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Clouds are an important parameter of artificial water augmentation, which is of substantial significance to judge the precipitation capacity. Xinjiang is an arid region in northwestern China, where weather stations are sparsely distributed, the types of underlying surface are complex, and the climate between the southern and northern region varies greatly. However, the retrieval of the total cloud cover (TCC) from satellite in arid areas is a challenging task. Based on the TCC data observed by ground observation stations (GOSs) from June 2015 to May 2016 considering the complex underlying surfaces and different weather conditions, the precision, consistency, and error between the cloud total amount from the FengYun-2F stationary satellite (FY-2F/CTA) and manually observed TCC are compared and evaluated in the Xinjiang region. The findings of this study are as follows: (1) the precision rate (PR) of FY-2F/CTA in the Xinjiang region is 75.6 %, which gradually decreases from north to south, demonstrating a high false rate (FR) and a low missing rate (MR). The consistency rate (CR) is 51.5 %, with little difference among three subregions of Xinjiang, all showing a high weak rate (WR) and low strong rate (SR), which means that the TCC values inverted from FY-2 satellite data are generally lower than those observed by GOSs, especially in southern Xinjiang. The bias is - 20 %, and all the error indexes (EIs) including bias, MAE, and RMSE increase from central to the north and south of Xinjiang; that means the EIs are the lowest in Tianshan and the highest in southern Xinjiang. FY-2F/CTA exhibits higher PR and CR in the underlying surface of vegetation compared to non-vegetation; that is to say that FY-2F/CTA performs best in the underlying surfaces of forest and plowland, while their performance is relatively poorer in the underlying surface of snow and ice. (2) With rising temperature the PR and CR of FY-2F/CTA increase, while the EIs decrease. Under various temperature conditions, FY-2F/CTA has always exhibited high MR, low FR (on the contrary in January), high WR, and low SR. From low elevation to high elevation, the PR and CR of FY-2F/CTA decrease, but the PR increases significantly when the altitude is higher than 2000 m. (3) Dust reduces the CR of FY-2F/CTA and increases their WR and MR but has a relatively minor impact on the identification of cloud and non-cloud. (4) Under different cloud cover levels, the PR and EIs of FY-2F/CTA are directly proportional to the amount of TCC, while the CR is inversely proportional to it: that is, the CR is higher and the PR and EIs are lower under clear-sky and partly cloudy conditions, and the CR is lower and the PR and EIs are higher under cloudy and overcast conditions. This study assessed the FY-2F/CTA under various conditions in arid areas of Xinjiang, including complex underlying surface, various temperature and altitude, dust effects, and different cloud cover levels. Thus, the research finding could serve as a valuable reference for satellite-based retrieval and applications related to TCC in arid regions. [ABSTRACT FROM AUTHOR]

The inversion data of the microwave radiometer atmospheric temperature profile were systematically analyzed with the temperature observation data of the microwave radiometer in coastal areas of Fujian. By comparing the microwave radiometer temperature inversion data with sounding and ERA5 temperatures, the ability of microwave radiometer to detect atmospheric temperature and the quality of the inversion data were analyzed, and the microwave radiometer inversion data were further applied to analyze the daily variation of atmospheric temperature in the boundary layer. The results show that the microwave radiometer temperature is in good agreement with the sounding temperature, with a correlation coefficient of 0.971, a mean deviation of 2.716 °C, and a root mean square error of 5.131 °C; the greater the intensity of rainfall, the more significant the effect of rainfall on the accuracy of the microwave radiometer in detecting atmospheric temperature. The correlation coefficients, mean deviations and root mean square errors of ERA5 and microwave radiometer are consistent from month to month; the temperature deviations between ERA5 and microwave radiometer in the middle atmosphere are smaller than those in the near-surface and upper atmosphere in each month; above 2 km in height, the temperature profiles of ERA5 and microwave radiometer are consistent. Above 2 km in altitude, the trend of ERA5 and microwave radiometer temperature profiles are basically the same. Below 3 km altitude, the daily variation of summer temperature is smaller than that of winter temperature at the same altitude. With the increase of altitude, the variation of atmospheric temperature in summer is large and that in winter is small [ABSTRACT FROM AUTHOR]

Based on the ozone monitoring instrument (OMI)satellite data products OMO3PR and ERA5 reanalysis data from 2010 to 2019, the spatial and temporal distribution characteristics of ozone (O3) mass concentration in the lower troposphere (altitude ≤3 000 m) and wind were studied in Shanghai and nearby sea area in recent 10 years. Taking Pudong area as an example, the characteristics of sea-land breezes, relative pollution coefficients and their effects on O mass concentration were studied. The results show that O mass concentration shows an overall increasing trend during the decade with obvious seasonal variations, with the highest mass concentration in summer and the lowest mass concentration in winter. The spatial distribution shows that O3 mass concentration on land are higher than that on the sea, and the maximum mass concentration of O3 is 129.3 µg/m³. The wind speed in summer and winter are higher than that in spring and autumn. The frequency of wind speed less than 5.4 m/s in land area is as high as 82.4%. In spring and summer, wind at the seas and offshore coastal areas easily diffuses O3 to the inland. The frequency of sea-land breeze is higher in spring and summer. During summer and autumn sea breeze, the relative pollution coefficient of west-southwest and southwest direction are higher than other directions. It indicates that the diffusion probability of O3 in Pudong Airport area to the northwest and area is higher at this time, which increases the mass concentration of O3 in land area. In summer and autumn, sea-land breeze can aggravate inland O3 pollution, and sea breeze has a stronger ability to aggravate inland O3 pollution than land breeze. [ABSTRACT FROM AUTHOR]

At present, most of the studies on the influence of cloud on the retrieval accuracy of satellite relative humidity (RH) profiles are mainly concerned with cloud fraction, while there are few studies on the influence of other cloud attributes. Cloud top height is also an important factor affecting the retrieval accuracy of satellite RH profiles. In this study, the L-band encrypted radiosonde data from Shanghai Baoshan Station was used to analyze the accuracy of AIRS/Aqua (Atmospheric Infrared Sounder) retrieved RH profiles under different quality control and cloud conditions from July to September. The purpose of this study is to make preparation for the assimilation of relevant data and to assess the influence of AIRS RH products on the accuracy of regional numerical prediction. The results show that: (1) The error of the AIRS retrieved RH profiles gradually increases with the increase of cloud fraction. With the increase of atmospheric pressure, the difference of the root mean squared errors of RH in each pressure layer tends to increase gradually when there are few clouds or it is cloudy. (2) The higher the cloud top height is, the worse the accuracy of AIRS retrieved RH profiles is. The retrieval accuracy of RH profiles above cloud top is higher, while the retrieval error below cloud top is larger. (3) Under high-level cloud and cloudy conditions, the accuracy of the AIRS retrieved RH profiles is the worst. At 850hPa, the minimum absolute error between the RH data retrieved by AIRS and the radiosonde data reaches -63.51%. (4) Although the accuracy of AIRS retrieved RH profiles in the troposphere is not as high as that of radiosonde when the quality control is 0, the retrieval accuracy is obviously improved compared with that when the quality control is 1. [ABSTRACT FROM AUTHOR]