Harmonized Landsat/Sentinel-2 Products for Land Monitoring

The Harmonized Landsat-8 and Sentinel-2 (HLS) project is a NASA initiative aiming to produce a seamless, harmonized surface reflectance record from the Operational Land Imager (OLI) and Multi-Spectral Instrument (MSI) aboard Landsat-8 and Sentinel-2 remote sensing satellites, respectively. The HLS products are based on a set of algorithms to obtain seamless products from both sensors (OLI and MSI): atmospheric correction, cloud and cloud-shadow masking, geographic co-registration and common gridding, bidirectional reflectance distribution function normalization and bandpass adjustment. As of version 1.3, the HLS v1.3 data set covers 9.12 million km2 and spans from first Landsat-8 data (2013) to present. HLS products provide near-daily surface reflectance information with a common geometric framework, and are suitable for a variety of agricultural and vegetation monitoring tasks, including analysis of crop type, condition, and phenology

The Sentinel-2 MSI Can Increase the Temporal Resolution of 30m Satellite-Derived LAI Estimates

The successful launch of the European Space Agency (ESA) Sentinel-2A (S2-A) on 23 June 2015 with its MultiSpectral Instrument (MSI) provides an important means to augment Earth-observation capabilities following the legacy of Landsat. After the three-month satellite commissioning campaign, the MSI onboard S-2A is performing very well (ESA, 2015). By 3 December 2015, the sensor data records have achieved provisional maturity status and have been accessed in level-1C Top-Of-Atmosphere (TOA) reflectance by the remote sensing community worldwide. Near-nadir observations by the MSI onboard S-2A and the Operational Land Imager (OLI) onboard Landsat 8 were collected during Simultaneous Nadir Overpasses as well as nearly coincident overpasses. This paper presents a processing chain using harmonized S-2A MSI and Landsat 8 OLI sensors to obtain increased temporal resolution in Leaf Area Index (LAI) estimates using the red-edge band B8A of MSI to replace the NIR band B08. Results demonstrate that LAI estimates from the MSI and OLI are comparable, and, given sufficient preprocessing for atmospheric correction and geometric rectification, can be used interchangeably to improve the frequency with which low LAI canopies can be monitored

Harmonized Landsat/Sentinel-2 Reflectance Products for Land Monitoring (Invited)

Many land applications require more frequent observations than can be obtained from a single 'Landsat class' sensor. Agricultural monitoring, inland water quality assessment, stand-scale phenology, and numerous other applications all require near-daily imagery at better than 1ha resolution. Thus the land science community has begun expressing a desire for a '30-meter MODIS' global monitoring capability. One cost-effective way to achieve this goal is via merging data from multiple, international observatories into a single virtual constellation. The Harmonized Landsat/Sentinel-2 (HLS) project has been working to generate a seamless surface reflectance product by combining observations from USGS/NASA Landsat-8 and ESA Sentinel-2. Harmonization in this context requires a series of radiometric and geometric transforms to create a single surface reflectance time series agnostic to sensor origin. Radiometric corrections include a common atmospheric correction using the Landsat-8 LaSRC/6S approach, a simple BRDF adjustment to constant solar and nadir view angle, and spectral bandpass adjustments to fit the Landsat-8 OLI reference. Data are then resampled to a consistent 30m UTM grid, using the Sentinel-2 global tile system. Cloud and shadow masking are also implemented. Quality assurance (QA) involves comparison of the output 30m HLS products with near-simultaneous MODIS nadir-adjusted observations. Prototoype HLS products have been processed for approximately 7% of the global land area using the NASA Earth Exchange (NEX) compute environment at NASA Ames, and can be downloaded from the HLS web site (https://hls.gsfc.nasa.gov). A wall-to-wall North America data set is being prepared for 2018. This talk will review the objectives and status of the HLS project, and illustrate applications of high-density optical time series data for agriculture and ecology. We also discuss lessons learned from HLS in the general context of implementing virtual constellations

Harmonizing Landsat and Sentinel-2 Reflectances for Better Land Monitoring

When combined, Landsat and ESA Sentinel-2 observations can provide 2-4 day coverage for the global land area. A collaboration among NASA GSFC (Goddard Space Flight Center), University of Maryland, and NASA Ames has developed a processing chain to create seamless, "harmonized" reflectance products using standardized atmospheric correction, BRDF (Bidirectional Reflectance Distribution Function) adjustment, spectral bandpass adjustment, and gridding algorithms. These products point the way to a "30-m MODIS (Moderate Resolution Imaging Spectroradiometer)" capability for agricultural and ecosystem monitoring by leveraging international sensors

Climate change, precipitation and impacts on an estuarine refuge from disease

© The Author(s), 2011. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PLoS One 6 (2011): e18849, doi:10.1371/journal.pone.0018849.Oysters play important roles in estuarine ecosystems but have suffered recently due to overfishing, pollution, and habitat loss. A tradeoff between growth rate and disease prevalence as a function of salinity makes the estuarine salinity transition of special concern for oyster survival and restoration. Estuarine salinity varies with discharge, so increases or decreases in precipitation with climate change may shift regions of low salinity and disease refuge away from optimal oyster bottom habitat, negatively impacting reproduction and survival. Temperature is an additional factor for oyster survival, and recent temperature increases have increased vulnerability to disease in higher salinity regions. We examined growth, reproduction, and survival of oysters in the New York Harbor-Hudson River region, focusing on a low-salinity refuge in the estuary. Observations were during two years when rainfall was above average and comparable to projected future increases in precipitation in the region and a past period of about 15 years with high precipitation. We found a clear tradeoff between oyster growth and vulnerability to disease. Oysters survived well when exposed to intermediate salinities during two summers (2008, 2010) with moderate discharge conditions. However, increased precipitation and discharge in 2009 reduced salinities in the region with suitable benthic habitat, greatly increasing oyster mortality. To evaluate the estuarine conditions over longer periods, we applied a numerical model of the Hudson to simulate salinities over the past century. Model results suggest that much of the region with suitable benthic habitat that historically had been a low salinity refuge region may be vulnerable to higher mortality under projected increases in precipitation and discharge. Predicted increases in precipitation in the northeastern United States due to climate change may lower salinities past important thresholds for oyster survival in estuarine regions with appropriate substrate, potentially disrupting metapopulation dynamics and impeding oyster restoration efforts, especially in the Hudson estuary where a large basin constitutes an excellent refuge from disease.Funding was provided by the Hudson River Foundation, grant number 00607A, and the New York State Department of Environmental Conservation (MOU 2008)

