Simon KraatzUnited States Department of Agriculture | USDA · Agricultural Research Service (ARS)
Simon Kraatz
Ph.D.
Remote sensing of vegetation and soil properties
About
56
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620
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Introduction
Skills and Expertise
Publications
Publications (56)
Global forests are increasingly threatened by disturbance events such as wildfire. Spaceborne Synthetic Aperture Radar (SAR) missions at L‐ (or P‐) band, such as the upcoming NASA ISRO SAR (NISAR), have great potential to advance global mapping of above‐ground biomass (AGB). AGB mapping with SAR is challenging due to lack of available L‐ or P‐ band...
Cropland mapping is important for monitoring agricultural practices, cropland distribution and for supporting food security programs. Radar remote sensing will likely provide a means of cropland mapping, which can be efficient, accurate, and globally applied. Algorithms used for spaceborne radar cropland mapping are still undergoing calibration and...
Tsunamis, such as the 2004 Indian and 2011 Japan tsunamis, routinely cause severe
damage along coasts. Coastal vegetation serves as an excellent, naturally occurring
protection from tsunamis. However, prior studies of focusing on the wave attenuation
by vegetation assumed that solitary waves would adequately represent the major
aspects of tsunamis....
Coral reefs are abundant in tropical and subtropical coastal regions. Besides their important role to ecosystems, coral reefs also act as natural buffers that help protect coastal regions from impacts of extreme surge and waves, such as those generated during hurricanes and tsunamis. Recent studies revealed that the bottom of coral reef has very si...
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Many coastal countries are concerned with sustainable energy generation to meet their current and future energy needs. Tidal energy is an attractive resource as in-stream turbines can generate electricity even at moderate flow velocities. However, not all coastal areas are equally well-suited for tidal energy development. The survey of potential lo...
Accurate knowledge of the distribution, breadth and change in agricultural activity is important to food security and the related trade and policy mechanisms. Routine observations afforded by spaceborne Synthetic Aperture Radar (SAR) allows for high-fidelity monitoring of agricultural parameters at the field scale. Here we evaluate the approach to...
The extreme surges and waves generated in tsunamis can cause devastating damages to coastal infrastructures and threaten the intactness of coastal communities. After the 2004 Indian Ocean tsunami, extensive physical experiments and numerical simulations have been conducted to understand the wave attenuation of tsunami waves due to coastal forests....
Extreme waves, such as freak waves or rogue waves, occur unexpectedly in the ocean and have extremely large wave heights. Extreme waves often are attributed to the process of wave focusing. Coastal structures such as bridges are highly susceptible to extreme waves and have caused substantial damage to coastal infrastructure in the past. Although im...
Crop area mapping is important for tracking agricultural production and supporting food security. Spaceborne approaches using synthetic aperture radar (SAR) now allow for mapping crop area at moderate spatial and temporal resolutions. Multi-frequency SAR data is highly useful for crop monitoring because backscatter response from vegetation canopies...
Vegetation optical depth (VOD) retrieved from microwave radiometry correlates with the total amount of water in vegetation, based on theoretical and
empirical evidence. Because the total amount of water in vegetation varies with relative water content (as well as with biomass), this correlation
further suggests a possible relationship between VOD a...
Abstract Synthetic Aperture Radar (SAR) data are well‐suited for change detection over agricultural fields, owing to high spatiotemporal resolution and sensitivity to soil and vegetation. The goal of this work is to evaluate the science algorithm for the NASA ISRO SAR (NISAR) Cropland Area product using data collected by NASA's airborne Uninhabited...
Planned satellite launches will provide open access and operational L-band radar data streams at space-time resolutions not previously available. To further prepare, the Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) platform was used to observe cropland sites across the southern United States to support the development of L-band (24...
Vegetation optical depth (VOD) retrieved from microwave radiometry correlates with the total amount of water in vegetation, based on theoretical and empirical evidence. Because the total amount of water in vegetation varies with relative water content (as well as with biomass), this correlation further suggests a possible relationship between VOD a...
Soil moisture dynamics in the presence of dense vegetation canopies are determinants of ecosystem function and biogeochemical cycles, but the capability of existing spaceborne sensors to support reliable and useful estimates is not known. New results from a recently initiated field experiment in the northeast United States show that the National Ae...
In Summer/Fall 2019, the UAVSAR platform was used to collect dense time series over several agricultural and biomass sites in the southeastern US. This data is to be used for developing ecosystem science algorithms for the upcoming NASA-ISRO SAR (NISAR) mission. Development and testing of these algorithms require routine SAR processing steps such a...
Coastal bridges are vulnerable to extreme surges and waves during tsunamis and hurricanes. Many of them have been significantly damaged or destroyed during past extreme weather events, such as Hurricane Katrina in 2005. Although extensive experimental work and numerical simulations have been carried out focusing on identifying the damage mechanisms...
