Case Study of Atmospheric Retrievals of MWHTS aboard FY-3C Satellite

The mesoscale numerical model WRF is used to simulate the No. 8 hurricane Matthew in 2016. The radar and radiometer observations are assimilated by WRF Var. With the verification to the real situation, the process of the hurricane rainstorm is well simulated by WRF in this case that it could basically show the hurricane evolution. We use the simulation results which are model outputs with high spatial and temporal resolution to do diagnostic analysis on the short term heavy rainstorm caused by Matthew, with a comparison between the best track and forecasting tracks using active and passive microwave observations from WRFDA model. In order to analyze the inner structure, the nadiral satellite-based observations were matched between the Microwave Humidity and Temperature Sounder (MWHTS) instrument aboard the FY-3C polar-orbiting platform since Sept 30, 2013 and dual-frequency radar named PR aboard GPM satellite and then separate retrievals are demonstrated in data assimilation for extreme weather with the retrieved root-mean-square errors of about 0.9 K and 17% and 10 mm/h for precipitation products, which demonstrates the impact of 118 GHz observations in data assimilation model.

information on temperature and hydrometeors. The Goddard Profiling Algorithm is a noteworthy system which uses a Bayesian inversion for all surface types, and now has been evolved to a fully parametric approach used operationally on global precipitation measurement (GPM) microwave imager (GMI) [2].
The microwave-integrated retrieval system (MiRS, https://www.star.nesdis.noaa.gov/mirs/), which has been operational since 2007 at the National Oceanic and Atmospheric Administration (NOAA), is an inversion algorithm based on physical forward modeling and can invert observed multichannel radiances simultaneously to determine key components of the atmosphere and surface state.
At present, traditional mathematic modeling methods, such as multi-analysis, and time series analysis, are widely used in the statistical prediction method to forecast typhoon track [3] [4], in which the future state of prediction object is forecasted through a statistical prediction equation. Ensemble numerical prediction (ENP) is a novel technique developed in the past ten and odd year, and the ENP model, whether created by using model configurations with different model physical process parameterization schemes or by different model initial conditions from a Monte Carlo approach, formally consists of many different ensemble members. This paper is organized as follows. The microwave instrument is first introduced, and it is demonstrated that multiple receiver arrays can be used to multiplex a large set of channels onto a single spot on the ground. An overview of the data sets and physical models used in the simulation is provided. We next point out that 118 GHz as the unique adoption on polar-orbiting business satellite provide abundant layered information about temperature and humidity distribution. Then this paper adapts two methods to realize data assimilation based on profiles and radiance separately and in combination, and then compare with the impacts in 1Dvar model [5]. Finally, we summarize and provide suggestions for further research and development of data application about polar-orbital satellite.  (2 -9) respond to the thermal radiation at various altitudes as shown by their weighting function distributions. Channels 1 and 10 as window channels mainly detect radiation background, clouds, rain as well as surface

Description of Instrument
properties. Since the satellite provides a nominal spatial resolution of 15 km at its nadir, the temperature perturbations from synoptic to mesoscale can be reasonably depicted. The instrument also contains five channels (11 -15; see Table   1) and provides the atmospheric profile of moisture, as shown in Table 1. The fifteen channels from MWHTS are designed for sounding atmospheric temperature and water vapor in all weather conditions except for heavy precipitation [12]. Since these instruments are designed as cross-track scanners, the instrument viewing angle is different for different pixels along a scan line. The horizontal resolution of MWHTS is 15 km at nadir. A combination of several imaging channels at frequencies of 89, and 150 GHz has been utilized to determine cloud liquid and ice water contents, because they directly respond to the emission from liquid droplets and the scattering from ice particles. MWHTS channels are non-polarized at nadir and mix-polarized off nadir. The polarization mixture reduces the angular dependence of the surface emissivity.

Data Processing
The In this study, we consider spherical and cylindrical ice particles, with either completely random orientation or horizontally alignment with random azimuthally orientation. The single-scattering properties for these particles are obtained software derived from the random and fixed matrix codes of Mishchenko. Because of the computational expense of the matrix calculations, single-scattering properties are pre-calculated, imported in XML format, and interpolated as required. The complex refractive index of ice is obtained from the tabulated data of Warren.
Considering the calibration accuracy and model error, bias correction of brightness temperature is in need. The calibration accuracy consists of contributions distributed in four parts: uncertainty of cold target, warm target, nonlinear term and the random noise of receiver. Table 2 shows the expression of calibration accuracy [15].

Case Study
The statistical retrieval method and the physical retrieval method are used to retrieve the atmospheric temperature profiles in our study. The NN algorithm and

Neural Networks Retrieval Algorithm (NN)
The study area is the North Atlantic Ocean, located between 20˚ -40˚ N and 60˚ -80˚ W, as shown in Figure   in the least squares sense is found between the observed and simulated radiances. Short-term forecasts are used as a first guess. The resulting humidity profiles then form the analyses. Third, a hybrid technique is used between the two aforementioned techniques. According to the comparison of the retrieval results in typhoon area, we can find that the MWHTS has the better detection ability of temperature and humidity at levels from surface to 900 hPa due to the weighting function distribution of multi-channel observation. This can offer a possibility for improving the MWHTS retrieval accuracy of temperature and humidity profiles in the atmospheric layers using the MWHTS observations.

Conclusion and Future Work
The results provided by this study will provide more confidence to satel-     profiles are retrieved using the NN algorithm and the 1D-var algorithm from MWHTS. In our study, the MWHTS observed brightness temperatures, which represent 118.75 GHz and 183.31 GHz observations respectively, are used to carry out the retrieval trails of the atmospheric temperature and water vapor profiles. These are substantially smaller than the a priori temperature profile variations, demonstrating that 118-GHz aircraft or satellite observations can provide useful information on atmospheric vertical thermal structure. Combined with 183 GHz and window channels, water vapor profiles are also retrieved accurately to be used in Matthew typhoon and climate analysis and data assimilation model which validates the positive impacts in extreme weather forecasting and analysis in hurricane study case.