Table of Contents - The Atmospheric Studies Group at TRC
Table of Contents - The Atmospheric Studies Group at TRC Table of Contents - The Atmospheric Studies Group at TRC
Section 2: Geophysical Data Processors 2.1 TERREL Terrain Preprocessor TERREL is a preprocessing program that extracts and reformats Digital Elevation Model (DEM) terrain data according to the options selected by the user (domain, resolution, etc.). Eleven DEM formats are currently supported. TERREL has the ability to produce Cartesian gridded fields of terrain elevations or a polar grid of terrain elevations. For the Cartesian gridded field option, TERREL averages all of the terrain data points which fall within the grid cell to obtain the elevation assigned to the center of the userspecified grid cell. When using the polar grid option, TERREL uses the maximum terrain elevation in the area either from the current ring out to the next ring (user input switch - SCREEN) or halfway between adjacent rings (user input switch - NORMAL) and halfway between the adjacent radials. TERREL can produce terrain data files in the formats compatible with the following models: CALMET, MESOPAC, NUATMOS, and ISC3. TERREL requires at least one input file and produces four output files. TERREL can first be run without any data files and the program will indicate for the user the latitude and longitude of the four corners of the area required to cover the user-specified domain. A message indicates how many terrain data files of each type are required based on the domain parameters supplied by the user. This is helpful, for example, when only UTM coordinates are known, but not the latitude and longitude of the corners of the modeling domain. Once the appropriate data files are obtained, the TERREL input file must be modified to reflect the names and types of the data files and TERREL must be run again to process the terrain data. This could be done in one run or as an iterative process, where intermediate results are stored in a binary file (e.g., TERREL.SAV) and incorporated into the next TERREL run using the next set of digital terrain input data. The .SAV file option is helpful if the user doesn't have the available disk space to store all of the raw terrain files at once. TERREL has an input (ITHRES) which is used for quality assurance purposes. ITHRES is a whole number (%) identifying the acceptable threshold of variance from the average number of data points ('hits') per cell. If a particular grid cell had less than ITHRES percent of the average number of data 'hits' per cell, a warning message is written to alert the user to check the results. If using a mix of 1-degree DEM data and 30 meter DEM data, the grid cells using the 30 meter data will have many more 'hits' than the 1-degree DEM grid cells. The user might want to adjust the value of ITHRES to reduce the number of warning messages written. TERREL has the option (variable PMAP) to define the gridded output fields for a number of map projections. Note that CALMET currently supports Universal Transverse Mercator (UTM) grid, Lambert Conformal Projection (LCC) and Tangential Transverse Mercator (TTM). Lambert Conformal Projection should be used when the modeling domain is large, (> 300 km), because a Lambert Conformal grid accounts for the earth's curvature. If the LCC option is specified, TERREL uses the user-specified standard parallels (latitudes) and reference longitude to calculate a "cone constant" and the east-west distance from the reference longitude. The reference longitude is the longitude at which true north and map north are defined to be the same. It also defines where x=0 in the Lambert Conformal grid. The reference latitude defines where y=0 in the Lambert Conformal grid. 2-3
