposed novel HA model is promising and paves the way for a new low cost alternative approach for space AD applications. [ABSTRACT FROM AUTHOR]

The thermodynamics of the seasonal evolution of the Southwestern Tropical Atlantic Warm Pool (hereafter SWTAWP), which is delimited by the 28 °C isotherm, is investigated using the Regional Ocean Modeling System (ROMS). Results indicate that the net heat flux is responsible for the appearance and extinction of the SWTAWP. From March to May, the SWTAWP attains its maximum development and sometimes merges with equatorial warm waters towards the African continent, whose development follows the same period. Along the equator, the combination of oceanic terms (i.e., advection and diffusion) is important to promote the separation – when it occurs – of equatorial warm waters from southwestern tropical waters, which develops off the Brazilian coast. An analysis of the relative contribution of the temperature tendency terms of the mixed layer (ML) heat budget over the appearance, development and extinction of the SWTAWP is also done. The most important term for warming and cooling inside of the ML is the net heat flux at the sea surface. The ML is heated by the atmosphere between October and April, whereas the upper ocean cools down between May and September. The highest heat content values occur during the lower-temperature period (August to October), which is linked to the deepening of the ML during this time period. The horizontal advection along the equator is important, particularly at the eastern domain, which is influenced by the cold tongue. In this area, the vertical diffusive term is also significant; however, it presents values near zero outside the equator. These results contribute to a better understanding of the behavior of the heat budget within the tropical Atlantic, as previous studies over this region focused along the equator only. [ABSTRACT FROM AUTHOR]

When forested riparian zones are cleared for agriculture or development, major changes can occur in the stream temperature regime and consequently in ecosystem structure and function. Our main objective was to compare the summer temperature regimes of streams with and without forest canopy cover at multiple sites. The secondary objective was to identify the components of the stream heat budget that had the greatest influence on the stream temperature regime. Paired stream reaches (one forested and one non-forested or 'open') were identified at 11 sites distributed across the USA and Canada. Stream temperature was monitored at the upstream and downstream ends of 80 to 130-m-long reaches during summer, and five variables were calculated to describe the stream temperature regime. Overall, compared with forested reaches, open reaches tended to have significantly higher daily mean (mean difference = 0.33 ± 1.1°C) and daily maximum (mean difference = 1.0 ± 1.7°C) temperatures and wider daily ranges (mean difference = 1.1 ± 1.7°C). Mean and maximum daily net heat fluxes in open reaches tended to be greater (or less negative) than those in forested reaches. However, certain sites showed the opposite trends in some variables because of the following: (i) Daily mean and maximum temperatures were biased by differences in inflow temperature between paired reaches and (ii) inputs of cold groundwater exerted a strong influence on temperature. Modelling and regression results suggested that within sites, differences in direct solar radiation were mainly responsible for the observed differences in stream temperature variables at the daily scale. © 2014 The Authors. River Research and Applications published by John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

ABSTRACT On the basis of the datasets obtained for the monthly turbulent heat flux (1984-2009) from the Objectively Analyzed Air-Sea Heat Flux (OAFlux), the radiation flux from the International Satellite Cloud Climatology Project (ISCCP), the variability characteristics of the net heat flux (Qnet) over the Kuroshio System (KS) and its relationship with the climate in China were studied. The results reveal that except for a steady enhancement in the period 1984-2009, the boreal winter Qnet over the KS is characterized by obvious interannual variation of the period quasi-5 year as well as decadal variability shifting from negative to positive anomalies in the mid-1990s. In the wintertime, the increasing KS Qnet is primarily responsible for the intensification of the East Asia winter monsoon (EAWM) via a deepening of the Aleutian low and an enhancement of the Siberia high and has a correlation coefficient of 0.72 with a 1-month delay. The enhanced-EAWM induces colder winters in Northeast China and higher Qnet over the KS by carrying significantly greater amounts of cold air mass. During the low Qnet winter, the EAWM is weakened, and the southwesterly wind that contains abundant water vapour enhances and pushes toward southern China, thereby bringing heavier rainfall. The anomalous Qnet over the KS in the wintertime lasts until the following spring with a weaker relative intensity. In the spring after the low KS Qnet winter, the anomalous easterly wind transfers colder air masses from the Sea of Japan to the North China and Yellow-Huaihe regions and then cools these regions. The warmer and wetter southwesterlies along the northwestern flank of the anomalous anticyclone east of Taiwan Island meet these colder easterlies accompanied by an anomalous upward motion, thereby inducing an anomalous northwest-southeast precipitation band in the central and eastern region of China, especially in the Yangtze-Huaihe region. [ABSTRACT FROM AUTHOR]

