Observing-System Research and Ensemble Data Assimilation at JAMSTEC - Data Assimilation for Atmospheric, Oceanic and Hydrologic Applications - page 511

Fig. 21.6 A histogram of precipitation in July 2003. Blue and red bars represent GPCP and
ALERA2, respectively. Numbers on the bars indicate the percentage in a bin

21.3.2 The Mirai Arctic Ocean Cruise 2010

Research vessel Mirai conducted a cruise in the Arctic Ocean from 2 September
to 16 October 2010. One of the major meteorological outcomes of this cruise is
an in-situ observation of an Arctic cyclone ( Inoue and Hori 2011 ). An OSE was
conducted to evaluate the impact of balloon observations from Mirai during the
cyclogenesis. Figure 21.7 shows the analysis ensemble spread of temperature at
250 hPa with shading and winds in vectors. During the cyclogenesis, the reduction
in error in the lower troposphere may be attributable to information over land carried
by southerly winds. In contrast, the balloon observations are the major contributor to
error reduction in the upper troposphere. In fact the analysis ensemble spread along
the track of Mirai is smaller than the surrounding region. The result of the OSE is
under detailed investigation.

21.3.3 VPREX 2010

A field campaign focusing on heavy precipitation in central Vietnam was conducted
from September 2010 to January 2011. The frequency of radio sonde observations
is doubled from twice to four times a day at Da Nang, Vietnam. Special balloon
observations are conducted twice a day at Mactan, Philippines. These observations
were transmitted to GTS and are included in PREPBUFR. Figure 21.8 shows
the westward migration of disturbances produced from ALERA2. The analysis
ensemble spread of the meridional wind correlates well with vorticity. A data denial
experiment was conducted to further investigate the impact of balloon observations
at a station at Da Nang, Vietnam and six locations in the Philippines, including