Scientific Online Letters on the Atmosphere (SOLA) is an online, open-access letter journal and was established to rapidly publish scientific discoveries, new findings, and advances of understanding in meteorology and atmospheric sciences as well as in related interdisciplinary areas. SOLA is committed to pursue the followings: rapid review cycle; rapid publication; and wide coverage in atmospheric sciences. SOLA aims to make final decision for the submitted papers within two months from the date of submission. After acceptance, the papers will appear on J-STAGE (https://www.jstage.jst.go.jp/browse/sola/) within one month. To cover wide areas in atmospheric sciences, the Editorial Committee of SOLA consists of 8 steering board members and 35 editors who specialize various fields in atmospheric sciences. SOLA was established in 2005 by the Meteorological Society of Japan. About 40 to 50 papers have been published each year, and in 2016 there were totally 67 papers in the regular volume and the special volume on The First Asian Conference on Meteorology.
The Editorial Committee of SOLA gives The SOLA Award to outstanding paper(s) published each year starting from 2010. The award winning papers are as follows: Ito et al. (2010), Inoue et al. (2011), Endo (2011), Iwasaki and Mochizuki (2012), Moteki and Manda (2013), Miyama and Hasegawa (2014), and Masuda and Ishioka (2015).
Among the 35 editors, 10 editors join the SOLA committee from the international research community outside Japan. SOLA welcomes submission from the international community in atmospheric sciences. We hope that SOLA would be a platform to publish researches in meteorology and atmospheric sciences including their related interdisciplinary fields.
The Editorial Committee of Scientific Online Letters on the Atmosphere (SOLA) gives The SOLA Award to outstanding paper(s) published each year. I am pleased to announce that The SOLA Award in 2016 is going to be presented to the paper by Dr. Toru Adachi et al., entitled with “Rapid volumetric growth of misocyclone and vault-like structure in horizontal shear observed by phased array weather radar” (Adachi et al. 2016).
Misocyclones are vertically oriented vortices with the horizontal scales from 40 m to 4 km and have a potential for wind disasters. This study investigates the rapid evolution of misocyclones that developed in the northern part of Osaka on 25 August 2013 by conducting high-temporal resolution observations with a phased array weather radar (PAWR). The PAWR observation showed that the top altitude of the misocyclones, developed in a horizontally sheared environment, was shown to rapidly grow from 1.2 km to 1.8 km height in two minutes and that the misocyclones gained a vault-like structure in the next two minutes. The analysis indicated that shear instability plays a role in the evolution of the misocyclones through stretching of vertically oriented vortices.
This study is highly evaluated in demonstrating an observational evidence that the structure of misocyclones rapidly changes within a few minutes. Such a rapid growth was captured for the first time with a PAWR that can observe three-dimensional structure of precipitation and wind at the 30-second interval. Because misocyclones have a potential for wind disasters, it is important to understand the evolution of misocyclones and the resulting wind gusts. Furthermore, misocyclones sometimes play a role in initiating strong convection, and therefore, monitoring misocyclones at high-temporal resolutions should contribute to advancing now-casting of severe weather. Therefore, the Editorial Committee of SOLA highly evaluates the excellence of the authors’ study.
With a goal of real-time, high-resolution, short-term prediction of heavy rainfall systems, the SCALE-LETKF was developed implementing the local ensemble transform Kalman filter with the Scalable Computing for Advanced Library and Environment-Regional Model (SCALE-RM). The system has been running in near real time experimentally since May 2015, configured for weather analyses and forecasts at 18-km resolution for a 5760 × 4320 km area around Japan. Among the data for more than one year, the near-real-time forecasts and the 3-km resolution downscaling simulations are demonstrated for a selected case of the September 2015 Kanto-Tohoku heavy rainfall associated with Typhoon Etau (2015). The typhoon track was successfully analyzed and predicted by the system, and the line-shaped rainband producing heavy rainfall can be reasonably forecasted by the downscaling simulation from the near-real-time data.
Future changes in precipitation extremes in East Asia are investigated using large ensemble simulations of about 100 members by a 60-km mesh atmospheric general circulation model (AGCM) for the present climate and 4 K warmer climates, employing six different sea surface temperature (SST) anomaly patterns projected by state-of-the-art climate models. The high-resolution AGCM demonstrates good performance for reproducing precipitation extremes such as annual maximum 1-day precipitation total (Rx1d). Under the warmer climates, Rx1d are robustly projected to increase throughout East Asia. However, there is large range of their quantitative estimates, arising from internal variability and uncertainty in future SST patterns. Over land regions such as inland China, internal variability is the major source of the uncertainty in climatological-mean Rx1d change. However, over oceanic regions including Japan, Korea and coastal China, uncertainty in the SST patterns contributes greatly to the uncertainty in Rx1d through modulation of tropical cyclone activity, suggesting large regional variations in the relative importance of the two sources of uncertainty.
