Active-Layer Soil Moisture Content Regional Variations in Alaska and Russia by Ground-Based and Satellite-Based Methods, 2002 through 2014

Soil moisture is a vital physical parameter of the active-layer in permafrost environments, and associated biological and geophysical processes operative at the microscopic to hemispheric spatial scales and at hourly to multi-decadal time scales. While?in-situ?measurements can give the highest quality of information on a site-specific basis, the vast permafrost terrains of North America and Eurasia require space-based techniques for assessments of cause and effect and long-term changes and impacts from the changes of permafrost and the active-layer. Satellite-based 6.925 and 10.65 GHz sensor algorithmic retrievals of soil moisture by Advanced Microwave Scanning Radiometer-Earth Observation System (AMSR-E) onboard NASA-Aqua and follow-on AMSR2 onboard JAXA-Global Change Observation Mission—Water-1 are ongoing since July 2002. Accurate land-surface temperature and vegetation parameters are critical to the success of passive microwave algorithmic retrieval schemes. Strategically located soil moisture measurements are needed for spatial and temporal co-location evaluation and validation of the space-based algorithmic estimates. We compare on a daily basis ground-based (subsurface-probe) 50- and 70-MHz radio-frequency soil moisture measurements with NASA- and JAXA-algorithmic retrieval passive microwave retrievals. We find improvements in performance of the JAXA-algorithm (AMSR-E reprocessed and AMSR2 ongoing) relative to the earlier NASA-algorithm version. In the boreal forest regions, accurate land-surface temperatures and vegetation parameters are still needed for algorithmic retrieval success. Over the period of AMSR-E retrievals, we find evidence of at the high northern latitudes of growing terrestrial radio-frequency interference in the 10.65 GHz channel soil moisture content. This is an important error source for satellite-based active and passive microwave remote sensing soil moisture retrievals in Arctic regions that must be addressed.

Energy and mass changes of the Eurasian permafrost regions by multi-satellite and in-situ measurements

We investigate changes in total water equivalent mass, land-surface temperature and atmospheric CO2 by satellite-based measurements from August 2002 through December 2008. Our region of interest spans 75 to 165°E and 50 to 80oN centered on the Lena River watershed as a physical reference frame. We find energy and mass changes on the continuous and discontinuous permafrost zones indicating: 1) Arctic uplands such as the Siberian Plateau show strongly positive water equivalent mass and strongly negative land-surface temperature gradients during May months. 2) Arctic lowlands such as the thaw-lake regions of Kolyma, Lena Delta, and Taymyr show strongly negative water equivalent mass and strongly positive land-surface temperature gradients during September months. 3) Areas with strongly positive water equivalent mass and negative land-surface temperature gradients during May months have weakly positive CO2 gradients 4) Areas with strongly negative water equivalent mass and strongly positive land-surface temperature gradients during September months have strongly positive CO2 gradients. This indicates that continuous and discontinuous permafrost ecosystem responses are correlated in phase with energy and mass changes over the period. The Laptev and East Siberia Sea have increasing trends of CO2 atmosphere concentration 2.23 ± 0.15 ppm/yr and 2.40 ± 0.21 ppm/yr, respectively. Increasing trends and strong positive gradients of CO2atmosphere concentration during Aprils-Mays are evidence that the Arctic Ocean is a strong emitter of CO2 during springtime lead formation. We hypnotize that the increasing CO2 from land and ocean regions is from permafrost thawing and degradation and ecosystem microbial activity.

Multi-Satellite and Sensor Derived Trends and Variation of Snow Water Equivalent on the High-Latitudes of the Northern Hemisphere

Utilizing more than 30 years of satellite-microwave sensor derived snow water equivalent data on the high-latitudes of the northern hemisphere we investigate regional trends and variations relative to elevation. On the low-elevation tundra regions encircling the Arctic we find high statistically significant trends of snow water equivalent. Across the high Arctic Siberia and Far East Russia through North America and northern Greenland we find increasing trends of snow water equivalent with local region variations in strength. Yet across the high Arctic of western Russia through Norway we find decreasing trends of snow water equivalent of varying strength. Power density spectra identify significant power at quasi-biennial and associated lunar nodal cycles. These cycles of the upper atmosphere circulation, ENSO and ocean circulation perturbations from tides forms the causative linkage between increasing snow water equivalent on low-elevation tundra landscapes and decreasing coastal sea ice cover as part of the Arctic system energy and mass cycles.

