scholarly journals Seasonality Analysis of Sentinel-1 and ALOS-2/PALSAR-2 Backscattered Power over Salar de Aguas Calientes Sur, Chile

2020 ◽  
Vol 12 (6) ◽  
pp. 941
Author(s):  
Analia Delsouc ◽  
Matías Barber ◽  
Audrey Gallaud ◽  
Francisco Grings ◽  
Paulina Vidal-Páez ◽  
...  
Keyword(s):  
Temporal Frequency ◽  
Weather Conditions ◽  
Seasonal Patterns ◽  
Austral Winter ◽  
Backscatter Coefficient ◽  
Backscattering Coefficient ◽  
Episodic Events ◽  
Salt Crust ◽  
Flooding Events ◽  
Surface Crust

Seasonal changes control the development of salt crust over the Salar de Aguas Calientes Sur located in Andes Highlands, Chile. Precipitations throughout the Altiplanic winter (December to March) and austral winter (June to September) caused ponds to enlarge and surface salt crusts to dissolve driving roughness and dielectric features of the salar surface change over time. A four-year time series backscattering coefficient analysis, obtained by Sentinel 1 and ALOS-2/PALSAR-2 with 10 m of spatial resolution, demonstrated the capability of microwaves to discriminate seasonal patterns illustrated in this paper. Both sensors showed to be sensitive to changes in the surface crust due to weather conditions. Backscattered power gradually increased during the driest months as the rough salt crusts develop and decreased rapidly due to precipitations or flooding events, which lead to a smoothing appearance to radar. The high temporal frequency of acquisition in Sentinel 1 (5–13 scenes/month) allowed the discrimination among climate and annual seasonality and episodic events in the C-band backscatter coefficient. On the other hand, ALOS-2/PALSAR-2 showed subsurface changes at L-band since the salinity of the brine in the soil reduces the penetration depth of backscattered power for shorter wavelengths. Results might be useful to monitor salars with geographic and weather conditions similar to Salar de Aguas Calientes Sur.

scholarly journals EPISODIC EVENTS ON RADAR AND MULTISPECTRAL REMOTE SENSORS FROM SALAR DE AGUAS CALIENTES, CHILE

2020 ◽  
Vol XLII-3/W12-2020 ◽  
pp. 297-301
Author(s):  
A. S. Delsouc ◽  
M. E. Barber ◽  
W. Perez-Martinez ◽  
I. Briceño-De-Urbaneja
Keyword(s):  
Environmental Changes ◽  
Global Climate ◽  
Weather Conditions ◽  
Austral Winter ◽  
Episodic Events ◽  
Radar Images ◽  
Episodic Event ◽  
Salt Pan ◽  
Flooding Events ◽  
Short Time

Abstract. Restricted episodic changes occurred in a short time period and over large spatial extents. Extreme weather conditions usually give rise to restricted episodic changes. Sentinel-1 radar images of the Salar de Aguas Calientes in Chile acquired in the Altiplanic winter (March 2015 and June 2017), 2018 austral winter and 2017–2018 springtime, demonstrates the ability to monitor episodic events remotely. The results of the backscattered power are encouraging and show episodic variations in VV polarization at C-band. The surface features in Salar de Aguas Calientes Sur change in response to snowfalls during either the Altiplanic or austral winter with an increase of the backscattering in presence of dry snow over the salt pan crust. Flooding events related to snow-melting during spring 2017–2018 showed a decrease in the backscattering signal over ponded water and an increase when wind blows over the water. Remote-sensing observations of the salar can provide a means for monitoring changes in the surface of the salar and a better understanding of the associated climatic episodic event processes. Furthermore, it can help to have a better understanding of environmental changes in arid regions and the understanding of global climate change.

scholarly journals Damages from extreme flooding events to cultural heritage and landscapes: water component estimation for Centa River (Albenga, Italy)

2018 ◽  
Vol 45 ◽  
pp. 389-395 ◽  
Author(s):  
Branka Cuca ◽  
Luigi Barazzetti
Keyword(s):  
River Estuary ◽  
Weather Conditions ◽  
Archaeological Site ◽  
Remote Access ◽  
Impact Monitoring ◽  
Medium Resolution ◽  
Ground Survey ◽  
Extreme Flooding ◽  
Flooded Area ◽  
Flooding Events

