JMSJ, 2015, Vol. 93, No. 3 (June)
Maruyama et al. (2015)
Maruyama, F., K. Kai, and H. Morimoto, 2015: Wavelet-based multifractal analysis on climatic regime shifts. J. Meteor. Soc. Japan, 93, 331-341.
https://doi.org/10.2151/jmsj.2015-018 Graphical Abstract
- A climatic regime shift is characterized by an abrupt transition from one quasi-steady climatic state to another. We examined the effectiveness of multifractal analysis to identify climatic regime shift, and attempted to explain the changes of the multifractal behavior of climate indices when regime shift occurs. We used the wavelet transform method to analyze the multifractal behavior of the Niño3.4 index, PDO index, and NPI. We used the Daubechies wavelet as the analyzing wavelet and calculated the multifractal spectrum τ(q) of different moments q for individual records of the climate indices. We showed the change of multifractality by plotting τ(q = −6).
- When the wavelet coherence between the Niño3.4 index and NPI, NPI and PDO index, and Niño3.4 and PDO indices became strong, changes from multifractal to monofractal behavior were observed at climatic regime shifts. When fluctuations became large and multifractality became strong, a climatic regime shift occurred and a change of fractality was observed. The strong interactions of climatic phenomena such as the ENSO, PDO, and AL caused climatic regime shift.
- The changes of fractality associated with the PDO index almost corresponded to regime shifts (Fig. 1). In terms of multifractal analysis, we conclude that a climatic regime shift corresponds to a change from multifractality to monofractality of the PDO index.
Li et al. (2015)
Li, Y., L. Yu, and B. Chen, 2015: An assessment of design of the observation network over the Tibetan Plateau based on Observing System Simulation Experiments (OSSE). J. Meteor. Soc. Japan, 93, 343-358.
https://doi.org/10.2151/jmsj.2015-019 Graphical Abstract
- The rationality and regional representation of the layout of the upper-air observation system and their actual significance were studied over the Tibetan Plateau and neighboring areas based on An Observing System Simulation Experiment (OSSE).
- For the different layouts over the Tibetan Plateau and neighboring areas (Fig. 1), there were significant differences of winds, temperature, relative humidity and heights in prediction. The layout with both existing and planned observation stations was better than the ones with only existing or only planned stations in terms of forecast accuracy, especially around the areas with new observations added (Fig. 2).
- It also validated the layout of the observations and indicated the necessity to add planned observations over the Tibetan Plateau and neighboring areas.
Adachi et al. (2015)
Adachi, A., T. Kobayashi, and H. Yamauchi, 2015: Estimation of raindrop size distribution and rainfall rate from polarimetric radar measurements at attenuating frequency based on the self-consistency principle. J. Meteor. Soc. Japan, 93, 359-388.
https://doi.org/10.2151/jmsj.2015-020 Graphical Abstract
- This study proposes a new method for estimating raindrop size distribution (DSD) and rainfall rate (R) from polarimetric radar at attenuating frequency.
- Since the proposed algorithm retrieves the co-polar (AH) and differential specific attenuation (ADP) from the interrelation among the polarimetric measurements, it needs no external reference data such as 2DVD measurements for attenuation corrections.
- In addition, this method corrects not only the systematic bias in Z measurements but also the bias due to the wet radome by matching the theoretical ΦDP value estimated from Z and ZDR (red line in Fig. 4) with the observed value (black line) using an expanded version of an autocalibration technique (blue line: original technique) proposed by Goddard et al. (1994).
- The evaluation of the algorithm showed that the retrieved three DSD parameters of raindrops, R, Z, and ZDR from actual C-band polarimetric radar data (black closed circles in Fig. 8) have fairly good agreement with those obtained by surface measurements (blue line).