风云三号C星微波湿度计资料全天候同化对台风玛莉亚预报的影响

随着风云三号系列卫星的成功发射,越来越多的卫星微波直接观测资料应用于数值天气预报的资料同化系统。并且由于卫星微波全天候同化技术可以充分利用晴天及云雨区微波观测资料,在增加同化使用的观测数据的基础上,有效提高数值天气预报准确率,该技术在卫星资料同化领域也颇受瞩目。本研究选取2018年7月的台风玛莉亚,利用WRF(Weather Research and Forecasting)模式及其同化系统WRFDA(WRF Data Assimilation)中三维变分方法,探讨风云三号C星微波湿度计观测资料的全天候同化技术在区域模式中的适用性,以及其在不同模式驱动场中的预报表现。通过对比仅同化晴空区域卫星资料的试验和全天候同化的试验结果发现,全天候条件下更多的云雨区域观测资料被有效利用,能够更好地模拟出台风玛莉亚核心区域的暖心和对称风速结构,有效改善湿度场的预报,对台风路径的预报误差平均降低了大约34%~62%,且这种正面影响均能在不同模式驱动场中得到体现。

多波束测深仪在内陆水域测绘中的实践与思考

根据国务院批复的《全国基础测绘中长期规划纲要(2015—2030年)》的要求,抓紧“启动内陆水体水下地形测绘”[1]。针对内陆水域水下地形测绘的特点、难点,文章提出相应的思考建议及补充方法,并选取贵州省沿河县画廊天街周边区域作为项目试点,使用多波束测深仪开展水下测量试点工作,同时,使用机载Lidar测量系统,作为内陆水域测绘的重要补充,形成水域测绘数字产品,并对数字产品精度进行验证。

Added Benefit of the Early-Morning-Orbit Satellite Fengyun-3E on the Global Microwave Sounding of the Three-Orbit Constellation

The three-orbit constellation can comprehensively increase the spatial coverage of polar-orbiting satellites,but the polar-orbiting satellites currently in operation are only mid-morning-orbit and afternoon-orbit satellites.Fengyun-3E(FY-3E)was launched successfully on 5 July 2021 in China.As an early-morning-orbit satellite,FY-3E can help form a complete three-orbit observation system together with the mid-morning and afternoon satellites in the current mainstream operational system.In this study,we investigate the added benefit of FY-3E microwave sounding observations to the midmorning-orbit Meteorological Operational satellite-B(Met Op-B)and afternoon-orbit Fengyun-3D(FY-3D)microwave observations in the Chinese Meteorological Administration global forecast system(CMA-GFS).The results show that the additional FY-3E microwave temperature sounder-3(MWTS-3)and microwave humidity sounder-2(MWHS-2)data can increase the global coverage of microwave temperature and humidity sounding data by 14.8% and 10.6%,respectively.It enables the CMA-GFS to achieve nearly 100% global coverage of microwave-sounding observations at each analysis time.Furthermore,after effective quality control and bias correction,the global biases and standard deviations of the differences between observations and model simulations are also reduced.Based on the Advanced Microwave Sounding Unit A and the Microwave Humidity Sounder onboard Met Op-B,and the MWTS-2 and MWHS-2 onboard FY-3D,adding the microwave sounding data of FY-3E can further reduce the errors of analysis results and improve the global prediction skills of CMA-GFS,especially for the southern-hemisphere forecasts within 96 hours,all of which are significant at the 95% confidence level.

集成化水深测量装置研发及应用

为更好地解决码头前沿及其下方、浅水区等船舶行驶受限区域的水深测量难的问题,研制了一种新型集成化测深装置。该装置采用一体化设计,集成了电源模块、测深模块、水文参数测量模块和专业测深软件等。以传统单波束测深仪的测量数据为参照,对集成化测深装置的吃水深度、声速、内符合和外符合方面的测量数据进行分析和评价。结果证明:集成化测深装置的测量准确性和性能稳定性较好,可实时高效地获取码头前沿及其下方、浅水区等船舶行驶受限区域的高精度水深数据。

