Development of the GEOS-5 atmospheric general circulation model: evolution from MERRA to MERRA2

Molod, Andrea; Takacs, Lawrence L.; Suárez, Max J.; Bacmeister, Julio T.

doi:10.5194/gmd-8-1339-2015

Cited by 1,009 publications

(846 citation statements)

References 41 publications

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“…MERRA-2 (Gelaro et al, 2017) uses a similar model and assimilation system to MERRA, with updates also described by Bosilovich et al (2015), Molod et al (2015), and Takacs et al (2016). Some of the changes between MERRA and MERRA-2 that may affect UTLS dynamical fields are as follows:…”

Section: Merra and Merra-2mentioning

confidence: 99%

Reanalysis comparisons of upper tropospheric–lower stratospheric jets and multiple tropopauses

et al. 2017

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Abstract. The representation of upper tropospheric–lower stratospheric (UTLS) jet and tropopause characteristics is compared in five modern high-resolution reanalyses for 1980 through 2014. Climatologies of upper tropospheric jet, subvortex jet (the lowermost part of the stratospheric vortex), and multiple tropopause frequency distributions in MERRA (Modern-Era Retrospective analysis for Research and Applications), ERA-I (ERA-Interim; the European Centre for Medium-Range Weather Forecasts, ECMWF, interim reanalysis), JRA-55 (the Japanese 55-year Reanalysis), and CFSR (the Climate Forecast System Reanalysis) are compared with those in MERRA-2. Differences between alternate products from individual reanalysis systems are assessed; in particular, a comparison of CFSR data on model and pressure levels highlights the importance of vertical grid spacing. Most of the differences in distributions of UTLS jets and multiple tropopauses are consistent with the differences in assimilation model grids and resolution – for example, ERA-I (with coarsest native horizontal resolution) typically shows a significant low bias in upper tropospheric jets with respect to MERRA-2, and JRA-55 (the Japanese 55-year Reanalysis) a more modest one, while CFSR (with finest native horizontal resolution) shows a high bias with respect to MERRA-2 in both upper tropospheric jets and multiple tropopauses. Vertical temperature structure and grid spacing are especially important for multiple tropopause characterizations. Substantial differences between MERRA and MERRA-2 are seen in mid- to high-latitude Southern Hemisphere (SH) winter upper tropospheric jets and multiple tropopauses as well as in the upper tropospheric jets associated with tropical circulations during the solstice seasons; some of the largest differences from the other reanalyses are seen in the same times and places. Very good qualitative agreement among the reanalyses is seen between the large-scale climatological features in UTLS jet and multiple tropopause distributions. Quantitative differences may, however, have important consequences for transport and variability studies. Our results highlight the importance of considering reanalyses differences in UTLS studies, especially in relation to resolution and model grids; this is particularly critical when using high-resolution reanalyses as an observational reference for evaluating global chemistry–climate models.

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Section: Merra and Merra-2mentioning

confidence: 99%

Reanalysis comparisons of upper tropospheric–lower stratospheric jets and multiple tropopauses

et al. 2017

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“…This effect has the potential to suppress precipitation and lead to a greater retention of liquid water within the cloud (the second indirect, lifetime, or Albrecht effect) (Albrecht, 1989;Gryspeerdt et al, 2016;Sekiguchi et al, 2003). Empirical studies have established some evidence supporting the existence of these effects in 30 liquid clouds (Gryspeerdt et al, 2016;Quaas et al, 2008;Nakajima et al, 2001;Sekiguchi et al, 2003;McCoy et al, 2017;Meskhidze and Nenes, 2006), although it has been argued that compensating physical processes Atmos. Chem.…”

