The fixed-point refined analysis and forecast evaluation of meteorological elements are of great significance to the meteorological guarantee of major sports events. Based on the precipitation analysis product of three-source fusion data from the National Meteorological Information Center and the ERA5 reanalysis data from European Centre for Medium-Range Weather Forecasts (ECMWF), the characteristics of meteorological elements were studied at the key venues (Xi’an Olympic Sports Centre, Yan’an University Gymnasium and Hanjiang open water area in Ankang) of the 14th National Games, and the prediction performance of precipitation, temperature and wind products of ECMWF, China Meteorological Administration Mesoscale Model (CMA-MESO) and grid-guided precipitation forecast products (SCMOC) was inspected at the three key venues. The main conclusions are as follows: (1) The probability of precipitation at the three key venues was all high in the historical period of the 14th National Games. On the opening and closing days at Xi’an venue, the probability of precipitation was 46% and 44% and the average daily precipitation was 24.6 mm and 9.8 mm, respectively, and the peak of precipitation and precipitation probability mostly appeared from afternoon to evening. (2) The temperature was relatively low at night and increased rapidly in the daytime, and the daily average temperature mostly fluctuated between 12 ℃ and 18 ℃ at the three venues during the 14th National Games, which is generally appropriate to race. The easterly or southerly winds prevailed at the three venues, and the wind speed at Xi’an and Ankang venues was low, which is suitable to sport events, while the frequency of wind force above grade 4 at Yan’an venue was higher, which may have an adverse effect to sport events. (3) In general, the rain probability prediction accuracy of SCMOC at the three venues was the highest in the historical same period of the 14th National Games, but the frequency of precipitation forecast was significantly lower than the observation, which had the risk of missing forecast. In addition, SCMOC had obvious advantages for the rain probability prediction to precipitation processes with circulation situation of blocking pattern and two-trough and one-ridge pattern, while ECMWF had better performance to precipitation processes with low vortex bottom pattern, and TS value was stable. The accuracy of temperature prediction of ECMWF was better than that of SCMOC and CMA-MESO, while the wind speed forecast of SCMOC had absolute advantages. (4) During the 14th National Games, the performance differences among three forecast products were basically consistent with the historical period, but the overall forecast scores were higher than the historical period.

The sunflower growing region in northern China is mainly located in arid and semi-arid areas, and the yield is governed by wet and dry conditions. The non-homogeneous variation of water resources between different regions in the context of climate change has increased uncertainty of sunflower production. Based on daily meteorological data from 296 stations in the sunflower growing region in northern China, the wetness index and standardized precipitation evapotranspiration index (SPEI) calculated on the basis of precipitation and crop evapotranspiration are used to analyze the spatial and temporal characteristics of dry and wet conditions and the influence of major meteorological factors on crop evapotranspiration in the sunflower growing season from 1961 to 2020, and the causes of changes in dry and wet conditions are explored by using sensitivity and contribution rate method. The results show that the frequency of drought in sunflower growing season in northern China generally presented a spatial distribution decreasing from west to east, among which the frequency of drought was higher in northern Xinjiang, northern Ningxia and western Inner Mongolia. In the last 60 years, both precipitation and evapotranspiration in sunflower growing season decreased. The SPEI had an abrupt change in 1980, and compared with the period of 1961-1980, the frequency of slight, medium and severe drought during 1981-2020 generally decreased by 5.63%, 4.41%, 2.49%. Obvious differences between different regions in terms of dry and wet conditions were found, with the climate in Chifeng of Inner Mongolia, southern Liaoning and the North China plain showing a warm and dry trend, and the climate in western Inner Mongolia and Xinjiang becoming wet. The change in temperature and relative humidity increased crop evapotranspiration, but the change in sunshine hours and wind speed decreased crop evapotranspiration in the last 60 years in sunflower growing season. The contribution rate of wind speed and sunshine hours at 55.39% stations to crop evapotranspiration is greater than that of temperature, resulting in a significant decrease of crop evapotranspiration.

 Using FY-2G satellite data, ERA5 reanalysis data, and the integrated hourly resolution precipitation data from automatic weather stations, as well as CMORPH precipitation products, this paper focused on a comparative analysis of cloud-image characteristics, circulation features, and the parcel buoyancy instability of a pseudo adiabatic process and a reversible adiabatic process in two particularly strong precipitation periods from 03:00 BST to 15:00 BST 28 (the period 1) and from 20:00 BST 28 to 08:00 BST 29 (the period 2) during a heavy rain process occurring at the boundary between Sichuan and Shaanxi from June 26 to 29, 2015. The results show that the maintenance of strong divergence on 200 hPa, a steady shear on 500 hPa, and maintenance of 850 hPa wind convergence at this boundary provided favorable conditions for the occurrence and development of heavy rain during the period 1. The heavy precipitation in the period 1 forming at the boundary between Sichuan and Shaanxi was affected by a MαCS (meso-α convective system) moving northward steered by the southwest flow in middle to upper levels. The 500 and 700 hPa shear and the maintenance of a southerly airflow in the lower layers were important factors leading to heavy rain in the period 2. The development and merging of convective cloud clusters near the shear contributed to the formation of heavy rain in the period 2 at the boundary between Sichuan and Shaanxi. The low-level water vapor content over the rainstorm center in the period 1 was higher than that in the period 2. The updraft area over the rainstorm area extended higher, the updraft was stronger, and the cloud layer in the rainstorm area was deeper and denser in the period 1 than in the period 2. In both periods, the instability of the parcel’s vertical displacement according to a reversible adiabatic process was higher than that according to a pseudo-adiabatic process over the center of the heavy rain. The high-value areas of CAPE over the rainstorm centers of both periods all distributed between 800 and 700 hPa, which indicated that the parcel lifted between 800 and 700 hPa had large buoyancy during the adiabatic process. The favorable instability condition and the water vapor condition reinforced one another in the lower layer, which was conducive to development of heavy rain.