scholarly journals Grounding and calving cycle of Mertz Ice Tongue revealed by shallow Mertz Bank

2016 ◽  
Vol 10 (5) ◽  
pp. 2043-2056 ◽  
Author(s):  
Xianwei Wang ◽  
David M. Holland ◽  
Xiao Cheng ◽  
Peng Gong
Keyword(s):  
Remote Sensing ◽  
Flow Direction ◽  
Remote Sensing Data ◽  
Sea Surface ◽  
Seafloor Topography ◽  
Ice Flow ◽  
Air Content ◽  
Cyclic Variations ◽  
Cyclical Process ◽  
Height Data

Abstract. A recent study, using remote sensing, provided evidence that a seafloor shoal influenced the 2010 calving event of the Mertz Ice Tongue (MIT), by partially grounding the MIT several years earlier. In this paper, we start by proposing a method to calculate firn air content (FAC) around Mertz from seafloor-touching icebergs. Our calculations indicate the FAC around Mertz region as 4.87 ± 1.31 m. We then design an indirect method of using freeboard and sea surface height data extracted from ICESat/GLAS, FAC, and relatively accurate seafloor topography to detect grounding sections of the MIT between 2002 and 2008 and analyze the process of grounding prior to the calving event. By synthesizing remote sensing data, we point out that the grounding position was localized northeast of the Mertz ice front close to the Mertz Bank. The grounding outlines of the tongue caused by the Mertz Bank are extracted as well. From 2002 to 2008, the grounding area increased and the grounding became more pronounced. Additionally, the ice tongue could not effectively climb over the Mertz Bank in following the upstream ice flow direction and that is why MIT rotated clockwise after late 2002. Furthermore, we demonstrate that the area-increasing trend of the MIT changed little after calving (∼  36 km2 a−1), thus allowing us to use remote sensing to estimate the elapsed time until the MIT can reground on and be bent by the shoal. This period is approximately 70 years. Our observations suggest that the calving of the MIT is a cyclical process controlled by the presence of the shallow Mertz Bank location and the flow rate of the tongue. This calving cycle also explains the cyclic variations in sea-surface conditions around the Mertz detected by earlier studies.

scholarly journals Grounding and Calving Cycle of Mertz Ice Tongue Revealed by Shallow Mertz Bank

2016 ◽  
Author(s):  
Xianwei Wang ◽  
David M. Holland ◽  
Xiao Cheng ◽  
Peng Gong
Keyword(s):  
Remote Sensing ◽  
Flow Direction ◽  
Surface Condition ◽  
Remote Sensing Data ◽  
Seafloor Topography ◽  
Ice Flow ◽  
Air Content ◽  
Time Period ◽  
Level Data ◽  
Increasing Trend

Abstract. A recent study, using remote sensing, provided some evidence that a seafloor shoal influenced the 2010 calving event of the Mertz Ice Tongue (MIT), by partially grounding the MIT several years earlier. In this paper, we propose a method to calculate firn air content (FAC) around Mertz from seafloor-touching icebergs. Our calculations indicate the FAC around Mertz region as 4.87 ± 1.31 m. We design an indirect method of using freeboard and sea level data extracted from ICESat/GLAS, FAC, and highly accurate seafloor topography to detect grounding sections of the MIT between 2002 and 2008 and analyze the process of grounding before the calving. By synthesizing remote sensing data, we point out that the grounding position was just localized northeast of the Mertz ice front close to the Mertz Bank. The grounding outlines of the tongue caused by the Mertz Bank are extracted as well, however the length is only limited in several kilometers since late 2002. From 2002 to 2008, the grounding area increased and the grounding became more pronounced. Additionally, the ice tongue could not climb over the Mertz Bank in following the upstream ice flow direction and that is why MIT rotated clockwise after late 2002. Furthermore, we demonstrate that the area-increasing trend of the MIT changed little after calving (~36 km2/a), thus allowing us to use remote sensing to estimate the elapsed time until the MIT can reground on the shoal. This time period is approximately 70 years. The calving of MIT can be repeatable because of the shallow Mertz Bank and the calving cycle of the MIT explains the cycle of sea-surface condition change around Mertz. Keywords: Mertz Ice Tongue, Firn air content, iceberg grounding, Mertz Bank, iceberg scouring, calving cycle.

scholarly journals Remote radiological assessment in the marine environment: A pilot study based on Cs-137 measurements and satellite observations in the Aegean Sea

2019 ◽  
Vol 24 ◽  
pp. 191
Author(s):  
G. Mavrokefalou ◽  
H. Florou ◽  
O. Sykioti
Keyword(s):  
Remote Sensing ◽  
Real Time ◽  
Satellite Data ◽  
Sea Water ◽  
Remote Sensing Data ◽  
Aegean Sea ◽  
137Cs Activity ◽  
Sea Surface ◽  
Sensing Data ◽  
Activity Concentrations

