Ningxia Meteorological Bureau

Abstract. Aerosol acidity plays a key role in secondary aerosol formation. The high-temporal-resolution PM2.5 pH and size-resolved aerosol pH in Beijing were calculated with ISORROPIA II. In 2016–2017, the mean PM2.5 pH (at relative humidity (RH) > 30 %) over four seasons was 4.5±0.7 (winter) > 4.4±1.2 (spring) > 4.3±0.8 (autumn) > 3.8±1.2 (summer), showing moderate acidity. In coarse-mode aerosols, Ca2+ played an important role in aerosol pH. Under heavily polluted conditions, more secondary ions accumulated in the coarse mode, leading to the acidity of the coarse-mode aerosols shifting from neutral to weakly acidic. Sensitivity tests also demonstrated the significant contribution of crustal ions to PM2.5 pH. In the North China Plain (NCP), the common driving factors affecting PM2.5 pH variation in all four seasons were SO42-, TNH3 (total ammonium (gas + aerosol)), and temperature, while unique factors were Ca2+ in spring and RH in summer. The decreasing SO42- and increasing NO3- mass fractions in PM2.5 as well as excessive NH3 in the atmosphere in the NCP in recent years are the reasons why aerosol acidity in China is lower than that in Europe and the United States. The nonlinear relationship between PM2.5 pH and TNH3 indicated that although NH3 in the NCP was abundant, the PM2.5 pH was still acidic because of the thermodynamic equilibrium between NH4+ and NH3. To reduce nitrate by controlling ammonia, the amount of ammonia must be greatly reduced below excessive quantities.

Abstract Joint size and fall velocity distributions of raindrops were measured with a Particle Size and Velocity (PARSIVEL) precipitation particle disdrometer in a field experiment conducted during July and August 2007 at a semiarid continental site located in Guyuan, Ningxia Province, China (36°N, 106°16′E). Data from both stratiform and convective clouds are analyzed. Comparison of the observed raindrop size distributions shows that the increase of convective rain rates arises from the increases of both drop concentration and drop diameter while the increase of the rain rate in the stratiform clouds is mainly due to the increase of median and large drop concentration. Another striking contrast between the stratiform and convective rains is that the size distributions from the stratiform (convective) rains tend to narrow (broaden) with increasing rain rates. Statistical analysis of the distribution pattern shows that the observed size distributions from both rain types can be well described by the gamma distribution. Examination of the raindrop fall velocity reveals that the difference in air density leads to a systematic change in the drop fall velocity while organized air motions (updrafts and downdrafts), turbulence, drop breakup, and coalescence likely cause the large spread of drop fall velocity, along with additional systematic deviation from terminal velocity at certain raindrop diameters. Small (large) drops tend to have superterminal (subterminal) velocities statistically, with the positive deviation from the terminal velocity of small drops being much larger than the negative deviation of large drops.

Abstract The authors investigate the relationship between sea surface temperature (SST) in the tropical Indian Ocean (TIO) and the seasonal atmosphere circulation in the Asian monsoon region (AMR) using the maximum covariance analyses (MCAs). The results show that the Asian monsoon circulation is significantly correlated with two dominant SST anomaly (SSTA) modes: the Indian Ocean Basin mode (IOB) and the Indian Ocean dipole mode (IOD). The peak SSTA of the IOB appears in spring and has a much stronger relationship with the Asian summer monsoon than the peak of the IOD does, whereas the peak SSTA for the IOD appears in fall and shows a stronger link to the Asian winter monsoon than to the Asian summer monsoon. In addition, the IOB in spring has a relatively stronger link with the atmospheric circulation in summer than in other seasons. The large-scale atmospheric circulation and SSTA patterns of the covariability of the first two dominant MCA modes are described. For the first MCA mode, a warm IOB, persists from spring to summer, and the atmospheric circulation is enhanced by the establishment of the climatological summer monsoon. The increased evaporative moisture associated with the warm IOB is transported to South Asia by the climatological summer monsoon, which increases the moisture convergence toward this region, leading to a significant increase in summer monsoon precipitation. For the second MCA mode, a positive IOD possibly corresponds to a weaker Indian winter monsoon and more precipitation over the southwestern and eastern equatorial TIO.