Abstract. The monitoring of hazardous events through change detection has an important role in the emergency management. Such actions can be performed shortly after the hazardous event for first rapid mapping but also over longer periods of time for recovery purposes and risk mapping. The use of medium resolution free-of-charge multi-spectral satellite imagery for purposes of flood extension and impact monitoring can be extremely valuable due to their ability to offer an “easy” and remote access to information, even in cases of extreme weather conditions, but also due to their high compatibility with GIS environments. The case study regards Centa River estuary that hosts an important archaeological site of Albenga within the boundaries of its riverbed. The authors propose a workflow that uses Copernicus Sentinel-2 data to provide the comparison changes firstly in the single relevant bands and successively in the indexes NDVI e NDWI, suitable for the estimation of water component. The results of this study were useful for observing the extension of the flooded area, to evaluate its impact on the archaeological remains and to further propose more targeted UAV-born and ground survey.

scholarly journals Timescales of emergence of chronic flooding in the major economic center of Guadeloupe

2021 ◽  
Vol 21 (2) ◽  
pp. 703-722
Author(s):  
Gonéri Le Cozannet ◽  
Déborah Idier ◽  
Marcello de Michele ◽  
Yoann Legendre ◽  
Manuel Moisan ◽  
...  
Keyword(s):  
Sea Level ◽  
Tide Gauge ◽  
Ground Motions ◽  
Weather Conditions ◽  
Coastal Zones ◽  
Tide Gauge Records ◽  
Sea Levels ◽  
Vertical Ground Motions ◽  
Vertical Ground ◽  
Flooding Events

Abstract. Sea-level rise due to anthropogenic climate change is projected not only to exacerbate extreme events such as cyclones and storms but also to cause more frequent chronic flooding occurring at high tides under calm weather conditions. Chronic flooding occasionally takes place today in the low-lying areas of the Petit Cul-de-sac marin (Guadeloupe, West Indies, French Antilles). This area includes critical industrial and harbor and major economic infrastructures for the islands. As sea level rises, concerns are growing regarding the possibility of repeated chronic flooding events, which would alter the operations at these critical coastal infrastructures without appropriate adaptation. Here, we use information on past and future sea levels, vertical ground motion, and tides to assess times of emergence of chronic flooding in the Petit Cul-de-sac marin. For RCP8.5 (Representative Concentration Pathway 8.5; i.e., continued growth of greenhouse gas emissions), the number of flood days is projected to increase rapidly after the emergence of the process so that coastal sites will be flooded 180 d a year within 2 decades of the onset of chronic flooding. For coastal locations with the lowest altitude, we show that the reconstructed number of floods is consistent with observations known from a previous survey. Vertical ground motions are a key source of uncertainty in our projections. Yet, our satellite interferometric synthetic-aperture radar results show that the local variability in this subsidence is smaller than the uncertainties in the technique, which we estimate to be between 1 (standard deviation of measurements) and 5 mm/yr (upper theoretical bound). Despite these uncertainties, our results imply that adaptation pathways considering a rapid increase in recurrent chronic flooding are required for the critical port and industrial and commercial center of Guadeloupe. Similar processes are expected to take place in many low-elevation coastal zones worldwide, including on other tropical islands. The method used in this study can be applied to other locations, provided tide gauge records and local knowledge of vertical ground motions are available. We argue that identifying times of emergence of chronic flooding events is urgently needed in most low-lying coastal areas, because adaptation requires decades to be implemented, whereas chronic flooding hazards can worsen drastically within years of the first event being observed.

scholarly journals International Charter Support during Major Flood Disasters in India

2014 ◽  
Vol XL-8 ◽  
pp. 1501-1505
Author(s):  
G. Srinivasa Rao ◽  
C. M. Bhatt ◽  
P. G. Diwaker
Keyword(s):  
Disaster Management ◽  
Satellite Data ◽  
Communication Systems ◽  
Satellite Images ◽  
Temporal Frequency ◽  
Weather Conditions ◽  
Satellite Observation ◽  
Jammu And Kashmir ◽  
Major Disaster ◽  
Multi Temporal