This study evaluates the performance of the Non-hydrostatic Regional Climate Model (NHRCM) in simulating the present climate over Southeast Asia to determine its applicability in downscaling climate projections in the region. Simulations from 1989 to 2008 are conducted over the region at 25-km resolution using boundary conditions from the ECMWF ERA-Interim dataset. The topographic effect on rainfall is well represented in NHRCM but can result in wet (dry) biases in the windward (leeward) side of mountains. NHRCM is able to reduce the overestimated rainfall in ERA-Interim, particularly over eastern Philippines and in the Maritime Continent, with improvements in spatial patterns. Both seasonality and daily distribution of rainfall are represented in most regions. On the other hand, there is a tendency to underestimate the number of wet days, especially during the respective wet season of the subregion, and to overestimate daily rainfall intensity. NHRCM also has an overall cold model bias, which reduces the warm bias in ERA-Interim, except for some parts of Indochina during boreal winter and spring. These results indicate the improved representation of present climate in Southeast Asia using NHRCM, and its potential applicability in downscaling climate projections to increase projected climate scenarios for the region.
The impact of the radiosonde observations of cold surge over the Philippine Sea on the tropical region and the Southern Hemisphere has been investigated by the assimilation of radiosonde data obtained during the R/V Hakuho Maru cruise KH–12–6 in late December 2012. After assimilating the observation data, the modified surface winds of the cold surge were generally stronger than those before the assimilation. In addition, cyclonic rotations around the 4 developing tropical cyclones in the Northern and Southern Hemispheres were more intensified. Furthermore, the analysis errors over the Indian Ocean and the Pacific Ocean in the Northern and Southern Hemispheres were reduced by 1 to 10%.
The impacts of the additional radiosonde observations in the cold surge immediately propagated up to the updraft region near the equator and to the mid-latitude downdraft regions through the local Hadley circulation. After the impact spread in the lower troposphere, large impacts were deepened around the tropical cyclones and depressions within 2 days. The propagation process of the additional observation impact over the Philippine Sea suggested that the cold surge could affect large-scale circulation, including typhoons and tropical depressions in the tropics and the mid-latitude regions.
Since around 2013, the globally averaged sea surface temperature has rapidly warmed up and reached its highest on record. During this time, there was an intensifying El Niño event that caused positive temperature anomalies in the tropical Pacific Ocean. Compared with the conditions observed in 1997/98, when the previous highest record was marked associated with strong El Niño event, there were notable differences detected in the recent conditions. In the tropical Pacific, remarkable warming near sea surface associated with strong El Niño event in 2015/16 started from significantly warmed conditions along with positive temperature anomaly redistributed from the western part since early 2014, resulting in positive anomalies in the central to eastern part remaining for more than two years, much longer than 1997/98 event. In addition, substantial warming was observed in the North Pacific around 2013 and contribution of the North Pacific region to the global averaged SST anomaly marked significantly large value and was comparable to that of the tropical Pacific.
An inverse modeling system for estimating Asian dust emissions was developed by combining the GEOS-Chem chemical transport model with the Green's function method. We applied the system to two heavy dust storms that occurred in 2014 (10-25 March and 24 May to 5 June), using surface-based polarization optical particle counter (POPC) observations at Fukuoka. Validation by independent observation datasets, including POPC measurements and PM10 observations at Seoul, showed that the use of a posteriori dust emissions improved overestimations in the a priori simulation and achieved much better agreement with observations. Satellite observations, surface synoptic observations, and modeled wind fields indicated that the major dust source region differed between the two dust storms; the major dust outbreak of one storm occurred in the northeastern Gobi Desert, whereas that of the other occurred in the southern Gobi Desert. The a posteriori dust emissions successfully reproduced this difference. Thus, the inverse modeling system developed in this study was able to improve the estimation of not only the intensity but also the geographical distribution of dust emissions.
This study examined the impact of an active phase of the Madden–Julian Oscillation (MJO) on a torrential rain event that occurred on the western coast of Sumatra Island on 12 December 2015, using surface meteorological observations, meteorological radar observations, and balloon sounding data obtained from the pre-Years of the Maritime Continent field campaign. Strong MJO activity took place in mid-December 2015 into January 2016. Radar observations revealed that a convergence and convective cloud merger of mesoscale convective systems from an eastward propagating MJO and westward moving diurnal convection over the western coast of the island was the immediate cause of the torrential rain. An investigation of the occurrence of convection over the island showed that both westward moving diurnal convection from the mountains and eastward propagating convection from the Indian Ocean occurred on 12 December, because the westerly winds in the lower troposphere associated with the MJO were only just initiated and were weak on the day. The results suggest that the leading edge of the MJO westerly wind bursts provided favorable conditions for an active phase of the MJO to work with the westward moving diurnal convection and cause torrential rain on the western coast of Sumatra Island.
The observation operators in the local ensemble transform Kalman filter (LETKF) were improved to enable use of observations in the vicinity of the poles in the data assimilation system composed of the atmospheric general circulation model for the Earth Simulator (AFES) and the LETKF. The improved observation operators allow to assimilate the observations located south (north) of southernmost (northernmost) Gaussian grid latitudes. An algorithm for searching the nearest observations from an analyzed grid for error covariance localization was also modified to efficiently assimilate observations near the poles.
The new algorithms were incorporated into the LETKF, and the impacts of routine radiosonde observations at the South Pole during the periods of July 2012 and January 2013 were assessed. The radiosonde observations suppressed an artificial expansion of the analysis ensemble spread which occasionally caused numerical instability in the upper troposphere and the lower stratosphere over the Antarctic regions. The analysis was also improved in the Antarctic regions.