New Directions in Immigration Policy: Canada's Evolving Approach to the Selection of Economic Immigrants

Canada's immigration system is currently undergoing significant change driven by several goals that include (1) a desire to improve the economic outcomes of entering immigrants; (2) an attempt to better respond to short-term regional labor market shortages often associated with commodity booms, and (3) a desire to shift immigration away from the three largest cities to other regions of the country. These goals reflect the implementation of new immigration programs in the 2000s. The paper discusses the recent changes to Canadian immigration policy, examines preliminary evaluations of the new programs and discusses potential future issues emanating from the changes

International School Leadership and the Diffusion of Distance Education in East Asian International Schools

Change is critical in most organizations. International schools attempting to redefine 21st century education for their students are innovating pedagogies and schools\u27 structures. However, the leader of an organization or school may be the most influential advocate for or barrier to change. International schools\u27 leaders continue to play a role in the diffusion of distance education. This study identified the knowledge and experience of international school leaders and identified themes that are related to the likelihood distance education would or would not be adopted by the schools they lead. This applied dissertation describes international school leaders\u27 knowledge and use of innovation diffusion theory in adopting distance education into kindergarten-Grade 12 East Asia Regional Council of Schools (EARCOS). International schools are a unique niche in the global educational environment. Due to the global nature of international schools, the high cost of tuition, an abundance of instructional resources, and the demands of educating children for matriculation to university, instructional technology has become an important aspect in international education. Many schools have adopted 1:1 laptop programs and learning management systems to manage instructional resources for classes and to deliver web-enhanced and blended learning. Triangulating data from EARCOS school leaders collected through individual innovativeness surveys and coding open-ended interview transcripts provided insight to school leaders\u27 knowledge and use of innovation diffusion theory when applied to adopting or rejecting the use of distance education within their schools. Data collected in this study indicated that EARCOS school leaders\u27 use of formalized planning when diffusing innovations, including distance education, within their schools varied depending on the scale of the innovation and the stakeholders involved. EARCOS school leaders rated themselves higher on average in individual innovativeness when compared to other innovativeness survey normative groups. Several other key themes emerged from the data including the following: **Opinion leadership and change agents play a vital role in diffusing innovations in EARCOS schools. School leaders need to be adaptable and recognize opinion leadership within their schools to diffuse innovations efficiently. **EARCOS school leaders rated themselves as highly innovative but were reluctant to explore innovative ways of delivering instruction, including distance education. **Distance education was not seen as relevant in EARCOS schools, even though school leaders recognized their students would be exposed to online learning upon matriculation. **Barriers to the diffusion of distance education exist in EARCOS schools including cost to develop distance education programs and courses, existing school structures, and the perceived absence of need

International School Leadership and the Diffusion of Distance Education in East Asian International Schools

Change is critical in most organizations. International schools attempting to redefine 21st century education for their students are innovating pedagogies and schools\u27 structures. However, the leader of an organization or school may be the most influential advocate for or barrier to change. International schools\u27 leaders continue to play a role in the diffusion of distance education. This study identified the knowledge and experience of international school leaders and identified themes that are related to the likelihood distance education would or would not be adopted by the schools they lead. This applied dissertation describes international school leaders\u27 knowledge and use of innovation diffusion theory in adopting distance education into kindergarten-Grade 12 East Asia Regional Council of Schools (EARCOS). International schools are a unique niche in the global educational environment. Due to the global nature of international schools, the high cost of tuition, an abundance of instructional resources, and the demands of educating children for matriculation to university, instructional technology has become an important aspect in international education. Many schools have adopted 1:1 laptop programs and learning management systems to manage instructional resources for classes and to deliver web-enhanced and blended learning. Triangulating data from EARCOS school leaders collected through individual innovativeness surveys and coding open-ended interview transcripts provided insight to school leaders\u27 knowledge and use of innovation diffusion theory when applied to adopting or rejecting the use of distance education within their schools. Data collected in this study indicated that EARCOS school leaders\u27 use of formalized planning when diffusing innovations, including distance education, within their schools varied depending on the scale of the innovation and the stakeholders involved. EARCOS school leaders rated themselves higher on average in individual innovativeness when compared to other innovativeness survey normative groups. Several other key themes emerged from the data including the following: **Opinion leadership and change agents play a vital role in diffusing innovations in EARCOS schools. School leaders need to be adaptable and recognize opinion leadership within their schools to diffuse innovations efficiently. **EARCOS school leaders rated themselves as highly innovative but were reluctant to explore innovative ways of delivering instruction, including distance education. **Distance education was not seen as relevant in EARCOS schools, even though school leaders recognized their students would be exposed to online learning upon matriculation. **Barriers to the diffusion of distance education exist in EARCOS schools including cost to develop distance education programs and courses, existing school structures, and the perceived absence of need

The Harmonized Landsat and Sentinel-2 surface reflectance data set

International audienc