| snippet:
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20260127 4km Spatial Surrogates feature service - download individual spatial surrogates |
| summary:
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20260127 4km Spatial Surrogates feature service - download individual spatial surrogates |
| extent:
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[[-126.76450039924,30.9551735145955],[-113.30159233647,42.1870842657942]] |
| accessInformation:
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| thumbnail:
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thumbnail/thumbnail.png |
| maxScale:
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1.7976931348623157E+308 |
| typeKeywords:
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["ArcGIS","ArcGIS Server","Data","Feature Access","Feature Service","providerSDS","Service"] |
| description:
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<p>Planning emissions are available as totals at level of a county/air basin/district for different emissions inventory categories (EICs). Regions for which these emissions totals are available are referred to as Geographic Areas of Interest (GAI). For air quality modeling, these emissions totals must be spatially distributed to model grid cells in each GAI. The spatial surrogates provided in this package represent the fractions of GAI emissions to be assigned to each model grid cell and are based on underlying geographic weighting data associated with different EICs. </p><p><br />This package contains surrogates compatible with California Air Resources Board's 4 km2 gridded air quality modeling domain (ca_4km_384x399) and GAI boundaries (coabdis_gai_oc1_oc2_mm5_sphere_20240702).</p><p><br />The surrogate files in this package are in the form of a geodatabase (.gdb). They were generated using the 'spatialsurrogates' R package developed by CARB's Atmospheric Modeling and Support Section. The name of each surrogate file contains the surrogate ID, modeling resolution/domain, and year associated with the underlying data. Detailed information on the data source(s) and processing methods can be found in the Snapshot 20260127 Spatial Surrogate Methodology document.<br />The polygon features represent portions of model grid cells within each GAI that had non-zero surrogate fractions for this surrogate. Grid cells intersecting more than one GAI are divided into separate polygons. In the few cases where a specific surrogate used an attribute to define which GAI a specific weighting feature was associated with instead of geometric intersection with the GAI boundaries file, slight differences in geometries could lead to grid cells not actually intersecting the GAI to be assigned weight. In these few cases a separate circular polygon was added to the usual geometry to indicate this assignment for purposes of visualization. </p><p><br />The following attributes are available in the file: </p><p><br />GAI = Geographical Area of Interest, a code indicating a specific region for which emissions inventories are available. Corresponds to the combination of County, Air Basin, and District geometries.</p><p><br />CO_NAME = Name of the County associated with GAI</p><p><br />AB = Abbreviation of Air Basin associated with GAI</p><p><br />DIS = Abbreviation of Air District associated with GAI</p><p><br />I_CELL = I grid cell number (x-direction)</p><p><br />J_CELL = J grid cell number (y-direction)</p><p><br />SRGID = Surrogate identification number</p><p><br />SRG_FRACT = Fraction of GAI emissions to be allocated in the grid cell.</p><p><br />AREA_FRACT = Fraction of the GAI area in the grid cell, which represents the default grid cell fraction when no spatial information is available and emissions would be spread uniformly over the GAI. </p><p> <br />RATIO = SRG_FRACT divided by AREA_FRACT, representing the surrogate fraction normalized by area fraction. A value greater than one indicates greater emissions allocation than a uniform allocation across the GAI and a value less than one indicates less emission allocation in the grid cell than would be expected from a uniform allocation. RATIO can be more informative than SRG_FRACT for visualization of allocation with multiple GAIs, since the effect of GAI size (as well as grid resolution) is eliminated by this normalization. </p><p><br />RATIO_VIZ = RATIO, but with three transformations to facilitate visualization with a continuous color ramp across multiple surrogate IDs, grid resolutions, and GAI sizes. Outlier values greater than 100 have been set to 100, values less than 0.01 have been set to 0.01, and the base 2 logarithm has been taken so that the visualization color ramp is symmetric around RATIO value of 1 and color scale variation is greater within the typical range. <br /><br /></p> |
| licenseInfo:
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<p>Please reference the California Air Resources Board.</p> |
| catalogPath:
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|
| title:
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20260127 4km Spatial Surrogates feature service |
| type:
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Feature Service |
| url:
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|
| tags:
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["Snapshot 20260127","spatial surrogates"] |
| culture:
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en-US |
| portalUrl:
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|
| name:
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20260127_4km_Spatial_Surrogates_gdb_gdb |
| guid:
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D8F76604-BE27-4B30-8942-C111F060F36B |
| minScale:
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0 |
| spatialReference:
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MM5_sphere |