JMSJ, 2015, Vol. 93, No. 5 (October)
Invited Review Article
- Recent advancements of studies using heavy stable water isotopes (i.e., HDO and H218O) in climatology, meteorology and hydrology are reviewed with particular focuses on the progresses in spectroscopic measurement technologies and in global and regional isotopic modeling.
- Fractionation (i.e., heavy stable water isotopes preferably remain in liquid phase than gas phase) is the main reason of causing spatiotemporal variability in isotope concentration, and that is why the isotopes can be used to trace back the hydrologic path and origin on the Earth. (Fig. 1)
- Comparing with the conventional method based on empirical relationships, two new methods are introduced. The first is “Forward Proxy Modeling,” in which isotope-incorporated GCMs/RCMs are used to understand the physical mechanism of isotopic signals. The second is “Isotope Data Assimilation,” in which isotopic data are used to directly constrain the model to analyze the physically consistent environmental condition. (Fig. 8)
Xie et al. (2015)
Xie, R., F.-F. Jin, F. Huang, 2015: An improved atmospheric component of Zebiak-Cane model for simulating ENSO winds J. Meteor. Soc. Japan, 93, 551-570.
Taniguchi et al. (2015)
Taniguchi, K., and K. Sho, 2015: Applications of the pseudo global warming dynamic downscaling method for the Tokai heavy rain in 2000. J. Meteor. Soc. Japan, 93, 551-570.
https://doi.org/10.2151/jmsj.2015-043 Graphical Abstract
- A record heavy rainfall event in the Tokai region on 11 September (the Tokai Heavy Rain) was simulated, and variations of the event in future climate were investigated using numerical simulations with pseudo global warming (PGW) conditions by 11 different climate projections in CMIP3. Ensemble member were prepared for the control run (CTL) and each PGW run to examine whether the variations were caused by chaotic behaviors or global warming.
- Spatial distributions of total precipitation in most of PGW runs are similar to that of CTL. However, no significant rainfall around the Tokai region was found in some PGW runs (Fig.1). Spatial patterns of total precipitation were similar among ensemble members for each PGW run. Thus differences in precipitation between CTL and PGW run were not caused by chaotic behavior but global warming.
- There was a wide variety in the maximum hourly precipitation among five ensemble members in CTL and PGW runs. However, the maximum hourly precipitation rate tended to increase in the future, and heavy rainfall over short periods may occur in wider area in future (Fig. 2).
Notes and Correspondence
Kawase et al. (2015)
Kawase, H., H. Sasaki, A. Murata, M. Nosaka, and N. N. Ishizaki, 2015: Future changes in winter precipitation around Japan projected by ensemble experiments using NHRCM. J. Meteor. Soc. Japan, 93, 571-580.
https://doi.org/10.2151/jmsj.2015-034 Graphical Abstract
- Future changes in winter precipitation around Japan and their uncertainties are investigated using the downscalings of a non-hydrostatic regional climate model (NHRCM) with 20-km grid spacing based on ensemble global climate projections.
- Most ensemble members show decreases in the winter precipitation on the coast of the Sea of Japan and over the Pacific Ocean in the south of the Japanese archipelago, while the winter precipitation increases over the northernmost part of Japan (Hokkaido) (Fig. 1, Fig. 2).
- The decreases in precipitation results from a weakened winter monsoon and the changes in extratropical cyclone number in the coast of the Sea of Japan and over the Pacific Ocean, respectively (Fig. 2). In Hokkaido, the strengthened northwesterly, which results from the reduction of sea ice in the Sea of Okhotsk, brings about the increase in precipitation in the inland area of Hokkaido. In addition, moistening due to global warming also relates to the increase in precipitation in extremely cold regions (Fig. 1).
Mori et al. (2015)
Mori, K., and T. Sato, 2015: Evaluating the role of snow cover in urban canopy layer on the urban heat island in Sapporo, Japan with a regional climate model. J. Meteor. Soc. Japan, 93, 581-592.
https://doi.org/10.2151/jmsj.2015-039 Graphical Abstract
- This study assesses the effect of snow cover in urban canopy on winter heat islands using the Weather Research and Forecasting Model coupled with an urban canopy model.
- A sensitivity test with realistic snow cover run (CTL) and snow-free urban run (NO_SNOW_UCM) reveals that snow cover in urban areas acts to decrease surface air temperature (Fig. 1), with a stronger decrease in daily maximum temperatures (0.4−0.6 °C) than daily minimum temperatures (0.1−0.3 °C).
- The increase in surface albedo due to snow cover is primarily responsible for the decrease in net shortwave radiation and the sensible heat flux. In addition, increased evaporation causes a weakened sensible heat flux. The decrease in sensible heat flux at 1200 JST (50.6 W m−2) is comparable magnitude to the anthropogenic heat release.
- Snow cover on the building roofs reduces surface air temperature because of sensible heat flux decrease (43.1 W m−2), corresponding to 85% of the total sensible heat flux decrease at 1200 JST in the UCM (Fig. 2).