On the contribution of internal variability and external forcing factors to the Cooling trend over the Humid Subtropical Indo-Gangetic Plain in India

Role of local absorbing aerosols in modulating Indian summer monsoon rainfall

Absorbing aerosols and their impact on the Indian monsoon system is highly complex and demands more scientific understanding. Our study using a chemistry-coupled regional climate model (RegCM 4.5) with idealized experiments observed that natural and anthropogenic absorbing aerosols (i.e., dust and carbonaceous aerosols) reduce monsoon precipitation in a seasonal time scale. More than 1 mm day-1 decline in mean summertime rainfall was observed over parts of the central Indian region and Indo-Gangetic plane for dust aerosol. A substantial reduction in the land-sea pressure gradient and lower tropospheric moisture distribution were found to control the observed modulation in rainfall. Near-surface wind circulation responded distinctly to natural (dust) and anthropogenic (carbonaceous) aerosols. The dust forcing weakened the monsoon trough by creating an anomalous anticyclonic circulation. The Northern Arabian Sea acted as a moisture source for the carbonaceous aerosol forcing. Intraseasonal rainfall over central India appeared to have a sharp reduction for dust forcing during early June, with a moderate increase for carbonaceous aerosols. Such quantification is essential for understanding the impact of aerosol forcing on regional climate change and the water cycle and has implications for emissions management and mitigation policies.

Stable reference gene selection for quantitative real-time PCR normalization in passion fruit (Passiflora edulis Sims.)

BACKGROUND

Passiflora edulis is a tropical fruit with high nutrient and medicinal values that is widely planted in southern China. However, the molecular biology of P. edulis has not been well studied. There are few reports regarding the choice of reference genes for gene expression studies of passion fruit.

METHODS AND RESULTS

By using three algorithms, implemented in geNorm, NormFinder and BestKeeper, we have selected ten candidate reference genes to explore their transcriptional expression stability in various tissues and under cold stress conditions. EF1 and HIS were stably expressed in five tissues. Ts and OTU were stably in vegetative organs. 50 S and Liom were stably in reproductive organs. The transcriptional abundance of EF1 and UBQ was stable in cold-treated and recovery treated leaf samples of P. edulis. In all samples, EF1 and Ts exhibited the highest expression stability. Evaluation of selected genes using simple statistical methods (ANOVA and post hoc analysis). Overall, EF1 emerged as the optimum reference gene for qRT-PCR normalize in P. edulis. In addition, the qRT-PCR analysis revealed that expression of ICE1 increases with the duration of cold treatment.

CONCLUSIONS

In this study, we successfully screened stable reference genes from 10 candidates in P. edulis and verified the results by analyzing the expression level of ICE1. The results provide reliable and effective reference genes for future research on gene expression analysis in P. edulis, and lay a foundation for follow-up research on functional genes in P. edulis.

Temperature Projections over the Indus River Basin of Pakistan Using Statistical Downscaling

We assessed maximum (Tmax) and minimum (Tmin) temperatures over Pakistan’s Indus basin during the 21st century using statistical downscaling. A particular focus was given to spatiotemporal heterogeneity, reference and General Circulation Model (GCM) uncertainties, and statistical skills of regression models using an observational profile that could significantly be improved by recent high-altitude observatories. First, we characterized the basin into homogeneous climate regions using K-means clustering. Predictors from ERA-Interim reanalysis were then used to model observed temperatures skillfully and quantify reference and GCM uncertainties. Thermodynamical (dynamical) variables mainly governed reference (GCM) uncertainties. The GCM predictors under RCP4.5 and RCP8.5 scenarios were used as “new” predictors in statistical models to project ensemble temperature changes. Our analysis projected non-uniform warming but could not validate elevation-dependent warming (EDW) at the basin scale. We obtained more significant warming during the westerly-dominated seasons, with maximum heating during the winter season through Tmin changes. The most striking feature is a low-warming monsoon (with the possibility of no change to slight cooling) over the Upper Indus Basin (UIB). Therefore, the likelihood of continuing the anomalous UIB behavior during the primary melt season may not entirely be ruled out at the end of the 21st century under RCP8.5.