Mohammed Shokr

• Environment Canada

Sea ice concentration (SIC) has been monitored with passive microwave (PM) observations for decades. Various techniques have been developed for its improvement. While techniques such as weather filters are commonly used, the necessity of combing radiative transfer model (RTM)-based atmospheric correction and dynamic tie points remains an open quest...

Arctic sea-ice surface temperature (IST) is an important environmental and climatic parameter. Currently, wide-swath sea-ice surface temperature products have a spatial resolution of approximately 1000 m. The Medium Resolution Spectral Imager (MERSI-I) offers a thermal infrared channel with a wide-swath width of 2900 km and a high spatial resolutio...

Retrieval of Thin-Ice Thickness (TIT) using thermodynamic modeling is sensitive to the parameterization of the independent variables (coded in the model) and the uncertainty of the measured input variables. This article examines the deviation of the classical model’s TIT output when using different parameterization schemes and the sensitivity of th...

The neutral form drag coefficient is an important parameter when estimating surface turbulent fluxes over Arctic sea ice. The form drag caused by surface features (𝑪) dominates the total drag in the winter, but long-term pan-Arctic records of 𝑪 are still lacking for Arctic sea ice. In this study, we first developed an improved surface feature detec...

The neutral form drag coefficient is an important parameter when estimating surface turbulent fluxes over Arctic sea ice. The form drag caused by surface features ( Cdn,fr) dominates the total drag in the winter, but long-term pan-Arctic records of Cdn,fr are still lacking for Arctic sea ice. In this study, we first developed an improved surface fe...

Leads are almost linear fractures within the ice pack, which are commonly observed in polar regions. In wintertime, leads promote energy flux from the underlying ocean to the atmosphere. Synthetic aperture radar (SAR) can monitor leads at a finer spatial resolution than other spaceborne datasets, regardless of solar illumination and atmospheric con...

The current climate change episode has impacted sea ice in the 2 polar regions differently. In the Arctic, remarkable sea ice extent and thickness declines have been observed with a stunning depletion rate of old ice. No similar changes have been observed in the Antarctic. In this paper, the question posed in the title is addressed by reviewing fin...

Based on the polar polynya-related 1,677 publications derived from the Web of Science from 1980 to 2021, this study analyses the scientific performance of polar polynya research with respect to publication outputs, scientific categories, journals, productive countries and partnerships, co-cited references, bibliographic documents and the thermal tr...

Arctic sea ice type (SITY) variation is a sensitive indicator of climate change. However, systematic inter-comparison and analysis for SITY products are lacking. This study analysed eight daily SITY products from five retrieval approaches covering the winters of 1999–2019, including purely radiometer-based (C3S-SITY), scatterometer-based (KNMI-SITY...

Polar sea ice is one of the Earth's climate components that has been significantly affected by the recent trend of global warming. While the sea ice area in the Arctic has been decreasing at a rate of about 4 % per decade, the multi-year ice (MYI), also called perennial ice, is decreasing at a faster rate of 10 %–15 % per decade. On the other hand,...

Fully polarimetric (FP) and compact polarimetry (CP) modes are advanced technologies of synthetic aperture radar (SAR). Compared to the parameters available from traditional orthogonal backscatter coefficients, these technologies offer extra parameters, called polarimetric parameters, that fully characterizes the polarization status and the phase s...

The North Water Polynya (NOW) is the largest recurrent Arctic coastal polynya. The formation of the NOW is critically dependent on the development of an ice arch that defines its northern boundary. In this study, high‐resolution ENVISAT Advanced Synthetic Aperture Radar data, Sentinel‐1A data, and Moderate Resolution Imaging Spectroradiometer data...

Arctic sea ice, especially the multiyear ice (MYI), is decreasing rapidly, partly due to melting triggered by global warming, in turn partly due to the possible acceleration of ice export from the Arctic Ocean to southern latitudes through identifiable gates. In this study, MYI and total sea ice areal flux through six Arctic gateways over the winte...

Sea ice cover plays an important role in modulating local temperature through heat and moisture fluxes. The influence of thin ice, lead and polynya has been well investigated, however, the effect of perennial ice (also called multiyear ice, MYI) has not. This study is motivated by it and investigated a hypothesis that changes in MYI concentration i...

Arctic sea ice type (SIT) variation is a sensitive indicator of climate change. However, systematic inter-comparison and analysis for SIT products are lacking. This study analyzed nine SIT products from five SIT retrieval approaches covering the winters from 1999 to 2018. These SIT products were inter-compared towards sea ice age product and evalua...

