Abstract The degree of improvement in convective representation in NWP with horizontal grid spacings finer than 3 km remains debatable. While some research suggests subkilometer horizontal grid spacing is needed to resolve details of convective structures, other studies have shown that decreasing grid spacing from 3–4 to 1–2 km offers little additional value for forecasts of deep convection. In addition, few studies exist to show how changes in vertical grid spacing impact thunderstorm forecasts, especially when horizontal grid spacing is simultaneously decreased. The present research investigates how warm-season central U.S. simulated MCS cold pools for 11 observed cases are impacted by decreasing horizontal grid spacing from 3 to 1 km, while increasing the vertical levels from 50 to 100 in WRF runs. The 3-km runs with 100 levels produced the deepest and most negatively buoyant cold pools compared to all other grid spacings since updrafts were more poorly resolved, resulting in a higher flux of rearward-advected frozen hydrometeors, whose melting processes were augmented by the finer vertical grid spacing, which better resolved the melting layer. However, the more predominant signal among all 11 cases was for more expansive cold pools in 1-km runs, where the stronger and more abundant updrafts focused along the MCS leading line supported a larger volume of concentrated rearward hydrometeor advection and resultant latent cooling at lower levels.
more »
« less
Large Changes in Sea Ice Triggered by Small Changes in Atlantic Water Temperature
More Like this
-
-
Abstract Background As human activity alters the planet, there is a pressing need to understand how organisms adapt to environmental change. Of growing interest in this area is the role of epigenetic modifications, such as DNA methylation, in tailoring gene expression to fit novel conditions. Here, we reanalyzed nine invertebrate (Anthozoa and Hexapoda) datasets to validate a key prediction of this hypothesis: changes in DNA methylation in response to some condition correlate with changes in gene expression. Results In accord with previous observations, baseline levels of gene body methylation (GBM) positively correlated with transcription, and negatively correlated with transcriptional variation between conditions. Correlations between changes in GBM and transcription, however, were negligible. There was also no consistent negative correlation between methylation and transcription at the level of gene body methylation class (either highly- or lowly-methylated), anticipated under the previously described “seesaw hypothesis”. Conclusion Our results do not support the direct involvement of GBM in regulating dynamic transcriptional responses in invertebrates. If changes in DNA methylation regulate invertebrate transcription, the mechanism must involve additional factors or regulatory influences.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1175/JCLI-D-17-0802.1