A program concept has been developed to utilize sea parameters like sea surface temperature (SST), ocean colour (OC) and sea surface salinity (SSS), in order to explore their potential relations with 137Cs activity concentrations in sea water. These relations are expected to lead to the creation of an innovative tool based on remote sensing data and in real time 137Cs measurements, for the remote radioactivity detection of the Greek marine ecosystem both for routine control and emergency recordings. The presented results are a preliminary effort of the tool’s development. Remote sensing data have been acquired from MIRAS and MODIS instruments on-board ESA-SMOS and NASA-TERRA/AQUA satellites respectively. Satellite data comprise of SST and OC measurements. The ERL’s data of 137Cs activity concentrations (204 measurements) in seawater have been used for the period March 2012 to February 2015. Therefore, a) map analyses in a GIS including interpolation and integration of 83 real time measurements corrected with the effective half live of 7.2 y according to the monthly data of satelites and spatial linear regression have been implemented for the Aegean Sea, b) additional temporal analyses using linear and polynomial regression have been performed for the area of Souda- Crete, for which the most frequent measurements of 137Cs activity concentration in sea water have been measured in ERL. In this study, the first derived results on the correlation between SST measurements with 137Cs activity concentrations are presented, whereas the respective correlation with OC is being under invstigation. Further investigations include multivariate polynomial analyses into the Geographic Information System (GIS) platform with more extensive sampling and satellite data from new systems, whereas comparative correlations of 137Cs with seawater parameters derived by conventional means will be performed.

scholarly journals Does Social Distancing Have an Effect on Water Quality? : An Evidence from Chlorophyll-a Level in the Water of Populated Southeast Asian Coasts

2020 ◽  
Author(s):  
Andrio Adwibowo
Keyword(s):  
Remote Sensing ◽  
Water Quality ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Chlorophyll A ◽  
Anthropogenic Activities ◽  
Remote Sensing Data ◽  
Sea Surface ◽  
Nutrient Contents ◽  
Social Distancing

The COVID 19 related social distancing is hypothesized can affect the environmental quality including the air and water quality. Correspondingly, this study aims to study how the reduction of activities of people living near the rivers and the coastal areas due to social distancing may decrease the discharges of materials and nutrients to the water body. The chlorophyll-a was used as bio indicators of nutrient contents related to the anthropogenic activities in the coast. The study was conducted in the Jakarta coast considering that this coast was surrounded by populated cities with total population equal to 16 million people. The chlorophyll-a was measured in mg/m3 and monitored using remote sensing data from January to April 2020 representing the period before and after the implementation of social distancing. The determinant environmental factor measured was sea surface temperature (0C). The study considered that there were reductions of levels and areas of chlorophyll-a in the coast. The chlorophyll-a levels were reduced from January to April (p<0.05). The chlorophyll-a levels for January, February, March, and April were 7.36 mg/m3 (95%CI: 6.34-8.37), 7.90 mg/m3 (95%CI: 7.32-8.47), 6.52 mg/m3 (95%CI: 5.37-7.66), and 4.21 mg/m3 (95%CI: 3.34-5.07) respectively. However, the differences of chlorophyll-a were not influenced by the sea surface temperature factor (p>0.05). Based on remote sensing data in January and February, the sizes of coastal areas with chlorophyll-a levels >7.00 mg/m3 were larger than areas observed in March and April. Contrarily, the coastal area sizes with low chlorophyll-a levels <5.00 mg/m3 were increasing in April. To conclude the dynamic of anthropogenic activities in coastal setting is responsible and associated with the water quality and nutrient contents as indicated by chlorophyll-a levels.

scholarly journals Removing Striping Noise from Cloudy Level 2 Sea Surface Temperature and Ocean Color Datasets

2016 ◽  
Author(s):  
Brahim Boussidi ◽  
Ronan Fablet ◽  
Bertrand Chapron
Keyword(s):  
Remote Sensing ◽  
Wavelet Transform ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Ocean Color ◽  
Remote Sensing Data ◽  
Sea Surface ◽  
Discrete Wavelet ◽  
Sensing Data ◽  
Fourier Filtering

This paper introduces a new destriping algorithm for remote sensing data. The method is based on combined Haar Stationary Wavelet transform and Fourier filtering. State-of-the-Art methods based on the discrete wavelet transform (DWT) may not always be effective and may cause different artifacts. Our contribution is three-fold: i) we propose to use the Undecimated Wavelet transform (UWT) to avoid as much as possible shortcomings of the classical DWT; ii) we combine a spectral filtering and UWT using the simplest possible wavelet, the Haar basis, for a computational efficiency; iii) we handle 2D fields with missing data, as commonly observed in ocean remote sensing data due to atmospheric conditions (e.g., cloud contamination). The performances of the proposed filter are tested and validated on the suppression of horizontal strip artifacts in cloudy L2 Sea Surface Temperature (SST) and ocean color snapshots.

Sign in / Sign up

Export Citation Format

Share Document