UV index and UV dose: HDF-4 data file structure
data version 2.x

go to TEMIS Home Page

UV radiation
monitoring:
UV index
UV dose
Main data product description page
 

HDF-4 data file structure

This page describes the format of the daily HDF-4 files with daily data.
The yearly netCDF files with daily data are described here.
The daily data of UV index and UV dose fields is stored in daily HDF-4 data files.
These files can be downloaded from the individual archive pages of both the
operational and the MSR-2 processing.

Simply said, such a file has the following structure:

There are several tools around on the web for viewing and treating HDF-4 files, notably at the The HDF Group Home Page. Software for viewing and reading HDF-4 files is available at the HDF(4) tools page, where you can find a binary distributions for several operating systems (UNIX, Linux, Windows). See in particular the HDF tools by catergory overview, and the HDFview program. Furthermore, it is relative easy to convert HDF-4 to the more common HDF-5 format; see this page.

 
Daily UV index & UV dose HDF-4 data file structure

The following table gives as an overview of the HDF-4 file structure for daily UV index & UV dose data in two sections:

  1. The global attributes of the HDF-4 file
  2. The data sets daily data and their attributes
Per entry multiple lines are used to list the different possibilities, where:
  * Entries with white background are UV index entries
  * Entries with blue background are UV dose entries
  * Entries with page colour background are entries for both

 
Global attribute Value
   * YYYY, MM, DD = product date
Product Erythemal UV index
Product Erythemal UV dose (kJ/m2)
Vitamin-D UV dose (kJ/m2)
DNA-damage UV dose (kJ/m2)
Product_date YYYY, MM, DD
Product_date_format year, month, day
Product_filename uviefYYYYMMDD.hdf
Product_filename uvdecYYYYMMDD.hdf
uvdvcYYYYMMDD.hdf
uvddcYYYYMMDD.hdf
Product_version  [1] 2.x
Cloud_info Cloud-free datasets only
Cloud_info Cloud-free & cloud-modified datasets
Cloud_modification Derived from MSG CPP surface downwelling solar radiation (SDS) data
No data available: cloud-modification datasets are empty
UV_data_website http://www.temis.nl/uvradiation/UVindex.html
UV_data_website http://www.temis.nl/uvradiation/UVdose.html
UV_data_description http://www.temis.nl/uvradiation/product/
Authors M. van Weele  &  J. van Geffen
Affiliation KNMI (Royal Netherlands Meteorological Institute)
Email weelevm@knmi.nl  &  geffen@knmi.nl
Data_created_by TM3-DAM, version 4.3  &  temisuv, version {Product_version}
Ozone_data_source TEMIS operational ozone processing, started 01 July 2002
Number_of_longitudes 1440
Longitude_range -179.8750, 179.8750
Longitude_step 0.25
Number_of_latitudes 720
Latitude_range -89.87500,89.87500
Latitude_step 0.2500000
Earth-Sun_factor 0.9690452
AOD_368nm 0.3
Aerosol_ssa 0.9
UVI_field Erythemal UV index
UVI_error Error on the Erythemal UV index
UVI_units 1   [ 1 UV index unit equals 25 mW/m2 ]
UVI_scale_factor 0.001
UVD_cloud-free Cloud-free Erythemal UV dose
Cloud-free Vitamin-D UV dose
Cloud-free DNA-damage UV dose
UVD_cloud-free_error Error on the cloud-free Erythemal UV dose
Error on the cloud-free Vitamin-D UV dose
Error on the cloud-free DNA-damage UV dose
UVD_cloud-modified Cloud-modified Erythemal UV dose
Cloud-modified Vitamin-D UV dose
Cloud-modified DNA-damage UV dose
UVD_cloud-modified_error Error on the cloud-modified Erythemal UV dose
Error on the cloud-modified Vitamin-D UV dose
Error on the cloud-modified DNA-damage UV dose
UVD_units kJ/m2
UVD_scale_factor 0.001
Cloud_modification_factor Daily average of the cloud modification factor
Cloud_modification_units 1
Cloud_modification_scale_factor 0.001
Ozone_column Assimilated ozone field at local noon
Ozone_units Dobson units (DU)
Ozone_scale_factor 0.1
Surface_albedo GOME-2A based 0.25x0.25 degree surface albedo at 340nm,
                                            interpolated to Product_date
Surface_albedo_version Product algorithm version 2.1  or  3.1
Surface_albedo_data http://www.temis.nl/uvradiation/product/albedo.php
Surface_albedo_correction (1.0-0.25*0.09)/(1.0-0.25*albedo)   [ w.r.t De Bilt=0.09 ]
Surface_elevation GMTED2010 elevation data regridded at 0.250 degree resolution
Surface_elevation_data http://temis.nl/data/gmted2010/
Product_code  [2] tiefdv
Product_code  [2] tdecdv
tdvcdv
tddcdv
  1. The Product_version is 2.0, 2.1, ...; see this list for a version overview.
  2. See this page for info on the meaning of the product code.