测深器和螺钉无透视辅助技术在使用交锁髓内钉治疗股骨干骨折患者中的应用

目的:探讨测深器和螺钉无透视辅助技术在使用交锁髓内钉治疗股骨干骨折中的应用.方法:选取2022年1月-2023年1月采用交锁髓内钉治疗股骨干骨折的60例患者为研究对象.根据辅助技术的不同,分为研究组和对照组,各30例.研究组采用测深器和螺钉无透视辅助技术,对照组采用透视下改良徒手锁钉技术.对比2组治疗效果、术中X线透视次数、手术时长、术中出血量、住院时间、术后深静脉血栓形成和骨折愈合情况.结果:研究组与对照组相比,手术时间更短,出血量及术中X线透视次数更少,差异有统计学意义(P<0.05).2组引流量、住院时间及骨折愈合时间比较,组间差异无统计学意义(P>0.05).2组优良率比较,差异无统计学意义(P<0.05).结论:测深器和螺钉无透视辅助技术应用于使用交锁髓内钉治疗股骨干骨折患者中,可以明显减少X线透视次数,缩短手术时长,减少患者出血量.

基于单波束条带测深仪的大中型水库水下地形图测绘方法

在大中型水库的水下地形图测绘中,常规方法主要依赖数据高程特征匹配,却常因信号介质差异而引发不可忽视的误差,从而影响测绘精度。为了提升测绘的准确性,本文提出基于单波束条带测深仪的大中型水库水下地形图测绘方法。在大中型水库的水下区域进行单波束条带测深仪的点位高程布设,并基于声速数据差值的计算结果对信号数据误差进行修正。定义水下地形图的深度基准面,在此基础上,将网格化的单波束信号数据进行线性差值,完成高精度的水下地形图的测绘。实验结果表明:本文所提方法应用后得出的测绘结果,表现出的地形极点差异度较小,测绘精度较高,满足了大中型水库在建设与运维过程中的高精度测绘需求。

GPS-RTK联合数字测深仪在凤河河道横断面测量中的应用

以台山市新昌水凤河河道横断面测量为例,由于水下地形复杂,传统的河道横断面测量方法效率低、精度差,已无法满足现代水利建设的需要。为了能够提高河道横断面的测量精度和效率,减少误差,采用GPS RTK技术联合测深仪进行河道横断面测量,可以快速、准确地获取凤河河道横断面的位置坐标、水深、高程等数据。通过两种技术的联合应用,实现对新昌水(凤河)河道横断面的精确测量,为新昌水(凤河)治理工程的设计和建设提供准确的数据支持。

Value-added Impact of Geostationary Hyperspectral Infrared Sounders on Local Severe Storm Forecasts——via a Quick Regional OSSE

Accurate atmospheric temperature and moisture information with high temporal/spatial resolutions are two of the key parameters needed in regional numerical weather prediction(NWP) models to reliably predict high-impact weather events such as local severe storms(LSSs). High spectral resolution or hyperspectral infrared(HIR) sounders from geostationary orbit(GEO) provide an unprecedented source of near time-continuous, three-dimensional information on the dynamic and thermodynamic atmospheric fields—an important benefit for nowcasting and NWP-based forecasting. In order to demonstrate the value of GEO HIR sounder radiances on LSS forecasts, a quick regional OSSE(Observing System Simulation Experiment)framework has been developed, including high-resolution nature run generation, synthetic observation simulation and validation, and impact study on LSS forecasts. Results show that, on top of the existing LEO(low earth orbit) sounders, a GEO HIR sounder may provide value-added impact [a reduction of 3.56% in normalized root-mean-square difference(RMSD)] on LSS forecasts due to large spatial coverage and high temporal resolution, even though the data are assimilated every 6 h with a thinning of 60 km. Additionally, more frequent assimilations and smaller thinning distances allow more observations to be assimilated, and may further increase the positive impact from a GEO HIR sounder. On the other hand, with denser and more frequent observations assimilated, it becomes more difficult to handle the spatial error correlation in observations and gravity waves due to the limitations of current assimilation and forecast systems(such as a static background error covariance). The peak reduction of 4.6% in normalized RMSD is found when observations are assimilated every 3 h with a thinning distance of 30 km.