Section 2: Geophysical Data Processors TERREL INPUT: 1. Terrain Database: Table 2-1 defines the types of terrain databases which can be processed by TERREL. Eleven types of terrain data can be read, corresponding to different resolutions and formats: 30 arc-seconds (900 m spacing, GTOPO30, USGSLA, or ARM3 format), 3 arc-seconds (90m spacing, USGS DEM, SRTM3, or Rocky Mtn. Communications (3CD) format), 1 arc-second (30m spacing, SRTM1 format), 30 meters (7.5 minute USGS DEM format), and Canadian Digital Map Data Format (DMDF) data (~100 m resolution). Two are generic formats, one based on a system used in New Zealand (NZGEN), based on row#, elevation (m), latitude, longitude and one designed to enable a user to reformat existing gridded terrain files into a simple format for TERREL (GEN) based on (X, Y, Z) format. The terrain data ordered from the USGS can be obtained through file transfer protocol (FTP) access, on CD-ROM, or on magnetic tape, or follow the direct links from www.src.com. Attachment 2-A contains a complete description of the USGS Digital Elevation Models taken fromhttp://eros.usgs.gov/#/Guides/dem.Attachment 2-G describes the Canadian DMDF format and Attachment 2-B describes the SRTM format. 2. Obtaining the Data: Links to downloading all the terrain data can be found on http://www.src.com/datasets/. 3 arc-second terrain data are also available from the USGS site (http://edc2.usgs.gov/geodata/ )with file names corresponding to the 1:250,000-scale map names followed by -e or -w for the eastern and western portions respectively. In some regions, 30m data are also available with the names corresponding to the 1:100,000-scale map names. The user must first identify the names of the quadrants encompassed by the domain. A copy of the USGS website is provided in Attachment 2-C. The Shuttle RADAR Topography Mission (SRTM) data are available in 1arc-second (30m), 3 arcsecond (90m), and 30arc-second (1000m) resolutions. The 30 arc-second data are combined with the GTOPO30 data and processed by TERREL in the same way as the GTOPO30 data, so these data files should be presented as GTOPO30. The 1 and 3 arc-second data files must be processed as type SRTM1 and SRTM3, respectively. The SRTM data are available from links to the USGS site directly from the ASG website at http://www.src.com/datasets/datasets_terrain.html documentation is available at the Jet Propulsion laboratory, California Institute of Technology, at http://www2.jpl.nasa.gov/srtm/and is included in Attachment 2-B. 30 arc-second terrain data for the globe are available from the USGS WWW site: (http://eros.usgs.gov/#/Find_Data/Products_and_Data_Available/GTOPO30). 2-4
- Page 9 and 10: Section 1: Introduction Table 9-4:
- Page 11 and 12: Section 1: Introduction Table 9-65:
- Page 13 and 14: Section 1: Introduction introductio
- Page 15 and 16: Section 1: Introduction released a
- Page 17 and 18: Section 1: Introduction CALMET Upd
- Page 19 and 20: Section 1: Introduction To enhance
- Page 21 and 22: Section 1: Introduction Meteorologi
- Page 23 and 24: Section 1: Introduction READ62 is a
- Page 25 and 26: Section 1: Introduction contained i
- Page 27 and 28: Section 1: Introduction OPTHILL uti
- Page 29 and 30: Section 1: Introduction From CALPUF
- Page 31 and 32: Section 1: Introduction Observation
- Page 33 and 34: Section 1: Introduction Slope Flows
- Page 35 and 36: Section 1: Introduction CALPUFF con
- Page 37 and 38: Section 1: Introduction Table 1-2:
- Page 39 and 40: Section 1: Introduction 1.5 Summary
- Page 41 and 42: Section 1: Introduction If the uppe
- Page 43 and 44: Section 1: Introduction Table 1-4:
- Page 45 and 46: Section 1: Introduction Table 1-5:
- Page 47 and 48: Section 1: Introduction Table 1-5 (
- Page 49 and 50: Section 1: Introduction Table 1-5 (
- Page 51 and 52: Section 1: Introduction Table 1-5 (
- Page 53 and 54: Section 1: Introduction Table 1-6:
- Page 55 and 56: Section 1: Introduction 1-44
- Page 57 and 58: Section 1: Introduction technical o
- Page 59: Section 2: Geophysical Data Process
- Page 63 and 64: Section 2: Geophysical Data Process
- Page 65 and 66: Section 2: Geophysical Data Process
- Page 67 and 68: Section 2: Geophysical Data Process
- Page 69 and 70: Section 2: Geophysical Data Process
- Page 71 and 72: Section 2: Geophysical Data Process
- Page 73 and 74: Section 2: Geophysical Data Process
- Page 75 and 76: Section 2: Geophysical Data Process
- Page 77 and 78: Section 2: Geophysical Data Process
- Page 79 and 80: Section 2: Geophysical Data Process
- Page 81 and 82: Section 2: Geophysical Data Process
- Page 83 and 84: Section 2: Geophysical Data Process
- Page 85 and 86: Section 2: Geophysical Data Process
- Page 87 and 88: Section 2: Geophysical Data Process
- Page 89 and 90: Section 2: Geophysical Data Process
- Page 91 and 92: Section 2: Geophysical Data Process
- Page 93 and 94: Section 2: Geophysical Data Process
