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titleList of acronyms


Acronym

Description

tediv

Divergence of vertical integral of atmospheric moist static plus kinetic energy flux 

tefle

Vertical integral of eastward atmospheric moist static plus kinetic energy flux

tefln

Vertical integral of northward atmospheric moist static plus kinetic energy flux

tetend 

Tendency of vertical integral of atmospheric total energy

lhdiv

Divergence of vertical integral of atmospheric latent heat flux

lhfle

Vertical integral of eastward atmospheric latent heat flux

lhfln

Vertical integral of northward atmospheric latent heat flux

lhtend

Tendency of vertical integral of atmospheric latent heat

wvdiv

Divergence of vertical integral of atmospheric water vapour flux

wvfle

Vertical integral of eastward atmospheric water vapour flux

wvfln

Vertical integral of northward atmospheric water vapour flux

wvtend

Tendency of vertical integral of atmospheric water vapour

ReResidual of the dry air mass budget
TTemperature in Kelvin
TcTemperature in Celsius
qSpecific humidity
vHorizontal wind field vector
pSSurface pressure
PPrecipitation
EEvaporation
ΦGeopotential
kKinetic energy of air
LvLatent heat of vaporization
gGravitational acceleration (9.81 m s-2)
cp Specific heat capacity of dry air at constant pressure (1004.70 J kg-1 K-1)
cvSpecific heat capacity of dry air at constant volume (717.65 J kg-1 K-1)
clSpecific heat of liquid water (4218.00 J kg-1 K-1)
cpvSpecific heat of water vapor at constant pressure (1846.10 J kg-1 K-1)


Introduction

Executive Summary

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table1
table1
Table 1: Dataset general attributes

Dataset attribute

Details

Data typeGridded
ProjectionRegular grid
Horizontal coverageGlobal
Horizontal resolution0.25° x 0.25°
Vertical coverageSurface to top of atmosphere
Vertical resolutionSingle level
Temporal coverage1979/01 - present
Temporal resolutionMonthly
File FormatNetCDF 4


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table2
table2
Table 2: Variables summary

Variable name

Description

Units

Divergence of vertical integral of atmospheric moist static plus kinetic energy flux

This parameter is the horizontal rate of flow of moist static plus kinetic energy integrated over an atmospheric column extending from the surface of the Earth to the top of the atmosphere. The moist static energy is the sum of sensible heat, latent heat (with latent heat of vaporization varying with temperature), and potential energy. The moist static plus kinetic energy flux is the horizontal rate of flow of energy per metre. Its horizontal divergence is positive for a moist static plus kinetic energy flux that is spreading out, or diverging, and negative for a moist static plus kinetic energy flux that is concentrating, or converging. The sensible heat is referenced to 0 degree Celsius, whereby sensible heat of water vapour is neglected. Winds used for computation of fluxes of moist static plus kinetic energy are mass-adjusted according to the diagnosed imbalance between divergence of vertically integrated dry mass flux and tendency of dry air mass. This parameter is truncated at wave number 180 to reduce numerical noise.

W m-2

Vertical integral of eastward atmospheric moist static plus kinetic energy flux

This parameter is the eastward component of the moist static plus kinetic energy flux integrated over an atmospheric column extending from the surface of the Earth to the top of the atmosphere. The moist static energy is the sum of sensible heat, latent heat (with latent heat of vaporization varying with temperature), and potential energy. This parameter is the horizontal rate of flow of energy per metre in east-west direction. It is positive for a moist static plus kinetic energy flux in eastward direction, and negative for a moist static plus kinetic energy flux in westward direction. The sensible heat is referenced to 0 degree Celsius, whereby sensible heat of water vapour is neglected. Winds used for computation of fluxes of moist static plus kinetic energy are mass-adjusted according to the diagnosed imbalance between divergence of vertically integrated dry mass flux and tendency of dry air mass.

