scholarly journals Snow-stratification investigation on an Antarctic ice stream with an X-band radar system

1991 ◽  
Vol 37 (127) ◽  
pp. 323-325 ◽  
Author(s):  
Richard R. Forster ◽  
Curt H. Davis ◽  
Timothy W. Rand ◽  
Richard K. Moore
Keyword(s):  
Remote Sensing ◽  
High Resolution ◽  
Microwave Remote Sensing ◽  
Snow Accumulation ◽  
Radar System ◽  
Accumulation Rates ◽  
X Band ◽  
Local Topography ◽  
Cw Radar ◽  
Insight Into

AbstractAn X-band FM-CW radar was used to determine the feasibility of observing annual snow-accumulation layers in Antarctica with a high-resolution inexpensive radar system. The formation of layering boundaries, their resultant electromagnetic discontinuity and their detection by reflected energy are presented. Large returns from depths corresponding to reasonable positions for annual layers were found. The average accumulation rates calculated from the radar returns agree with those measured in a previous pit study done in the same area. The detection of the annual accumulation layers with this system implies a simple, inexpensive mobile radar could be used to profile large areas allowing the distorting effects of local topography to be removed.This type of system with a concurrent pit study could provide insight into the effect of sub-surface strata on spaceborne or airborne microwave remote sensing.

scholarly journals Snow-stratification investigation on an Antarctic ice stream with an X-band radar system

1991 ◽  
Vol 37 (127) ◽  
pp. 323-325 ◽  
Author(s):  
Richard R. Forster ◽  
Curt H. Davis ◽  
Timothy W. Rand ◽  
Richard K. Moore
Keyword(s):  
Remote Sensing ◽  
High Resolution ◽  
Microwave Remote Sensing ◽  
Snow Accumulation ◽  
Radar System ◽  
Accumulation Rates ◽  
X Band ◽  
Local Topography ◽  
Cw Radar ◽  
Insight Into

AbstractAn X-band FM-CW radar was used to determine the feasibility of observing annual snow-accumulation layers in Antarctica with a high-resolution inexpensive radar system. The formation of layering boundaries, their resultant electromagnetic discontinuity and their detection by reflected energy are presented. Large returns from depths corresponding to reasonable positions for annual layers were found. The average accumulation rates calculated from the radar returns agree with those measured in a previous pit study done in the same area. The detection of the annual accumulation layers with this system implies a simple, inexpensive mobile radar could be used to profile large areas allowing the distorting effects of local topography to be removed.This type of system with a concurrent pit study could provide insight into the effect of sub-surface strata on spaceborne or airborne microwave remote sensing.

scholarly journals A representative density profile of the North Greenland snowpack

2016 ◽  
Vol 10 (5) ◽  
pp. 1991-2002 ◽  
Author(s):  
Christoph Florian Schaller ◽  
Johannes Freitag ◽  
Sepp Kipfstuhl ◽  
Thomas Laepple ◽  
Hans Christian Steen-Larsen ◽  
...  
Keyword(s):  
Remote Sensing ◽  
High Resolution ◽  
Density Profile ◽  
Accumulation Rate ◽  
Sampling Technique ◽  
Data Sets ◽  
Accumulation Rates ◽  
The North ◽  
North Greenland ◽  
Good Agreement

Abstract. Along a traverse through North Greenland in May 2015 we collected snow cores up to 2 m depth and analyzed their density and water isotopic composition. A new sampling technique and an adapted algorithm for comparing data sets from different sites and aligning stratigraphic features are presented. We find good agreement of the density layering in the snowpack over hundreds of kilometers, which allows the construction of a representative density profile. The results are supported by an empirical statistical density model, which is used to generate sets of random profiles and validate the applied methods. Furthermore we are able to calculate annual accumulation rates, align melt layers and observe isotopic temperatures in the area back to 2010. Distinct relations of δ18O with both accumulation rate and density are deduced. Inter alia the depths of the 2012 melt layers and high-resolution densities are provided for applications in remote sensing.

scholarly journals Cartographic Remote-Sensing Monitoring of Glaciological Systems (Example, Mount El‛ Brus, U.S.S.R.) (Abstract)

1987 ◽  
Vol 9 ◽  
pp. 247-248
Author(s):  
Yu. F. Knizhnikov ◽  
V.I. Kravtsova ◽  
I.A. Labutina
Keyword(s):  
Remote Sensing ◽  
High Resolution ◽  
Large Scale ◽  
Quantitative Information ◽  
Snow Accumulation ◽  
Aerial Photographs ◽  
Small Scale ◽  
Medium Scale ◽  
Remote Sensing Monitoring ◽  
Periglacial Zone