Assimilation of Feng-Yun-3B Satellite Microwave Humidity Sounder Data over Land

The ECMWF has been assimilating Feng-Yun-3B （FY-3B） satellite microwave humidity sounder （MWHS） data over ocean in an operational forecasting system since 24 September 2014, It is more difficult, however, to assimilate microwave observations over land and sea ice than over the open ocean due to higher uncertainties in land surface temperature, surface emissivity and less effective cloud screening. We compare approaches in which the emissivity is retrieved dynamically from MWHS channel l [150 GHz （vertical polarization）] with the use of an evolving emissivity atlas from 89 GHz observations from the MWHS onboard NOAA and EUMETSAT satellites. The assimilation of the additional data over land improves the fit of short-range forecasts to other observations, notably ATMS （Advanced Technology Microwave Sounder） humidity channels, and the forecast impacts are mainly neutral to slightly positive over the first five days. The forecast impacts are better in boreal summer and the Southern Hemisphere. These results suggest that the techniques tested allow for effective assimilation of MWHS/FY-3B data over land.

The alternative of CubeSat-based advanced infrared and microwave sounders for high impact weather forecasting

The advanced infrared(IR) and microwave(MW) sounding systems have been providing atmospheric sounding information critical for nowcasting and improving weather forecasts through data assimilation in numerical weather prediction. In recent years, advanced IR and MW sounder systems are being proposed to be onboard CubeSats that are much more cost efficient than traditional satellite systems. An impact study using a regional Observing System Simulation Experiment on a local severe storm(LSS) was carried out to evaluate the alternative of using advanced MW and IR sounders for high-impact weather forecasting in mitigating the potential data gap of the Advanced Technology Microwave Sounder(ATMS) and the Cross-track Infrared Sounder(CrIS) on the Suomi-NPP(SNPP) or Joint Polar Satellite System(JPSS). It was found that either MicroMAS-2 or the CubeSat Infrared Atmospheric Sounder(CIRAS) on a single CubeSat was able to provide a positive impact on the LSS forecast, and more CubeSats with increased data coverage yielded larger positive impacts.MicroMAS-2 has the potential to mitigate the loss of ATMS, and CIRAS the loss of CrIS, on SNPP or JPSS, especially when multiple CubeSats are launched. There are several approximations and limitations to the present study, but these represent efficiencies appropriate to the principal goal of the study — gauging the relative values of these sensors.

Assessment and Assimilation of FY-3 Humidity Sounders and Imager in the UK Met Office Global Model

China＇s FengYnn 3 （FY-3） polar orbiting satellites axe set to become an important sonrce of observational data for nu- merical weather prediction （NWP）, atmospheric reanalyses, and climate monitoring studies over the next two decades. As part of the Climate Science for Service Partnership China （CSSP China） prograln, FY-3B Microwave Humidity Sounder 1 （MWHS-1） and FY-3C MWHS-2 observations have been thoroughly assessed and prepared for operational assimilation. This represents the first time observations from China＇s polar orbiting satellites have been used in the UK＇s global NWP model. Since 2016, continuous data quality monitoring has shown occasional bias changes found to be correlated to changes in the energy supply scheme regulating the platform heating system and other transient anomalies. Nonetheless, MWHS-1 and MWHS-2 significantly contribute to the 24-h forecast error reduction by 0.3% and 0.6%, respectively, and the combination of both instruments is shown to improve the fit to the model background of independent sounders by up to 1%. The observations from the Microwave Radiation Imager （MWRI） also are a potentially significant source of benefits for NWP models, but a solar-dependent bias observed in the instrument half-orbits has prevented their assimilation. This paper presents the bases of a correction scheme developed at the Met Office for the purpose of a future assimilation of MWRI data.

Recent progress on space-borne microwave sounder pre-launch calibration technologies in China

The development processes and the application achievements of space-borne microwave sounder pre-launch calibration technologies in China are introduced briefly. Then, the general project plan for pre-launch calibration, the latest research achievements on the optimization and development of the microwave wide band calibration targets, emissivity measurement technologies and the system level uncertainty analysis of the laboratory, and the thermal/vacuum microwave sounder calibration system for ＂FY-3＂ meteorological satellite are reported, respectively. Finally, the key technological problems of the calibration technologies under researching are analyzed predictively.

