folder Arctic Land Cover Change Index

michigan-tech-logo webCAFF is working to produce a set of satellite-based remote sensing products with a geographic focus on the pan-Artic.

MODIS satellite standard products of relevance to arctic processes are being converted to a more arctic-friendly projection facilitating a top-of-the-world analysis perspective. Satellite products are being developed for use by different stakeholder groups and products will be organized by terrestrial, marine, coastal, and freshwater disciplines. Landsat images will be used to generate additional remote sensing products at fine scale (30 meter). 

  • Michigan Tech Research Institute (MTRI) is assisting CAFF on selecting and providing MODIS satellite products for this system. This is an on-going effort that will continue to evolve and improve over time. 
  • Cursory analyses have been conducted to display the potential of the MODIS suite of products in studying the pan-Arctic ecosystem.  These include early warning indictaors such as [Land Cover; Land Surface Temperature; Snow Covered Area; Net Primary Production; Chlorophyll-a; Sea Surface Temperature; Colored Dissolved Organic Matter (CDOM)].

    To help guide provide guidance on next steps to better incorporate remotely sensed observations into CAFFs Circumpolar Biodiversity Monitoring Programme (CBMP), a workshop was held December 1 in Trondheim, Norway as part of the Arctic Biodiversity Congress

    ArcticSDIIn cooperation with the Arctic SDI CAFF is working to make this data available through the ABDS.

    Categories

    folder Albedo (MCD43C3)

    albedoAlbedo is a reflection coefficient that describes the reflecting power of a surface. It is a ratio of the reflected to incident radiation of a surface. Albedo values are dimensionless with values from zero (no reflection) to one (perfect reflection). Fresh snow, for example, will have values near 0.9 and charcoal will have values near 0.04. Albedo depends on the frequency of radiation; therefore the standard MODIS product for Albedo includes data layers for MODIS Bands 1 through 7.

    Accurately measuring albedo at high latitudes is challenging. Reflectance measurements made at high solar zenith angles pose difficulties in calibration and atmospheric correction. About half of available satellite observations during the sunlit season Summary of Products in the Arctic are obtained under conditions where the solar zenith angle exceeds 70° resulting in lower-quality results.

    The standard MODIS product includes data for black sky albedo (BSA) and white sky albedo (WSA). Actual albedo is a combination of the BSA and WSA albedo, and will depend on the particular atmospheric conditions when observations are made. An accuracy assessment of the MODIS standard albedo product to in-situ measurements on the Greenland ice sheet (Stroeve et al. 2005) found that at most solar zenith angles, the BSA and WSA bracket the actual albedo, and at 50° local solar noon zenith angles, BSA and WSA were identical and therefore close to actual albedo. Additionally it was found that during spring and autumn when the solar zenith angle often exceeds 50°, the quality of the MODIS albedos was often flagged as poor (e.g., a backup algorithm was used and the statistical differences between the BSA and WSA had more to do with backup versus main algorithm retrievals than with BSA versus WSA).

    This MODIS product is available on a 16-day acquisition cycle, but produced every 8 days. For the CAFF System, the first production of every month has been provided. Note: The Albedo layers of this product require a scale factor that can be found in the Appendix.

     

    For usage please see ABDS Data Policy
    Suggested citation:
    CAFF (2015). Albedo: Arctic Land Cover Change Index. Conservation of Arctic Flora and Fauna, Arctic Biodiversity Data Service (ABDS).

     

    folder Colored Dissolved Organic Matter (CDOM) (MYD24)

    CDOMColored, or Chloromorphic, Dissolved Organic Matter (CDOM) is a measurement of the absorption of light in the UV and visible spectrum by the colored component of the dissolved organic carbon (DOC).A monthly, 4 km spatial resolution product has been provided to CAFF for the months of March-October. In the winter months, sea ice limits the detection of ocean primary production, so little CDOM can be seen until the sea ice thaws. CDOM is measured by a CDOM Index, which has no units.

     

    For usage please see ABDS Data Policy
    Suggested citation:
    CAFF (2015). CDOM: Arctic Land Cover Change Index. Conservation of Arctic Flora and Fauna, Arctic Biodiversity Data Service (ABDS).

     

    folder Land Cover Dynamics (Vegetation Phenology) (MCD12Q2)

    Example of MODIS Land Cover Dynamics Vegetation Phenology product vegetation peak tile 558 h12v02 from 2002Land Cover Dynamics (Vegetation Phenology) (MCD12Q2) The Land Cover Dynamics MODIS product is a yearly product that represents the timing of vegetation phenology globally. Sub-datasets include vegetation growth, maturity, senescence, and dormancy. This product also includes the NBAR-(Nadir Bidirectional reflectance distribution function (BRDF) adjusted Reflectance) based EVI, in part because the EVI is used to create the Land Cover Dynamics.

