scholarly journals Impact of MODIS sensor calibration updates on Greenland ice sheet surface reflectance and albedo trends

2017 ◽  
Author(s):  
Kimberly A. Casey ◽  
Chris M. Polashenski ◽  
Justin Chen ◽  
Marco Tedesco
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Sensor Calibration ◽  
Surface Reflectance ◽  
Product Analysis ◽  
Modis Data ◽  
Albedo Change ◽  
Wet Snow ◽  
Sensor Degradation ◽  
Lower Magnitude

Abstract. We evaluate Greenland Ice Sheet (GrIS) surface reflectance and albedo trends using the newly released Collection 6 (C6) MODIS products over the period 2001–2016. We find that the correction of MODIS sensor degradation provided in the new C6 data products reduces the magnitude of the surface reflectance and albedo decline trends obtained from previous MODIS data (i.e. Collection 5, C5). Collection 5 and 6 data product analysis over GrIS is characterized by surface (i.e. wet vs. dry) and elevation (i.e. 500 m–2000 m, 2000 m and greater) conditions over the summer season from June 1–August 31. Notably, the visible-wavelength declining reflectance trends identified in several bands MODIS C5 data from previous studies are only slightly detected, at reduced magnitude in the C6 versions over the dry snow zone. Wet snow albedo decline over the MODIS record remains in the C6 product, albeit at a lower magnitude than obtained using C5 data. Further analysis of C6 spectral reflectance trends show both reflectance increases and decreases in select bands and regions, suggesting that several competing processes are contributing to ice sheet albedo change. Investigators using MODIS data in other fields may consider similar re-examinations of trends previously established using C5 data.

scholarly journals Impact of MODIS sensor calibration updates on Greenland Ice Sheet surface reflectance and albedo trends

2017 ◽  
Vol 11 (4) ◽  
pp. 1781-1795 ◽  
Author(s):  
Kimberly A. Casey ◽  
Chris M. Polashenski ◽  
Justin Chen ◽  
Marco Tedesco
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Sensor Calibration ◽  
Surface Reflectance ◽  
Product Analysis ◽  
Modis Data ◽  
Wet Snow ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Sensor Degradation ◽  
Lower Magnitude

Abstract. We evaluate Greenland Ice Sheet (GrIS) surface reflectance and albedo trends using the newly released Collection 6 (C6) MODIS (Moderate Resolution Imaging Spectroradiometer) products over the period 2001–2016. We find that the correction of MODIS sensor degradation provided in the new C6 data products reduces the magnitude of the surface reflectance and albedo decline trends obtained from previous MODIS data (i.e., Collection 5, C5). Collection 5 and 6 data product analysis over GrIS is characterized by surface (i.e., wet vs. dry) and elevation (i.e., 500–2000 m, 2000 m and greater) conditions over the summer season from 1 June to 31 August. Notably, the visible-wavelength declining reflectance trends identified in several bands of MODIS C5 data from previous studies are only slightly detected at reduced magnitude in the C6 versions over the dry snow area. Declining albedo in the wet snow and ice area remains over the MODIS record in the C6 product, albeit at a lower magnitude than obtained using C5 data. Further analyses of C6 spectral reflectance trends show both reflectance increases and decreases in select bands and regions, suggesting that several competing processes are contributing to Greenland Ice Sheet albedo change. Investigators using MODIS data for other ocean, atmosphere and/or land analyses are urged to consider similar re-examinations of trends previously established using C5 data.

scholarly journals Discrimination of glacier facies using multi-temporal SAR data

1998 ◽  
Vol 44 (146) ◽  
pp. 42-53 ◽  
Author(s):  
K. C. Partington
Keyword(s):  
European Space Agency ◽  
Greenland Ice Sheet ◽  
Sensor Calibration ◽  
Lower Altitude ◽  
Mount Pinatubo ◽  
South Central ◽  
Space Agency ◽  
Wet Snow ◽  
Multi Temporal ◽  
Sar Data