Earth observation (EO) satellites provide near real time, comprehensive, synoptic and multi-temporal coverage of inaccessible areas at frequent intervals, which is required support for a quick response and planning of emergency operations. Owing to their merits, satellite images have become an integral part of disaster management and are being extensively used globally for mapping, monitoring and damage assessment of extreme disaster events. During major disaster, information derived from satellite observation is not only highly useful, it may at times be indispensable because of the unfavourable weather conditions, collapse of communication systems and inaccessibility to the area. Satellite images help in identifying the location of the disaster, its severity and the extent. The International Charter "Space and Major Disasters" has been the major sources of satellite data, in times of catastrophic disasters, due to availability of data from large number of sensors (with 15 organisations as signatories), which can be planned with the required temporal frequency and spectral range to cover a disaster event. During last three years, International Charter has been activated regularly, during major disasters in India. Satellite data from different sensors is obtained and was used for improving the frequency of observations, and extracting detailed information. This is used during floods in Assam (2012), floods in Uttarakhand (2013), cyclone Phailin (2013) and floods in Jammu and Kashmir (2014). The present paper discusses the role of International Charter in effective flood disaster management in India during recent past.

scholarly journals Investigation of Aerosol Properties and Structures in Two Representative Meteorological Situations over the Vipava Valley Using Polarization Raman LiDAR

Atmosphere ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 128 ◽  
Author(s):  
Longlong Wang ◽  
Samo Stanič ◽  
William Eichinger ◽  
Griša Močnik ◽  
Luka Drinovec ◽  
...  
Keyword(s):  
Optical Properties ◽  
Hot Spot ◽  
Weather Conditions ◽  
Raman Lidar ◽  
Backscatter Coefficient ◽  
First Case ◽  
Lidar Ratio ◽  
Bora Wind ◽  
Aerosol Types ◽  
Aerosol Properties

Vipava valley in Slovenia is a representative hot-spot for complex mixtures of different aerosol types of both anthropogenic and natural origin. Aerosol loading distributions and optical properties were investigated using a two-wavelength polarization Raman LiDAR, which provided extinction coefficient, backscatter coefficient, depolarization ratio, backscatter Ångström exponent and LiDAR ratio profiles. Two different representative meteorological situations were investigated to explore the possibility of identifying aerosol types present in the valley. In the first case, we investigated the effect of strong downslope (Bora) wind on aerosol structures and characteristics. In addition to observing Kelvin–Helmholtz instability above the valley, at the height of the adjacent mountain ridge, we found new evidence for Bora-induced processes which inject soil dust aerosols into the free troposphere up to twice the height of the planetary boundary layer (PBL). In the second case, we investigated aerosol properties and distributions in stable weather conditions. From the observed stratified vertical aerosol structure and specific optical properties of different layers we identified predominant aerosol types in these layers.

scholarly journals Impact of elevation and weather patterns on the isotopic composition of precipitation in a tropical montane rainforest

2013 ◽  
Vol 17 (1) ◽  
pp. 409-419 ◽  
Author(s):  
D. Windhorst ◽  
T. Waltz ◽  
E. Timbe ◽  
H.-G. Frede ◽  
L. Breuer
Keyword(s):  
Temporal Variability ◽  
Cloud Forest ◽  
Weather Conditions ◽  
Trade Wind ◽  
Spatial And Temporal Variability ◽  
Austral Winter ◽  
Deuterium Excess ◽  
Altitude Effect ◽  
Trade Winds ◽  
Air Masses

Abstract. This study presents the spatial and temporal variability of δ18O and δ2H isotope signatures in precipitation of a south Ecuadorian montane cloud forest catchment (San Francisco catchment). From 2 September to 25 December 2010, event sampling of open rainfall was conducted along an altitudinal transect (1800 to 2800 m a.s.l.) to investigate possible effects of altitude and weather conditions on the isotope signature. The spatial variability is mainly affected by the altitude effect. The event based δ18O altitude effect for the study area averages −0.22‰ × 100 m−1 (δ2H: −1.12‰ × 100 m−1). The temporal variability is mostly controlled by prevailing air masses. Precipitation during the times of prevailing southeasterly trade winds is significantly enriched in heavy isotopes compared to precipitation during other weather conditions. In the study area, weather during austral winter is commonly controlled by southeasterly trade winds. Since the Amazon Basin contributes large amounts of recycled moisture to these air masses, trade wind-related precipitation is enriched in heavy isotopes. We used deuterium excess to further evaluate the contribution of recycled moisture to precipitation. Analogously to the δ18O and δ2H values, deuterium excess is significantly higher in trade wind-related precipitation. Consequently, it is assumed that evaporated moisture is responsible for high concentrations of heavy isotopes during austral winter.