Remote-sensing methods in monitoring the glacierization of Mount EI‛ brus are used to produce base and dynamic maps, and to obtain quantitative information (dynamic indices) about the rate, intensity, and variations of the process. The monitoring system is divided, according to scope and territory covered, into small-scale for total glacierization and the periglacial zone, medium-scale for separate glaciers, and large-scale (detailed) for part of the glaciers or sectors of the adjoining slopes. The approximate relationship of even scales is 1 : 4. Small-scale monitoring remote-sensing systems are important for making maps showing the complex characteristics of the glaciological system. A series of maps was produced including geographical, those of high-altitude zones, slope and exposure angles, geological, glaciomorphological, climatic (temperature, precipitation, and winds), distribution of direct solar radiation, hydrological (source of streams), seats of avalanches, and landslides. All these data serve as a cartographical basis in monitoring the glacierization of Mount EI‛ brus. They are compiled from remotely sensed and Earth-based data. Current monitoring on a small scale includes observations of the conditions which determine the existence of the glacial system - this includes data on winter snowfall and the period of snow cover. These observations were obtained from meteorological and resource satellites, and from scanner data of medium and high resolution. Also important are observations of changes in the outline of glaciers, times of snowfall and character of the distribution of snow, and its redistribution due to avalanches and snowstorms. High-resolution space photographs, small-scale aerial photographs, and aerovisual observations provide the data for these observations. It has been determined that the area of the glaciers of Mount El‛ brus has been reduced by 1 % in the last 25 years, i.e. the rate of its deglacierization dropped sharply as compared to preceding decades. The role of quantitative information gains importance in the medium-scale level of monitoring. Topographical maps of separate glaciers compiled from aerial photographs or data from ground stereo-photogrammetric surveys constitute the base maps at this level. The main method used in monitoring were large-scale surveys from aircraft, perspective surveys from helicopters, and phototheodolite surveys. Multi-date surveys of the glaciers provide data about the changes in their outlines and height, the character of their relief, their moraines, the amount of snow accumulation and ablation in separate years, the surface rates of ice flow and their fluctuations. The techniques by which quantitative information is obtained about changes in the glaciers are derived from processing the data of multi-date surveys. The organization and techniques of phototheodolite surveys have been improved. A theory evolved for determining the surface-ice movement by stereo-photogrammetric means and the technique for it has also improved; algorithms and programs for machine processing of the data of multi-date surveys (ground and from aircraft) have been produced At this level of monitoring, it has been found that the retreat rate of most glaciers has slowed down and several glaciers are now in equilibrium. Several glaciers became active at the beginning of the 1970s and 1980s; this was accompanied by an increase in their height and forward movement. For example, activation of Kyukyurtlyu Glacier has been recorded (higher surface and increasing flow rate) which has caused the glacier to move forward 100 m. Surveys at an interval of 2 years recorded the beginning of the process of retreat of this glacier. Detailed monitoring is used to detect the mechanism of the dynamic processes and to study it on local representative sectors. On a glacier it may take the form of annual surveys of its tongue, which makes it possible to observe the processes of formation of moraines and glacio-fluvial relief. Studies may also be made of the mechanism of the movement of avalanches and landslides, deducing their quantitative characteristics and appraising the results of avalanches and landslides. Multi-date surveys of sectors of the slopes provide information about processes in the periglacial zone. At this level, regularly repeated ground stereo-photogrammetric surveys are the main means of observation. Glaciological remote-sensing monitoring provides a wealth of data for theoretical development in the field of glaciology. It makes it possible to forecast and produce warnings about hazardous processes and phenomena.

Development of a consistent soil moisture decadal data record from multiple satellites

2020 ◽  
Author(s):  
Steven Chan
Keyword(s):  
Remote Sensing ◽  
Soil Moisture ◽  
Microwave Radiometer ◽  
Microwave Remote Sensing ◽  
Precipitation Measurement ◽  
X Band ◽  
Data Record ◽  
System Data ◽  
Global Precipitation Measurement ◽  
Global Precipitation