On the basis of the datasets obtained for the monthly turbulent heat flux (1984-2009) from the Objectively Analyzed Air-Sea Heat Flux (OAFlux), the radiation flux from the International Satellite Cloud Climatology Project (ISCCP), the variability characteristics of the net heat flux (Qnet) over the Kuroshio System (KS) and its relationship with the climate in China were studied. The results reveal that except for a steady enhancement in the period 1984-2009, the boreal winter Qnet over the KS is characterized by obvious interannual variation of the period quasi-5 year as well as decadal variability shifting from negative to positive anomalies in the mid-1990s. In the wintertime, the increasing KS Qnet is primarily responsible for the intensification of the East Asia winter monsoon (EAWM) via a deepening of the Aleutian low and an enhancement of the Siberia high and has a correlation coefficient of 0.72 with a 1-month delay. The enhanced-EAWM induces colder winters in Northeast China and higher Qnet over the KS by carrying significantly greater amounts of cold air mass. During the low Qnet winter, the EAWM is weakened, and the southwesterly wind that contains abundant water vapour enhances and pushes toward southern China, thereby bringing heavier rainfall. The anomalous Qnet over the KS in the wintertime lasts until the following spring with a weaker relative intensity. In the spring after the low KS Qnet winter, the anomalous easterly wind transfers colder air masses from the Sea of Japan to the North China and Yellow-Huaihe regions and then cools these regions. The warmer and wetter southwesterlies along the northwestern flank of the anomalous anticyclone east of Taiwan Island meet these colder easterlies accompanied by an anomalous upward motion, thereby inducing an anomalous northwest-southeast precipitation band in the central and eastern region of China, especially in the Yangtze-Huaihe region. [ABSTRACT FROM AUTHOR]

Using the Simple Ocean Data Assimilation Version 2.2.4 dataset from 1950 to 2010, we analyzed the interannual variations in wintertime temperature inversions in the Gulf of Alaska (GOA), and the linkages to the Aleutian Low are also examined. The results show that the climatological wintertime temperature inversions is predominantly distributed in the northwestern GOA (NWGOA) and northern GOA (NGOA), in which it is stronger in the NWGOA than in the NGOA. Interannual variations in the temperature difference (∆ T) are pronounced and are mainly controlled by the temperature minimum (T min) of the inversions layer. The temperature inversions layer became warmer and shallower during 1950–2010, among T min and the temperature maximum (T max) was notably warming, and the upper edge depth (D min) and lower edge depth (D max) revealed significant shoaling. ∆ T decreased by 0.12 °C from 1950 to 2010 in the NWGOA but had no trend in the NGOA. The interannual variations in wintertime temperature inversions are controlled by the mixed-layer temperature anomalies and are closely correlated with the changes in the Aleutian Low. The weakened (deepened) Aleutian Low during strong (weak) ∆ T winters could cause the weakening (enhancement) of the cyclone wind field in the North Pacific subarctic region, which is conducive to slowing down (spinning up) the flow of the Alaskan Gyre and the transportation of warm air into the GOA. Thus, a negative (positive) T min anomalies within the mixed layer is larger than T max anomalies, resulting in a larger (smaller) ∆ T ; meanwhile, the strong (weak) cooling effect leads to a deeper (shallower) D max. The interannual variations in the wintertime temperature inversions could be influenced by net heat flux and advection anomalies in the NWGOA, but only caused by net heat flux anomalies in the NGOA. • Interannual variations in wintertime temperature inversions in the Gulf of Alaska were studied. • Temperature inversions layer became warmer and shallower during 1950–2010. • The temperature difference anomalies are related to the changes in the Aleutian Low. • These anomalies are contributed to net heat flux and advection anomalies in the NWGOA. • However, these anomaly is only caused by net heat flux anomaly in the NGOA. [ABSTRACT FROM AUTHOR]

A numerical method is used to inversely solve the net heat flux radiated to the red pine external surfaces with black and white paint and coloured drawing under four types of artificial light: high-pressure sodium lamp, tungsten halogen lamp, metal halide lamp and fluorescent lamp. Firstly, the temperature values of the external surface centre and the internal centre of the samples are obtained through experiments by using thermocouple. Secondly, a finite-volume method is used to fit the experimental values by changing the net heat flux radiated to the external surface. The results show that the net heat flux under artificial light sources with low power and close distance lighting is one order lower than the net heat flux under solar radiation. For different artificial light sources, the characteristics of the net heat flux have certain universality. [ABSTRACT FROM AUTHOR]