scholarly journals Precipitation characteristics and associated weather conditions on the eastern slopes of the Canadian Rockies during March–April 2015

2018 ◽  
Vol 22 (8) ◽  
pp. 4491-4512 ◽  
Author(s):  
Julie M. Thériault ◽  
Ida Hung ◽  
Paul Vaquer ◽  
Ronald E. Stewart ◽  
John W. Pomeroy
Keyword(s):  
Doppler Radar ◽  
Water Cycle ◽  
Weather Conditions ◽  
Doppler Velocity ◽  
Canadian History ◽  
Critical Aspect ◽  
Air Masses ◽  
Precipitation Characteristics ◽  
Flooding Events ◽  
Precipitation Events

Abstract. Precipitation events that bring rain and snow to the Banff–Calgary area of Alberta are a critical aspect of the region's water cycle and can lead to major flooding events such as the June 2013 event that was the second most costly natural disaster in Canadian history. Because no special atmospheric-oriented observations of these events have been made, a field experiment was conducted in March and April 2015 in Kananaskis, Alberta, to begin to fill this gap. The goal was to characterize and better understand the formation of the precipitation at the surface during spring 2015 at a specific location in the Kananaskis Valley. Within the experiment, detailed measurements of precipitation and weather conditions were obtained, a vertically pointing Doppler radar was deployed and weather balloons were released. Although 17 precipitation events occurred, this period was associated with much less precipitation than normal (−35 %) and above-normal temperatures (2.5 ∘C). Of the 133 h of observed precipitation, solid precipitation occurred 71 % of the time, mixed precipitation occurred 9 % and rain occurred 20 %. An analysis of 17 504 precipitation particles from 1181 images showed that a wide variety of crystals and aggregates occurred and approximately 63 % showed signs of riming. This was largely independent of whether flows aloft were upslope (easterly) or downslope (westerly). In the often sub-saturated surface conditions, hydrometeors containing ice occurred at temperatures as high as 9 ∘C. Radar structures aloft were highly variable with reflectivity sometimes >30 dBZe and Doppler velocity up to −1 m s−1, which indicates upward motion of particles within ascending air masses. Precipitation was formed in this region within cloud fields sometimes having variable structures and within which supercooled water at least sometimes existed to produce accreted particles massive enough to reach the surface through the relatively dry sub-cloud region.

scholarly journals Seasonal Occurrence of Sympatric Blue Whale Subspecies: the Chilean and Southeast Indian Ocean Pygmy Blue Whales With the Antarctic Blue Whale

2021 ◽  
Vol 8 ◽  
Author(s):  
Gary Truong ◽  
Tracey L. Rogers
Keyword(s):  
Indian Ocean ◽  
Southern Hemisphere ◽  
Lower Latitude ◽  
Seasonal Patterns ◽  
Austral Winter ◽  
Blue Whale ◽  
Acoustic Data ◽  
The Pacific ◽  
The Antarctic ◽  
Blue Whales

There are multiple blue whale acoustic populations found across the Southern Hemisphere. The different subspecies of blue whales feed in separate areas, but during their migration to lower-latitude breeding areas each year, Antarctic blue whales become sympatric with pygmy and Chilean blue whales. Few studies have compared the degree of this overlap of the Southern Hemisphere blue whale subspecies across ocean basins during their migration. Using up to 16 years of acoustic data, this study compares the broad seasonal presence of Antarctic blue whales, Chilean blue whales, and Southeast Indian Ocean (SEIO) pygmy blue whales across the Pacific and Indian Oceans. Antarctic blue whales were sympatric with the other two blue whale subspecies during the migrating season of every year. Despite this overlap, Chilean and pygmy blue whale detections peaked earlier during the austral autumn (April–May) while Antarctic blue whale detections peaked later during the austral winter (June). Chilean (Pacific Ocean) and SEIO (Indian Ocean) pygmy blue whales showed similar seasonal patterns in detections despite occurring in different ocean basins. Though we have shown that Antarctic blue whales have the potential to encounter other blue whale subspecies during the breeding season, these distinct groups have remained acoustically stable through time. Further understanding of where these whales migrate will enable a better insight as to how these subspecies continue to remain separate.

