LRO DIVINER Gridded Data Record Level 3 (GDR_L3)

GDR_L3 – Gridded Data Record Level 3

Instrument:Diviner Lunar Radar Experiment

PDS Data Set ID: LRO-L-DLRE-5-GDR-V1.0

For more information about Diviner GDR_L2 products, see the RDR and Derived Product SIS.

For more information about all Diviner products, see the Diviner Archive SIS.

The Diviner Lunar Radar Experiment Gridded Data Record (GDR) Level 3 data products include Christiansen Feature (CF) position, Rock Abundance, Soil Temperature, and Root Mean Square (RMS) fitting errors between measured and modeled radiances.

The CF position is the wavelength of a major mid-infrared emissivity peak near 8 microns. It is a measure of silicate composition and shifts to shorter wavelengths for feldspathic lithologies (e.g. highlands) and longer wavelengths for mafic lithologies (e.g. maria). The CF position is also correlated with geochemical composition (generally shorter CF position for higher Si, Na, Ca and longer for higher Fe, Mg). The CF position is calculated from Diviner channels 3, 4, and 5 radiances. Each radiance is binned and averaged and then converted to brightness temperature. The three point brightness temperature spectrum is solved quadratically to determine the maximum brightness temperature. Emissivity values are then calculated for channels 3, 4, and 5. The emissivity spectrum is solved quadratically to determine the CF position.

Two types of CF maps are created:

  1. Standard CF: CF calculated using a quadratic fit to the three 8-micron channels to determine the wavelength location of the emissivity peak. This map includes the best TOD data available for each longitude.

  2. Normalized to Equatorial Noon (NEN) CF: Standard CF normalized to equatorial noon by the “best effort” of the Diviner science team.

Rock Abundance and Soil Temperature are derived from nighttime Diviner Channel 6, 7, and 8 observations by fitting the measured radiances to a two component model that assumes that the observed scene consists of an unknown mixture of soil and rock. The temperature of the rock component taken from thermal model results assumes a semi-infinite rock thermal inertia of 1000 (MKS units) and the rock fractional coverage and the soil temperature are fitted parameters.

RMS fitting errors are with respect to measured and modeled Diviner radiance in channels 6, 7, and 8 using the rock abundance and soil temperature determination technique described in Bandfield et al. 2011 (doi:10.1029/2011JE003866).

For Rock Abundance, Soil Temperature, and RMS fitting error, ten lunar-hourly maps spanning the local time range of 19:30 to 5:30 are produced. All maps are simple cylindrical projections covering the latitude range -60 to +60 degrees at 32 ppd resolution.

All GDRs consist of images employing scaled binary 16-byte integers with the extension .IMG, and associated geotagged JPEG2000 format files with the extension .JP2, as well as a sample low-resolution JPEG image with the extension .JPG, for easy viewing. Each format has a detached PDS label that describes their contents and includes useful metadata. The label has the extension .LBL.

The following table lists the values in each gridded data product:

Value

Description

STD_CF

Standard Christiansen Feature position.  One cumulative map.

NEN_CF

Normalized to Equatorial Noon Christiansen Feature position.  One cumulative map.

RA

Rock Abundance.  A ration from 0 to 1.  Nighttime hourly, and all hours averaged together.

ST

Soil Temperature.  Average temperature in degrees Kelvin.  Nighttime hourly, and all hours averaged together.

STN

Soil Temperature normalized to remove local latitudinal variations.  Average temperature in degrees Kelvin.  All hours averaged together.

RMS

Root Mean Square fitting errors between measured and modeled radiances.  Nighttime hourly only.

TBOL

Bolometric Temperature.

There are a number of different file naming conventions for GDR_L3 products. For all, CYL means cylindrical projection, POL means polar projection, AVG = averaged bin type, and CLC = calculated bin type.

Diviner GDR_L3 CF products have the following file names:

DGDR_vvv_CF_CLC_CYL_rrr_xxx (with detached PDS labels for each product)

where:

vvv = value binned (STD or NEN)

rrr = resolution in pixels/degree

xxx = file type/extension

IMG.IMG = 16-bit LSB binary integers

JP2.JP2 = JPEG2000

Diviner GDR_L3 RA and ST products have the following file names:

DGDR_RA_AVG_CYL_rrr_xxx (with detached PDS labels for each product)

DGDR_RA_CLC_CYL_hhmm_rrr_xxx (with detached PDS labels for each product)

DGDR_RA_CLC_CYL_yyyymmddt_rrr_xxx (with detached PDS labels for each product)

where:

hhmm = beginning local time of the lunar hour in hours and minutes

yyyymmdd = date beginning the mapping cycle

t = time of day

D = daytime

N = nighttime

rrr = resolution in pixels/degree

xxx = file type/extension

IMG.IMG = 16-bit LSB binary integers

JP2.JP2 = JPEG2000

Diviner GDR_L3 STN products have the following file names:

DGDR_STN_AVG_CYL_rrr_xxx (with detached PDS labels for each product)

where:

rrr = resolution in pixels/degree

xxx = file type/extension

IMG.IMG = 16-bit LSB binary integers

JP2.JP2 = JPEG2000