Runoff-induced vertical thermal dynamics in a canyon-shaped reservoir during the summer monsoon

2005 ◽  
Vol 56 (7) ◽  
pp. 959 ◽  
Author(s):  
Do-Seong Byun ◽  
Yang-Ki Cho ◽  
In-Ae Huh ◽  
Deirdre E. Hart
Keyword(s):  
Water Mass ◽  
Weather Conditions ◽  
Nutrient Concentrations ◽  
Fair Weather ◽  
Physical Processes ◽  
Surface Cooling ◽  
Vertical Temperature ◽  
Vertical Temperature Profile ◽  
Thermal Dynamics ◽  
Before And After

During the summer rainy season, double thermoclines were observed in a small canyon-shaped reservoir. The physical processes leading to thermocline evolution are examined from the vertical temperature profile observed along the reservoir before and after rain. Observations show that their evolution is related to the inflow of runoff, which is colder than the reservoir surface water and post-rain fair-weather conditions. Tongue-like distributions of turbidity, conductivity and nutrient concentrations downstream from the headwater clearly reveal the presence of runoff-induced intermediate inflows. In addition to supplying nutrients, the inflow provides the oxygen-deficient intermediate layer with a rich supply of dissolved oxygen. Concurrently, in the upper part of the reservoir runoff-induced inflows may drive the oxygen-deficient bottom water to shift downstream along the layer beneath the runoff-induced inflow. The water mass between the two thermoclines may operate as a source of nutrients for algal development in early autumn when the upper thermocline is destroyed by the convective overturn owing to the surface cooling.

scholarly journals MORPHODYNAMIC OF BEACH SCARPS ON A MACROTIDAL COAST DURING EXCEPTIONAL WATER LEVEL EVENTS (NORMANDY, FRANCE)

2012 ◽  
Vol 1 (33) ◽  
pp. 11
Author(s):  
Yoann Bonte ◽  
Franck Levoy
Keyword(s):  
Water Level ◽  
Conceptual Models ◽  
High Tide ◽  
Weather Conditions ◽  
Qualitative Description ◽  
Field Observations ◽  
Fair Weather ◽  
Physical Processes ◽  
Data Set ◽  
Local Conditions

Although there are numerous studies on the morphology and physical processes affecting the dune's scarp and many conceptual models describing beach scarps on microtidal and mesotidal environments (Sunamura, 1985a ; Short,1999), really quantitative informations about the beach scarp formation is lacking, especially along tidal environments where the tide controls the level of wave attack. However, Sherman and Nordstrom(1985) give a qualitative description of beach scarp formations and evolution based on field observations but without data set. The coast of Calvados (Normandy, France) is a fine example of a macrotidal coast, where beach scarps have been often observed. Along macrotidal beaches, the formation of a berm is classically observed during fair weather conditions which contribute to stabilize the coastline. During stormy conditions, the low atmosphere pressure, short waves and onshore winds cause an increase of the water level, which during spring tides, increases the high tide water level time action. Consequently, the natural berm protecting the dune foot, or sometimes a seawall foot, is threatened by erosion and often destroyed. The goal of this study is to quantify the beach scarp destruction (foot and crest scarp retreat speed, eroded volume...) in relation with the hydraulic and morphologic local conditions.

scholarly journals A Study of the Effects of Rain, Snow and Hail on the Atmospheric Electric Field near Ground

Atmosphere ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 996
Author(s):  
Athanasios Karagioras ◽  
Konstantinos Kourtidis
Keyword(s):  
Frequency Distribution ◽  
Complex Structure ◽  
Potential Gradient ◽  
Weather Conditions ◽  
The Other ◽  
Fair Weather ◽  
Northern Greece ◽  
Rain Events ◽  
The Impact ◽  
Bounce Back