- Page 95 and 96: Section 2: Geophysical Data Process
- Page 97 and 98: Section 2: Geophysical Data Process
- Page 99 and 100: Section 2: Geophysical Data Process
- Page 101 and 102: Section 2: Geophysical Data Process
- Page 103 and 104: Section 2: Geophysical Data Process
- Page 105 and 106: Section 2: Geophysical Data Process
- Page 107 and 108: Section 2: Geophysical Data Process
- Page 109 and 110: Section 2: Geophysical Data Process
Section 2: Geophysical D<strong>at</strong>a Processors<br />
TERREL INPUT:<br />
1. Terrain D<strong>at</strong>abase: <strong>Table</strong> 2-1 defines the types <strong>of</strong> terrain d<strong>at</strong>abases which can be processed by<br />
TERREL. Eleven types <strong>of</strong> terrain d<strong>at</strong>a can be read, corresponding to different resolutions and<br />
form<strong>at</strong>s: 30 arc-seconds (900 m spacing, GTOPO30, USGSLA, or ARM3 form<strong>at</strong>), 3 arc-seconds<br />
(90m spacing, USGS DEM, SRTM3, or Rocky Mtn. Communic<strong>at</strong>ions (3CD) form<strong>at</strong>), 1 arc-second<br />
(30m spacing, SRTM1 form<strong>at</strong>), 30 meters (7.5 minute USGS DEM form<strong>at</strong>), and Canadian Digital<br />
Map D<strong>at</strong>a Form<strong>at</strong> (DMDF) d<strong>at</strong>a (~100 m resolution). Two are generic form<strong>at</strong>s, one based on a<br />
system used in New Zealand (NZGEN), based on row#, elev<strong>at</strong>ion (m), l<strong>at</strong>itude, longitude and one<br />
designed to enable a user to reform<strong>at</strong> existing gridded terrain files into a simple form<strong>at</strong> for TERREL<br />
(GEN) based on (X, Y, Z) form<strong>at</strong>. <strong>The</strong> terrain d<strong>at</strong>a ordered from the USGS can be obtained through<br />
file transfer protocol (FTP) access, on CD-ROM, or on magnetic tape, or follow the direct links from<br />
www.src.com. Attachment 2-A contains a complete description <strong>of</strong> the USGS Digital Elev<strong>at</strong>ion<br />
Models taken fromhttp://eros.usgs.gov/#/Guides/dem.Attachment 2-G describes the Canadian<br />
DMDF form<strong>at</strong> and Attachment 2-B describes the SRTM form<strong>at</strong>.<br />
2. Obtaining the D<strong>at</strong>a: Links to downloading all the terrain d<strong>at</strong>a can be found on<br />
http://www.src.com/d<strong>at</strong>asets/. 3 arc-second terrain d<strong>at</strong>a are also available from the USGS site<br />
(http://edc2.usgs.gov/geod<strong>at</strong>a/ )with file names corresponding to the 1:250,000-scale map names<br />
followed by -e or -w for the eastern and western portions respectively. In some regions, 30m d<strong>at</strong>a are<br />
also available with the names corresponding to the 1:100,000-scale map names. <strong>The</strong> user must first<br />
identify the names <strong>of</strong> the quadrants encompassed by the domain. A copy <strong>of</strong> the USGS website is<br />
provided in Attachment 2-C.<br />
<strong>The</strong> Shuttle RADAR Topography Mission (SRTM) d<strong>at</strong>a are available in 1arc-second (30m), 3 arcsecond<br />
(90m), and 30arc-second (1000m) resolutions. <strong>The</strong> 30 arc-second d<strong>at</strong>a are combined with the<br />
GTOPO30 d<strong>at</strong>a and processed by TERREL in the same way as the GTOPO30 d<strong>at</strong>a, so these d<strong>at</strong>a files<br />
should be presented as GTOPO30. <strong>The</strong> 1 and 3 arc-second d<strong>at</strong>a files must be processed as type<br />
SRTM1 and SRTM3, respectively. <strong>The</strong> SRTM d<strong>at</strong>a are available from links to the USGS site directly<br />
from the ASG website <strong>at</strong> http://www.src.com/d<strong>at</strong>asets/d<strong>at</strong>asets_terrain.html document<strong>at</strong>ion is<br />
available <strong>at</strong> the Jet Propulsion labor<strong>at</strong>ory, California Institute <strong>of</strong> Technology, <strong>at</strong><br />
http://www2.jpl.nasa.gov/srtm/and is included in Attachment 2-B.<br />
30 arc-second terrain d<strong>at</strong>a for the globe are available from the USGS WWW site:<br />
(http://eros.usgs.gov/#/Find_D<strong>at</strong>a/Products_and_D<strong>at</strong>a_Available/GTOPO30).<br />
2-4
Change language