Sea ice motion is an essential parameter when determining sea ice deformation, regional advection, and the outflow of ice from the Arctic Ocean. The Robeson Channel, which is located between Ellesmere Island and northwest Greenland, is a narrow but crucial channel for ice outflow. Only three Eulerian sea ice motion products derived from ocean/sea i...

Fully polarimetric (FP) SAR systems offer parameters that describe and quantify the scattering mechanisms from the surface cover. These are usually derived from decomposition of matrices derived from the original scattering matrix from observations at each pixel. Power from scattering mechanisms have potential for retrieval of sea ice information,...

As a result of global warming, multiyear ice (MYI) is being replaced by first-year ice (FYI) in the Arctic. Microwave scatterometers in the Ku-band and C-band can provide daily observations of sea ice type. However, their comparative capabilities in mapping ice type have not been thoroughly evaluated. We present a systematic intercomparison of the...

In this paper, the performance of C-band synthetic aperture radar (SAR) Gaofen-3 (GF-3) quad-polarization Stripmap (QPS) data is assessed for classifying late spring and summer sea ice types. The investigation is based on 18 scenes of GF-3 QPS data acquired in the Arctic Ocean in 2017. In this study, floe ice (FI), brash ice (BI) between floes and...

Synthetic aperture radar (SAR) is a valuable tool for lake ice monitoring. The recently proposed SAR configuration for Earth observation called compact polarimetric (CP) SAR could be a good compromised choice between conventional (single or dual) and fully polarimetric (FP) SAR for operational ice applications, including lake ice. Given its enhance...

Compact Polarimetric (CP) Synthetic Aperture Radar (SAR) is expected to gain more and more ground for Earth observation applications in the coming years. This comes in light of the recently launched RADARSAT Constellation Mission (RCM), which uniquely provides CP SAR imagery in operational mode. In this study, we present observations about the sens...

The Northwest Passage (NWP) in the Arctic is usually covered with hazardous multi-year ice (MYI) and seasonal first-year ice (FYI) in winter, with possible thin ice and open-water areas during transition seasons. Ice classification is important for both marine navigation and climate change studies. Satellite-based Synthetic Aperture Radar (SAR) sys...

Accurate and high-resolution sea ice surface temperature (IST) data is of great importance for Arctic climate studies. However, the validation of high-resolution IST data using in situ measurements in polar sea ice regions is lacking. This study assesses the accuracy of three split-window (SW) and two single-channel (SC) methods, based on Landsat 8...

This study examines links between two sets of parameters obtained from Radarsat-2 Quad-pol data and geophysical information of lake ice and landfast sea ice in the Resolute Bay area, Nunavut, Canada. The first set includes the three orthogonal backscatter coefficients (σhh⁰, σvv⁰, σvh⁰) in addition to the total backscatter power (SPAN). The second...

Landfast ice is an important component of the Antarctic sea ice regime. It affects the Antarctic climate and ecological system. In this study, the first high-resolution, long time series of the landfast ice edge from 2006 to 2011 and 2016 to 2017 is presented. The dataset was produced based on the improved net gradient difference algorithm using 24...

Antarctic polynyas play an important role in regional atmosphere-ice-ocean interactions and are considered to help generate the global deep ocean conveyer belt. Polynyas therefore have a potential impact on the Earth’s climate in terms of the production of sea ice and high-salinity shelf water. In this study, we investigated the relationship betwee...

Abstract. Sea ice has been monitored in terms of concentration and types with microwave satellite observations since the late 1970s. However, it remains an open question as to which sea ice type concentration (SITC) method is most appropriate for ice type distribution and hence climate monitoring. This paper presents key results of inter-comparison...

The temporal and spatial variability of the Antarctic coastline is a clear indicator of change in extent and mass balance of ice sheets and shelves. In this study, the Canny edge detector was utilized to automatically extract high-resolution information of the Antarctic coastline for 2005, 2010, and 2017, based on optical and microwave satellite da...

Mapping landfast sea ice at a fine spatial scale is not only meaningful for geophysical study, but is also of benefit for providing information about human activities upon it. The combination of unmanned aerial systems (UAS) with structure from motion (SfM) methods have already revolutionized the current close-range Earth observation paradigm. To t...

Landfast ice is an important component of the Antarctic sea ice. Its edge generally advances offshore to its annual maximum extent by mid-winter before retreating later in spring. This study presents an automated method to detect the seaward landfast ice edge (SLIE) at its maximum extent in the beginning in the austral spring (October) for a region...