The purpose of the present study is to investigate the impact of rain, snow and hail on potential gradient (PG), as observed in a period of ten years in Xanthi, northern Greece. An anticorrelation between PG and rainfall was observed for rain events that lasted several hours. When the precipitation rate was up to 2 mm/h, the decrease in PG was between 200 and 1300 V/m, in most cases being around 500 V/m. An event with rainfall rates up to 11 mm/h produced the largest drop in PG, of 2 kV/m. Shortly after rain, PG appeared to bounce back to somewhat higher values than the ones of fair-weather conditions. A decrease in mean hourly PG was observed, which was around 2–4 kV/m during the hail events which occurred concurrently with rain and from 0 to 3.5 kV/m for hail events with no rain. In the case of no drop, no concurrent drop in temperature was observed, while, for the other cases, it appeared that, for each degree drop in temperature, the drop in hourly mean PG was 1000 V/m; hence, we assume that the intensity of the hail event regulates the drop in PG. The frequency distribution of 1-minute PG exhibits a complex structure during hail events and extend from −18 to 11 kV/m, with most of the values in the negative range. During snow events, 1-minute PG exhibited rapid fluctuations between high positive and high negative values, its frequency distribution extending from −10 to 18 kV/m, with peaks at −10 and 3 kV/m.

scholarly journals Impact of the Kuroshio intrusion on the nutrient inventory in the upper northern South China Sea: insights from an isopycnal mixing model

2013 ◽  
Vol 10 (10) ◽  
pp. 6419-6432 ◽  
Author(s):  
C. Du ◽  
Z. Liu ◽  
M. Dai ◽  
S.-J. Kao ◽  
Z. Cao ◽  
...  
Keyword(s):  
South China Sea ◽  
Water Column ◽  
South China ◽  
Water Mass ◽  
Northern South China Sea ◽  
Mixing Model ◽  
Nutrient Concentrations ◽  
Kuroshio Intrusion ◽  
China Sea ◽  
The Kuroshio

Abstract. Based on four cruises covering a seasonal cycle in 2009–2011, we examined the impact of the Kuroshio intrusion, featured by extremely oligotrophic waters, on the nutrient inventory in the central northern South China Sea (NSCS). The nutrient inventory in the upper 100 m of the water column in the study area ranged from ∼200 to ∼290 mmol m−2 for N + N (nitrate plus nitrite), from ∼13 to ∼24 mmol m−2 for soluble reactive phosphate and from ∼210 to ∼430 mmol m−2 for silicic acid. The nutrient inventory showed a clear seasonal pattern with the highest value appearing in summer, while the N + N inventory in spring and winter had a reduction of ∼13 and ∼30%, respectively, relative to that in summer. To quantify the extent of the Kuroshio intrusion, an isopycnal mixing model was adopted to derive the proportional contribution of water masses from the SCS proper and the Kuroshio along individual isopycnal surfaces. The derived mixing ratio along the isopycnal plane was then employed to predict the genuine gradients of nutrients under the assumption of no biogeochemical alteration. These predicted nutrient concentrations, denoted as Nm, are solely determined by water mass mixing. Results showed that the nutrient inventory in the upper 100 m of the NSCS was overall negatively correlated to the Kuroshio water fraction, suggesting that the Kuroshio intrusion significantly influenced the nutrient distribution in the SCS and its seasonal variation. The difference between the observed nutrient concentrations and their corresponding Nm allowed us to further quantify the nutrient removal/addition associated with the biogeochemical processes on top of the water mass mixing. We revealed that the nutrients in the upper 100 m of the water column had a net consumption in both winter and spring but a net addition in fall.

scholarly journals Exploring the relation between aerosol optical depth and PM<sub>2.5</sub> at Cabauw, the Netherlands

2008 ◽  
Vol 8 (5) ◽  
pp. 17939-17986 ◽  
Author(s):  
M. Schaap ◽  
A. Apituley ◽  
R. M. A. Timmermans ◽  
R. B. A. Koelemeijer ◽  
G. de Leeuw
Keyword(s):  
The Netherlands ◽  
Ground Level ◽  
Weather Conditions ◽  
Fair Weather ◽  
Modis Aod ◽  
Data Points ◽  
Set Up ◽  
The Relationship ◽  
Lidar Observations ◽  
Pm2.5 Concentration

