Rainfall Atlas of Hawaii

Image files of the color zone rainfall maps as well as the isohyets have been created and are available for download as *.TIF files. The user has a choice of inches or millimeters, and each compressed *.zip file contains all 12 months plus the annual map. The color maps are available at a statewide extent as well as for each county, while the isohyets maps are only available for each island county (Maui Nui includes the islands of Maui, Moloka‘i, Lāna‘i and Kaho‘olawe).

Isohyets:

These images show the mean monthly rainfall as isohyets, or lines of equal rainfall. Both sets of isohyets (inches and mm) were created at appropriate intervals for their units, and therefore are not direct conversions of each other, though they are derived from the same data. The labels are included where they can fit, which means that not all isohyets are labeled, especially in steep gradient areas. Please see the interactive map or download the GIS or Google Earth layers for more information on isohyets labels.

Files for download:

Color Maps:

Unlike the interactive map which shows the rainfall as a continuous color ramp, these images display the rainfall in categories. The categories were set based on the natural breaks in the rainfall values for each extent, with the minimum and maximum values in the legend corresponding to the minimum and maximum values shown in the map extent. The categories were set independently for inches and millimeters, so the two sets will differ slightly.

Files for download:

GIS layers of the rainfall isohyets, rainfall grids, raingage stations, and uncertainty have been made available for download. Users can download the isohyets and stations as shapefiles, and the rainfall and uncertainty grids have been made available in ESRI and ASCII grid formats. These are available in either inches or millimeters, and each compressed *.zip file contains all 12 months plus the annual map. Rainfall isohyets and grids are available for the entire state or users can choose to download individual islands (Maui Nui includes the islands of Maui, Moloka‘i, Lāna‘i and Kaho‘olawe). Two station shapefiles are available (the same station information used in the interactive map), and the uncertainty grids are only available at the statewide extent. All files use geographic coordinates, WGS84 datum.

For more information about GIS, how to use GIS layers, or to obtain more Hawai‘i layers, please refer to the Hawai‘i State GIS page, http://www.state.hi.us/dbedt/gis/download.htm.  After downloading, users can upload layers to ArcGIS Online to make their own maps as an alternative to using a desktop GIS program, http://www.arcgis.com/home/.

Rainfall Grids:

Raster files are available at 250m resolution (0.00225 x 0.00225 cell size) for each island and for the state. These are available in inches or millimeters, and can be downloaded in ESRI grid format or ASCII grid format. These are the main output of this project, with the isohyets and other products being produced from these grids.

• Rainfall Grid Metadata
  
  

ESRI Grid Format:

ASCII Grid Format:

Rainfall Isohyets:

Rainfall isohyet files are available as polyline shapefiles for each island and for the state. These are available in inches or millimeters, and the "Contour" column in the attribute table contains the isohyet labels. Both sets of isohyets (inches and mm) were created at appropriate intervals for their units, and therefore are not direct conversions of each other, though they are derived from the same data.

• Isohyet Metadata

Raingage Stations:

Two point shapefiles containing station information are available for download. "RFAtlasStations" refers to the stations used to create the final rainfall atlas maps. "OtherStations" refers to all other stations that have operated in Hawai‘i, but for various reasons could not be included in the final analysis. The data available in the attribute table can also be downloaded as a *.csv or Microsoft Excel *.xslx file (see Tabular Downloads). 

Uncertainty:

The uncertainty grids are available at 250m resolution (0.00225 x 0.00225 cell size) for the state. These are available in inches or millimeters, and can be downloaded in ESRI grid format or ASCII grid format. These layers contain the combined standard error from all input sources to the final maps - see Methods for more information.

• Uncertainty Grid Metadata

ESRI Grid Format:

ASCII Grid Format:

The same files seen in the interactive map have also been converted into *.KML (*.KMZ) files which can be viewed in Google Earth. The stations and isohyets (lines of equal rainfall) will display their attribute information when an element is clicked on in Google Earth. The color rainfall maps do not contain the value information as they do on the interactive site, so the best way to view these in Google Earth is to set the transparency to overlay it onto the imagery. Maui Nui includes the islands of Maui, Moloka‘i, Lāna‘i and Kaho‘olawe.

The StationsKML.zip file contains two station files: "RFAtlas Stations" refers to the stations used to create the final rainfall atlas maps. "Other Stations" refers to all the other stations that have operated in Hawai‘i, but for various reasons could not be included in the final analysis. Click on a station for more information. The symbols are set automatically for these stations to be the same as on the interactive map:

• StationsKMLs.zip

The isohyet KMLs are available in inches or millimeters, with "Contour" referring to the isohyet label when you click on a line (labels will not be displayed unless you click on a line). Both sets of isohyets (inches and mm) were created at appropriate intervals for their units, and therefore are not direct conversions of each other, though they are derived from the same data.

Color Map KMLs are available by island: (use transparency in Google Earth for best viewing, as no legend is available at this time for these layers):

• HawaiiRainfall_KML.zip
• OahuRainfall_KML.zip
• MauiNuiRainfall_KML.zip
• KauaiRainfall_KML.zip

Raingage station data is available in *.csv (comma separated values) format as well as Microsoft Excel *.xlsx format.  The mean monthly data are available only for the stations used in the Rainfall Atlas (RFAtlas Stations).  The station information for all other stations is available as well (referred to as "Other Stations").  The monthly data is available in three different formats: Processed original data (data that has been screened for outliers and inhomogeneities), Filled Dataset (processed original data plus filled data from 1920-2007, used to create the rainfall atlas means), and Raw Original Monthly Data (the original data before removing inhomogeneities and other suspicious records).  All data files contain mm and inches.

An "About" tab has been included with each of these files to further explain the contents.  For details about the processing or gap filling, please read the final report, available for download below the tabular files.

Rainfall Atlas of Hawai‘i 2011 - Final Report