We analyzed the evolution processes of two tabular icebergs, C28A and C28B, originating from iceberg C28, using continuous multisource radar remote sensing data. The monitoring began during the calving of iceberg C28 from the Mertz Ice Tongue in February 2010 and ended in April 2012. The evolution of the iceberg area was determined from ENVISAT ASA...

In this study, sea ice thickness (SIT) and sea ice extent (SIE) in the Bohai Sea from 2000 to 2016 were investigated. A surface heat balance equation was applied to calculate SIT using ice surface temperatures estimated from the Moderate Resolution Imaging Spectroradiometer (MODIS) data with input from air temperature and wind speed from reanalyzin...

Sea ice adversely impacts nautical, logistical and scientific missions in polar regions. Ship navigation benefits from up-to-date sea ice analyses at both regional and local scales. This study presents a satellite-based sea ice navigation system (SatSINS) that integrates observations and scientific output from remote sensing and meteorological data...

Antarctic tabular icebergs are important active components in the ice sheet-ice shelf-ocean system. Seafloor topography is the key factor that affects the drifting and grounding of icebergs, but it has not been fully investigated. This study analyzes the impact of seafloor topography on the drifting and grounding of Antarctic tabular icebergs using...

Ground cover classification is one of the core applications in remote sensing. Classification of imaging radar data using conventional single-channel or dual-channel usually results in poor accuracy due to limited number of observations. For this reason, applications of full polarimetric data are growing. In this article, Radarsat-2 quad-pol data o...

Multiyear ice (MYI) concentration can be retrieved from passive or active microwave remote sensing observations. One of the algorithms that combines both observations is the Environmental Canada Ice Concentration Extractor (ECICE). However, factors such as ridging, snow wetness and metamorphism can cause significant changes in brightness temperatur...

Multiyear ice (MYI) characteristics can be retrieved from passive or active microwave remote sensing observations. One of the algorithms that combine both observations to identify partial concentrations of ice types (including MYI) is the Environment Canada Ice Concentration Extractor (ECICE). However, cycles of warm-cold air temperature trigger we...

Tidal cracks are linear features that appear parallel to coastlines in fast ice regions due to the actions of periodic and non-periodic sea level oscillations. They can influence energy and heat exchange between the ocean, ice, and atmosphere, as well as human activities. In this paper, the LINE module of Geomatics 2015 software was used to automat...

Multiyear ice (MYI) characteristics can be retrieved from passive or active microwave remote sensing observations. One of the algorithms that combine both observations to identify partial concentrations of ice types (including MYI) is the Environment Canada's Ice Concentration Extractor (ECICE). However, cycles of warm-cold air temperature trigger...

Sea ice concentration has been retrieved in polar regions with satellite microwave radiometers for over 30 years. However, the question remains as to what is an optimal sea ice concentration retrieval method for climate monitoring. This paper presents some of the key results of an extensive algorithm inter-comparison and evaluation experiment. The...

Sea ice concentration (SIC) has been derived globally from satellite passive microwave observations since the 1970s by a multitude of algorithms. However, existing datasets and algorithms, although agreeing in the large-scale picture, differ substantially in the details and have disadvantages in summer and fall due to presence of melt ponds and thi...

Sea ice concentration has been measured globally with satellite microwave radiome-ters for over 30 years. However there is still a need for better understanding of corresponding challenges and consequently identifying an optimal method for sea ice concentration retrieval suitable for climate monitoring. The method should minimize inter-5 sensor cal...

Fulfilling the broader impact of a research project in Earth and environmental sciences is an excellent opportunity for educational and outreach activities that connect scientists and society and enhance students and community engagement in STEM fields in general and in Earth, space, and environmental sciences in particular. Here we present the exp...

Aerosols are indicators of air quality as they reduce visibility and adversely affect public health. Aerosol optical depth (AOD) is a measure of the radiation extinction due to interaction of radiation with aerosol particles in the atmosphere. Using this optical measure of atmospheric aerosols we explore the seasonal and annual patterns of aerosols...

RÉSUMÉ Pour décrire certaines caractéristiques générales de formation de chenaux dans le bassin Arctique et déterminer les phénomènes extrêmes de formation de chenaux, on a animé le relevé sur dix ans, de 1987 à aujourd'hui, des images de températures de luminance SSM/I à 85,5 GHz. On a étudié en détail deux phénomènes particuliers, en se fondant s...

