Evaporation from Land

Terrestrial evaporation is an important process in the global water cycle. It acts like an air conditioner for the surface, as it absorbs radiation (latent heat) that otherwise would be used to warm up the atmosphere (sensible heat). At the same time, water vapour acts as a greenhouse gas by trapping radiation in the lower atmosphere. Evaporation acts as a climate change diagnostic, being very sensitive to changes in atmospheric composition and the Earth's radiation balance. Moreover, it plays a crucial role in dampening the intensification of drought and heatwave events, it is a pivotal variable for agriculture that determines the needs for irrigation, and it constrains human water management.

Evaporation from Land

Figure: Global Map of Evaporation from Land in 2018.

Source: The figure is based on data from the Global Land Evaporation Amsterdam Model (GLEAM)(https://www.gleam.eu/#datasets).

ECV Products and Requirements

These products and requirements reflect the Implementation Plan 2022 (GCOS-244).

Products			Sensible Heat Flux	Latent Heat Flux	Bare Soil Evaporation	Interception Loss	Transpiration
	*()**	Unit	Values	Values	Values	Values	Values
Horizontal Resolution	G	km	1	0.1	0.1	0.1	0.1
	B		–	1	1	1	1
	T		25	25	25	25	25
Vertical Resolution	G		-	-	-	-	-
	B		-	-	-	-	-
	T		-	-	-	-	-
Temporal Resolution	G	h	1	1	1	1	1
	B		-	6	6	6	6
	T		24	24	24	24	24
Timeliness	G	d	1	1	1	1	1
	B		30	30	30	30	30
	T		365	365	365	365	365
Required Measurement Uncertainty (2-sigma)	G	%	10	10	20	20	20
	B		20	20	30	30	40
	T		40	40	50	50	50
Stability	G	W m^-2 y^-1	0.015	0.015	0.015	0.015	0.015
	B		-	-	–	–	–
	T		0.03	0.03	0.03	0.03	0.03

The requirements are found in the complete 2022 ECVs Requirements document as well: ECV Evaporation from Land.(*) Goal (G): an ideal requirement above which further improvements are not necessary. Breakthrough (B): an intermediate level between threshold and goal which, if achieved, would result in a significant improvement for the targeted application. The breakthrough value may also indicate the level at which specified uses within climate monitoring become possible. It may be appropriate to have different breakthrough values for different uses. Threshold (T): the minimum requirement to be met to ensure that data are useful.

Data sources

This list provides sources for openly accessible data sets with worldwide coverage for which metadata is available. It is curated by the respective GCOS ECV Steward(s). The list does not claim to be complete. Anyone with a suitable dataset who wishes it to be added to this list should contact the abombelliwmo [dot] int (GCOS Secretariat).

FLUXCOM
Global Land Evaporation Amsterdam Model (GLEAM)
MOD16
Penman–Monteith–Leuning (PML)
Priestley–Taylor, Jet Propulsion Laboratory (PT-JPL)
ORG (Inventory for Reanalysis)

Domain:

Land

Subdomain:

Hydrology

Scientific Area:

Hydrosphere

ECV Steward:

Diego Miralles

Products:

Sensible Heat Flux, Latent Heat Flux, Bare Soil Evaporation, Interception Loss, Transpiration