Sensitivity of tropical deep convection in global models: effects of horizontal resolution, surface constraints, and <scp>3D</scp> atmospheric nudging

Chemel, Charles; Russo, M. R.; Hosking, J. Scott; Telford, P.; Pyle, J. A.

doi:10.1002/asl2.540

Cited by 5 publications

(6 citation statements)

References 32 publications

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“…As for the expiration, it is an important link of the water balance and energy balance, and is an important process for contacting the hydrology dynamic changes with the variations of vegetation ecology. Namely, the expiration process is the most important link in coupling effect of hydrologic cycle of land atmosphere system (Miller and Russell, ; Chemel et al ., ). In addition, it should be pointed out that river runoff has been evolving with the change of the earth and the world.…”

Section: Introductionmentioning

confidence: 97%

Multi‐scale response of runoff to climate fluctuation in the headwater region of the Kaidu River in Xinjiang of China

Liu

Wang

et al. 2017

Atmospheric Science Letters

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Section: Introductionmentioning

confidence: 97%

Multi‐scale response of runoff to climate fluctuation in the headwater region of the Kaidu River in Xinjiang of China

Liu

Wang

et al. 2017

Atmospheric Science Letters

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“…Previous studies have addressed how the model skill and representation of cloud systems change as the horizontal resolution (Chemel et al, ; Hanley et al, ; Stein et al, ) or vertical resolution (Barrett et al, ) are changed. However, to our knowledge, no study has so far looked at the impact of changing the model time step independently from resolution changes.…”

Section: Introductionmentioning

confidence: 99%

“…There are numerous potential causes for these weaknesses, such as convective initiation affected by interactions with the land surface (Hanley et al, 2011;Schneider et al, 2018) or errors in simulation at the synoptic scale (Barrett et al, 2015), only partially resolving the convective structures because of model resolution (e.g., Chemel et al, 2015), the weakness of single-moment microphysical parameterizations compared to double-moment schemes (Igel et al, 2015), or the inherent unpredictability of convective events (Barthlott et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

One Step at a Time: How Model Time Step Significantly Affects Convection‐Permitting Simulations

Barrett

Wellmann

Seifert

et al. 2019

J Adv Model Earth Syst

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We show that there is a strong sensitivity of cloud microphysics to model time step in idealized convection‐permitting simulations using the COnsortium for Small‐scale MOdeling model. Specifically, we found a 53% reduction in precipitation when the time step is increased from 1 to 15 s, changes to the location of precipitation and hail reaching the surface, and changes to the vertical distribution of hydrometeors. The effect of cloud condensation nuclei perturbations on precipitation also changes both magnitude and sign with the changing model time step. The sensitivity arises because of the numerical implementation of processes in the model, specifically the so‐called “splitting” of the dynamics (e.g., advection and diffusion) and the parameterized physics (e.g., microphysics scheme). Calculating one step at a time (sequential‐update splitting) gives a significant time step dependence because large supersaturation with respect to liquid is generated in updraft regions, which strongly affect parameterized microphysical process rates—in particular, ice nucleation. In comparison, calculating both dynamics and microphysics using the same inputs of temperature and water vapor (hybrid parallel splitting) or adding an additional saturation adjustment within the dynamics reduces the time step sensitivity of surface precipitation by limiting the supersaturation seen by the microphysics, although sensitivity to time step remains for some processes.

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“…The horizontal distribution of convection is less realistic in models with a coarse resolution (e.g., Russo et al, 2011;Chemel et al, 2015). In particular, coarse-resolution models fail to correctly represent geographical features around the Maritime Continent, where CHBr 3 emissions might be large , such as coastlines (Schiemann et al, 2014) and orography (Kirshbaum and Smith, 2009).…”

Section: Introductionmentioning

confidence: 99%

On the emissions and transport of bromoform: sensitivity to model resolution and emission location

et al. 2015

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Abstract. Bromoform (CHBr 3 ) is a short-lived species with an important but poorly quantified ocean source. It can be transported to the Tropical Tropopause Layer (TTL), in part by rapid, deep convective lifting, from where it can influence the global stratospheric ozone budget. In a modelling study, we investigate the importance of the regional distribution of the emissions and of model resolution for the transport of bromoform to the TTL. We use two idealized CHBr 3 emission fields (one coastal, one uniformly distributed across the oceans) implemented in high-and coarse-resolution (HR and CR) versions of the same global model and focus on February as the period of peak convection in the West Pacific. Using outgoing long-wave radiation and precipitation as metrics, the HR version of the model is found to represent convection better. In the more realistic HR model version, the coastal emission scenario leads to 15-20 % more CHBr 3 in the global TTL, and up to three times more CHBr 3 in the TTL over the Maritime Continent, than when uniform emissions of the same tropical magnitude are employed. Using the uniform emission scenario in both model versions, the distribution of CHBr 3 at 15.7 km (approximately the level of zero net radiative heating) is qualitatively consistent with the differing geographic distributions of convection. However, averaged over the whole tropics, the amount of CHBr 3 in the TTL in the two model versions is similar. Using the coastal scenario, in which emissions are particularly high in the Maritime Continent because of its long coastlines, the mixing ratio of CHBr 3 in the TTL is enhanced over the Maritime Continent in both model versions. The enhancement is larger, and the peak in CHBr 3 mixing ratio occurs at a higher altitude, in the HR model version. Our regional-scale results indicate that using aircraft measurements and coarse global models to infer CHBr 3 emissions will be very difficult, particularly if (as is possible) emissions are distributed heterogeneously and in regions of strong convective activity. In contrast, the global-scale agreement between our CR and HR calculations suggests model resolution is less vital for studies focused on the transport of bromine into the global stratosphere.

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Sensitivity of tropical deep convection in global models: effects of horizontal resolution, surface constraints, and 3D atmospheric nudging

Cited by 5 publications

References 32 publications

Multi‐scale response of runoff to climate fluctuation in the headwater region of the Kaidu River in Xinjiang of China

Multi‐scale response of runoff to climate fluctuation in the headwater region of the Kaidu River in Xinjiang of China

One Step at a Time: How Model Time Step Significantly Affects Convection‐Permitting Simulations

On the emissions and transport of bromoform: sensitivity to model resolution and emission location

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