Northwest China forms the main part of the arid and semiarid areas in China, and even includes some extremely arid areas. This zone of interaction is affected by the westerlies and monsoons making it sensitive to global climate change. Drought is the main type of natural disaster affecting northwest China. Global warming has caused a gradual strengthening of the frequency and intensity of hot extremes, when dry conditions and heatwaves occur simultaneously or successively; as a result, that socioeconomic risks can increase considerably. The present study examined changes in concurrent droughts and hot extremes in northwest China during 1961–2017 based on data from 119 meteorological stations. The result shows that the frequency of concurrent droughts and hot extremes exhibited an increasing trend over most parts of northwest China, while a negative trend occurred in western Xinjiang and at some sites in Qinghai. Concurrent droughts and hot extremes appeared more often in May in western Xinjiang, and in summer in other parts of northwest China. Overall, the trends of such concurrent events, regardless of different definitions, increased from 1961–2017 over northwest China. In particular, from 1981–2017, the trend rose more significantly than in other decades, and reached an abrupt point of change in 1996. Although the trend changed from a positive significant signal to a negative one from 2001–2017, the trend grew 2–3 times from 1997–2017. Changes in large‐scale atmospheric circulation show that an anticyclonic circulation strengthened, increasing in geopotential height over the midhigh latitudes of Eurasia and was centred on Mongolia and Lake Baikal. This enhanced relative humidity in western Xinjiang and eastern Qinghai, and weakened it elsewhere from 1997–2017. These changes have contributed to the changes in the spatial distribution and trends in concurrent droughts and hot extremes in northwest China.

Abstract We analyzed 40 year data sets of daily average visibility (a proxy for surface aerosol concentration) and hourly precipitation at seven weather stations, including three stations located on the Taihang Mountains, during the summertime in northern China. There was no significant trend in summertime total precipitation at almost all stations. However, light rain decreased, whereas heavy rain increased as visibility decreased over the period studied. The decrease in light rain was seen in both orographic‐forced shallow clouds and mesoscale stratiform clouds. The consistent trends in observed changes in visibility, precipitation, and orographic factor appear to be a testimony to the effects of aerosols. The potential impact of large‐scale environmental factors, such as precipitable water, convective available potential energy, and vertical wind shear, on precipitation was investigated. No direct links were found. To validate our observational hypothesis about aerosol effects, Weather Research and Forecasting model simulations with spectral‐bin microphysics at the cloud‐resolving scale were conducted. Model results confirmed the role of aerosol indirect effects in reducing the light rain amount and frequency in the mountainous area for both orographic‐forced shallow clouds and mesoscale stratiform clouds and in eliciting a different response in the neighboring plains. The opposite response of light rain to the increase in pollution when there is no terrain included in the model suggests that orography is likely a significant factor contributing to the opposite trends in light rain seen in mountainous and plain areas.

Abstract Using observational data and phase 5 of the Coupled Model Intercomparison Project (CMIP5) model outputs [the preindustrial (PI) control run of the Community Climate System Model, version 4 (CCSM4) and historical simulations of 17 CMIP5 models], Indian Ocean dipoles (IODs) with a peak in fall are categorized into three types. The first type is closely related to the development phase of El Niño/La Niña. The second type evolves from the basinwide warming (cooling) in the tropical Indian Ocean (IO), usually occurring in the year following El Niño (La Niña). The third type is independent of El Niño and La Niña. The dominant trigger condition for the first (third) type of IOD is the anomalous Walker circulation (anomalous cross-equatorial flow); the anomalous zonal sea surface temperature (SST) gradient in the tropical IO is the trigger condition for the second type. The occurrence of anomalous ocean Rossby waves during the forming stage of IO basinwide mode and their effect on SST in the southwestern IO during winter and spring are critical for early development of the second type of IOD. Although most models simulate a stronger El Niño–Southern Oscillation and IOD compared to the observations, this does not influence the phase-locking and classification of the IOD peaking in the fall.

In this paper, drought status of northwestern China is evaluated using the Terra–Moderate Resolution Imaging Spectroradiometer (MODIS) data with a newly developed method called perpendicular drought index (PDI), which is defined as a line segment that is parallel with the soil line and perpendicular to the normal line of soil line intersecting the coordinate origin in the two‐dimensional scatter plot of red against near infrared (NIR) wavelength reflectance. To validate the PDI in macroscale applications, quantitative evaluation of drought conditions in Ningxia, Northwestern China is carried out by comparing the PDI with one of the well‐known drought indexes, namely, temperature‐vegetation index (TVX). Linear regression between ground‐measured soil moisture data and the PDI and the TVX was made. Results show that satellite based PDI and TVX has significant correlation with 0–20 cm averaged soil moisture obtained over the meteorological observing stations across the whole study area. The highest correlation of R 2 = 0.48 for the PDI and R 2 = 0.40 for the TVX is obtained when compared with average soil moisture from 0 to 20 cm soil depth. According to the drought critical values defined by soil hydrologic parameters including soil moisture, wilting coefficient and field moisture capacity, the PDI based drought guidelines are established, and then the drought status in the study area is evaluated using the PDI. It is evident from the results showing the spatial distribution of drought in northwestern China that the PDI is highly accordant with field drought status.

Observational analysis and model experiments show that the sea surface temperature anomaly associated with the Indian Ocean Basin mode (IOBM), which persists from spring to summer, can generate significant circumglobal teleconnection (CGT) in the Northern Hemisphere summer midlatitude atmosphere. A warm IOBM can induce a new atmospheric heating source in the south Asia through a positive feedback. An enhanced Indian summer monsoon through the increased precipitation in the south Asia induces an atmospheric heating source there. This new atmospheric heating source generates an anomalous high to its northwest over the western‐central Asia, which in turn generates an eastward downstream atmospheric wave train, forming the CGT.