W m-1

Vertical integral of northward atmospheric moist static plus kinetic energy flux

This parameter is the northward component of the moist static plus kinetic energy flux integrated over an atmospheric column extending from the surface of the Earth to the top of the atmosphere. The moist static energy is the sum of sensible heat, latent heat (with latent heat of vaporization varying with temperature), and potential energy. This parameter is the horizontal rate of flow of energy per metre in north-south direction. It is positive for a moist static plus kinetic energy flux in northward direction, and negative for a moist static plus kinetic energy flux in southward direction. The sensible heat is referenced to 0 degree Celsius, whereby sensible heat of water vapour is neglected. Winds used for computation of fluxes of moist static plus kinetic energy are mass-adjusted according to the diagnosed imbalance between divergence of vertically integrated dry mass flux and tendency of dry air mass.

W m-1

Tendency of vertical integral of atmospheric total energy

This parameter is the rate of change of moist static plus kinetic energy integrated over an atmospheric column extending from the surface of the Earth to the top of the atmosphere. The total energy is the sum of internal energy, latent heat (with latent heat of vaporization varying with temperature), potential, and kinetic energy. The vertical integral of total energy is the total amount of atmospheric energy per unit area. Its tendency, or rate of change, is positive if the total energy increases and negative if the total energy decreases in an atmospheric column. The sensible heat is referenced to 0 degree Celsius, whereby sensible heat of water vapour is neglected. This parameter represents monthly changes and is computed as exact difference of total energy from 00 UTC at the first of month to the first of following month divided by the number of seconds of month using analyzed state quantities from ERA5.

W m-2

Divergence of vertical integral of atmospheric latent heat flux

This parameter is the horizontal rate of flow of latent heat integrated over an atmospheric column extending from the surface of the Earth to the top of the atmosphere. Latent heat is the amount of energy required to convert liquid water to water vapour. The latent heat flux is the horizontal rate of flow per metre. Its horizontal divergence is positive for a latent heat flux that is spreading out, or diverging, and negative for a latent heat flux that is concentrating, or converging. Winds used for computation of fluxes of latent heat are mass-adjusted according to the diagnosed imbalance between divergence of vertically integrated dry mass flux and tendency of dry air mass. The latent heat of vaporization is computed as a function of temperature. This parameter is truncated at wave number 180 to reduce numerical noise.

W m-2

Vertical integral of eastward atmospheric latent heat flux

This parameter is the eastward component of the latent heat flux integrated over an atmospheric column extending from the surface of the Earth to the top of the atmosphere. Latent heat is the amount of energy required to convert liquid water to water vapour. This parameter is the horizontal rate of flow of latent heat per metre in east-west direction. It is positive for a latent heat flux in eastward direction, and negative for a latent heat flux in westward direction. Winds used for computation of fluxes of latent heat are mass-adjusted according to the diagnosed imbalance between divergence of vertically integrated dry mass flux and tendency of dry air mass. The latent heat of vaporization is computed as a function of temperature.

W m-1

Vertical integral of northward atmospheric latent heat flux

This parameter is the northward component of the latent heat flux integrated over an atmospheric column extending from the surface of the Earth to the top of the atmosphere. Latent heat is the amount of energy required to convert liquid water to water vapour. This parameter is the horizontal rate of flow of latent heat per metre in north-south direction. It is positive for a latent heat flux in northward direction, and negative for a latent heat flux in southward direction. Winds used for computation of fluxes of latent heat are mass-adjusted according to the diagnosed imbalance between divergence of vertically integrated dry mass flux and tendency of dry air mass. The latent heat of vaporization is computed as a function of temperature.

W m-1

Tendency of vertical integral of atmospheric latent heat

This parameter is the rate of change of latent heat integrated over an atmospheric column extending from the surface of the Earth to the top of the atmosphere. Latent heat is the amount of energy required to convert liquid water to water vapour. The vertical integral of latent heat is the total amount of latent heat per unit area. Its tendency, or rate of change, is positive if the latent heat increases and negative if the latent heat decreases in an atmospheric column. The latent heat of vaporization is computed as a function of temperature. This parameter represents monthly changes and is computed as exact difference of latent heat from 00 UTC at the first of month to the first of following month divided by the number of seconds of month using analyzed state quantities from ERA5.