L-Band InSAR Penetration Depth Experiment, North Slope Alaska

Since the first spacecraft-based synthetic aperture radar (SAR) mission NASA’s SEASAT in 1978 radars have been flown in Low Earth Orbit (LEO) by other national space agencies including the Canadian Space Agency, European Space Agency, India Space Research Organization and the Japanese Aerospace Exploration Agency. Improvements in electronics, miniaturization and production have allowed for the deployment of SAR systems on aircraft for usage in agriculture, hazards assessment, land-use management and planning, meteorology, oceanography and surveillance. LEO SAR systems still provide a range of needful and timely information on large and small-scale weather conditions like those found across the Arctic where ground-base weather radars currently provide limited coverage. For investigators of solid-earth deformation attention must be given to the atmosphere on Interferometric SAR (InSAR) by aircraft and spacecraft multi-pass operations. Because radar has the capability to penetrate earth materials at frequencies from the P- to X-band attention must be given to the frequency dependent penetration depth and volume scattering. This is the focus of our new research project: to test the penetration depth of L-band SAR/InSAR by aircraft and spacecraft systems at a test site in Arctic Alaska using multi-frequency analysis and progressive burial of radar mesh-reflectors at measured depths below tundra while monitoring environmental conditions. Knowledge of the L-band penetration depth on lowland Arctic tundra is necessary to constrain analysis of carbon mass balance and hazardous conditions arising from permafrost degradation and thaw, surface heave and subsidence and thermokarst formation at local and regional scales.

Remote Sensing, Model-Derived and Ground Measurements of Snow Water Equivalent and Snow Density in Alaska

Snow water equivalent (SWE) is important for investigations of annual to decadal-scale changes in Arctic environment and energy-water cycles. Passive microwave satellite-based retrieval algorithm estimates of SWE now span more than three decades. SWE retrievals by the Advanced Microwave Scanning Radiometer for the Earth Observation System (AMSR-E) onboard the NASA-Aqua satellite ended at October 2011. A critical parameter in the AMSR-E retrieval algorithm is snow density assumed from surveys in Canada and Russia from 1940s-1990s. We compare ground SWE measurements in Alaska to those of AMSR-E, European Space Agency GlobSnow, and GIPL model. AMSR-E SWE underperforms (is less than on average) ground SWE measurements in Alaska through 2011. Snow density measurements along the Alaska permafrost transect in April 2009 and 2010 show a significant latitude-gradient in snow density increasing to the Arctic coast at Prudhoe Bay. Large differences are apparent in comparisons of our measured mean snow densities on a same snow cover class basis March-April 2009-2011 Alaska to those measured in Alaska winter 1989-1992 and Canadian March-April 1961-1990. Snow density like other properties of snow is an indicator of climate and a non-stationary variable of SWE.

MODIS-Derived Nighttime Arctic Land-Surface Temperature Nascent Trends and Non-Stationary Changes

Arctic nighttime land-surface temperatures derived by the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors onboard the NASA Terra and Aqua satellites are investigated. We use the local equator crossing times of 22:30 and 01:30, respectively, in the analysis of changes, trends and variations on the Arctic region and within 120° sectors. We show increases in the number of days above 0°C and significant increase trends over their decadal periods of March 2000 through 2010 (MODIS Terra) and July 2002 through 2012 (MODIS Aqua). The MODIS Aqua nighttime Arctic land-surface temperature change, +0.2°C ± 0.2°C with P-value of 0.01 indicates a reduction relative to the MODIS Terra nighttime Arctic land-surface temperature change, +1.8°C ± 0.3°C with P-value of 0.01. This reduction is a decadal non-stationary component of the Arctic land-surface temperature changes. The reduction is greatest, -1.3°C ± 0.2°C with P-value of 0.01 in the Eastern Russia— Western North American sector of the Arctic during the July 2002 through 2012.

ICESat-Derived Elevation Changes on the Lena Delta and Laptev Sea, Siberia

We employ elevation data from the Ice, Cloud, and land Elevation Satellite (ICESat) Geoscience Laser Altimeter System (GLAS) to investigate surface changes across the Lena Delta and sea ice of the coastal Laptev Sea, Siberia during winters of 2003 through 2008. We compare ICESat GLAS-derived elevation changes on sea ice and the Bykovskaya and Sardakhskaya Channels with datum-corrected tide gauge height measurements from Danai, Sannikova and Tiksi stations. We find the coastal sea ice and large inland ice covered channels elevation changes are in phase with the tide-height changes on a same month-year and datum-controlled basis. Furthermore, we find elevation change on tundra drained lake basins to be +0.03 ± 0.02 m, on average. These findings indicate that ICESat GLAS is capable of detection of tide fluxes of ice covered coastal rivers, and with a small error range, it is suitable for investigations of active-layer and permafrost dynamics associated with seasonal freezing (heave) and thawing (subsidence) using repeat-location profiles.