<p>In recent decades, passive microwave remote sensing at lower frequencies (1-10 GHz) has become a primary means to routinely monitor soil moisture on a global scale. Despite the success of a number of L- and C/X-band radiometers independently developed and launched by various government agencies over the last two decades, there has not been a concerted effort to leverage the combined brightness temperature (T<sub>B</sub>) observations from these instruments to derive an integrated soil moisture data record within a consistent geophysical inversion framework. The availability of such a consistent data record would provide critical insights into the dynamics of surface hydrological processes, including anomaly detection, interannual variability, and monitoring of the onset and evolution of long-term spatial and temporal variability due to natural or anthropogenic changes in land surface conditions.</p><p>Recent advances in T<sub>B</sub> intercalibration on current and historical satellites have resulted in the availability of consistent T<sub>B</sub> observations that extend from years to decades. For passive microwave remote sensing of soil moisture, satellite intercalibration undertaken by the Global Precipitation Measurement (GPM) mission [1-2] has resulted in a decadal repository of intercalibrated T<sub>B</sub> observations at X-band (10.7 GHz) frequencies from GMI (2014-present), AMSR2 (2012-present), WindSat (2003-present), TMI (1997-2015) and AMSR-E (2002-2011). Likewise, recent studies on relative calibration by SMOS (2009-present) and SMAP (2015-present) teams have also enabled the production of a similar repository of intercalibrated T<sub>B</sub> observations for soil moisture estimation at L-band (1.41 GHz) frequencies [3]. When used as inputs to a common geophysical inversion model, these T<sub>B</sub> observations can be used for soil moisture estimation. Because consistency has been reinforced at the level of T<sub>B</sub> observations among satellites, the resulting record of soil moisture retrieval is expected to exhibit the same internal consistency. Together, therefore, these T<sub>B</sub> repositories provide the foundation for the development of current and historical consistent soil moisture data records with more frequent and wider coverage than any single satellite can achieve alone.</p><p>In this presentation, we will describe a NASA-funded initiative [4] (MEaSUREs: Making Earth System Data Records for use in Research Environments) to create a consistent soil moisture decadal data record from multiple satellites for terrestrial hydrological applications. Preliminary results, ancillary data preparation, product delivery schedule, and deliverables of this initiative will be discussed in this presentation.</p><p>References:</p><ol><li>Berg, W., S. Bilanow, R. Chen, S. Datta, D. Draper, H. Ebrahimi, S. Farrar, W. Jones, R. Kroodsma, D. McKague, V. Payne, J. Wang, T. Wilheit, and J. Yang. 2016. “Intercalibration of the GPM Microwave Radiometer Constellation,” J. Atmos. Oceanic Technol., 33, pp. 2639–2654, doi: 10.1175/JTECH-D-16-0100.1.</li> <li>Biswas, S. K., S. Farrar, K. Gopalan, A. Santos-Garcia, W. L. Jones and S. Bilanow. 2013. “Intercalibration of Microwave Radiometer Brightness Temperatures for the Global Precipitation Measurement Mission,” in IEEE Transactions on Geoscience and Remote Sensing, vol. 51, no. 3, pp. 1465–1477. doi: 10.1109/TGRS.2012.2217148.</li> <li>Bindlish, R., S. Chan, T. Jackson, A. Colliander, and Y. Kerr. 2018. “Integration of SMAP and SMOS Observations,” 2018 IEEE IGARSS, Valencia, Spain.</li> <li>"MEaSUREs: Making Earth System Data Records for Use in Research Environments," Accessed Nov 8, 2018. [Online]. Available: https://earthdata.nasa.gov/community/community-data-system-programs/measures-projects</li> </ol>

Atmospheric history of carbon monoxide since preindustrial times reconstructed from multiple Greenland ice cores

2021 ◽  
Author(s):  
Xavier Faïn ◽  
Rachael Rhodes ◽  
Philip Place ◽  
Vasilii Petrenko ◽  
Kévin Fourteau ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
High Resolution ◽  
Ice Core ◽  
Ice Cores ◽  
Snow Accumulation ◽  
Absolute Calibration ◽  
Chemical Compositions ◽  
Accumulation Rates ◽  
Mixing Ratios ◽  
Enhanced Absorption

<p>Carbon monoxide (CO) is a regulated pollutant and one of the key components determining the oxidizing capacity of the atmosphere. Obtaining a reliable record of atmospheric CO mixing ratios since pre-industrial times is necessary to evaluate climate-chemistry models in conditions different from today. We present high-resolution measurements of CO mixing ratios from ice cores drilled at five different sites on the Greenland ice sheet which experience a range of snow accumulation rates, mean surface temperatures, and different chemical compositions. An optical-feedback cavity-enhanced absorption spectrometer (OF-CEAS) was coupled to continuous melter systems and operated during four analytical campaigns conducted between 2013 and 2019. The CFA-based CO measurements exhibit excellent external precision (ranging 3.3 - 6.6 ppbv, 1σ), and achieve consistently low blanks (ranging from 4.1±1.2 to 12.6±4.4 ppbv). Good accuracy and absolute calibration of CFA-based CO records enable paleo-atmospheric interpretations. The five CO records all exhibit variability in CO mixing ratios that is too large and rapid to reflect past atmospheric mixing ratio changes. Complementary tests conducted on discrete ice samples demonstrate that such patterns are not related to the analytical process (i.e., production of CO from organics in the ice during melting), but very likely are related to in situ CO production within the ice before analyses. Evaluation of signal resolution and co-investigation of high-resolution records of CO and TOC show that past atmospheric CO concentration can be extracted from the records’ baselines at four sites with accumulation rates higher than 20 cm water equivalent per year (weq yr<sup>-1</sup>). However, such baselines should be taken as upper bounds of past atmospheric CO burden. CO records from four sites are combined to produce a multisite average ice core reconstruction of past atmospheric CO for the Northern Hemisphere high latitudes, covering the period from 1700 to 1957 CE. From 1700 to 1875 CE, this record reveals stable or slightly increasing values remaining in the 100-115 ppbv range. From 1875 to 1957 CE, the record indicates a monotonic increase from 114±4 ppbv to 147±6 ppbv. The ice-core multisite CO record exhibits an excellent overlap with the atmospheric CO record from Greenland firn air which span the 1950-2010 time period. The combined ice-core and firn air CO history, spanning 1700-2010 CE, largely exhibits patterns that are consistent with the recent anthropogenic and biomass burning CO emission inventories. This brand new time series will be compared with the most recent results from Earth System Models involved in the CMIP6-AerChemMIP multi-model exercise.</p>

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