UV Atlas

More information about NIWA's UV Atlas

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Download UV Atlas version 2.2

The installation package for UV Atlas version 2.2 can be downloaded, after registration, by following the link below. Download the file named setup.exe and save it to your computer, then run setup.exe from your computer to install the program.

Register to receive UV Atlas version 2.2

The first time that you run the program it is recommended that you also download some data to work with. This version of the UV Atlas gets updates of the data files from the internet (although some sample data files are provided). Select the Data Update menu option to get the data that you need from the NIWA server. The data files that the program uses will be regularly updated and so if you find that the data that you need is not in the files that you have, please use this data update facility to get the latest files.

Note: this program will run only under the Microsoft Windows operating system. If you are running a different operating system, you will not be able to use this software to view the data. Please contact us for alternatives.

A two page extended abstract, from the release of UV Atlas version 2 (at the UV Workshop in Dunedin, 19-21 April 2006), which details some of the new features added is available below.

More about UV Atlas version 2 (PDF 107 KB)

If the data and/or plots provided through the NIWA UV Atlas project are intended for use in scientific publications, please contact us so that we can discuss appropriate acknowledgement for use of the UV Atlas data.

Regular updates to the software, together with details of bug fixes and improvements, will be available from this web page in the future. Please check this web page regularly for updates.

A description of the UV Atlas

The aim of the UV Atlas project is to produce maps and time series of parameters describing the UV radiation environment over New Zealand since 1960. Maps are produced for the area around New Zealand (34° to 48°S, 166° to 180°E) while time series are produced at sites where broadband radiation measurements are available.

The input data to the UV Atlas project are as follows:

  • hourly temperature, sea level pressure, measured broadband radiation and humidity data from the National Climate Database.
  • 12 hourly, 2.5° x 2.5°, sea level pressure fields from the NCEP/NCAR reanalysis project.
  • daily total column ozone fields from the NIWA assimilated total column ozone data base. The data are gridded to 1° latitude x 1.25° longitude. More information on this ozone database is available in the following publication: Bodeker, G.E.; Shiona, H.; Eskes, H. (2005). Indicators of Antarctic ozone depletion. Atmospheric Chemistry and Physics 5: 2603-2615.
  • New Zealand topography (altitude in meters) at ~1km horizontal resolution.

National Climate Database

NCEP/NCAR reanalysis project 

All of the data from the National Climate Database have been passed through strict data quality control procedures. The sea level pressure and total column ozone data are used to calculate the clear-sky UV irradiance (Emodel) using a radiative transfer model. The sea level pressure, temperature, and humidity are used to calculate the clear-sky broadband irradiance (Imodel) using a radiative transfer model. The estimated true UV irradiance, including the effect of clouds, is then calculated from:

Etrue = Emodel × A × (Imeas/Imodel)P

where Imeas is the measured broadband radiation and A and P are coefficients that depend on solar zenith angle. This technique is described in more detail in:

Bodeker, G.E.; McKenzie, R.L. (1996). An algorithm for inferring surface UV irradiance including cloud effects. Journal of Applied Meteorology 35(10): 1860–1877.

Description of data products

The data products produced by the UV Atlas project include maps of:

  • clear-sky erythemal UV
  • estimated true erythemal UV
  • sea level pressure
  • surface pressure
  • total column ozone

For maps at hourly resolution, the following 9 UV irradiance products can be plotted:

  • UV Index (UVI)
  • Erythemally Weighted UV (McKinlay and Diffey, 1987)
  • Plant Damage Weighted UV (Caldwell, 1989)
  • DNA Damage Weighted (Setlow 1993)
  • Plant Damage Weighted UV (Flint and Caldwell, 2003)
  • USC Skin Cancer (de Gruijl et al. 1993)
  • UVB 280-315nm
  • UVB 280-320nm
  • Vitamin D synthesis (McLaughlin et al. 1982)

The primary UV product (and the most accurate) is the erythemally-weighted UV, or UV Index. For the other weighting functions, a radiative transfer model was used to pre-calculate look-up tables, which are functions of solar zenith angle and ozone column amount, to convert erythemally weighted UV to the new weighting, as described in McKenzie, R., D. Smale, and M. Kotkamp, Relationship between UVB and erythemally weighted radiation, Photochemical & Photobiological Sciences, 3 (3), 252 – 256, 2004.

For maps at daily, monthly, or annual resolution, only erythemal irradiances can be plotted. Future versions of the UV Atlas will include the other irradiance products at these temporal resolutions.

Maps are produced for every hour of every day, except for total column ozone which is produced daily. Daily, monthly, and annual means of these maps are also provided, except for estimated true UV irradiances which are provided only at hourly resolution.

The time series provided at each location where broadband radiation is measured include:

  • clear-sky UV irradiance (hourly, daily, monthly and annual)
  • estimated true UV irradiance (hourly, daily, monthly and annual)
  • cloud cover modification factors (hourly, daily, monthly and annual)
  • modelled broadband radiation (hourly, daily, monthly and annual)
  • measured broadband radiation (hourly, daily, monthly and annual)
  • temperature (hourly, daily, monthly and annual)
  • surface pressure (hourly, daily, monthly and annual)
  • sea level pressure (hourly, daily, monthly and annual)
  • humidity (hourly, daily, monthly and annual)
  • total column ozone (daily, monthly and annual).

All 9 UV irradiance products, listed above, are available for location time series. As part of the data quality control, auxiliary data files (best estimates of the parameter based on measurements at surrounding locations) are produced for temperature, sea level pressure and humidity. Data quality report files are produced for temperature, sea level pressure, humidity and measured broadband radiation. The auxiliary and data quality report files are also made available. In addition to daily, monthly and annual means, maxima, minima and totals are also provided.

Contact details

For problems with the UV Atlas version 2.2 software and general information on the UV Atlas project:

NIWA Private Bag 50061 Omakau Central Otago New Zealand Fax: +64 3 4473348 Phone: +64 3 4473411

Related links

NIWA Contacts