Non-stationary drivers of polar sea ice area

From 2002 through 2008 the secular rate of de-creasing sea ice area in the northern hemisphere accelerated by a factor of 18, whereas the secular rate of increasing sea ice area in the southern hemisphere accelerated by a factor of 16, relative to the rates from 1978 through 2007. These were derived from the daily sea ice area retrieved from the Scanning Multi-channel Microwave Radiometer – Special Sensor Microwave/Imager and the Advanced Microwave Scan- ning Radiometer for the Earth Observation Sys- tem. The “annual” cycle of northern and southern sea ice areas, the number of days between maxima and minima is 372.4, on average, a frequency modulation, with a recurrence interval of 61.7 years. Significant spectral power occurs at the quasi-4-day through 120-day frequencies. The frequency content and modulation of the daily time series’ are consistent inter-monthly to inter-seasonal frequencies of solar irradiance, atmospheric-oceanic Rossby waves, length-of- day, and polar motion. This suggests conserva-tion of angular momentum of the atmosphere – sea-ice – ocean system. The near 60-year modu- lation and analysis of the detrended daily time series of the Arctic and Antarctic sea ice areas suggest the accelerations shown by the secular trends are relatively short-lived and reversible within an interval of one-quarter (15-years) to one-half (30-years) of the modulation period.

ICESat GLAS Elevation Changes and ALOS PALSAR InSAR Line-of-Sight Changes on the Continuous Permafrost Zone of the North Slope, Alaska

Measuring centimeter-scale and smaller surface changes by satellite-based systems on the periglacial terrains and permafrost zones of the northern hemisphere is an ongoing challenge. We are investigating this challenge by using data from the NASA Ice, Cloud, and land Elevation Satellite Geoscience Laser Altimeter System (ICESat GLAS) and the JAXA Advanced Land Observing Satellite Phased Array type L-band Synthetic Aperture Radar (ALOS PALSAR) on the continuous permafrost zone of the North Slope, Alaska. Using the ICESat GLAS exact-repeat profiles in the analysis of ALOS PALSAR InSAR Line-Of-Sight (LOS) changes, we find evidence of volume scattering over much of the tundra vegetation covered active-layer and surface scattering from river channel/banks (deposition and erosion), from rock outcropping bluffs and ridges. Pingos, ice-cored mounds common to permafrost terrains can be used as benchmarks for assessment of LOS changes. For successful InSAR processing, topographic and tropospheric phase cannot be assumed negligible and must be removed. The presence of significant troposphere phase in short-period repeat interferograms renders stacking ill suited for the task of deriving verifiable centimeter-scale surface deformation phase and reliable LOS changes.

GRACE, the Chandler Wobble and Interpretations of Terrestrial Water Transient Storage

Measuring Terrestrial Water Transient Storage in its various components of Earth by orbiting sensors on satellites has been a quest for more than 40 years. Not only in the Hydrology community but also Climatology and Meteorology, Geology, Geodesy, Geophysics and Oceanography have the challenge to attempt to first learn how to measure, then measure and assess the results. The importance is that Earth’s environments are changing and human communities, local and national governing bodies need ability to assess current hazards and to have predictive capabilities for society both local and international. So too the Gravity Recovery and Climate Experiment (GRACE) has joined the ongoing international space-based missions. There will be more after GRACE. For now is an important juncture in the effort to measure Terrestrial Water Transient Storage to ask, “What can GRACE measure and what is GRACE measuring”? Results of this investigation of the GRACE datasets by spectral methods indicate the detection of the Chandler Wobble but the Annual Wobble is aliased and below significance. Therefore, interpretations of Terrestrial Water Transient Storage are failed.

To Measure the Changing Relief of Arctic Rivers: A Synthetic Aperture RADAR Experiment in Alaska

