Owing to the deficiency of conventional observations over oceans

particularly under typhoon conditions

numerical simulation has become the foremost approach to the study of the thermal and dynamic structures of typhoons

and the accuracy of the numerical simulation depends on the initial structure of the typhoon and the accuracy of the model.As the first operational satellite

FY-3C was successfully launched into a morning-configured orbit on September 23

2013.The MWTS onboard the FY-3C is designed with significantly more channels

finer spatial resolution

and better sensor precision than those of FY-3A and FY-3B.Moreover

the observed radiance is insignificantly affected by non-precipitating clouds

making MWTS measurements more suitable to detect the thermal features of typhoons.Radiance in the microwave band is linearly proportional to the entire layer of atmospheric temperature.The weighting functions of all the sounding channels of MWTS are substantially steady

and atmospheric temperature at a given pressure can be expressed as a linear combination of brightness temperatures measured at certain sounding channels.In this study

a stepwise linear regression analysis with a 1%significance level is used.Under a clear-sky condition

the brightness temperatures at channels 3-10 are used to retrieve the temperatures at 21 pressure levels ranging from 100 hPa to 1000 hPa

but channels 3 and 4 are not used for retrieval under precipitation conditions.When the temperature profiles are retrieved

the tangential winds around typhoon "Rammasun" are calculated using hydrostatic equilibrium and gradient balance equations based on the retrieved temperature profiles.Under a clear-sky condition

the root-mean-square error of the retrieved temperature is 1.4 K at the most and even lower than 1.1 K in the upper troposphere and lower stratosphere.These error values are sufficiently low;thus

the thermal structure of typhoons can be monitored.Applied to the super typhoon "Rammasun"

the method excellently described the warm core eye and the temperature gradients across the eyewall.The results generated by the proposed method are more accurate than the results generated from the NCEP reanalysis data.The warm core is identified throughout the troposphere

with maximum temperatures ranging from 8℃ to 10℃ near 200 hPa;the warm core extends to the sea surface.This finding on the warm core is seemingly more realistic compared with the typical one.From the anomaly field

the radius of the typhoon eye at the sea surface is approximately 100 km

and the eye tilts outward with height.The maximum wind speed radius is approximately 80 km

and the maximum wind speed can reach up to 51 m/s.Among the most important parameters in monitoring typhoon intensity

studying typhoon inner core dynamics

and constructing the initial vortex for a typhoon simulation

the three-dimensional warm core and tangential wind features derived from FY-3C MWTS measurements are investigated in this study.Evidently

MWTS has considerable potential for improving our knowledge of typhoons and hurricanes.However

only a single typhoon case is analyzed in this study;more cases should be studied to verify the retrieval method.