In the Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA-2) system the land is forced by replacing the model-generated precipitation with observed precipitation before it reaches the surface. This approach is motivated by the expectation that the resultant improvements in soil moisture will lead to improved land surface latent heating (LH). Here we assess aspects of the MERRA-2 land surface energy budget and 2 m air temperatures (T(sup 2m)). For global land annual averages, MERRA-2 appears to overestimate the LH (by 5 W/sq m), the sensible heating (by 6 W/sq m), and the downwelling shortwave radiation (by 14 W/sq m), while underestimating the downwelling and upwelling (absolute) longwave radiation (by 10-15 W/sq m each). These results differ only slightly from those for NASA's previous reanalysis, MERRA. Comparison to various gridded reference data sets over Boreal summer (June-July-August) suggests that MERRA-2 has particularly large positive biases (>20 W/sq m) where LH is energy-limited, and that these biases are associated with evaporative fraction biases rather than radiation biases. For time series of monthly means during Boreal summer, the globally averaged anomaly correlations (R(sub anom)) with reference data were improved from MERRA to MERRA-2, for LH (from 0.39 to 0.48 vs. GLEAM data) and the daily maximum T(sup 2m) (from 0.69 to 0.75 vs. CRU data). In regions where T(sup 2m) is particularly sensitive to the precipitation corrections (including the central US, the Sahel, and parts of south Asia), the changes in the T(sup 2m) R(sub anom) are relatively large, suggesting that the observed precipitation influenced the T(sup 2m) performance.
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