scholarly journals On the changes in the sea surface temperature in the Benguela upwelling region. Part 1: season cycle

2019 ◽  
pp. 33-44
Author(s):  
A. B. Polonsky ◽  
A. N. Serebrennikov
Keyword(s):  
Surface Temperature ◽  
Seasonal Variability ◽  
Surface Wind ◽  
Water Layer ◽  
Hydrodynamic Characteristics ◽  
Entire Area ◽  
Near Surface ◽  
Sea Level Anomalies ◽  
Benguela Upwelling ◽  
Upwelling Index

Based on daily ocean surface temperature values for 1982–2017, near-surface wind for 1988–2017. and sea level anomalies for 1993–2017, obtained from satellite data, the seasonal variability of the hydrodynamic characteristics of the upper water layer in the vicinity of the Benguela upwelling is investigated. It is shown that the thermal upwelling index averaged over the entire area with lower temperature values does not give a correct idea on the seasonal course of the water lifting rate in the upwelling zone due to the significant horizontal advection of waters of upwelling origin. The seasonal variations of the vertical velocity of wind origin in the Benguela upwelling zone are characterized by the presence of two extremes from October to March, which is manifested in the predominance of the semiannual harmonic. At the same time, the thermal upwelling index in the zone of distribution of upwelling waters is subject to seasonal variability with an annual period.

scholarly journals On the changes in the sea surface temperature in the benguela upwelling region. Part 2: the long-term tendencies

2019 ◽  
pp. 29-39 ◽  
Author(s):  
A. B. Polonsky ◽  
A. N. Serebrennikov
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Wind Field ◽  
Surface Wind ◽  
Field Structure ◽  
Sea Surface ◽  
Near Surface ◽  
Tangential Wind ◽  
Benguela Upwelling

The paper examines the issue on the long-term trends in the sea surface temperature (SST) in the Benguela upwelling zone and their causes using the daily SST satellite data for 1985–2017’s and the daily near-surface wind for 1988–2017”s. It is shown that in the Benguela upwelling region, there is a significant intensification of driving winds in the last 20 yrs. This is accompanied by a decrease of the thermal upwelling index (taking into account the sign of the index or an increase of its absolute values) in the southern part of the Benguela upwelling, but practically does not influence this indicator in its northern part. The likely reason for this difference is the change in the wind field structure, as a result of which there are opposite trends in the magnitude of the vorticity of the tangential wind stress in different parts of the Benguela upwelling. In the southern part of the Benguela upwelling, both the Ekman’s upwelling and the vertical velocities due to the vorticity of the driving wind intensify, while in the northern part the corresponding trends have the opposite signs. This leads to a partial compensation of these two effects in the northern part of the Benguela upwelling. The reason for the change in the wind field structure is the displacement of the center of the Subtropical High to the south-east and the concomitant reversal of the near-surface wind vector in the coastal zone.

scholarly journals Impact of COVID-19-Related Traffic Slowdown on Urban Heat Characteristics

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 243
Author(s):  
Bernardo Teufel ◽  
Laxmi Sushama ◽  
Vincent Poitras ◽  
Tarek Dukhan ◽  
Stéphane Bélair ◽  
...  
Keyword(s):  
Heat Stress ◽  
Surface Temperature ◽  
Urban Areas ◽  
Heavy Traffic ◽  
Urban Climate ◽  
Surface Wind ◽  
Warm Season ◽  
Well Being ◽  
Urban Centre ◽  
Near Surface

Governments around the world have implemented measures to slow down the spread of COVID-19, resulting in a substantial decrease in the usage of motorized transportation. The ensuing decrease in the emission of traffic-related heat and pollutants is expected to impact the environment through various pathways, especially near urban areas, where there is a higher concentration of traffic. In this study, we perform high-resolution urban climate simulations to assess the direct impact of the decrease in traffic-related heat emissions due to COVID-19 on urban temperature characteristics. One simulation spans the January–May 2020 period; two additional simulations spanning the April 2019–May 2020 period, with normal and reduced traffic, are used to assess the impacts throughout the year. These simulations are performed for the city of Montreal, the second largest urban centre in Canada. The mechanisms and main findings of this study are likely to be applicable to most large urban centres around the globe. The results show that an 80% reduction in traffic results in a decrease of up to 1 °C in the near-surface temperature for regions with heavy traffic. The magnitude of the temperature decrease varies substantially with the diurnal traffic cycle and also from day to day, being greatest when the near-surface wind speeds are low and there is a temperature inversion in the surface layer. This reduction in near-surface temperature is reflected by an up to 20% reduction in hot hours (when temperature exceeds 30 °C) during the warm season, thus reducing heat stress for vulnerable populations. No substantial changes occur outside of traffic corridors, indicating that potential reductions in traffic would need to be supplemented by additional measures to reduce urban temperatures and associated heat stress, especially in a warming climate, to ensure human health and well-being.

