JMSJ, 2014, Vol. 92, No. 4 (August)
- The development of the energy balance climatology is traced back to the origin of this branch of science in thermodynamics and radiation of the 19th century.
- The paper follows development with respect to theory, observational capability and computational skill.
- The most frequent problem hampering progress in this field has been the failure to utilize the observed fluxes. This problem continues to present, as for example witnessed in varying interpretations of the global mean energy balance even in the recent literatures.
- A persistent problem is the underestimation of absorbance due to water vapour, both in the solar and terrestrial wavelength ranges, which results in an overestimation of the solar irradiance and an underestimation of the terrestrial atmospheric irradiance at the earth’s surface.
- For example, the estimate of the global mean terrestrial incoming irradiance at the earth’s surface is close to 350 W m-2, and increasing at a rate of 2.5 W m-2/decade as a result of the increasing greenhouse gas concentration in the atmosphere.
- In a decadal time scale the surface fluxes can change in an order of 5 W m-2. These and the resulting problems need to be solved in the future.
Ohtake et al. (2014)
Ohtake, H., M. Murakami, N. Orikasa, A. Hashimoto, A. Saito, and T. Kato, 2014: Statistical validation of a cloud resolving model using aircraft observations of orographic snow clouds. J. Meteor. Soc. Japan, 92, 287-304.
http://dx.doi.org/10.2151/jmsj.2014-402 Graphical Abstract
- Cold rain processes simulated with a non-hydrostatic cloud-resolving model developed by the Japan Meteorology Agency / Meteorological Research Institute and run at 1 km horizontal resolution (1-km-NHM) with a two-moment bulk parameterization scheme are validated using in-situ aircraft observations for orographic snow clouds.
- To statistically validate the cold rain processes simulated by the 1-km-NHM, aircraft observations collected during two winter seasons (March and December 2007, a total of 21 flights) over the Echigo Mountains are analyzed and compared with the model.
- The horizontal wind direction, wind speed, and vertical wind velocity exhibit reasonable agreement between the numerical simulations and the aircraft observations.
- The simulated liquid water contents at every height interval and over every analysis area are significantly underestimated compared to the aircraft observations (Fig.1).
- The ratios of simulated cloud ice number concentrations to snow number concentrations are less than unity and much smaller than the corresponding ratios obtained from the aircraft observations (Fig.2).
- This suggests that the overall conversion from cloud ice to snow in the 1-km-NHM, which occurs primarily through depositional growth, is faster than that in real clouds.
Yamaura et al. (2014)
Yamaura, T., and T. Tomita, 2014: Two physical mechanisms controlling the interannual variability of Baiu precipitation. J. Meteor. Soc. Japan, 92, 305-325.
http://dx.doi.org/10.2151/jmsj.2014-403 Graphical Abstract
- The climatological atmospheric state near Japan is changed around late June, and the Baiu season can be divided into two by this change. The early period is from 26 May to 24 June (pentad 30–35), and the late period is from 25 June to 19 July (pentad 36–40). This division is related to the onset of the summer monsoon over the southwestern Philippine Sea with a specific meridional circulation referred to as the Pacific–Japan pattern.
- The interannual variability of Baiu precipitation is different between the two periods (Fig. 1). The Pacific–East Asian teleconnection controls the interannual variability in the early Baiu period, while the Indian Ocean capacitor adjusts the variability in the later one. Both of them follow the preceding wintertime El Niño/Southern Oscillation (ENSO) with different oceanic and atmospheric anomalies, especially in the tropical Indian Ocean (Fig. 2).
- The decay process of the ENSO induces the interannual variability of the Baiu precipitation. The positive sea surface temperature anomalies (SSTAs) in the central–eastern equatorial Pacific are common between the two processes in the previous winter (Fig. 2). However, the teleconnection to the Indian Ocean and the detailed distribution of SSTAs in the tropical Pacific are different in the following spring, leading to a weak and insignificant correlation between the EB and LB indices (Fig. 1). These differences have potential to lead more accurate prediction of the interannual tendency in the Baiu precipitation.
Mori et al. (2014)
Mori, K., and T. Sato, 2014: Spatio-temporal variation of high-temperature events in Hokkaido, North Japan. J. Meteor. Soc. Japan, 92, 327–346.
http://dx.doi.org/10.2151/jmsj.2014-404 Graphical Abstract
- The annual mean frequency of high-temperature events is lower at stations on the western side of Hokkaido than those on the eastern (Fig.1). Okhotsk area experiences the high-temperature events most frequently. These characteristics are found in every month.
- The frequency of high-temperature events in Okhotsk area has clear seasonal variation with two distinct peaks occurring in winter and spring (upper panel in Fig.2). The initial time of high-temperature events is classified into two types with respect to season: that from fall to early spring (March) is referred to as the winter type, and that from early spring (April) to early summer (July) is referred to as the spring type (lower panel in Fig.2). The spring and winter types have one diurnal peak, which are in the morning and in the evening, respectively. These characteristics are similar to the entire Hokkaido region.