    The Land Cover Dynamics product uses both Terra and Aqua MODIS data. Version 005 (provided) has a 500 m spatial resolution, which is an improvement from the 1,000 m version 004 product. This product is only available in MODIS tiles, so the tiles needed to cover the CAFF pan-Arctic region has been downloaded but not clipped to the pan-Arctic extent at this time. Note: Like the Vegetation Indices, the EVI layers of this product require scale factors that can be found in the Appendix.

     

    For usage please see ABDS Data Policy
    Suggested citation:
    CAFF (2015). Vegetation Phenology: Arctic Land Cover Change Index. Conservation of Arctic Flora and Fauna, Arctic Biodiversity Data Service (ABDS).

     

    folder Land Water Mask (MOD44W)

    Example of the MODIS Land Water Mask MODIS Tile 558 h22v02The MODIS Land Water Mask is created from MODIS 250 m imagery in combination with Shuttle Radar Topography Mission (SRTM) Water Body Data (SWBD) to create a global map of surface water at 250 m spatial resolution. Currently, only one map exists, created in 2009 by Carroll et al. (2009). Because only one MODIS-based map exists, an analysis of surface water change is not possible at this time.

     

    For usage please see ABDS Data Policy
    Suggested citation:
    CAFF (2015). Land Water Mask: Arctic Land Cover Change Index. Conservation of Arctic Flora and Fauna, Arctic Biodiversity Data Service (ABDS).

     

    folder LandCoverType

    Land Cover TypeThe MODIS Land Cover Type product is created yearly using three land classification schemes; the International Geosphere Biosphere Programme (IGBP) classification scheme, the Univertiy of Maryland (UMD) classification scheme, and a MODIS-derived Leaf Area Index /Fraction of Photosynthetically Active Radiation (LAI/fPAR) classification scheme

    (Summary of Products MTRI  17 Table 3). The International Geosphere Biosphere Programme (IGBP) identifies seventeen land cover classes, including eleven natural vegetation classes, three non-vegetated land
    classes, and three developed land classes. The product provided is derived using the same algorithm as the 500 m Land Cover Type (MOD12Q1), but is on a 0.05° Climate Model Grid (CMG), that has been clipped to the pan-Arctic extent. The UMD classification scheme is similar to the IGBP classification scheme, but it excludes the Permanent wetlands, Cropland/Natural vegetation mosaic, and the Snow and ice classes. The LAI/fPAR classification scheme is the smallest of the three, and focuses on forest structure; it only has
    eleven classes. All three land cover classification schemes are provided, but the IGBP classification scheme is the most amenable to the Pan-Arctic region.

     

    For usage please see ABDS Data Policy
    Suggested citation:
    CAFF (2015). Land Cover Type: Arctic Land Cover Change Index. Conservation of Arctic Flora and Fauna, Arctic Biodiversity Data Service (ABDS).

    folder LandSurfaceTemperature

    LandsurfacetempThe MODIS Land Surface Temperature (LST) product provided is a monthly
    composite configured on a 0.05° Climate Model Grid (CMG). It includes both daytime and
    nighttime surface temperatures, taken at 11 um and 4 um (night). This product has been
    scaled. To convert the raster values to a Kelvin temperature scale, multiply by a factor of
    0.02.
    Note: Multiple layers of this product require a scale factor, as well as some additional offsets,
    all of which can be found in the Appendix

     

    For usage please see ABDS Data Policy
    Suggested citation:
    CAFF (2015). Land Surface Temperature: Arctic Land Cover Change Index. Conservation of Arctic Flora and Fauna, Arctic Biodiversity Data Service (ABDS).

    folder Marine Chlorophyll a (MYD21)

    Marine ChlorophyllThe MODIS marine chlorophyll a product provided, similar to SST, is a 4 km global monthly composite based on smaller resolution daily imagery compiled by NASA. The imagery is reliant on clear ocean (free of clouds and ice) so only months from March to October have been provided, as the chlorophyll levels in the Arctic diminish during the winter months, when sea ice is prevalent. The marine chlorophyll a is measured in mg/m3.

     

    For usage please see ABDS Data Policy
    Suggested citation:
    CAFF (2015). Marine Chlorophyll: Arctic Land Cover Change Index. Conservation of Arctic Flora and Fauna, Arctic Biodiversity Data Service (ABDS).

     

    folder Marine Net PrimaryProductivity

    Marine Net Primary Productivity July 2013Marine primary productivity is not available from the NASA Ocean Color website. Currently the best product available for marine primary productivity is available through Oregon State University’s Ocean Productivity Project (O’Malley 2010). A monthly global Net Primary Productivity product at 9 km spatial resolution has been selected for the CAFF system, though more options are available from Oregon State’s Ocean Productivity website. The algorithm used to create the primary productivity is a Vertically Generalized Production Model (VGPM) created by Behrenfeld and Falkowski (1997). It is a “chlorophyll-based” model that estimates net primary production from chlorophyll using a temperature-dependent description of chlorophyll photosynthetic efficiency (O’Malley 2010). Inputs to the function are chlorophyll, available light, and photosynthetic efficiency. Marine primary production is measured in mg/m2/day.