scholarly journals Variability of Diurnal Sea Surface Temperature during Short Term and High SST Event in the Western Equatorial Pacific as Revealed by Satellite Data

2020 ◽  
Vol 12 (19) ◽  
pp. 3230
Author(s):  
Anindya Wirasatriya ◽  
Kohtaro Hosoda ◽  
Joga Dharma Setiawan ◽  
R. Dwi Susanto
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Surface Wind ◽  
Equatorial Pacific ◽  
Western Pacific ◽  
Sea Surface ◽  
Occurrence Rate ◽  
Near Surface ◽  
Western Equatorial Pacific ◽  
The Western Pacific

Near-surface diurnal warming is an important process in the climate system, driving exchanges of water vapor and heat between the ocean and the atmosphere. The occurrence of the hot event (HE) is associated with the high diurnal sea surface temperature amplitude (δSST), which is defined as the difference between daily maximum and minimum sea surface temperature (SST). However, previous studies still show some inconsistency for the area of HE occurrence and high δSST. The present study produces global δSST data based on the SST, sea surface wind data derived from microwave radiometers, and solar radiation data obtained from visible/infrared radiometers. The value of δSSTs are estimated and validated over tropical oceans and then used for investigating HE in the western equatorial Pacific. A three-way error analysis was conducted using in situ mooring buoy arrays and geostationary SST measurements by the Himawari-8 and Geostationary Operational Environmental Satellite (GOES). The standard deviation error of daily and 10-day validation is around 0.3 °C and 0.14–0.19 °C, respectively. Our case study in the western Pacific (from 110°E to 150°W) shows that the area of HE occurrence coincided well with the area of high δSST. Climatological analysis shows that the collocated area between high occurrence rate of HE and high δSST, which coincides with the western Pacific warm pool region in all seasons. Thus, this study provides more persuasive evidence of the relation between HE occurrence and high δSST.

scholarly journals Case Studies of Tropical Cyclones and Phytoplankton Blooms over Atlantic and Pacific Regions

2013 ◽  
Vol 17 (17) ◽  
pp. 1-19 ◽  
Author(s):  
Ashley M. Merritt-Takeuchi ◽  
Sen Chiao
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Case Studies ◽  
Tropical Cyclones ◽  
Surface Wind ◽  
Ocean Basin ◽  
Sea Surface ◽  
Phytoplankton Blooms ◽  
Near Surface ◽  
Chl A

Abstract This study investigates phytoplankton blooms following the passage of tropical cyclones in the Atlantic and Pacific Ocean basins. The variables of sea surface temperature (SST), chlorophyll (Chl-a), precipitation, and storm surface winds were monitored for two case studies, Typhoon Xangsane (2006) and Hurricane Earl (2010). Strong near-surface wind from tropical cyclones creates internal friction, which causes deep nutrient enriched waters to displace from the bottom of the ocean floor up toward the surface. In return, the abundance of upwelled nutrients near the surface provides an ideal environment for the growth of biological substances such as chlorophyll and phytoplankton. The inverse correlation coefficients of SST and Chl-a for this study are −0.67 and −0.26 for Xangsane and Earl, respectively. This suggests that, regardless of ocean basin, changing sea surface temperature and chlorophyll concentrations can be correlated to various characteristics of tropical cyclones including precipitation and surface wind, which in combination results in an increase of phytoplankton.

Recurrence Characteristics Analysis of Near-Surface Wind Speed Signal with Different Sampling Frequencies

2014 ◽  
Vol 599-601 ◽  
pp. 1605-1609 ◽  
Author(s):  
Ming Zeng ◽  
Zhan Xie Wu ◽  
Qing Hao Meng ◽  
Jing Hai Li ◽  
Shu Gen Ma
Keyword(s):  
Wind Speed ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Recurrence Plot ◽  
Sampling Frequency ◽  
Near Surface ◽  
Gas Leakage ◽  
Time Period ◽  
Characteristics Analysis ◽  
Quantification Analysis