Abstract. To acquire daily estimates of PM2.5 distributions based on satellite data one depends critically on an established relation between AOD and ground level PM2.5. In this study we aimed to experimentally establish the AOD-PM2.5 relationship for the Netherlands. For that purpose an experiment was set-up at the AERONET site Cabauw. The average PM2.5 concentration during this ten month study was 18 μg/m3, which confirms that the Netherlands are characterised by a high PM burden. A first inspection of the AERONET level 1.5 (L1.5) AOD and PM2.5 data at Cabauw showed a low correlation between the two properties. However, after screening for cloud contamination in the AERONET L1.5 data, the correlation improved substantially. When also constraining the dataset to data points acquired around noon, the correlation between AOD and PM2.5 amounted to R2=0.6 for situations with fair weather. This indicates that AOD data contain information about the temporal evolution of PM2.5. We had used LIDAR observations to detect residual cloud contamination in the AERONET L1.5 data. Comparison of our cloud-screed L1.5 with AERONET L2 data that became available near the end of the study showed favorable agreement. The final relation found for Cabauw is PM2.5=124.5*AOD–0.34 (with PM2.5 in μg/m3) and is valid for fair weather conditions. The relationship determined between MODIS AOD and ground level PM2.5 at Cabauw is very similar to that based on the much larger dataset from the sun photometer data, after correcting for a systematic overestimation of the MODIS data of 0.05. We applied the relationship to a MODIS composite map to assess the PM2.5 distribution over the Netherlands. Spatial dependent systematic errors in the MODIS AOD, probably related to variability in surface reflectance, hamper a meaningful analysis of the spatial distribution of PM2.5 using AOD data at the scale of the Netherlands.

scholarly journals EFFECT OF DUST AEROSOL LAYER ON VERTICAL TEMPERATURE PROFILE

MAUSAM ◽  
2022 ◽  
Vol 53 (4) ◽  
pp. 539-542
Author(s):  
A. P. DIMRI ◽  
V. K. JAIN ◽  
B. B. DASH
Keyword(s):  
Temperature Profile ◽  
Dust Aerosol ◽  
Aerosol Layer ◽  
Vertical Temperature ◽  
Vertical Temperature Profile

scholarly journals Identification of solar radiation effect on climatic indicators of the territory of Ukraine

2018 ◽  
Keyword(s):  
Solar Radiation ◽  
Solar Energy ◽  
Air Temperature ◽  
Temperature Regime ◽  
Atmospheric Pressure ◽  
Weather Conditions ◽  
Climatic Conditions ◽  
Practical Significance ◽  
Statistical Dependence ◽  
Physical Processes

Formulation of the problem. Understanding that solar energy is the main source of the majority of biological, chemical and physical processes on Earth, investigation of its influence on different climatic fields allows us to define the features of its space and hour fluctuations. To define radiation and temperature regime of the territory it is necessary to determine climatic features of the spreading surface, which absorbs and will transform solar energy. Considering the fact that modern climatic changes and their consequences cover all components of the system, today there is a problem of their further study for comprehension of atmospheric processes, modeling weather conditions on different territories depending on the properties. The purpose of the article is to determine interrelations between indexes of solar radiation (the Wolf's number) and air temperature, atmospheric pressure on the territory of Ukraine during 1965-2015, their change in space and time. Methods. Correlative method is one of the main methods of a statistical analysis which allows us to receive correlation coefficients of solar radiation variability indexes, air temperature, atmospheric pressure on the territory of the research. This technique estimates the extent of solar radiation influence on temperature regime of the territory and distribution of atmospheric pressure. Results. Coefficients of correlation, which characterize variability of solar radiation indexes, air temperature and atmospheric pressure on the explored territory have been received by means of statistical correlation analysis method. This technique allows us to estimate the degree and nature of solar radiation influence on a temperature regime of the territory and distribution of atmospheric pressure. It has been defined that direct correlative connection between indexes of solar radiation is characteristic of air temperature and atmospheric pressure fields. Significant statistical dependence between incoming solar radiation on the territory of Ukraine and atmospheric pressure has been noted during the spring and autumn periods mainly at the majority of stations. Between indexes of solar radiation and air temperature the inverse correlative connection in winter will be transformed to a direct connection during the spring and summer periods. Scientific novelty and practical significance. Physical processes, which happen in the atmosphere, are characterized by complex interrelations. For further research it is important to define solar radiation value and the extent of influence on climatic conditions.

scholarly journals A Hydrodynamical Model for Calculating the Vertical Temperature Profile in Lakes During Cooling