One of the potential applications of polarimetric Synthetic Aperture Radar (SAR) data is the classification of land cover, such as forest canopies, vegetation, sea ice types, and urban areas. In contrast to single or dual polarized SAR systems, full polarimetric SAR systems provide more information about the physical and geometrical properties of t...

The recently observed reduction in perennial ice in the Arctic has given rise to a corresponding increase in seasonal ice, which includes young ice (YI). This type of ice has a major impact on the weather and climate systems. However, only a limited number of studies have been dedicated to explore its spatial coverage and duration. This is mainly d...

The Environment Canada's Ice Concentration Extractor (ECICE) combines observations from several different satellite sensors to resolve heterogeneous components of a given footprint. To validate the algorithm and demonstrate its applicability, results are presented from combining the enhanced AMSR-E 36.5 GHz passive microwave data with dual-polariza...

The spectral signatures of natural objects in the visible and near-infrared spectral range are influenced by the object’s physical and biochemical properties. These signatures can be compiled in a database and used to retrieve information of land cover types and their physical composition from actual hyperspectral observations. This paper describes...

Ice concentration retrieved from spaceborne passive microwave observations is a prime input to operational sea ice monitoring programs, numerical weather prediction and global climate models. However, it is usually underestimated by existing algorithms due to surface conditions, especially in case of young ice types. Evaluation of those algorithms...

A wide variety of earth observation (EO) satellites with a broad range of sensors have become recently available and provided an enormous data volume for many applications. So far, the EO community in Egypt has not used the data to their full potential. A need to expand the utilization of the data and modernize applications has been identified by m...

A new algorithm has been developed to compile a database of radiometric measurements acquired by remote sensors from different surfaces that coexist in heterogeneous areas. An application is presented to compile a backscatter database of ice types during the freeze-up season in the Canadian Eastern Arctic using the operational visual analysis of RA...

Simulated sea ice was grown in an outdoor tank during the early winter seasons of 2001/2002 and 2005/2006. Microwave radiation was sampled every 5 min from the following three channels: 19, 37, and 85 GHz. Surface physical conditions were measured or observed to help in the interpretation of the radiometric behavior. This paper reports on results r...

A new algorithm, called Environment Canada's Ice Concentration Extractor (ECICE), has been developed to calculate total ice concentration and partial concentration of each ice type from remote-sensing observations. It employs two new concepts. First, it obtains a best estimate of ice concentrations by minimizing the sum of squared difference betwee...

The history of satellite remote sensing applications is not so recent, and there have been numerous national activities and international initiatives to promote the use of these applications for managing disasters of natural or manmade causes. Space-based remote sensing is carried out by means of both passive and active sensors onboard polar and ge...

A new algorithm has been developed to calculate sea ice concentration from any set of passive microwave observations. It was applied to estimate total ice concentration and partial concentration of three ice types using SSM/I 85 GHz observations. The essence of the algorithm is a mathematical optimization technique to determine the best solution fr...

Ice concentration retrieved from spaceborne passive-microwave observations is a prime input to operational sea-ice-monitoring programs, numerical weather prediction models, and global climate models. Atmospheric Environment Service (AES)-York and the Enhanced National Aeronautics and Space Administration Team (NT2) are two algorithms that calculate...

A three-dimensional variational data assimilation (3D-Var) system is developed as a first attempt to explore the potential use of data assimilation to improve a coupled ice-ocean model (CIOM) forecast of sea ice near the east coast of Canada. The accuracy of the resulting analysis is largely dependent upon the forecast-error covariance matrix. This...

The sea ice concentration from the enhanced NASA Team (NT2) algorithm was evaluated against coincident Radarsat images. The evaluation uses a new data fusion technique accounting for the sensor's antenna pattern. Evaluation can be performed visually or statistically. This study involves cases from the Gulf of St. Lawrence, Canada during the winter...

An important use of remote sensing data fusion is in retrieval of surface parameters form multisensor data. This requires using collocated observations from a least two sensors at pixel level. A method of multisensor data collocation has been developed to overlay each footprint form a coarse-resolution sensor onto a coincident finer resolution imag...

Sea ice in Canadian waters is monitored through an operational program conducted by Environment Canada. The program uses several remote sensing data sources and outputs a daily ice chart which is disseminated to marine users. The chart contains information on operational sea ice parameters; namely ice type, thickness, mechanical strength and surfac...