AbstractGlacier facies from the Greenland ice sheet and the Wrangell-St Elias Mountains, Alaska, are analyzed using multi-temporal synthetic aperture radar (SAR) data from the European Space Agency ERS-1 satellite. Distinct zones and facies are visible in multi-temporal SAR data, including the dry-snow facies, the combined percolation and wet-snow facies, the ice facies, transient melt areas and moraine. In Greenland and south-central Alaska, very similar multi-temporal signatures are evident for the same facies, although these facies are found at lower altitude in West Greenland where the equilibrium line appears to be found at sea level at 71°30?N during the year analyzed (1992-93), probably because of the cooling effect of the eruption of Mount Pinatubo. In Greenland, both the percolation and dry-snow facies are excellent distributed targets for sensor calibration, with backscatter coefficients stable to within 0.2 dB. However, the percolation facies near the top of Mount Wrangell are more complex and less easily delineated than in Greenland, and at high altitude the glacier facies have a multi-temporal signature which depends sensitively on slope orientation.

scholarly journals Weekly gridded Aquarius L-band radiometer/scatterometer observations and salinity retrievals over the polar regions – Part 2: Initial product analysis

2014 ◽  
Vol 8 (3) ◽  
pp. 915-930 ◽  
Author(s):  
L. Brucker ◽  
E. P. Dinnat ◽  
L. S. Koenig
Keyword(s):  
Sea Ice ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Sea Surface Salinity ◽  
Product Analysis ◽  
Surface Salinity ◽  
Initial Product ◽  
Band Frequency ◽  
Freeze Thaw ◽  
L Band

Abstract. Following the development and availability of Aquarius weekly polar-gridded products, this study presents the spatial and temporal radiometer and scatterometer observations at L band (frequency ~1.4 GHz) over the cryosphere including the Greenland and Antarctic ice sheets, sea ice in both hemispheres, and over sub-Arctic land for monitoring the soil freeze/thaw state. We provide multiple examples of scientific applications for the L-band data over the cryosphere. For example, we show that over the Greenland Ice Sheet, the unusual 2012 melt event lead to an L-band brightness temperature (TB) sustained decrease of ~5 K at horizontal polarization. Over the Antarctic ice sheet, normalized radar cross section (NRCS) observations recorded during ascending and descending orbits are significantly different, highlighting the anisotropy of the ice cover. Over sub-Arctic land, both passive and active observations show distinct values depending on the soil physical state (freeze/thaw). Aquarius sea surface salinity (SSS) retrievals in the polar waters are also presented. SSS variations could serve as an indicator of fresh water input to the ocean from the cryosphere, however the presence of sea ice often contaminates the SSS retrievals, hindering the analysis. The weekly grided Aquarius L-band products used are distributed by the US Snow and Ice Data Center at http://nsidc.org/data/aquarius/index.html , and show potential for cryospheric studies.

Atmospheric Blocking Drives Recent Albedo Change Across the Western Greenland Ice Sheet Percolation Zone

2021 ◽  
Vol 48 (10) ◽  
Author(s):  
Gabriel Lewis ◽  
Erich Osterberg ◽  
Robert Hawley ◽  
Hans Peter Marshall ◽  
Tate Meehan ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Atmospheric Blocking ◽  
Albedo Change ◽  
Percolation Zone

Evaluation the MOD10A1 daily snow albedo product (v. 6) on Livingston Island, Antarctica

2020 ◽  
Author(s):  
Alejandro Corbea-Pérez ◽  
Javier Fernández-Calleja ◽  
Carmen Recondo ◽  
Susana Fernández
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Remote Sensing Data ◽  
Global Scale ◽  
Sensor Calibration ◽  
Satellite Measurements ◽  
Snow Albedo ◽  
Livingston Island ◽  
Increasing Trend

