Northeast China Cold Vortex Observed by FY‐3 MWTS‐2 and MetOp AMSU‐A

Abstract

The northeast China cold vortex (NCCV) refers to a closed low‐pressure system over northeast China extending from China‐Siberia to the northwest Pacific coast region. It is cut off from the westerly jet belt in the middle and upper troposphere, has a cold core, lasts several days, and could bring heavy rain events in late spring and summer that are of great challenge to weather forecasters. This study investigates the possibility of observing temperature structures of NCCVs by two microwave temperature sounders, that is, the Microwave Temperature Sounder‐2 (MWTS‐2) and the Advanced Microwave Sounding Unit‐A (AMSU‐A) onboard the two polar‐orbiting operational environmental satellites (POES) Fenyun‐3 satellite FY‐3D and Meteorological Operational satellite MetOp‐B, respectively. The MWTS‐2 and AMSU‐A together provide 3D atmospheric temperatures in the middle and upper troposphere, as well as the lower stratosphere four times daily. Both limb‐corrected direct observations of brightness temperature and retrievals of atmospheric temperature within NCCVs are characterized by cold and warm cores below and above the tropopause, respectively, comparing favorably with the European Centre for Medium‐Range Weather Forecasts ERA5 reanalysis. Compared with the ERA5 reanalysis in June 2019, the MWTS‐2 retrieved atmospheric temperatures have no scan‐dependent biases, the biases are smaller than ±0.2K, and root‐mean‐square errors (RMSEs) are smaller than and 2.0K at all altitudes. This study suggests the possibility of using multiple POES microwave‐temperature‐sounding observations for near‐real‐time monitoring of NCCVs' 3D temperature structures.

Tracking the Early Movements of Northeast China Cold Vortices Using FY-3D MWTS-2 Observations of Brightness Temperature

“…There are few studies on NCCVs that directly used microwave temperature-sounding observations. Although Niu et al (2021) [30] creatively verified that the three-dimensional temperature structure of NCCVs can be retrieved from these TB observations, this study is the first attempt to directly apply the microwave temperaturesounding observations for tracking early signals of NCCVs. In this research, four NCCV cases from June to July 2019 are selected to track the origin and movement of NCCVs from MWTS-2 TB observations.…”

“…MWTS-2 TB observations were successfully applied to study the warm core of typhoons [28,29]. Recently, Niu et al (2021) [30] pointed out that there are some similarities between the structure of NCCVs and typhoons. They studied the synoptic scale NCCVs using MWTS-2 observations.…”

“…Compared with the ECMWF reanalysis V5 (ERA5) whose final release would have at least 2-3 months delay [31], polar-orbiting satellites offer global TB observations twice a day and are made available in real time. Radiosonde stations provide real-time data but are too sparse to capture horizontal structures of NCCVs [30]. It is practical to use satellite TB observations for realtime weather monitoring.…”