This document describes the format of the NewAtmosphere HDF database file format.
This describes version 2 of this data model. This file contains the all of the DIRSIG standard metadata as attributes on the document root. In addition to those attributes, the following are also defined on the document root:
Name  Data Type  Dimensions  Description 



3 
The WGS84 latitude, longitude and altitude of the origin of this data model. 
Custom Data Types
The following custom HDF data types are defined in this data models:
AngleRanges
Type 
Compound 
This type represents angle ranges for zenith and azimuth angles. Units are in radians. The following fields are defined:
Name  Data Type  Description 



Minimum zenith angle 


Maximum zenith angle 


Sampling period for zenith angle 


Minimum azimuth angle 


Maximum azimuth angle 


Sampling period for azimuth angle 
WavelengthInfoRecord
Type 
Compound 
This type represents a row in the spectral state metadata table. The following fields are defined:
Name  Data Type  Description 



The number of wavelengths in the spectral state 


The index in the wavelength list of the reference wavelength for the state 
/Altitudes
Type 
Dataset 
Data Type 

Dataspace Type 
Simple 
Dimensions 
N 
Contains a list of the altitudes that are sampled in this data model. Units for the altitudes are in meters. The size of this data set will determine the first dimension of all path tables in this data model. The following attributes are defined on this dataset:
Name  Data Type  Dimensions  Description 



1 
The sampling period for altitude samples that was used to generate these samples. Units are meters. 
/SkyAngleRanges
Type 
Dataset 
Data Type 

Dataspace Type 
Simple 
Dimensions 
1 
Contains the angle ranges that are used when generating sky path tables. This dataset can be used to calculate the size of the angle dimension of those tables. The number of samples in each angle can be calculated via:
floor((max  min) / delta + 1.5)
and the total number of angular samples is the product of the number of samples in each angle.
/SpectralStates
Type 
Group 
Contains information about the spectral states that are referenced by the combo states in this data model.
WavelengthInfoTable
Type 
Dataset 
Data Type 

Dataspace Type 
Simple 
Dimensions 
N 
Contains metadata about each spectral state. Rows in this table correspond to the spectral state index and also the row in WavelengthSamplesTable.
WavelengthSamplesTable
Type 
Dataset 
Data Type 

Dataspace Type 
Simple 
Dimensions 
N x M 
Contains the wavelength samples for each spectral state. Units are in microns. The rows correspond to the spectral state index and have a corresponding row in WavelengthInfoTable. Each row has the same number of columns, however, not all columns are necessarily used. The row in WavelengthInfoTable describes how many columns are valid for each state.
/State:index
Type 
Group 
Contains the atmospheric data for the combo state with and index of :index
.
:index
is a zerobased integer index with no zeropadding. The following
attributes are defined on this group:
Name  Data Type  Dimensions  Description 



1 
Azimuth of the moon [degrees] 


1 
Phase angle of the moon [degrees] 


1 
Phase fraction of the moon 


1 
Zenith of the moon [degrees] 


1 
Azimuth of the sun [degrees] 


1 
Zenith of the sun [degrees] 


1 
Index of the referenced spectral state 


1 
Index of the referenced temporal state 
LunarIrradiance
Type 
Dataset 
Data Type 

Dataspace Type 
Simple 
Dimensions 
N 
Contains the lunar exoatmospheric irradiance spectrum. Units are
W / (cm^2 micron)
. The size of this dataset is the same as the number of
wavelength samples in the spectral state.
LunarTransmission
Type 
Dataset 
Data Type 

Dataspace Type 
Simple 
Dimensions 

Contains the lunar transmission spectrum as a function of altitude. The size of
this dataset is N_alt x N_w
, where N_alt
is the number altitude samples and
N_w
is the number of wavelength samples in the spectral state.
SensorAngleRanges
Type 
Dataset 
Data Type 

Dataspace Type 
Simple 
Dimensions 
1 
Contains the angle ranges that are used when generating sensor path tables. This dataset can be used to calculate the size of the angle dimension of those tables. The number of samples in each angle can be calculated via:
floor((max  min) / delta + 1.5)
and the total number of angular samples is the product of the number of samples in each angle.
SensorExtinctions
Type 
Dataset 
Data Type 

Dataspace Type 
Simple 
Dimensions 

This is the sensor path table for extinction. Units are 1 / m
. The size of
this dataset is N_alt x N_ang,sens x N_w
, where N_alt
is the number of
altitude samples, N_ang,sens
is the number of sensor angular samples, given
by SensorAngleRanges, and N_w
is the number of wavelength samples in the
spectral state.
SensorRadiances
Type 
Dataset 
Data Type 

Dataspace Type 
Simple 
Dimensions 

This is the sensor path table for radiance.
Units are W / (cm^2 sr micron) / m
.
The size of this dataset is N_alt x N_ang,sens x N_w
, where N_alt
is the
number of altitude samples, N_ang,sens
is the number of sensor angular
samples, given by SensorAngleRanges, and N_w
is the number of wavelength
samples in the spectral state.
SensorRanges
Type 
Dataset 
Data Type 

Dataspace Type 
Simple 
Dimensions 

This table stores the range at which the sensor path tables were calculated. It
can be used to scale path radiances to the actual path length needed in the
simulation. The size of this data set is N_alt x N_ang,sens
, where N_alt
is
the number of altitude samples, N_ang,sens
is the number of sensor angular
samples, given by SensorAngleRanges.
SkyRadiances
Type 
Dataset 
Data Type 

Dataspace Type 
Simple 
Dimensions 

This is the sky path table for radiances. Units are W / (cm^2 sr micron)
.
The size of this dataset is N_alt x N_ang,sky x N_w
, where N_alt
is the
number of altitude samples, N_ang,sky
is the number of sky angular samples,
given by /SkyAngleRanges, and N_w
is the number of wavelength samples in
the spectral state.
SkyTransmission
Type 
Dataset 
Data Type 

Dataspace Type 
Simple 
Dimensions 

This is the sky path table for transmissions. The size of this dataset is
N_alt x N_ang,sky x N_w
, where N_alt
is the number of altitude samples,
N_ang,sky
is the number of sky angular samples, given by /SkyAngleRanges,
and N_w
is the number of wavelength samples in the spectral state.
SolarIrradiance
Type 
Dataset 
Data Type 

Dataspace Type 
Simple 
Dimensions 
N 
Contains the solar exoatmospheric irradiance spectrum. Units are
W / (cm^2 micron)
. The size of this dataset is the same as the number of
wavelength samples in the spectral state.
SolarTransmission
Type 
Dataset 
Data Type 

Dataspace Type 
Simple 
Dimensions 

Contains the solar transmission spectrum as a function of altitude. The size of
this dataset is N_alt x N_w
, where N_alt
is the number altitude samples and
N_w
is the number of wavelength samples in the spectral state.
/TemporalStates
Type 
Dataset 
Data Type 

Dataspace Type 
Simple 
Dimensions 
N 
Contains information about the temporal states referenced by the combo states in this data model. Each element is the temporal offset from the reference data time, in units of multiples of the time delta. Both of these quantities are given as attributes on this data set:
Name  Data Type  Dimensions  Description 



1 
ISO8601 string encoding the reference date/time of this data model. 


1 
The time in seconds used to scale the temporal offsets in this data set. 