Coastal bridges are vulnerable to extreme surges and waves generated during hurricanes and tsunamis. Over the past few decades, extensive research works were conducted to study the damage mechanisms of coastal bridges under the impact of extreme surges and waves. However, these research efforts mainly focused on the hydrodynamic characteristics inv...
The U.S. encompasses over 4 million roadway miles, with about half of them located in seasonal frost areas. Roads are especially susceptible to damage when the subsurface is saturated with water (i.e., spring thaw). Spring load restrictions (SLR) are important for maintaining the integrity of roads. Routine determinations of road freeze–thaw (FT) s...
Extreme ocean surface waves generated during hurricanes or tsunamis can cause severe damage to coastal communities and infrastructures, especially coastal bridges. In this paper, installation of floating breakwater is proposed to protect coastal bridge decks against strong ocean surface waves. As an environmental-friendly wave-reduction device, flo...
Seasonal freeze-thaw (FT) affects over half the northern hemisphere and impacts many key processes of the Earth System such as energy exchange, hydrology and vegetation. Nearly all past studies using spaceborne FT retrievals have focused on characterizing FT specifically for natural environments. FT in the built environment is also routinely studie...
The seasonal cycle of freeze/thaw (FT) has a significant impact on surface and subsurface water fluxes and pathways, heat fluxes, soil–atmosphere fluxes of trace gases and carbon budget. The onset of FT transition periods is emerging as a critical area of study in natural landscapes. In parallel, FT studies in the built environment are underway in...
Human‐induced landscape changes affect hydrologic responses (e.g., floods) that can be detected from a suite of satellite and model data sets. Tapping these vast data sets using machine learning algorithms can produce critically important and accurate insights. In the Red River of the North Basin in the United States, agricultural subsurface draina...
Accurate identification of soil freeze or thaw (FT) is important for road management, because it greatly affects a road’s load bearing capacity. Despite low-volume roads (LVR) being more susceptible to damage because of FT transitions compared with high-volume roadways, relatively few LVRs are monitored via temperature data probes (TDP). Frequent a...
To balance the competing interests of minimizing road damage while maximizing economic opportunities on low-volume roadways located in seasonal frost areas, road management agencies typically apply spring load restrictions (SLR). The Alaska Department of Transportation and Public Facilities (ADOT&PF) uses an observational approach to determine SLR,...
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Submarine pipelines have been extensively used for marine oil and gas extraction due to their high efficiency, safety, and low price. However, submarine pipelines are vulnerable to extreme waves (i.e., tsunami waves). Previous research has often used solitary waves as a basis for studying the impacts of tsunami waves on submarine pipelines, althoug...
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Submarine pipelines have been extensively used for marine oil and gas extraction due to their high efficiency, safety, and low price. However, submarine pipelines are vulnerable to extreme waves (i.e., tsunami waves). Previous research has often used solitary waves as a basis for studying the impacts of tsunami waves on submarine pipelines, although...
Seasonal freeze and thaw impact a road's ability to bear loads. Temperature index models are one of the methods being used to manage seasonal weight restrictions on roads. Many of these methods are limited to specific regions in which they have been calibrated and more universally applicable models are sought. We conducted a multi-year study of roa...
Seasonal freeze-thaw (FT) impacts much of the northern hemisphere and is an important control on its water, energy, and carbon cycle. Although FT in natural environments extends south of 45°N, FT studies using the L-band have so far been restricted to boreal or greater latitudes. This study addresses this gap by applying a seasonal threshold algori...
Low volume roads are highly susceptible to damage from trafficking during mid-winter- and spring-thaws. To minimize damage, road management agencies typically apply Seasonal Load Restrictions (SLRs), which restrict allowable loads on thaw-weakened pavements. Although SLR methods vary widely, mathematical models that incorporate indirect measurement...
Spatially detailed characterization of the distribution, amounts and timing of river ice is important for identifying and predicting potential ice hazards. Although information on ice cover over inland water bodies is provided within the VIIRS and MODIS snow products, this information has little practical value for river ice monitoring. First, rive...
The capability of frequently and accurately monitoring ice on rivers is important, since it may be possible to timely identify ice accumulations corresponding to ice jams. Ice jams are dam-like structures formed from arrested ice floes, and may cause rapid flooding. To inform on this potential hazard, the CREST River Ice Observing System (CRIOS) pr...
Solitary waves have been commonly used as an initial condition in the experimental and numerical modelling of tsunamis for decades. However, the main component of a tsunami waves acts at completely different spatial and temporal scales than solitary waves. Thus, use of solitary waves as approximation of a tsunami wave may not yield realistic model...
Spatially detailed characterization of the distribution, amount and timing of river ice is important for identifying and predicting potential ice hazards. Although information on the ice cover over inland water bodies is provided within MODIS snow products (MOD10 and MYD10), this information has little practical value for river ice monitoring. Firs...