<p>One of the factors that can most influence climate changes on a global scale is the albedo decrease, associated with a temperature increase and a snow cover decrease, mainly in the polar areas, where the remote sensing data are essential because there is much difficulty access to obtain measurements in situ. Therefore, evaluations of satellite measurements are essential.</p><p>The daily MOD10A1 snow product provides daily measurements of albedo. Version 6 is currently available. In Antarctica, and more specifically on Livingston Island (South Shetland Archipelago), where one of the Spanish Antarctic bases is located, the daily snow albedo product of MODIS (MOD10A1) has been evaluated using version 5 data (Calleja et al. 2019). However, several authors have recommended updating the analyses based on version 6 data (Box et al. 2012, Casey et al. 2017), as they are more accurate.</p><p>In this work, we have analyzed the albedo behavior using MOD10A1 version 6 data between 2006 and 2015 and we have seen an increasing trend of albedo. Version 5 showed an increase of 0.07 per decade. However, version 6 data show less variability (0.04 per decade), and its results are closer to those obtained in the measurements in situ (0.03 per decade). In addition, the results obtained allow us to affirm that the MOD10A1 daily albedo product (v. 6) can be used to determine the albedo in the study area.</p><p>References:</p><p>Box, J. E., Fettweis, X., Stroeve, J. C., Tedesco, M., Hall, D. K., & Steffen, K. (2012). Greenland ice sheet albedo feedback: thermodynamics and atmospheric drivers. The Cryosphere, 6(4), 821-839.</p><p>Calleja, J. F., Corbea-Pérez, A., Fernández, S., Recondo, C., Peón, J., & de Pablo, M. Á. (2019). Snow Albedo Seasonality and Trend from MODIS Sensor and Ground Data at Johnsons Glacier, Livingston Island, Maritime Antarctica. Sensors, 19(16), 3569.</p><p>Casey, K. A., Polashenski, C. M., Chen, J., & Tedesco, M. (2017). Impact of MODIS sensor calibration updates on Greenland Ice Sheet surface reflectance and albedo trends. The Cryosphere, 11(4), 1781-1795.</p>

scholarly journals Satellite-derived surface type and melt area of the Greenland ice sheet using MODIS data from 2000 to 2005

2007 ◽  
Vol 46 ◽  
pp. 35-42 ◽  
Author(s):  
Robert S. Fausto ◽  
Christoph Mayer ◽  
Andreas P. Ahlstrøm
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Surface Type ◽  
Glacier Surface ◽  
Automated Algorithm ◽  
Wet Snow ◽  
Glacier Ice ◽  
Moderate Resolution ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
The Impact

AbstractA new surface classification algorithm for monitoring snow and ice masses based on data from the moderate-resolution imaging spectroradiometer (MODIS) is presented. The algorithm is applied to the Greenland ice sheet for the period 2000–05 and exploits the spectral variability of ice and snow reflectance to determine the surface classes dry snow, wet snow and glacier ice. The result is a monthly glacier surface type (GST) product on a 1 km resolution grid. The GST product is based on a grouped criteria technique with spectral thresholds and normalized indices for the classification on a pixel-by-pixel basis. The GST shows the changing surface classes, revealing the impact of climate variations on the Greenland ice sheet over time. The area of wet snow and glacier ice is combined into the glacier melt area (GMA) product. The GMA is analyzed in relation to the different surface classes in the GST product. The results are validated with data from weather stations and similar types of satellite-derived products. The validation shows that the automated algorithm successfully distinguishes between the different surface types, implying that the product is a promising indicator of climate change impact on the Greenland ice sheet.

scholarly journals Discrimination of glacier facies using multi-temporal SAR data

1998 ◽  
Vol 44 (146) ◽  
pp. 42-53 ◽  
Author(s):  
K. C. Partington
Keyword(s):  
European Space Agency ◽  
Greenland Ice Sheet ◽  
Sensor Calibration ◽  
Lower Altitude ◽  
Mount Pinatubo ◽  
South Central ◽  
Space Agency ◽  
Wet Snow ◽  
Multi Temporal ◽  
Sar Data

