Overview

Overview of the GLASS products

The Global Land Surface Satellite (GLASS) Product suite has been expanded from the original five products (Liang, et al., 2013a,b) to the current 14 products: Leaf Area Index (LAI), Broadband Albedo (Albedo), Broadband Emissivity (BBE), Fraction of Absorbed Photosynthetically Active Radiation (FAPAR), Downward Shortwave Radiation (DSR), Photosynthetically Active Radiation (PAR), Net Long-wave Radiation (LWNR), Net Radiation (NR), Land Surface Temperature (LST), Fractional Vegetation Coverage (FVC), Latent Heat Flux (LE), Gross Primary Production (GPP), Snow Cover Extent over the Tibetan Plateau (TPSCE), and Global Aboveground Biomass (AGB).

The GLASS products have several unique features, for example

1. many of these products span over 35 years -- from 1981 to the present, especially valuable for long-term environmental change studies;

2. the radiation products have the spatial resolution of 5km, much finer than the commonly used products (e.g., CERES, GEWEX);

3. all products are spatially and temporally continuous with no gaps and missing values;

4. The broadband longwave emissivity product is the first product of this kind in the world at 8-day temporal resolution and 1km spatial resolution;

5. the GLASS products have been demonstrated to have high quality and accuracies. They have been widely used.

HDF file naming convention

GLASS level-3 products are stored in HDF-EOS format, including twelve products, including LAI, Albedo, BBE, PAR, DSR, LWNR, NR, LST, FPAR, FVC, ET, and GPP. The overall naming rules of HDF files for each product are as follows.

(1) Basic format：

GLASSXXNYY. VXX. AYYYYDDD.HRRVPP.YYYYDDD.hdf.

where GLASS represents The Global Land Surface Satellite (GLASS) Product.

GLASS + variable number + spatial resolution + tile information + production date.

(2) XX: variable number

Number	Abbr.	Full Name
01	LAI	Leaf Area Index
02	Albedo	Surface Broadband Albedo
03	BBE	Broadband Emissivity
04	PAR	Photosynthetically Active Radiation
05	DSR	Downward Shortwave Radiation
06	LWNR	Surface Longwave Net Radiation
07	NR	Surface All-wave Net Radiation
08	LST	Land Surface Temperature
09	FAPAR	Fraction of Photosynthetically Active Radiation
10	FVC	Fractional Vegetation Cover
11	ET	Evapotranspiration
12	GPP	Gross Primary Production

(3) N: spatial resolution mark, specifically

GLASSXXAYY: 1 km spatial resolution

GLASSXXBYY: 0.05° spatial resolution

GLASSXXCYY: 5km spatial resolution

GLASSXXDYY: 250m spatial resolution

GLASSXXEYY: 500m spatial resolution

GLASSXXFYY: 0.01° spatial resolution

GLASSXXGYY: 0.5° spatial resolution

GLASSXXHYY: 0.1° spatial resolution

GLASSXXJYY: 0.25° spatial resolution

(4) YY: data source. ‘01’ means it is retrieved from MODIS; ‘02’ means it is retrieved from AVHRR data.

(5) VXX: product version, e.g., V40

(6) AYYYYDDD: Year and Day of Year

(7) HRRVPP: tile information in sinusoidal projection, same as the MODIS level-3 products

HRR-Horizontal Line Number

VPP-Vertical Column Number

MODIS Sinusoidal Tiles: https://modis-land.gsfc.nasa.gov/MODLAND_grid.html

Note: HRRVPP is ignored when global products (e.g., 0.05 AVHRR-based products) are released

(8) YYYYDDD：production date

References

[1].Liang, S., Zhao, X., Yuan, W., Liu, S., Cheng, X., Xiao, Z., Zhang, X., Liu, Q., Cheng, J., Tang, H., Qu, Y.H., Bo, Y., Qu, Y., Ren, H., Yu, K., & Townshend, J. (2013a). A Long-term Global LAnd Surface Satellite (GLASS) Dataset for Environmental Studies. International Journal of Digital Earth, 6, 5-33

[2].Liang, S., Zhang, X., Xiao, Z., Cheng, J., Liu, Q., & Zhao, X. (2013b). Global LAnd Surface Satellite (GLASS) products: Algorithms, validation and analysis. Springer

[3].Liang, S., Cheng, C., Jia, K., Jiang, B., Liu, Q., Xiao, Z., Yao, Y., Yuan, W., Zhang, X., Zhao, X., & Zhou, J. (2020). The Global LAnd Surface Satellite (GLASS) products suite. Bulletin of the American Meteorological Society, DOI: 10.1175/BAMS-D-18-0341.1 [Download]