PML_V2 global evapotranspiration and gross primary production (2000.02-2023.12)

Summary

This data is an 8-day 5km (0.05°) data aggregated from the latest 8day 500m PML-V2 global evapotranspiration and gross primary production data in Google Earth Engine, available since 2000.2.26 to 2023 (latest and will update annually).

Notes

8-day means an average of the variable for the 8 days (xx d-1).

Land evapotranspiration (ET) can be computed as a sum of Ec, Ei, and Es, while in water, Penman evapotranspiration denotes actual evaporation (ET_water).

In a 5km resolution, please do not add ET_water to land ET as they represent a different coverage of area within the 5km pixel. Please see the coverage ratio file for each variable.

BandName
Units
Scale
Description

GPP
gC m-2 d-1
0.01
Gross primary product

Ec
mm d-1
0.01
Vegetation transpiration

Es
mm d-1
0.01
Soil evaporation

Ei
mm d-1
0.01
Interception from vegetation canopy

ET_water
mm d-1
0.01
Water body, snow and ice evaporation. Penman evapotranspiration is regarded as actual evaporation for them.

Changes

Here, this PML-V2 dataset denotes the latest update that follows the original implementation of Zhang et al., 2019, except with Terra LAI for longer temporal coverage and annual updates.

Temporal coverage lengthened to 2000.2-2023.12

Using MODIS Terra LAI (MOD15A2H) with original wWhd smoother processing as in Kong et al., 2019

Recalibrated with the new MODIS Terra LAI

Other climatic forcing and MODIS input remain the same

Google Earth Engine

Original 500m 8-day data in GEE

https://developers.google.com/earth-engine/datasets/catalog/CAS_IGSNRR_PML_V2_v018

Methods

Penman-Monteith-Leuning Evapotranspiration V2 (PML_V2) products include evapotranspiration (ET), its three components, and gross primary product (GPP) at 500m and 8-day resolution during 2000-2017 and with spatial range from -60°S to 90°N. The major advantages of the PML_V2 products are:

coupled estimates of transpiration and GPP via canopy conductance (Gan et al., 2018; Zhang et al., 2019)

partitioning ET into three components: transpiration from vegetation, direct evaporation from the soil and vaporization of intercepted rainfall from vegetation (Zhang et al., 2016).

The PML_V2 products perform well against observations at 95 flux sites across globe, and are similar to or noticeably better than major state-of-the-art ET and GPP products widely used by water and ecology science communities (Zhang et al., 2019).

References

Zhang, Y., Kong, D., Gan, R., Chiew, F.H.S., McVicar, T.R., Zhang, Q., and Yang, Y., 2019. Coupled estimation of 500m and 8-day resolution global evapotranspiration and gross primary production in 2002-2017. Remote Sens. Environ. 222, 165-182, doi:10.1016/j.rse.2018.12.031

Gan, R., Zhang, Y.Q., Shi, H., Yang, Y.T., Eamus, D., Cheng, L., Chiew, F.H.S., Yu, Q., 2018. Use of satellite leaf area index estimating evapotranspiration and gross assimilation for Australian ecosystems. Ecohydrology, doi:10.1002/eco.1974

Zhang, Y., Peña-Arancibia, J.L., McVicar, T.R., Chiew, F.H.S., Vaze, J., Liu, C., Lu, X., Zheng, H., Wang, Y., Liu, Y.Y., Miralles, D.G., Pan, M., 2016. Multi-decadal trends in global terrestrial evapotranspiration and its components. Sci. Rep. 6, 19124. doi:10.1038/srep19124