Ex situ echo sounder target strengths of ice krill Euphausia crystallorophias

Ice krill is the keystone species in the neritic ecosystem in the Southern Ocean, where it replaces the more oceanic Antarctic krill. It is essential to understand the variation of target strength （TS in dB re l m^2） with the different body size to accurately estimate ice krill stocks. However, there is comparatively little knowledge of the acoustic backscatter of ice krill. The TS of individual, formalin-preserved, tethered ice krill was measured in a freshwater test tank at 38, 120, and 200 kHz with a calibrated split-beam echo sounder system. Mean TS was obtained from 21 individual ice krill with a broad range of body lengths （L： 13-36 iron）. The length （L, mm） to wet weight （W; mg） relationship for ice krill was 11/=0.001 21g^103~L35s （R2=0.96）. The mean TS-to-length relationship were TS38kHz=-177.4＋57log10（L）, （R^2=0.86）; TS120kHz= -129.9＋31.561ogf0（L）, （R2=0.87）; and TS200kHz=-117.6＋24.661ogre（L）, （R2=0.84）. Empirical estimates of the relationship between the TS and body length of ice krill were established at 38, 120, and 200 kHz and compared with predictions obtained from both the linear regression model of Greene et al. （1991） and the Stochastic Distorted Wave Born Approximation （SDWBA） model. This result might be applied to improve acoustic detection and density estimation of ice krill in the Southern Ocean. Further comparative studies are needed with in situ target strength including various body lengths of ice krill.

Potential suitable sites for the calibration of Scientific Echo Sounder in the marginal seas around Antarctica

The in situ calibration of Scientific Echo Sounders(SESs)in the Southern Ocean is crucial for accurate assessments of Antarctic krill and fishery biomasses.Because of the occurrence of strong winds,waves,and sea ice coverage in most seasons,SES calibration is usually difficult to perform in the Southern Ocean.Accordingly,it is essential to identify potential sites suitable for SES calibration in the marginal seas around Antarctica to successfully calibrate SESs in the Southern Ocean.Using synthetic analyses of the wind,surface current,and sea ice concentration in the targeted seas,we found that the polynya in the southeast Prydz Bay,close to the Chinese Zhongshan Station,is an ideal location to calibrate SESs based on its weak wind and surface current and its ice-free coverage during Antarctic cruises.Calibrations of the SESs onboard the research vessels of Xuelong and Xuelong 2 during the 36th and 37th Chinese National Antarctic Research Expeditions indicate that this location is a potential suitable site for conducting SES calibration with the vessel in a drifting mode.

The Study of In-Orbit Calibration Accuracy of NOAA Satellite Infrared Sounder and Its Effect on Temperature Profile Retrievals

The calibration accuracy of High Resolution Infrared Radiation Sounder Mod. 2 (HIRS / 2) on NOAA-10 satellite is analyzed in this paper. The non-linear effect in the linear calibration curve induces a deviation of 1.5 degrees (k) of brightness temperature in the tenth channel (8.3 um, water vapor absorption) of the HIRS/2 and the non-linear effect affects the other channels to a different extent. Based on analyzing non- linearity in two-point calibration curve, a tri-point calibration equation is given. A numerical test of effects of the linear and non-linear calibration models on the accuracy of atmospheric temperature retrievals is carried out.

Estimating the Correlated Observation-Error Characteristics of the Chinese FengYun Microwave Temperature Sounder and Microwave Humidity Sounder

In operational data assimilation systems, observation-error covariance matrices are commonly assumed to be diagonal.However, inter-channel and spatial observation-error correlations are inevitable for satellite radiances. The observation errors of the Microwave Temperature Sounder(MWTS) and Microwave Humidity Sounder(MWHS) onboard the FengYun-3A(FY-3A) and FY-3B satellites are empirically assigned and considered to be uncorrelated when they are assimilated into the WRF model's Community Variational Data Assimilation System(WRFDA). To assimilate MWTS and MWHS measurements optimally, a good characterization of their observation errors is necessary. In this study, background and analysis residuals were used to diagnose the correlated observation-error characteristics of the MWTS and MWHS. It was found that the error standard deviations of the MWTS and MWHS were less than the values used in the WRFDA. MWTS had small inter-channel errors, while MWHS had significant inter-channel errors. The horizontal correlation length scales of MWTS and MWHS were about 120 and 60 km, respectively. A comparison between the diagnosis for instruments onboard the two satellites showed that the observation-error characteristics of the MWTS or MWHS were different when they were onboard different satellites. In addition, it was found that the error statistics were dependent on latitude and scan positions.The forecast experiments showed that using a modified thinning scheme based on diagnosed statistics can improve forecast accuracy.