Section: Introductionmentioning

confidence: 99%

“…However, based on observational case-studies and modelling it is known that both the synoptic-scale atmospheric processes and much smaller scale cloud microphysical processes play a role in regulating the cyclone lifecycle (Naud et al, 2016;Grandey et al, 2013;Lu and Deng, 2016;Thompson and Eidhammer, 2014;Igel et al, 2013). 25 In general for warm rain processes, enhanced aerosol that can act as cloud condensation nuclei (CCN) should enhance cloud droplet number concentration (CDNC, the first indirect, or Twomey effect) (McCoy et al, 2017;Nakajima et al, 2001;Charlson et al, 1992;Twomey, 1977).…”

Section: Introductionmentioning

confidence: 99%

“…25 In general for warm rain processes, enhanced aerosol that can act as cloud condensation nuclei (CCN) should enhance cloud droplet number concentration (CDNC, the first indirect, or Twomey effect) (McCoy et al, 2017;Nakajima et al, 2001;Charlson et al, 1992;Twomey, 1977). This effect has the potential to suppress precipitation and lead to a greater retention of liquid water within the cloud (the second indirect, lifetime, or Albrecht effect) (Albrecht, 1989;Gryspeerdt et al, 2016;Sekiguchi et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

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The aerosol-cyclone indirect effect in observations and high-resolution simulations

McCoy

Field

Schmidt

et al. 2017

Preprint

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Abstract. Aerosol-cloud interactions are a major source of uncertainty in predicting 21 st century climate change. Using highresolution, convection-permitting global simulations we predict that increased cloud condensation nuclei (CCN) interacting 10 with midlatitude cyclones will increase their cloud droplet number concentration (CDNC), liquid water (CLWP), and albedo.For the first time this effect is shown with 13 years of satellite observations. Causality between enhanced CCN and enhanced cyclone liquid content is supported by the 2014 eruption of Holuhraun. The change in midlatitude cyclone albedo due to enhanced CCN in a surrogate climate model is around 70% of the change in a high-resolution convection-permitting model, indicating that climate models may underestimate this indirect effect. 15

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“…The Modern-Era Retrospective analysis for Research and Applications-2 (MERRA2) is the current re-analysis of NASA's Goddard Earth Observing System-5 (GEOS-5) model with 3-hourly output extending up to 0.01 hPa (Molod et al, 2015). It is the successor of the discontinued MERRA re-analysis used in the intercomparison study by Kishore Kumar et al (2015).…”

mentioning

confidence: 99%

Validation of middle-atmospheric wind in observations and models

Rüfenacht

Baumgarten

Hildebrand

et al. 2017

Preprint

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Abstract. Wind profile information throughout the upper stratosphere and lower mesosphere (USLM) is important for the understanding of atmospheric dynamics but became available only recently, thanks to developments in remote sensing techniques and modelling approaches. However, as wind measurements from these altitudes are still very rare, such products havegenerally not yet been validated with (other) observations. This paper presents the first long-term intercomparison of wind observations in the USLM by opposing co-located microwave radiometer and lidar instruments at Andenes (69.3 • N, 16.0 • E). 5Good correspondence has been found at all altitudes for both horizontal wind components for nighttime as well as daylight conditions. Biases are mostly within the random errors and do not exceed 5-10 m/s which is less than 10% of the typically encountered wind speeds. Moreover, comparisons of the observations with the major re-analyses and models covering this altitude range are shown, especially also with the freshly released ERA5, ECMWF's first re-analysis to cover the whole USLM region. The agreement between models and observations is very good in general, but temporally limited occurrences of pro-10 nounced discrepancies (up to 40 m/s) exist. In the article's appendix the possibility of obtaining nighttime wind information about the mesopause region by means of microwave radiometry is investigated.

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Development of the GEOS-5 atmospheric general circulation model: evolution from MERRA to MERRA2

Cited by 1,009 publications

References 41 publications

Reanalysis comparisons of upper tropospheric–lower stratospheric jets and multiple tropopauses

Reanalysis comparisons of upper tropospheric–lower stratospheric jets and multiple tropopauses

The aerosol-cyclone indirect effect in observations and high-resolution simulations

Validation of middle-atmospheric wind in observations and models

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