This river crossing the lowland tundra-permafrost of the continuous permafrost zone of the Alaska North Slope can have extensive floodplain relief not simply created by channel migration during spring floods alone. Many of the rivers have channel-beds inherited from glacial landscapes and Holocene to present-day paraglacial and periglacial processes and mountain gradient sources [1] [2] [3] [4]. Interest is turning to understand effects from permafrost and ice wedge networks (ground ice) thaw, degradation and erosion and how such effects impact carbon and water equivalent mass balance. The 2015 flooding of the Sagavanirktok River crossing the Alaska North Slope brings this and additional impacts to-and-by human infrastructure into focus. Geodetic methods to measure centimeter to millimeter-scale changes using aircraft- and satellite-deployed Synthetic Aperture (SA) RAdio Detection And Ranging (RADAR) cannot ignore volume scattering. Backscatter and coherence at L-frequency and others possess both surface and volumetric scattering. On lowland tundra underlain by permafrost volume scattering dominants the RADAR backscatter coherence (the results of this work and [16]). Measurement of the L-frequency penetration depth for evaluation of mass change (carbon and water equivalent loss and transport) through permafrost and ground ice thaw-degradation with erosion is necessary. The Jet Propulsion Laboratory-National Aeronautical and Space Administration airborne Uninhabited Aerial Vehicle SAR (UAVSAR) L-frequency full quad-polarimetry cross-pole HHVV (polarization rotation, Horizontal to Vertical) confirms the dominance of volume scattering on lowland tundra (RADAR-soft targets) whereas surface scattering (HHHH or VVVV, no rotation) dominates on river channel deposits, rock outcrops and metal objects (RADAR-hard targets). Quantifying polarization rotation and the L-frequency penetration depth on lowland tundra are challenges for a new field validation and verification experiment.

Arctic Diurnal Land-Surface Temperature Range Changes Derived by NASA MODIS-Terra and -Aqua 2000 through 2012

The diurnal variation of surface temperature is a fundamental parameter as it is a driver of physical processes of atmosphere-land and -ocean energy and mass cycles playing a key role in meteorology and climatology. Our investigation focus is on the diurnal variation of land-surface temperature derived by the Moderate Resolution Imaging Spectroradiometer (MODIS) deployed on the NASA Terra and Aqua satellites. We key our investigation on the ascending and descending mode equator crossing times for daytime and nighttime land-surface temperature variations from March 2000 through 2010 (MODIS-Terra) and July 2002 through 2012 (MODIS-Aqua) and assess the diurnal land-surface temperature range changes at those sampling times. Our investigation shows non-stationary changes in the trends of land-surface temperature diurnal range. We identify changes in the diurnal range trends linked to increase of daytime and nighttime land-surface temperatures from March 2000 through 2010 and decrease in daytime and nighttime land-surface temperatures from July 2002 through 2012. The most recent decrease in daytime and nighttime land-surface temperatures and diurnal range will affect Arctic and other associated energy and mass cycles.

MODIS-Derived Arctic Land-Surface Temperature Trends

Across the Arctic changes in active layer, melting of glaciers and ground ice, thawing of permafrost and sequestration changes of carbon storage are driven in part by variations of land surface heat absorption, conduction and re-radiation relative to solar irradiance. We investigate Arctic land-surface temperature changes and regional variations derived by the MODIS sensors on NASA Aqua and Terra from March 2000 through July 2012. Over this decadal period we detect increase in the number of days with daytime land-surface temperature above 0℃. There are indications of increasing trends of land-surface temperature change. Regional variations of the changes in land-surface temperature likely arise due to surface material types and topography relative to the daytime variation of solar irradiance.

GOSAT CH₄and CO₂, MODIS Evapotranspiration on the Northern Hemisphere June and July 2009, 2010 and 2011

The Greenhouse gases Observing Satellite (GOSAT) affords an ability to assess and monitor CH4 and CO2 near-surface atmospheric concentrations globally on monthly scales pertaining to biogeochemical cycles and anthropogenic emissions. In addition to GOSAT our investigation incorporates global-monthly estimates of evapotranspiration (ET) from the Moderate Resolution Spectroradiometer (MODIS) and fire/wildfire locations for correspondence and comparison. We restrict the investigation to the months of June and July in years 2009, 2010 and 2011. After processing and assessment on the northern hemisphere we focus on two regions in Eurasia for interrogation: 40? to 80?E by 50? to 58?N and 100? to 140?E by 50? to 58?N. The regions allow for contrasting regional settings, an agricultural-industrial-urban west-region to a boreal-steppe discontinuous permafrost zone palsa and thaw lake east-region. Joint probability density functions allow us to identify significant modes, the highest probable values of background levels of CH4 and CO2 to ET and develop regressions for correlated relationships. We found that background levels of CH4, CO2 and ET were not affected by the wildfires of 2010. Regressions indicate significant inverse relationships of CH4 and CO2 to ET in the west-region and no significant relationships in the east-region. The east-region shows significantly higher background levels of CH4, CO2 and ET owing to the heterogeneity of ecosystems, hydrology, physical processes and terrain in the discontinuous permafrost zone of the central Siberian Plateau.