- An extratropical cyclone passage is responsible for winter type high-temperature events. The spring type high-temperature events are triggered by two different mechanisms related to solar insolation, which includes dynamic foehn and combination of airflow diabatically heated by surface sensible heat flux and dynamic foehn.
Ninomiya, K., 2014: Genesis of a weak polar mesoscale cyclone in the lee-side shear-zone south of the central part of Japan on 7-8 March 1992. : An observational case study. J. Meteor. Soc. Japan, 92, 347-361.
http://dx.doi.org/10.2151/jmsj.2014-405 Graphical Abstract
- Genesis of a weak polar mesoscale cyclone (PMC) over the coastal Pacific south of central part of Japan on 7-8 March 1992 is studied using data obtained at two research vessels and observation stations, satellite cloud images and ERA40 data.
- A lee-side shear-zone formed to the south of Japan under the weak polar-air outbreak, between the northwesterly streams passing along the western side of the high-mountains area and northeasterly streams passing along the eastern side of the high-mountains area of Japan.
- A cumulus-line that formed in the shear-zone developed into a comma-shaped cloud system of the PMC within several hours (Fig.1).
- Despite strong baroclinicity in the low-middle troposphere, the PMC did not develop into a significant depression, and disappeared with in ∼2 days after generation (Fig.2). The synoptic-scale conditions for this non-developed PMC are compared with conditions for developed PMCs studied in previous articles. The conditions for this non-developed PMC were characterized by absence of the associated upper cold trough, lack of significant background low-level cyclonic circulation, and PMC location outside a zone of strong sea-surface temperature gradient.
Wei et al. (2014)
Wei, C.-H., Y.-C. Chuang, T.-H. Hor, C.-C. Liao and N.-C. Yeh, 2014: Dual-Doppler radar investigation of a convective rainband during the impact of the southwesterly monsoonal flow on the circulation of typhoon Morakot (2009). J. Meteor. Soc. Japan, 92, 363-383.
http://dx.doi.org/10.2151/jmsj.2014-406 Graphical Abstract
- This study focuses on the characteristics and evolution of convection embedded within the principal band during the impact of the southwesterly monsoonal flow on the circulation of typhoon Morakot (2009) over Taiwan by analyzing Doppler radar data. The retrieved 3 dimensional wind field depicted that the southwesterly monsoonal flow was impinging upon the typhoon circulation. The speed of southerly component of the SW flow decreased and formed a convergence zone which led to the initiation and development of convection in the rainband (Fig. 1).
- The vertical kinematic characteristics of the rainband revealed that two types of downdrafts, inner-edge downdrafts (IEDs) and low-level downdrafts (LLDs), were found (Fig. 2). The IEDs coupled by the radially inward tilting convection were initiated by the precipitation drag. Dynamically, the existence of the perturbed high at 1.5 km altitude in the IEDs supported the finding. Furthermore, it is evident that the distribution of two perturbation highs in the vicinity of the rainband could lead to the SW flow deformation locally and fortify the mechanism of convergence, resulting in the merging of convective cells into the rainband.
- In summary, the characteristics of the typhoon rainband and the embedded convection, which developed in the circumstances that the environmental flow impinged on the typhoon circulation, were similar to previous concepts of the hurricane rainband, except that the triggering mechanism of the convective downdrafts might not be the same. Additionally, the consecutive volume radar data showed the evolution of convective cells at different stages and the maintaining mechanism of the rainband.
Ciesielski et al. (2014)
Ciesielski, P. E., R. H. Johnson, K. Yoneyama, and R. K. Taft, 2014: Mitigation of Sri Lanka Island effects in Colombo sounding data and its impact on DYNAMO analyses. J. Meteor. Soc. Japan, 92, 385-405.
http://dx.doi.org/10.2151/jmsj.2014-407 Graphical Abstract
- During the Dynamics of the MJO (DYNAMO) field campaign in 2011, 258 upper-air soundings were launched at Colombo, Sri Lanka as part of the enhanced northern sounding array (NSA) of the experiment. These soundings were affected at low levels by the diurnal heating of this large island and by flow blocking due to elevated terrain (> 2 km) to the east of the Colombo site. Because of the large spacing between sounding sites, these small-scale island effects are aliased onto the larger scale impacting analyses and atmospheric budgets over the DYNAMO NSA.
- To mitigate these local island effects on the large-scale budgets, a procedure was designed which used low-level ECMWF-analyzed fields in the vicinity of Sri Lanka (i.e., a 2.5° sampling radius from center of topographic feature seen in Fig. 2) to estimate open-ocean conditions at Colombo’s location as if the island were not present. These “unperturbed” ECMWF fields at low-levels were then merged with the observed Colombo soundings below 700 hPa.
- Results indicate a beneficial impact of using these adjusted fields on several aspects of the budget analyses (e.g., higher temporal correlations of budget-derived rainfall to independent estimates, elimination of negative budget rainfall during build-up phase of November MJO event, etc.).