Abstract: Fiftyyears (1960–2009) sea surface height (SSH) data derived from ECMWF ORA-S3 are analyzed in the South China Sea (SCS). Using stochastic dynamic analytic method to investigate characteristics of SSH on different timescales, it could be found that SSH in the SCS displays distinct seasonal (including annual and semiannaul) and interannual variations. The annual signal has minimum value in February and maximum value in August, and its amplitude is 1.81cm. The interannual SSH variability in the SCS is coherent with the ENSO/PDO/NPGO based on the lead-lag relationship. The seasonal SSH variations are induced by buoyancy fluxes and local wind stress. The local wind stress contribution to seasonal SSH in the east SCS is dominant (explain 20–65%), and buoyancy fluxes contribution is secondary (explain 30–40%). Buoyancy fluxes are determined by net heat fluxes in the upper ocean. Effect of freshwater fluxes can be neglected. Interannual variations are closely related to the subsurface water (depth about 100–300m). ENSO/PDO/NPGO signals affect the temperature and salinity changes of the subsurface water and further lead to interannual variations of SSH. [Copyright &y& Elsevier]

Abstract: The transient natural convection in an inclined enclosure filled with water is studied experimentally for the time-periodically-varying wall temperature on one side wall and constant average temperature on the opposing side wall. This system has no temperature difference between the opposing two side walls in time-averaged sense. The temperatures of two opposing walls and the heat flux across the enclosure are measured by a heat flux meter. Based on the experimental results, the effects of time-periodically-varying wall temperature and inclined angles of the enclosure on heat transfer characteristics are studied. The experimental results show that, with the upper wall temperature oscillating, the heat flux across the enclosure is also periodically varied with time, and the net heat flux is from the lower wall to the upper wall. Numerical computations are also conducted and numerical results are qualitatively assured by the experimental measurements. [ABSTRACT FROM AUTHOR]

The seasonal variability of sonic layer depth (SLD) in the central Arabian Sea (CAS) (0 to 25°N and 62-66°E) was studied using the temperature and salinity (T/S) profiles from Argo floats for the years 2002–2006. The atmospheric forcing responsible for the observed changes was explored using the meteorological data from NCEP/NCAR and Quickscat winds. SLD was obtained from sound velocity profiles computed from T/S data. Net heat flux and wind forcing regulated SLD in the CAS. Up-welling and down-welling (Ekman dynamics) associated with the Findlater Jet controlled SLD during the summer monsoon. While in winter monsoon, cooling and convective mixing regulated SLD in the study region. Weak winds, high insolation and positive net heat flux lead to the formation of thin, warm and stratified sonic layer during pre and post summer monsoon periods, respectively. [ABSTRACT FROM AUTHOR]

A comparative study between the output of the Flexible Global Climate Model Version 1.0 (FGCM-1.0) and the observations is performed. At 500 hPa, the geopotential height of FGCM is similar to the observations, but in the North Pacific the model gives lower values, and the differences are most significant over the northern boundary of the Pacific. In a net heat flux comparison, the spatial patterns of the two are similar in winter, but more heat loss appears to the east of Japan in FGCM than in COADS. On the interannual timescale, strong (weak) Kuroshio transports to the east of Taiwan lead the increasing (decreasing) net heat flux, which is centered over the Kuroshio Extension region, by 1–2 months, with low (high) pressure anomaly responses appearing at 500 hPa over the North Pacific (north of 25°N) in winter. The northward heat transport of the Kuroshio is one of the important heat sources to support the warming of the atmosphere by the ocean and the formation of the low pressure anomaly at 500 hPa over the North Pacific in winter. [ABSTRACT FROM AUTHOR]

The typhoon Wind-Pump induced upwelling and cold eddy often promote the significant growth of phytoplankton after the typhoon. However, the importance of eddy-pumping and wind-driven upwelling on the sea surface chlorophyll a concentration (Chl-a) during the typhoon are still not clearly distinguished. In addition, the air–sea heat flux exchange is closely related to the upper ocean processes, but few studies have discussed its role in the sea surface Chl-a variations under typhoon conditions. Based on the cruise data, remote sensing data, and model data, this paper analyzes the contribution of the vertical motion caused by the eddy-pumping upwelling and Ekman pumping upwelling on the surface Chl-a, and quantitatively analyzes the influence of air–sea heat exchange on the surface Chl-a after the typhoon Linfa over the northeastern South China Sea (NSCS) in 2009. The results reveal the Wind Pump impacts on upper ocean processes: (1) The euphotic layer-integrated Chl-a increased after the typhoon, and the increasing of the surface Chl-a was not only the uplift of the deeper waters with high Chl-a but also the growth of the phytoplankton; (2) The Net Heat Flux (air–sea heat exchange) played a major role in controlling the upper ocean physical processes through cooling the SST and indirectly increased the surface Chl-a until two weeks after the typhoon; (3) the typhoon-induced cyclonic eddy was the most important physical process in increasing the surface Chl-a rather than the Ekman pumping and wind-stirring mixing after typhoon; (4) the spatial shift between the surface Chl-a blooms and the typhoon-induced cyclonic eddy could be due to the Ekman transport; (5) nutrients uplifting and adequate light were two major biochemical elements supplying for the growth of surface phytoplankton. [ABSTRACT FROM AUTHOR]