AbstractGlacier facies from the Greenland ice sheet and the Wrangell-St Elias Mountains, Alaska, are analyzed using multi-temporal synthetic aperture radar (SAR) data from the European Space Agency ERS-1 satellite. Distinct zones and facies are visible in multi-temporal SAR data, including the dry-snow facies, the combined percolation and wet-snow facies, the ice facies, transient melt areas and moraine. In Greenland and south-central Alaska, very similar multi-temporal signatures are evident for the same facies, although these facies are found at lower altitude in West Greenland where the equilibrium line appears to be found at sea level at 71°30?N during the year analyzed (1992-93), probably because of the cooling effect of the eruption of Mount Pinatubo. In Greenland, both the percolation and dry-snow facies are excellent distributed targets for sensor calibration, with backscatter coefficients stable to within 0.2 dB. However, the percolation facies near the top of Mount Wrangell are more complex and less easily delineated than in Greenland, and at high altitude the glacier facies have a multi-temporal signature which depends sensitively on slope orientation.

scholarly journals Greenland ice-sheet surface properties observed by the Seasat-A scatterometer at enhanced resolution

1994 ◽  
Vol 40 (135) ◽  
pp. 213-230 ◽  
Author(s):  
David G. Long ◽  
Mark R. Drinkwater
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Base Line ◽  
Near Surface ◽  
Scatter Coefficient ◽  
Ice Surface ◽  
Microwave Radar ◽  
Enhanced Resolution ◽  
Wet Snow ◽  
A New Technique

AbstractFor 3 months in 1978, the 14.6 GHz Seasat-A scatterometer (SASS) measured the normalized microwave-radar back-scatter coefficient of the Earth’s surface for the purpose of estimating near-surface vector winds over the ocean. SASS also made back-scatter measurements over land and ice regions; however, the application of this data has been limited due to the low (50 km) resolution of the measurements. Using a new technique for generating 6 km enhanced-resolution SASS images of the radar back-scatter characteristics, we present a study of the 1978 condition of the Greenland ice sheet. We derive a time-series of back-scatter images spanning the period July–September 1978. These images show the extent of summer ablation along the ice-sheet periphery. Using the data and models relating firn structure and condition to radar back-scatter characteristics, we delineate and map the seasonal extent of zones which appear to correspond to dry-snow, percolation, wet-snow, and ablation facies, over virtually the entire ice sheet. The results provide a base line with which to compare current (ERS-1) and future Greenland radar maps of snow-and ice-surface conditions.

scholarly journals Greenland ice-sheet surface properties observed by the Seasat-A scatterometer at enhanced resolution

1994 ◽  
Vol 40 (135) ◽  
pp. 213-230 ◽  
Author(s):  
David G. Long ◽  
Mark R. Drinkwater
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Base Line ◽  
Near Surface ◽  
Scatter Coefficient ◽  
Ice Surface ◽  
Microwave Radar ◽  
Enhanced Resolution ◽  
Wet Snow ◽  
A New Technique

AbstractFor 3 months in 1978, the 14.6 GHz Seasat-A scatterometer (SASS) measured the normalized microwave-radar back-scatter coefficient of the Earth’s surface for the purpose of estimating near-surface vector winds over the ocean. SASS also made back-scatter measurements over land and ice regions; however, the application of this data has been limited due to the low (50 km) resolution of the measurements. Using a new technique for generating 6 km enhanced-resolution SASS images of the radar back-scatter characteristics, we present a study of the 1978 condition of the Greenland ice sheet. We derive a time-series of back-scatter images spanning the period July–September 1978. These images show the extent of summer ablation along the ice-sheet periphery. Using the data and models relating firn structure and condition to radar back-scatter characteristics, we delineate and map the seasonal extent of zones which appear to correspond to dry-snow, percolation, wet-snow, and ablation facies, over virtually the entire ice sheet. The results provide a base line with which to compare current (ERS-1) and future Greenland radar maps of snow-and ice-surface conditions.

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