GIS for Atmospheric Sciences and Hydrology
description
Transcript of GIS for Atmospheric Sciences and Hydrology
GIS for Atmospheric Sciences and Hydrology
By David R. Maidment
University of Texas at Austin
National Center for Atmospheric Research, 6 July 2005
GIS for Atmospheric Science and Hydrology
• Space-time data models
• Hydrologic observations data
• Weather and climate data
• Common data model
Atmospheric science – hydrology
• Weather and climate fields are the drivers – continuous in space and time across the nation
• Hydrologic flows in watersheds are the reactors – behaving according to watershed location and characteristics
Issues
• Atmospheric science describes a fluid domain continuous in space and time, globally connected
• The earth’s surface is a static, highly spatially varied domain whose water properties vary continuously in time, where water is concentrated in flow paths (streams and rivers)
Issues
• Atmospheric science data are spatially extensive (e.g. North America), involve many variables, are “thin” in time (one day, one forecast period, one month), and use UTC time coordinates
• Hydrologic data are spatially localized (e.g. my watershed), involve few variables (precipitation, evaporation, runoff), are “deep” in time (many decades), and use local time coordinates
This space-time recompositing problem Is not trivial!
Issues
• Atmospheric science data are stored in vary large binary files with specialized formats (Grib, netCDF, XMRG, ….) whose georeferencing may not be strong
• Hydrologic data are stored in tables in GIS and relational databases, and accessed using GIS spatial and SQL queries
How do we connect these very different data worlds?
Space, L
Time, T
Variables, V
D
Data Cube
Continuous Space-Time Data Model -- NetCDF
Space, L
Time, T
Variables, V
D
Coordinate dimensions
{X}
Variable dimensions{Y}
Space, FeatureID
Time, TSDateTime
Variables, TSTypeID
TSValue
Discrete Space-Time Data Model-- Arc Hydro
Geospatial Time Series
Value
Time
Shape
Time SeriesProperties
(Type)A Value-Time array
A time series that knows what geographic feature it describes and what type of time series it is
GIS for Atmospheric Science and Hydrology
• Space-time data models
• Hydrologic observations data
• Weather and climate data
• Common data model
Data Model for Hydrologic Observations
Relationships
USGS National Water Information System
Access is rapid enough that it is as if NWIS is a local disk on your computer
CUAHSI Data Portal
CUAHSI Data Portal
Plot from the Hydrology Data PortalProduced using a CUAHSI Hydrology Web Service: getDailyStreamflowChart
Applications and Services
Web ServicesLibrary
Web application: Data PortalYour application• Excel, ArcGIS, Matlab• Fortran, C/C++, Visual Basic• Hydrologic model• …………….
Your operating system• Windows, Unix, Linux, Mac
Internet
GIS for Atmospheric Science and Hydrology
• Space-time data models
• Hydrologic observations data
• Weather and climate data
• Common data model
http://wwwt.emc.ncep.noaa.gov/mmb/rreanl/
A retrospective study of weather and climate made by the National Centers for Environmental Prediction’s (NCEP)
numerical weather prediction model and observations from 1979 to 2003 to make 3 hour forecasts. 3 hour, daily and
monthly data are available on a 32 km grid over North America.
Using IDV and THREDDS to access NARR
NARR.xml
Get NARR.xml from NARR home page
NARR at Asheville, NC
IDV in Austin, TX
Precipitable Water and Specific Humidity over Gulf
0.005 0.020 Specific humidity (kg/kg)
Alti
tude
Precipitable Water and Specific Humidity over Texas
0.005 0.020 Specific humidity (kg/kg)
Alti
tude
Precipitation
July 2003, 1800Z
Surface evaporation
July 2003, 1800Z
GIS for Atmospheric Science and Hydrology
• Space-time data models
• Hydrologic observations data
• Weather and climate data
• Common data model
NetCDF-Java version 2.2 Common Data Model
John Caron
Unidata/UCAR
Dec 10, 2004
NetcdfDataset
Application
Scientific Datatypes
Grid Station Image
NetCDF-Java version 2.2 architecture
ADDEOpenDAPTHREDDS
Catalog.xml NetCDF-3
HDF5
I/O service provider
GRIB
GININIDS
NetcdfFile
NetCDF-4
…NexradDMSP
File Format#N
File Format#2
File Format#1
CDM
Visualization&Analysis
Goal: N + M instead of N * M things on your TODO List
NetCDF file
Data Server
Web Service
ArcGIS ModelBuilder Application for Automated Water Balancing
Conclusions
• Data access through web services can mask the variations in data structure between relational databases and data file systems
• We need a “Common, common” data model to better integrate GIS and weather and climate information
• We need tools for space-time recompositing of weather and climate information to make it suitable for hydrology