The North Water Polynya (NOW) is the largest and perhaps most active polynya in the Arctic region. A study of sea ice distribution and surface properties was conducted using multi sensor satellite remote sensing data in conjunction with surface measurements during an expedition in April/May 1998. The study utilized a data fusion technique which co-...

In response to the growing demand for a visual capability to display and assimilate very large volumes of remote sensing data, a very fast browsing and animation system has been developed. The system can browse very large images (order of a few gigabyte) and animate through thousands of images in a very fast mode to support educational and decision...

A new tool for remote sensing data fusion has been developed. The footprint which corresponds to a single pixel from a coarse-resolution sensor is defined using the geographic information in the data as well as the radiometric characteristics of the sensor. It is then overlaid on a background image acquired from a fine-resolution sensor. The single...

Radiometric observations from SSM/I 85 GHz and AVHRR infrared channels were co-located at pixel level. Ice surface temperature was calculated under cloud-free conditions from the AVHRR IR channels. The physical temperature of the radiation layer was calculated using a simplified form of the radiative transfer equation. The thickness of young ice ty...

The complex dielectric constant of first-year and multiyear sea ice was measured during the Seasonal Ice Monitoring and Modeling (SIMMS) field experiments, conducted in the Arctic in the spring of 1992, 1993, and 1995. The dielectric constant was also computed based on an established dielectric mixing model by using different assumptions about incl...

Quantitative integration of remote sensing data requires accurate co-location of pixels between data from different sensors. A technique has been developed, based on a simple spherical Earth model, to map ground resolution cells pertaining to pixel/grid points in a coarse-resolution sensor into an image acquired by a fine-resolution sensor. Pixels...

Quantitative integration of remote sensing data requires accurate co-location of pixels between data from different sensors. A technique has been developed, based on a simple spherical Earth model, to map ground resolution cells pertaining to pixel/grid points in a coarse-resolution sensor into an image acquired by a fine-resolution sensor. Pixels...

ERS-1 SAR images have been used to monitor sea ice in the Canadian east coast and the Gulf of St. Lawrence since December 1992. Operational ice parameters were obtained, in near real-time, through visual image analysis. The information was incorporated in standard daily operational products. Further analysis was conducted later to evaluate the data...

In this work we examine the seasonal co-evolution of: the microwave scattering coefficient (σ°) as observed with ERS-l; the radiative components of the surface energy balance; and the physical and electrical properties of the snow/ sea-ice system. We conduct three sets of hypothesis tests designed to illuminate specific aspects of this co-evolution...

The first field experiment in the 5 year seasonal Sea Ice Monitoring Site (SIMS) program was conducted in Resolute Passage, Canadian Eastern Arctic, between 15 May and 8 June 1990. This period signals the early melt season of sea ice in that region. A standard array of ice and snow measurements was collected on a daily basis from first-year and mul...

Sea ice microstructure characteristics relevant to ice microwave scattering were studied during SIMMS'91 field experiment in Resolute Bay in May/June 1991. Thin sections of the top 300 mm layer of first-year ice (from hummocks and melt ponds) were prepared and examined. Analysis is based mostly on qualitative observations, although statistics on bu...

The first field experiment in the 5 year seasonal Sea Ice Monitoring Site (SIMS) program was conducted in Resolute Passage, Canadian Eastern Arctic, between 15 May and 8June 1990. This period signals the early melt season of sea ice in that region. A standard array of ice and snow measurements was collected On a daily basis from first-year and mult...

Imagery data from three different SAR systems were used in this study. Five conventional texture parameters, derived from the gray level co-occurrence matrix (GLCM), were examined. Two of them were modified to ensure their invariant character under linear gray tone transformations. Results indicated that all parameters were highly correlated. The p...

Automated sea-ice classification from radar images has been identified as one of the prime goals of future sea-ice monitoring programs. The performance of any image-classification scheme depends on the image parameters selected to characterize the existing classes. Therefore a search for parameters that promise strong interpretation capabilities fo...

Automated sea-ice classification from radar images has been identified as one of the prime goals of future sea-ice monitoring programs. The performance of any image classification scheme, supervised or unsupervised, depends on the set of image properties chosen to characterize the existing classes. Therefore, further understanding of those properti...

Wind-tunnel simulations of neutrally-stable atmospheric boundary-layer flow over an isolated, low hill (Askervein) have been carried out at three different length scales in two wind-tunnel facilities. The objectives of these simulations were to assess the reliability with which changes in mean wind and turbulence structure induced by the prototype...