The first and a crucial step in development of tidal power, which is now attracting more and more attention worldwide, is a reliable survey of temporal and spatial distribution of tidal energy along coastlines. This paper first reviews the advance in assessment of tidal energy, in particular marine hydrokinetic (MHK) energy, and discusses involved...
Catastrophic flooding associated with sea-level rise and change of hurricane patterns has put the northeastern coastal regions of the United States at a greater risk. In this paper, we predict coastal flooding at the east bank of Delaware Bay and analyze the resulting impact on residents and transportation infrastructure. The three-dimensional coas...
Coastal flows involve different phenomena occurring at a vast range of spatial and temporal scales, and it is now becoming necessary to synchronously simulate them, especially those in nearshore processes. This paper targets an accurate as well as simultaneous prediction of multiphysics phenomena, such as surge bores and current circulations that a...
With the reality of climate change now widely accepted the world over by
recognized scientific organizations and governments, bridge owners are
beginning to consider how climate change predictions may affect the
safety of their bridges. In a study of bridge failure causes in the
United States, over 60% were due to hydraulic factors. Changes in
sea-...
In the United States, more than half of bridge failures are attributed to hydraulic factors. Under climate change conditions, in particular sea level rise and stronger hurricanes, coastal bridges could be at risk of damage and destruction due to severe hydrodynamic impacts. In this work, hydrodynamic forces are simulated at a coastal bridge of New...
As an important clean and renewable energy, tidal energy is attracting more and more attention, and various plan and projects are being made worldwide to generate power. First, this paper discusses the current status of tidal power generation, and then describes Marine Hydrokinetic (MHK) energy turbines and related facilities. Then, the paper propo...
As a consequence of many emerging issues such as the catastrophic Gulf of Mexico oil spill and potential coastline flooding due to sea level rise, there is an urgent need to develop our capabilities to predict small-scale and really 3D phenomena. In order to meet the need, we propose hybrid approaches and domain decomposition to couple different mo...
Terahertz near-field microscopy may serve as a novel tool to measure the high-frequency permittivity of dielectric surfaces on submicrometre semiconductor structures. We present an apertureless THz near-field microscope, which allows for spatial resolutions as small as 150 nm. A new model has been developed that considers the field coupling the sca...
We report on apertureless near-field microscopy in the far infrared. We identify a configurational resonance of the scanning tip-surface system to be the dominating mechanism that forms the image. Experimental data such as the high imaging contrast and its spectral properties can be well explained and make the framework of a mesoscopic resonance an...
Projects
Projects (6)
Amongst the project's goals are (1) to test whether soil moisture (SM) can be detected under moderately dense forest canopy when using L-band radiometer data, and (2) develop an algorithm for making SM estimates over forested regions (up to some biomass threshold).
The Soil Moisture Active Passive Validation Experiment (SMAPVEX) was originally slated for 2019 but had been delayed due to SMAP data acquisition issues (2019) and COVID travel restrictions (2020, 2021).
Meanwhile in situ soil moisture + temperature, phenology (upward looking camera), air temperature and tree dielectric and sap flow measurements are being collected near Millbrook, NY (by Cary Institute) and in Western Massachusetts (MIRSL). Harvard Forest site ('Hardwood Tower') also has L-band radiometer data. Data collections mainly focus on April - November, but some winter data also are available. Some preliminary data already are available at https://nsidc.org/data/SV19MB_TNET/versions/1 and https://nsidc.org/data/SV19MA_TNET/versions/1.
Release of calibrated results depends on the field data collections to be conducted sometime in the April - Nov 2022 window time required for QA/QC and re-processing.
This study is regarding the Indian Space Research Organization's L+S Airborne Synthetic Aperture Radar system (ASAR), with available here: https://uavsar.jpl.nasa.gov/cgi-bin/asar-data.pl). Here we look into the quality and new science possible using the S-band, in context of L band and Sentinel-1 C-band. There will be flights over Harvard Forest Summer 2021 and we will compare ASAR S-band data to our lab's airborne S-band SAR.
Here we develop tools to facilitate SAR data processing with a focus on polarimetric applications. For example, we provide a workflows for applying radiometric and terrain corrections of UAVSAR data to be used in conjunction with the InSAR Scientific Computing Environment (ISCE). Or for RTC processing of Sentinel-1 data using ISCE, there is rtcApp.py, now part of ISCE2 v2.3.3+.
Owing to our interest in forest biomass and forest stand heights, requiring LIDAR data, we also provide a workflow for obtaining and analyzing GEDI data.
The tools are available at https://github.com/UMassMIRSL and https://github.com/sgk0.
July 2021: A workflow similar to UAVSAR RTC was also developed for ALSO-2-PALSAR-2 (available at https://github.com/sgk0/isce_docker_tools/tree/master/alos2_rtc). Requires L1.1 CEOS data as input (tested for ISCE 2.4.2, but later versions should also work).
