Hi Patrick， I have attempted to simulate brightness temperature in a one-dimensional atmosphere and compared it with observed brightness temperature. The O-B (observation minus background) results have shown improvement. However, in this case, the sensor line of sight (sensor_los) is defined using scan zenith angle.
In the three-dimensional simulation, the data provided by the Fengyun satellite specifies instrument zenith angle and azimuth angle. SensorZenith is defined as the angle between the line connecting the center of the Earth observation pixel and the satellite, and the line perpendicular to the zenith direction. SensorAzimuth is defined as the angle between the line connecting the satellite and the projection point on the ground plane, and the reference direction (north). SensorZenith and SensorAzimuth do not seem to correspond directly to the sensor_los that we require in ARTS. How can I convert them to the required variable sensor_los in ARTS? Can you provide some help? Looking forward to your reply!Thank you! Best wishes. Sincerely, ZhangChao > -----原始邮件----- > 发件人: "Patrick Eriksson" <patrick.eriks...@chalmers.se> > 发送时间: 2023-10-05 03:55:05 (星期四) > 收件人: "张超" <zhangchao...@mails.ucas.ac.cn>, arts_users.mi@lists.uni-hamburg.de > 抄送: > 主题: Re: [arts-users] consultancy question > > Hi, > > > Thanks for the quick reply! Regarding the first point mentioned, the simulation is described in detail as follows. The first simulation example based on is the artscomponents/montecarlo.arts file, with the input of 3-dimensional ERA5 contour data including temperature, humidity, pressure, and altitude, and the absorption model including water vapor, nitrogen, and oxygen, with the water vapor and oxygen being MPM93 models. Then according to the product matching with the Microwave Thermometer of Fengyun3 Satellite (MWTS) to the height and line of sight of the sensor in flight, input to sensr_pos and sensor_los, the sensor setup adopts sensor_responseGenericAMSU. other agendas include the surface agendas as well as the non-refractive situation of the air. The surface is modeled using TELSEM for land and TESSEM for ocean depending on the situation. However, the simulation results are highly biased, in the teens of K or more. Can you please see where the problem is? Or is there any related work that you can recommend as a reference? > > My recommendation is to start with setting up a clear-sky simulation. > And focus on the channels not having a sensitivity to the surface. If > you still have problems, you have most likely an error in the input data > (check e.g. units) or a mistake when defining the absorption of gases > > > > One more question, I would like to ask if the OEM method of ARTS2.4 is perfect, I didn't use QPACK of matlab because I am more familiar with ARTS language. > > The OEM inside ARTS can do everything you can do in Qpack. > > Bye, > > Patrick </zhangchao...@mails.ucas.ac.cn></patrick.eriks...@chalmers.se>