scholarly journals Impact of elevation and weather patterns on the isotopic composition of precipitation in a tropical montane rainforest

2012 ◽  
Vol 9 (7) ◽  
pp. 8425-8453 ◽  
Author(s):  
D. Windhorst ◽  
T. Waltz ◽  
H.-G. Frede ◽  
L. Breuer
Keyword(s):  
Temporal Variability ◽  
Cloud Forest ◽  
Weather Conditions ◽  
Trade Wind ◽  
Spatial And Temporal Variability ◽  
Austral Winter ◽  
Deuterium Excess ◽  
Altitude Effect ◽  
Trade Winds ◽  
Air Masses

Abstract. This study presents the spatial and temporal variability of δ18O and δ2H isotope signatures in precipitation of a south Ecuadorian montane cloud forest catchment (San Francisco Catchment). From 2 September to 25 December 2010, event sampling of open rainfall was conducted along an altitudinal transect (1800 m a.s.l. to 2800 m a.s.l.) to investigate possible effects of altitude and weather conditions on the isotope signature. The spatial variability is mainly affected by the altitude effect. The event based δ18O altitude effect for the study area averages −0.22‰ × 100 m−1 (δ2H: −1.12‰ × 100 m−1). The temporal variability is mostly controlled by prevailing air masses. Precipitation during the times of prevailing southeasterly trade winds is significantly enriched in heavy isotopes compared to precipitation during other weather conditions. In the study area, weather during austral winter is commonly controlled by southeasterly trade winds. Since the Amazon Basin contributes large amounts of recycled moisture to these air masses, trade wind-related precipitation is enriched in heavy isotopes. We used deuterium excess to further evaluate the contribution of recycled moisture to precipitation. Analogously to the δ18O and δ2H values, deuterium excess is significantly higher in trade wind related precipitation. Consequently, it is assumed that evaporated moisture is responsible for high concentrations of heavy isotopes during austral winter.

scholarly journals Seasonal patterns of steppe landscapes functioning of the Karadag nature reserve

2021 ◽  
Vol 937 (4) ◽  
pp. 042089
Author(s):  
A Drygval ◽  
P Drygval ◽  
R Gorbunov ◽  
V Lapchenko
Keyword(s):  
Nature Reserve ◽  
Weather Conditions ◽  
Summer Season ◽  
Winter Period ◽  
Seasonal Patterns ◽  
Destruction Process ◽  
Parallel Processes ◽  
Methodical Approach ◽  
Diagnostic Signs ◽  
Is Development

Abstract The article is devoted to the study of steppe landscapes functioning of the Karadag nature reserve for the period of 6 years (2014-2019). The article uses a methodical approach to the assessment of intraday states of weather conditions to diagnose the nature of the steppe landscapes functioning. As results of the steppe landscapes functioning during the whole year the categories “development”, “destruction” both prerequisites and results of landscapes’ functioning, “accumulation” of prerequisites of landscapes development, and also mixed categories are distinguished. In general, the considered territory in the period from 2014 to 2019 is characterized by 85 variations of weather types. Considering of the steppe landscapes functioning in separate seasons, it is noted that, relatively alternating among them, in the winter period dominate the process of functioning prerequisites accumulation of steppe landscapes, and the process of prerequisites and results destruction of steppe landscapes functioning. The accumulation process is noted as the main result of steppe landscapes functioning in the spring season. It is dominant and fluctuates within 62.8 % and 96/8 % of the total number of functioning processes in steppe landscapes. The main result of functioning revealed in the summer season is development. It accounts for 63.2% (in 2014) to 99.9% (in 2015) of the diagnostic signs exhibited in steppe landscapes. In the autumn season the destruction process prevails, in a complex with parallel processes of various results of the steppe landscapes functioning.

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