The wind is the main factor to influence the propagation of gas in the atmosphere. Therefore, the wind signal obtained by anemometer will provide us valuable clues for searching gas leakage sources. In this paper, the Recurrence Plot (RP) and Recurrence Quantification Analysis (RQA) are applied to analyze the influence of recurrence characteristics of the wind speed time series under the condition of the same place, the same time period and with the sampling frequency of 1hz, 2hz, 4.2hz, 5hz, 8.3hz, 12.5hz and 16.7hz respectively. Research results show that when the sampling frequency is higher than 5hz, the trends of recurrence nature of different groups are basically unchanged. However, when the sampling frequency is set below 5hz, the original trend of recurrence nature is destroyed, because the recurrence characteristic curves obtained using different sampling frequencies appear cross or overlapping phenomena. The above results indicate that the anemometer will not be able to fully capture the detailed information in wind field when its sampling frequency is lower than 5hz. The recurrence characteristics analysis of the wind speed signals provides an important basis for the optimal selection of anemometer.

scholarly journals Evaluation of HRCLDAS and ERA5 Datasets for Near-Surface Wind over Hainan Island and South China Sea

Atmosphere ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 766
Author(s):  
Yi Jiang ◽  
Shuai Han ◽  
Chunxiang Shi ◽  
Tao Gao ◽  
Honghui Zhen ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
Surface Wind ◽  
Hainan Island ◽  
The South China Sea ◽  
Wind Data ◽  
The South ◽  
Near Surface ◽  
China Sea

Near-surface wind data are particularly important for Hainan Island and the South China Sea, and there is a wide range of wind data sources. A detailed understanding of the reliability of these datasets can help us to carry out related research. In this study, the hourly near-surface wind data from the High-Resolution China Meteorological Administration (CMA) Land Data Assimilation System (HRCLDAS) and the fifth-generation ECMWF atmospheric reanalysis data (ERA5) were evaluated by comparison with the ground automatic meteorological observation data for Hainan Island and the South China Sea. The results are as follows: (1) the HRCLDAS and ERA5 near-surface wind data trend was basically the same as the observation data trend, but there was a smaller bias, smaller root-mean-square errors, and higher correlation coefficients between the near-surface wind data from HRCLDAS and the observations; (2) the quality of HRCLDAS and ERA5 near-surface wind data was better over the islands of the South China Sea than over Hainan Island land. However, over the coastal areas of Hainan Island and island stations near Sansha, the quality of the HRCLDAS near-surface wind data was better than that of ERA5; (3) the quality of HRCLDAS near-surface wind data was better than that of ERA5 over different types of landforms. The deviation of ERA5 and HRCLDAS wind speed was the largest along the coast, and the quality of the ERA5 wind direction data was poorest over the mountains, whereas that of HRCLDAS was poorest over hilly areas; (4) the accuracy of HRCLDAS at all wind levels was higher than that of ERA5. ERA5 significantly overestimated low-grade winds and underestimated high-grade winds. The accuracy of HRCLDAS wind ratings over the islands of the South China Sea was significantly higher than that over Hainan Island land, especially for the higher wind ratings; and (5) in the typhoon process, the simulation of wind by HRCLDAS was closer to the observations, and its simulation of higher wind speeds was more accurate than the ERA5 simulations.

scholarly journals Thermal Characteristics of Breast Surface Temperature in Healthy Women

2021 ◽  
Vol 18 (3) ◽  
pp. 1097
Author(s):  
Anna Lubkowska ◽  
Monika Chudecka
Keyword(s):  
Mammary Gland ◽  
Temperature Distribution ◽  
Surface Temperature ◽  
Thermal Characteristics ◽  
The Body ◽  
Imaging Method ◽  
Infrared Thermal Imaging ◽  
Ir Camera ◽  
Entire Area ◽  
Healthy Women

Thermography is widely used in the medical field, including in the detection of breast disorders. The aim of the research was to characterize the range of breast surface temperature values, taking into account the entire area of the mammary gland and, independently, the nipple, in healthy women. An additional aim was to assess the symmetry of the breast temperature distribution (using an IR camera) and the correlation of temperatures with the content of adipose tissue. Thermograms were made for the right and left breasts, each time delineating the area of the entire breast and a separate area of the nipple, chest, and abdomen. Analyzing the intergroup differences in temperature of selected body areas (Tmean), it was shown that, in all cases, they were significantly higher in younger women. Statistical analysis showed no significant differences between breast and nipple temperatures in relation to the body sides. The highest temperatures within the mammary gland were recorded for the nipple area. The use of the high-resolution digital infrared thermal imaging method in early and screening preventive diagnoses of changes in the mammary gland requires individual interpretation of the results, taking into account the assessment of the physiological pattern of temperature distribution in both breasts.

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