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Table 1: Dataset general attributesAnchor table1 table1
Dataset attribute | Details |
| Data type | Gridded |
| Projection | Regular grid |
| Horizontal coverage | Global |
| Horizontal resolution | 0.25° x 0.25° |
| Vertical coverage | Surface to top of atmosphere |
| Vertical resolution | Single level |
| Temporal coverage | 1979/01 - present |
| Temporal resolution | Monthly |
| File Format | NetCDF 4 |
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Variable name | Description | Units |
Divergence of vertical integral of total energy flux | This parameter is the horizontal rate of flow of total energy integrated over an atmospheric column extending from the surface of the Earth to the top of the atmosphere. The total energy in this parameter is the sum of sensible heat, latent heat (with latent heat of vaporization varying with temperature), kinetic, and potential energy, which is also referred to as the moist static plus kinetic energy. The total energy flux is the horizontal rate of flow of energy per metre. Its horizontal divergence is positive for a total energy flux that is spreading out, or diverging, and negative for a total 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 total 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 total energy flux | This parameter is the eastward component of the total energy flux integrated over an atmospheric column extending from the surface of the Earth to the top of the atmosphere. The total energy in this parameter is the sum of sensible heat, latent heat (with latent heat of vaporization varying with temperature), kinetic, and potential energy, which is also referred to as the moist static plus kinetic energy. This parameter is the horizontal rate of flow of energy per metre in east-west direction. It is positive for a total energy flux in eastward direction, and negative for a total 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 total 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 total energy flux | This parameter is the northward component of the total energy flux integrated over an atmospheric column extending from the surface of the Earth to the top of the atmosphere. The total energy in this parameter is the sum of sensible heat, latent heat (with latent heat of vaporization varying with temperature), kinetic, and potential energy, which is also referred to as the moist static plus kinetic energy. This parameter is the horizontal rate of flow of energy per metre in north-south direction. It is positive for a total energy flux in northward direction, and negative for a total 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 total 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 total energy | This parameter is the rate of change of total energy integrated over an atmospheric column extending from the surface of the Earth to the top of the atmosphere. In this parameter, the total energy is the sum of internal energy, latent heat (with latent heat of vaporization varying with temperature), kinetic, and potential 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. | W m-2 |
Divergence of vertical integral of 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 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 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 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. | W m-2 |
Divergence of vertical integral of 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 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 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 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. | kg m-2 s-1 |
Table 3: versions historyAnchor table3 table3
Version | Release date | Changes from previous version |
| 1.0 | 2022-05-31 | (first release) |
Input Data
Table 4: Input datasetsAnchor table4 table4
Dataset | Summary | Variables used |
| ERA5 | Provides global 1-hourly analyzed state quantities on 137 atmospheric model levels as well as analyzed surface parameters. Data are represented either on a reduced Gaussian grid N320 or as spectral coefficients with T639 triangular truncation (see ERA5 data documentation). | Temperature, vorticity, divergence, surface geopotential, and logarithm of surface pressure in 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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- The divergence terms (tediv, lhdiv, wvdiv) with full spectral resolution show artificial pattern of numerical noise over high topography, which are thus spectrally truncated at wave number 180. The divergence fields with full spectral resolution (see example in Fig. 1) can be reconstructed by computing the divergence of corresponding north- and eastward fluxes provided in this dataset.
- The ocean-to-land energy transport as estimated from tediv exhibits an unrealistically strong gradual change in the late 1990s and early 2000s, which likely stems from changes in the observing system that has been assimilated by ERA5 (see Mayer et al. 2021 for discussion).
- Global ocean and land averages of wvdiv exhibit a reasonably strong but statistically insignificant trend over the available period, see Mayer et al. (2021) for further details.
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Figure 1: The divergence of the vertical integral of total energy flux (left) truncated at wave number 180, and (right) with full spectral resolution T639.
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