
Data is from 1860
The use of these data is mostly aimed at:

addressing outstanding scientific questions that arose as part of the IPCC reporting process;
improving the understanding of the climate system;
providing estimates of future climate change and related uncertainties;
providing input data for the adaptation to the climate change;
examining climate predictability and exploring the ability of models to predict climate on decadal time scales;
evaluating how realistic the different models are in simulating the recent past.

MAIN VARIABLES
Name	Units	Description
Air temperature	K	Temperature in the atmosphere. It has units of Kelvin (K). Temperature measured in kelvin can be converted to degrees Celsius (°C) by subtracting 273.15. This parameter is available on multiple levels through the atmosphere.
Capacity of soil to store water (field capacity)	kg m-2	The total water holding capacity of all the soil in the grid cell divided by the land area of the grid cell.
Daily maximum near-surface air temperature	K	Daily maximum temperature of air at 2m above the surface of land, sea or inland waters.
Daily minimum near-surface air temperature	K	Daily minimum temperature of air at 2m above the surface of land, sea or inland waters.
Eastward near-surface wind	m s-1	Magnitude of the eastward component of the two-dimensional horizontal air velocity 10m above the surface.
Eastward wind	m s-1	Magnitude of the eastward component of the two-dimensional horizontal air velocity.
Evaporation including sublimation and transpiration	kg m-2 s-1	The transfer of latent heat (resulting from water phase changes, such as evaporation, condensation, sublimation and transpiration) between the Earth's surface and the atmosphere through the effects of turbulent air motion. Evaporation from the Earth's surface represents a transfer of energy from the surface to the atmosphere. It indicates a vector component which is positive when directed downward (negative upward).
Grid-cell area for ocean variables	m2	The area of the grid cell in the ocean. The data is time-independent.
Land ice area percentage	%	Fraction of grid cell occupied by "permanent" ice (e.g. glaciers). The data is time-independent.
Moisture in upper portion of soil column	kg m-2	Vertical sum per unit area from the surface down to the bottom of the soil model of water in all phases contained in soil.
Near-Surface air temperature	K	Temperature of air at 2m above the surface of land, sea or inland waters. 2m temperature is calculated by interpolating between the lowest model level and the Earth's surface, taking account of the atmospheric conditions.
Near-surface relative humidity	%	Amount of moisture in the air near the surface divided by the maximum amount of moisture that could exist in the air at a specific temperature and location.
Near-surface specific humidity	Dimensionless	Amount of moisture in the air near the surface divided by amount of air plus moisture at that location.
Near-surface wind speed	m s-1	Magnitude of the two-dimensional horizontal air velocity near the surface.
Northward near-surface wind	m s-1	Magnitude of the northward component of the two-dimensional horizontal air velocity 10m above the surface.
Percentage of the grid cell occupied by land including lakes	%	The percentage of land or lake surface in a grid cell. The data is time-independent.
Precipitation	kg m-2 s-1	The sum of liquid and frozen water, comprising rain and snow, that falls to the Earth's surface. It is the sum of large-scale precipitation and convective precipitation. This parameter does not include fog, dew or the precipitation that evaporates in the atmosphere before it lands at the surface of the Earth. This variable represents amount of water per unit area and time.
Relative humidity	%	Amount of moisture in the air divided by the maximum amount of moisture that could exist in the air at a specific temperature and location.
Sea area percentage	%	The percentage of sea surface in a grid cell. The data is time-independent.
Sea ice thickness	m	Vertical extent of ocean sea ice.
Sea level pressure	Pa	The pressure (force per unit area) of the atmosphere at the surface of the Earth, adjusted to the height of sea level. It is a measure of the weight that all the air in a column vertically above a point on the Earth's surface would have, if the point were located at sea level. It is calculated over all surfaces - land, sea and inland water.
Sea surface height above geoid	m	Vertical distance between the actual sea surface and a surface of constant geopotential with which mean sea level would coincide if the ocean were at rest.
Sea surface salinity	PSU	Salt concentration close to the ocean's surface.
Sea surface temperature	K	Temperature of sea water near the surface.
Sea-ice area percentage on ocean grid	%	Area of the sea surface occupied by sea ice.
Snow depth	m	Mean thickness of snow.
Snowfall flux	kg m-2 s-1	Mass of water in the form of snow precipitating per unit area.
Specific humidity	Dimensionless	Amount of moisture in the air divided by amount of air plus moisture at that location.
Surface air pressure	Pa	The pressure (force per unit area) of the air at the lower boundary of the atmosphere. It is a measure of the weight that all the air in a column vertically above a point on the Earth's surface. It is calculated over all surfaces - land, sea and inland water.
Surface altitude	m	The height above the geoid (being 0.0 over the sea). The data is time-independent.
Surface downward eastward wind stress	Pa	Eastward component of the horizontal drag exerted by the atmosphere on the surface through turbulent processes.
Surface downward northward wind stress	Pa	Northward component of the horizontal drag exerted by the atmosphere on the surface through turbulent processes.
Surface downwelling longwave radiation	W m-2	Radiative longwave flux of energy downward at the surface.
Surface downwelling shortwave radiation	W m-2	Radiative shortwave flux of energy downward at the surface.
Surface snow amount	kg m-2	Snow amount on the ground, excluding that on the plant or vegetation canopy, per unit area.
Surface temperature	K	Temperature at the interface (not the bulk temperature of the medium above or below) between air and sea for open-sea regions.
Surface temperature of sea ice	K	Temperature that exists at the interface of the sea-ice and the overlying medium which may be air or snow.
Surface upward latent heat flux	W m-2	Flux per unit area of heat between the surface and the air on account of evaporation including sublimation. Positive when directed upward (negative downward).
Surface upward sensible heat flux	W m-2	Flux per unit area of heat between the surface and the air by motion of air only. Positive when directed upward (negative downward).
Surface upwelling longwave radiation	W m-2	Radiative longwave flux of energy from the surface per unit area.
Surface upwelling shortwave radiation	W m-2	Radiative longwave flux of energy from the surface per unit area.
TOA incident shortwave radiation	W m-2	Incoming solar radiation received from the Sun, at the top of the atmosphere.
TOA outgoing longwave radiation	W m-2	Longwave radiation from the top of the atmosphere to space per unit area.
TOA outgoing shortwave radiation	W m-2	Shortwave radiation from the top of the atmosphere to space per unit area.
Total cloud cover percentage	Dimensionless	Fraction of horizontal area occupied by clouds as seen from the surface to the top of the atmosphere in the whole atmosphere column.
Total runoff	kg m-2 s-1	Amount per unit area of surface and subsurface liquid water which drains from land.