 

Data set
      Attribute 		Rank --> dimensions
      Value
UVI_field
      Title
      Units
      Scale_factor
      No_data_value 		2 --> 1440 x 720
      Erythemal UV index
      1   [ 1 UV index unit equals 25 mW/m2 ]
      0.001
      -1000 * scale_factor
UVI_error
      Title
      Units
      Scale_factor
      No_data_value 		2 --> 1440 x 720
      Error on the Erythemal UV index
      1   [ 1 UV index unit equals 25 mW/m2 ]
      0.001
      -1000 * scale_factor
UVD_cloud-free
      Title
     
     
      Units
      Scale_factor
      No_data_value 		2 --> 1440 x 720
      Cloud-free Erythemal UV index
      Cloud-free Vitamin-D UV index
      Cloud-free DNA-damage UV index
      kJ/m2
      0.001
      -1000 * scale_factor
UVD_cloud-free_error
      Title
     
     
      Units
      Scale_factor
      No_data_value 		2 --> 1440 x 720
      Error on the cloud-free Erythemal UV index
      Error on the cloud-free Vitamin-D UV index
      Error on the cloud-free DNA-damage UV index
      kJ/m2
      0.001
      -1000 * scale_factor
UVD_cloud-modified
      Title
     
     
      Units
      Scale_factor
      No_data_value 		2 --> 1440 x 720
      Cloud-modified Erythemal UV index
      Cloud-modified Vitamin-D UV index
      Cloud-modified DNA-damage UV index
      kJ/m2
      0.001
      -1000 * scale_factor
UVD_cloud-modified_error
      Title
     
     
      Units
      Scale_factor
      No_data_value 		2 --> 1440 x 720
      Error on the cloud-modified Erythemal UV index
      Error on the cloud-modified Vitamin-D UV index
      Error on the cloud-modified DNA-damage UV index
      kJ/m2
      0.001
      -1000 * scale_factor
Cloud_modification_factor
      Title
      Units
      Scale_factor
      No_data_value 		2 --> 1440 x 720
      Daily average of the cloud modification factor
      1
      0.001
      -1000 * scale_factor
Ozone_column
      Title
      Units
      Scale_factor 		2 --> 1440 x 720
      Assimilated ozone field at local noon
      Dobson units (DU)
      0.1
Latitudes
      Title
      Units
      Step 		1 --> 720
      Latitudes of grid cell centres
      degrees north
      0.25
Longitudes
      Title
      Units
      Step 		1 --> 720
      Longitudes of grid cell centres
      degrees east
      0.25
Notes on data storage
The UV and ozone data are stored as scaled integers; the scale factor is listed
in the global and the dataset attributes: 1000 for the UV data and 10 for the
ozone data. These data is stored as 16-bit integers, to reduce file size.
The maximum number that fits in 16-bit integers is +32767, allowing for UV
index and daily UV dose values of up to 32, values which we assumed that
would not occur.
The ozone dat prior to the year 1979 has not been validated thoroughly and
should therefore be treated with care: the resulting UV index and daily UV
dose values are not reliable. It turns out that prior to 1979 the UV data may
show unrealistically(!) high values, even exceeding the value of 32.767, i.e.
exceeding the maximum number stored in the 16-bit integer, as a result of
which large negative values, e.g. -32.672, may appear. Given that a value
of -1.0 is used as fill value in case of no data, the recipe is as follows:
      if   UVval < -1   then   UVval_corrected = 65.536 + UVval
For example:   UVval = -32.672   means   UVval_corrected = 32.864

 

last modified: 20 July 2022
data product contact: Jos van Geffen & Michiel van Weele & Ronald van der A
Copyright © KNMI / TEMIS