W m-2

Divergence of vertical integral of atmospheric water vapour flux

This parameter is the horizontal rate of flow of water vapour integrated over an atmospheric column extending from the surface of the Earth to the top of the atmosphere. The water vapour flux is the horizontal rate of flow per metre. Its divergence is positive for a water vapour flux that is spreading out, or diverging, and negative for a water vapour flux that is concentrating, or converging. Winds used for computation of fluxes of water vapour are mass-adjusted according to the diagnosed imbalance between divergence of vertically integrated dry mass flux and tendency of dry air mass. This parameter is truncated at wave number 180 to reduce numerical noise.

kg m-2 s-1

Vertical integral of eastward atmospheric water vapour flux

This parameter is the eastward component of the water vapour flux integrated over an atmospheric column extending from the surface of the Earth to the top of the atmosphere. This parameter is the horizontal rate of flow of water vapour per metre in east-west direction. It is positive for a water vapour flux in eastward direction, and negative for a water vapour flux in westward direction. Winds used for computation of fluxes of water vapour are mass-adjusted according to the diagnosed imbalance between divergence of vertically integrated dry mass flux and tendency of dry air mass.

kg m-1 s-1

Vertical integral of northward atmospheric water vapour flux

This parameter is the northward component of the water vapour flux integrated over an atmospheric column extending from the surface of the Earth to the top of the atmosphere. This parameter is the horizontal rate of flow per metre in north-south direction. It is positive for a water vapour flux in northward direction, and negative for a water vapour flux in southward direction. Winds used for computation of fluxes of water vapour are mass-adjusted according to the diagnosed imbalance between divergence of vertically integrated dry mass flux and tendency of dry air mass.

kg m-1 s-1

Tendency of vertical integral of atmospheric water vapour

This parameter is the rate of change of water vapour integrated over an atmospheric column extending from the surface of the Earth to the top of the atmosphere. The vertical integral of water vapour is the total amount of atmospheric moisture per unit area. Its tendency, or rate of change, is positive if the water vapour increases and negative if the water vapour decreases in an atmospheric column. This parameter represents monthly changes and is computed as exact difference of water vapour from 00 UTC at the first of month to the first of following month divided by the number of seconds of month using analyzed state quantities from ERA5.

kg m-2 s-1

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table3
table3
Table 3: versions history

Version

Release date

Changes from previous version

1.02022-XX-XX(first release)

Input Data

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table4
table4
Table 4: Input datasets

Dataset

Summary

Variables used

ERA5

Provides global 1-hourly analyzed state quantities on 137 atmospheric levels on a reduced Gaussian grid N320 and as spherical harmonics with spectral resolution T639. 

Surface geopotential, temperature, vorticity, divergence, and logarithm of surface pressure and spherical harmonics. Specific humidity and total column water vapour in grid space.

Method

Background

All ERA5 input fields are transformed (for details see below) to a full Gaussian grid F480 (quadratic grid with respect to the native spectral resolution T639) to avoid aliasing effects. Vorticity and divergence are used to compute the horizontal wind vector at each atmospheric level. Before individual budget terms are computed, the three-dimensional wind field is iteratively adjusted according to the diagnosed imbalance between divergence of vertically integrated dry mass flux and tendency of dry air.  This procedure is repeated every time step. 

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Mayer, J., Mayer, M., Haimberger, L.,(2022):Atmospheric  Mass-consistent atmospheric energy and moisture budget data from 1979 to present derived from ERA5 reanalysis, v1.0, Copernicus Climate Change Service (C3S) Climate Data Store (CDS). (Accessed on <DD-MMM-YYYY>), <location i.e. doi/url TBC>.

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