Latitudinal and Scan-dependent Biases of Microwave Humidity Sounder Measurements and Their Dependences on Cloud Ice Water Path

The relationship between differences in microwave humidity sounder(MHS)–channel biases which represent measured brightness temperatures and model-simulated brightness temperatures, and cloud ice water path(IWP) as well as the influence of the cloud liquid water path(LWP) on the relationship is examined. Seven years(2011–17) of NOAA-18 MHS-derived measured brightness temperatures and IWP/LWP data generated by the NOAA Comprehensive Large Array-data Stewardship System Microwave Surface and Precipitation Products System are used. The Community Radiative Transfer Model, version2.2.4, is used to simulate model-simulated brightness temperatures using European Center for Medium-Range Weather Forecasts reanalysis data as background fields. Scan-angle deviations of the MHS window channel biases range from-1.7 K to1.0 K. The relationships between channels 2, 4, and 5 biases and scan angle are symmetrical about the nadir. The latitudedependent deviations of MHS window channel biases are positive and range from 0–7 K. For MHS non-window channels,the latitudinal deviations between measured brightness temperatures and model-simulated brightness temperatures are larger when the detection height is higher. No systematic warm or cold deviations are found in the global spatial distribution of difference between measured brightness temperatures and model-simulated brightness temperatures over oceans after removing scan-angle and latitudinal deviations. The corrected biases of five different MHS channels decrease differently with respect to the increase in IWP. This decrease is stronger when LWP values are higher.

The first near real-time inverted echo sounder observation in the South China Sea

We report the first near real-time inverted echo sounder(IES)observation in the South China Sea(Fig.1).Although the first IES observation in the South China Sea was in 2005,and the near real-time IES observation module was first developed in 2012(http://www.po.gso.uri.edu/dynamics/IES/hist.html),the real-time IES has never been deployed in the South China Sea until the reporting of observations in this study.IES is a bottom-mounted mooring that records the round-trip acoustic travel time from the bottom to the surface and back(τ).

A Method for the Removal of Ray Refraction Effects in Multibeam Echo Sounder Systems

To a multibeam echo sounder system (MBES), under water sound refraction plays an important role in depth measure- ment accuracy, and errors in sound velocity profile lead to inaccuracies in the measured depth (especially for outer beams). A method is developed to estimate the sound velocity profile based on the depth measured by vertical beam. Using this depth and other pa- rameters, such as t (sound pulse propagation time), θ (beam inclination angle), etc. We can estimate a simple sound velocity profile with which the depth error has been reduced. This method has been tested with a real dataset acquired in the East China Sea.

A Neural Network Based Single Footprint Temperature Retrieval for Atmospheric Infrared Sounder Measurements and Its Application to Study on Stratospheric Gravity Wave

Satellite hyperspectral infrared sounder measurements have better horizontal resolution than other sounding techniques as it boasts the stratospheric gravity wave(GW)analysis.To accurately and efficiently derive the three-dimensional structure of the stratospheric GWs from the single-field-of-view(SFOV)Atmospheric Infra Red Sounder(AIRS)observations,this paper firstly focuses on the retrieval of the atmospheric temperature profiles in the altitude range of 20-60 km with an artificial neural network approach(ANN).The simulation experiments show that the retrieval bias is less than 0.5 K,and the root mean square error(RMSE)ranges from 1.8 to 4 K.Moreover,the retrieval results from 20 granules of the AIRS observations with the trained neural network(AIRS_SFOV)and the corresponding operational AIRS products(AIRS_L2)as well as the dual-regression results from the Cooperative Institute for Meteorological Satellite Studies(CIMSS)(AIRS_DR)are compared respectively with ECMWF T799 data.The comparison indicates that the standard deviation of the ANN retrieval errors is significantly less than that of the AIRS_DR.Furthermore,the analysis of the typical GW events induced by the mountain Andes and the typhoon"Soulik"using different data indicates that the AIRS_SFOV results capture more details of the stratospheric gravity waves in the perturbation amplitude and pattern than the operational AIRS products do.