1983 ◽  
Vol 14 (4) ◽  
pp. 239-254 ◽  
Author(s):  
Jörgen Sahlberg
Keyword(s):  
Heat Flux ◽  
Temperature Profile ◽  
Vertical Mixing ◽  
Hydrodynamical Model ◽  
Measured Temperature ◽  
Vertical Temperature ◽  
Mixing Rate ◽  
Mixing Processes ◽  
Vertical Temperature Profile ◽  
Radiation Fluxes

A one-dimensional hydrodynamical model is used for simulating the vertical temperature profile in a lake during cooling conditions. The vertical mixing rate is calculated by solving the equations for turbulent kinetic energy, k, and dissipation of energy, ε. The heat exchange between the water and atmosphere consists of the radiation fluxes, sensible and latent heat flux. Temperature measurements from Lake Väsman during November-December, 1981, were used in the verification study. The agreement between calculated and measured temperature profiles is very good. This indicates that both the mixing processes and the net heat flux are well described in the model.

scholarly journals Atmospheric electric field in the Atlantic marine boundary layer: first results from the SAIL project

2020 ◽  
Author(s):  
Susana Barbosa ◽  
Mauricio Camilo ◽  
Carlos Almeida ◽  
José Almeida ◽  
Guilherme Amaral ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Electric Field ◽  
Marine Boundary Layer ◽  
Weather Conditions ◽  
Cape Verde ◽  
The Other ◽  
Atmospheric Electric Field ◽  
Fair Weather ◽  
Near Surface ◽  
First Results

&lt;p&gt;&lt;span&gt;The study of the electrical properties of the atmospheric marine boundary layer is important as the effect of natural radioactivity in driving near surface ionisation is significantly reduced over the ocean, and the concentration of aerosols is also typically lower than over continental areas, allowing a clearer examination of space-atmosphere interactions. Furthermore, cloud cover over the ocean is dominated by low-level clouds and most of the atmospheric charge lies near the earth surface, at low altitude cloud tops. &lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;The relevance of electric field observations in the marine boundary layer is enhanced by the the fact that the electrical conductivity of the ocean air is clearly linked to global atmospheric pollution and aerosol content. The increase in aerosol pollution since the original observations made in the early 20th century by the survey ship Carnegie is a pressing and timely motivation for modern measurements of the atmospheric electric field in the marine boundary layer. Project SAIL (Space-Atmosphere-Ocean Interactions in the marine boundary Layer) addresses this challenge by means of an unique monitoring campaign on board the ship-rigged sailing ship NRP Sagres during its 2020 circumnavigation expedition. &lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;The Portuguese Navy ship NRP Sagres departed from Lisbon on January 5th in a journey around the globe that will take 371 days. Two identical field mill sensors (CS110, Campbell Scientific) are installed &lt;/span&gt;&lt;span&gt;o&lt;/span&gt;&lt;span&gt;n the mizzen mast, one at a height of 22 m, and the other at a height of 5 meters. &lt;/span&gt;&lt;span&gt;A visibility sensor (SWS050, Biral) was also set-up on the same mast in order to have measurements of the extinction coefficient of the atmosphere and assess fair-weather conditions.&lt;/span&gt;&lt;span&gt; Further observations include gamma radiation measured with a NaI(Tl) scintillator from 475 keV to 3 MeV, cosmic radiation up to 17 MeV, and atmospheric ionisation from a cluster ion counter (Airel). The&lt;/span&gt;&lt;span&gt; 1 Hz measurements of the atmospheric electric field&lt;/span&gt;&lt;span&gt; and from all the other sensors&lt;/span&gt;&lt;span&gt; are &lt;/span&gt;&lt;span&gt;linked to the same rigorous temporal reference frame and precise positioning through kinematic GNSS observations. &lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;Here the first results of the SAIL project will be presented, focusing on fair-weather electric field over the Atlantic. The observations obtained in the first three sections of the circumnavigation journey, including Lisbon (Portugal) - Tenerife (Spain), from 5 to 10 January, Tenerife - Praia (Cape Verde) from 13 to 19 January, and across the Atlantic from Cape Verde to Rio de Janeiro (Brasil), from January 22nd to February 14th, will be presented and discussed.&lt;/span&gt;&lt;/p&gt;

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