     

    For usage please see ABDS Data Policy
    Suggested citation:
    CAFF (2015). Primary Productivity: Arctic Land Cover Change Index. Conservation of Arctic Flora and Fauna, Arctic Biodiversity Data Service (ABDS).

    folder SeaIceIndexPNGs

    For usage please see ABDS Data Policy
    Suggested citation:
    CAFF (2015). Sea Ice Index: Arctic Land Cover Change Index. Conservation of Arctic Flora and Fauna, Arctic Biodiversity Data Service (ABDS).

    folder SeaSurfaceTemperature

    Sea Surface TemperatureSST4MYD28The MODIS Sea Surface Temperature (SST) product provided is a 4 km resolution global monthly composite based on 1 km daily imagery. The imagery is from the MODIS Aqua satellite, and represents the 4 um nighttime measurements. Nighttime measurements provide a more accurate representation of the sea temperature, because during the day the top few centimeters of the water column may be affected by sunlight warming, while nighttime measurements do not have this factor of error. However, this may be less of an issue in the Arctic, due to continuous solar illumination during the ice-free months, but it is common practice to use the nighttime measures for SST.

     

    For usage please see ABDS Data Policy
    Suggested citation:
    CAFF (2015). Sea Surface Temperature: Arctic Land Cover Change Index. Conservation of Arctic Flora and Fauna, Arctic Biodiversity Data Service (ABDS).

    folder SnowCoveredArea

    MODIS Snow Covered-Area product from March 1 2013Snow Covered Area (MOD10CM)
    The Snow Covered Area product is based on a Normalized Difference Snow Index
    (NDSI), which is similar to NDVI, but exploits different bands in the equation (Equation 3),
    namely Green (Band 4) and Short Wavelength Near-infrared (SWNIR, Band 6). It is
    important to note that the Band 6 sensor on MODIS Aqua malfunctioned shortly after launch,
    so Snow Covered Area from the Aqua sensor is calculated using Bands 3 and 7. This may
    introduce errors in identifying snow in vegetated areas, as the use of Band 7 results in false
    snow detection. For this reason the MODIS Terra product has been provided for the CAFF
    system.

     

    For usage please see ABDS Data Policy
    Suggested citation:
    CAFF (2015). Snow Covered Area: Arctic Land Cover Change Index. Conservation of Arctic Flora and Fauna, Arctic Biodiversity Data Service (ABDS).

    folder Vegetation Indices (MOD13C1)

    Examples-of-MODIS-NDVI-left-and-EVI-right-products-from-July-2013Vegetation Indices (MOD13C1) Vegetation indices quantify the concentrations of green leaf vegetation (chlorophyll)
    around the globe, in an attempt to monitor and correlate vegetation health and stress. The
    MODIS vegetation products include the Normalized Difference Vegetation Index (NDVI)
    and an Enhanced Vegetation Index (EVI). Included in the MOD13C1 product is both NDVI
    and EVI, so both have been provided for the CAFF Dedicated Pan-Arctic Satellite Remote
    Sensing Products and Distribution System. These indices come in a variety of resolutions,
    but MTRI has provided a monthly global composite on a 0.05° Climate Model GRID
    (CMG).
    The NDVI algorithm exploits the relationship between the near-infrared (NIR) and
    the red wavelengths of the light spectrum, as healthy, green vegetation reflects large amounts
    of infrared and near-infrared light. This relationship can be seen in Equation 1. This
    algorithm calculates a value for each pixel in the raster with values ranging from -1 to 1.
    Values close to 1 represent healthy vegetation, zero represents no vegetation, and values
    close to -1 indicate absorption of the near-infrared wavelengths, and represent features such
    as water. NDVI is very sensitive to Chlorophyll, and can identify drought and water stress in
    areas with diminished reflectance of NIR light.
    EVI is similar to NDVI, and exploits the same relationship between red and NIR
    wavelengths, but is optimized to improve sensitivity in areas with high biomass levels, such
    as dense jungle-like vegetation. EVI is more responsive to canopy structure variations,
    including Leaf Area Index (LAI), canopy type, plant physiognomy, and canopy architecture.
    This is achieved by the inclusion of the blue band and some aerosol resistance terms, as
    shown in Equation 2 (Huete et al., 1999).
    It is important to note that with the presence of snow, NDVI decreases, but EVI
    increases. This distinction is important Arctic applications, so a comparison of both indices
    is suggested.

     

    For usage please see ABDS Data Policy
    Suggested citation:
    CAFF (2015). Vegetation Indices: Arctic Land Cover Change Index. Conservation of Arctic Flora and Fauna, Arctic Biodiversity Data Service (ABDS).

     

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