The Advances in Targeted Observations for Tropical Cyclone Prediction Based on Conditional Nonlinear Optimal Perturbation (CNOP) Method - Data Assimilation for Atmospheric, Oceanic and Hydrologic Applications - page 588

a b CNOP simulated dropping sites SV simulated dropping sites

26N
24N
22N
20N
18N
16N
14N
12N
10N
8N
6N
4N

26N
24N
22N
20N
18N
16N
14N
12N
10N
8N
6N
4N

110E 115E 120E 125E 130E 135E 140E 145E 110E 115E 120E 125E 130E 135E 140E 145E

Mirinae Mirinae

Fig. 24.16 Simulated dropping sites in sensitive regions calculated by ( a ) CNOPs and ( b )SVsfor
TC Mirinae (2009). Shaded regions are the same as those in Fig. 24.15 , squares represent the sites
for dropping sondes (From Qin and Mu 2011a )

That is, the deployment of dropsondes in CNOP sensitive areas have an overall
positive influence on typhoon track forecasts, suggesting in turn that CNOP can
be utilized as an adaptive method in determining sensitive regions in adaptive
observations.

24.4.3 Observation System Experiments (OSEs)

In the above section, we have demonstrated the utility of the CNOP sensitive areas
in the OSSEs by using the ideal observations. In this section, we would use the real
observations to show the utility of the CNOP sensitive areas ( Chen 2011 ).
The dropsonde observations were collected under the operational Dropsonde
Observations for Typhoon Surveillance near the Taiwan Region (DOTSTAR)
program. Typhoon Nida occurred in 2004 has been studied. Fifteen dropwindsondes
were released around Nida between 1000 and 1400 UTC 17 May 2004. The squares
in Fig. 24.18 show the location of the released dropsondes. Most dropsondes were
deployed every 150-200 km in a circular pattern with its center at Nida's central
position. The observations include data on wind speed, wind direction, height,
temperature, dewpoint temperature, and relative humidity below 196 hPa.
First, the CNOP sensitive areas and FSV sensitive areas (see Fig. 24.19 )have
been defined by using MM5 model. Then the 2nd, 3rd, 4th, and 5th dropsondes
located near the maximal VIE area of CNOP have been chosen as the CNOP targeted
observations. Similarly, the

th dropsondeslocated near the maximal VIE
area of FSV have been chosen as the FSV targeted observations. Additionally, the
8

10 th 13

th dropsondes at the south side of the initial storm center are used as
randomly targeted observations.

th 11