This review provides a comprehensive coverage of changes of the Hadley Cell extent and their impacts on the weather, climate, and society. The theories predicting the Hadley Cell width are introduced as a background for the understanding of the circulation changes and the metrics used for detection. A variety of metrics derived from various data sources have been used to quantify the Hadley Cell width. These metrics can be classified as dynamical, hydrological, thermal, and chemical metrics, based on the properties of the variables used. The dynamical metrics have faster trends than those based on thermal or hydrological metrics, with the values exceeding 1 degree per decade. The hydrological metric edge poleward trends were found a slightly faster expansion in the Northern Hemisphere than its southern counterpart. The chemical metrics show a poleward trend of more than 1 degree per decade in both hemispheres. We also suggest a few reasons for the discrepancy among trends in Hadley Cell expansion found in previous studies. Multiple forcings have been found responsible for the expansion, which seems to be more attributed to the natural variability than anthropogenic forcing. Validation of the scaling theories by the trends in Hadley Cell width suggests that theories considering the extratropical factor would be better models for predicting the Hadley Cell width changes. The Hadley Cell has an impact on different atmospheric processes on varying spatio-temporal scales, ranging from weather to climate, and finally on society. The remaining questions regarding Hadley Cell climate are briefly summarized at the end.

should be a promising material for a high performance TMA gas sensor.

Satellite-based precipitation estimates products, CMORPH and PERSIANN-CCS, were evaluated with a dense rain gauge network over Beijing and adjacent regions for an extremely heavy precipitation event on July 21 2012. CMORPH and PEERSIANN-CSS misplaced the region of greatest rainfall accumulation, and failed to capture the spatial pattern of precipitation, evidenced by a low spatial correlation coefficient (CC). CMORPH overestimated the daily accumulated rainfall by 22.84% while PERSIANN-CCS underestimated by 72.75%. In the rainfall center, both CMORPH and PERSIANN-CCS failed to capture the temporal variation of the rainfall, and underestimated rainfall amounts by 43.43% and 87.26%, respectively. Based on our results, caution should be exercised when using CMORPH and PERSIANN-CCS as input for monitoring and forecasting floods in Beijing urban areas, and the potential for landslides in the mountainous zones west and north of Beijing.

The head region of the Yellow River is the key area where climate change would affect the hydrological process, since it is in a high elevation and cold area. Temperature and precipitation are two important meteorologic factors influencing the hydrological process. In this study, runoff change was evaluated as a result of the hydrological process change and an evaluation of runoff response to the two factors was made. Data derived from the results of seven general circulation models (GCMs) under two intergovernmental panel on climate change scenarios (A2 and B2) were used as future climate scenarios. First, factual and future climate change is analyzed according to data observed and obtained from GCMs. It was found that temperature has been increasing since 1961 and would continue in the future. The change in future precipitation also showed an increasing tendency. Then, a distributed hydrologic model, taking into account the effect of snow and frozen soil, was developed based on observed data in order to investigate the impact of temperature and precipitation change on runoff. Simulated runoff corresponding to climate scenarios indicates that the runoff amount would change lightly before 2020 and then would decrease approximately 5% per year. Analysis of runoff characteristics showed that runoff would increase in the dry season, resulting in relatively uniform distribution of seasonal runoff. Large variablility in annual runoff in the future implies a high probability and severity of flooding as well as droughts.

Abstract Inorganic nitrate production is critical in atmospheric chemistry that reflects the oxidation capacity and the acidity of the atmosphere. Here we use the oxygen anomaly of nitrate (Δ 17 O( $$\rm{NO}_{3}^{-}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mrow><mml:mi>NO</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow><mml:mrow><mml:mo>−</mml:mo></mml:mrow></mml:msubsup></mml:math> )) in high-time-resolved (3 h) aerosols to explore the chemical mechanisms of nitrate evolution in fine particles during the winter in Nanjing, a megacity of China. The continuous Δ 17 O( $$\rm{NO}_{3}^{-}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mrow><mml:mi>NO</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow><mml:mrow><mml:mo>−</mml:mo></mml:mrow></mml:msubsup></mml:math> ) observation suggested the dominance of nocturnal chemistry (NO 3 + HC/H 2 O and N 2 O 5 + H 2 O/Cl − ) in nitrate formation in the wintertime. Significant diurnal variations of nitrate formation pathways were found. The contribution of nocturnal chemistry increased at night and peaked (72%) at midnight. Particularly, nocturnal pathways became more important for the formation of nitrate in the process of air pollution aggravation. In contrast, the contribution of daytime chemistry (NO 2 + OH/H 2 O) increased with the sunrise and showed a highest fraction (48%) around noon. The hydrolysis of N 2 O 5 on particle surfaces played an important role in the daytime nitrate production on haze days. In addition, the reaction of NO 2 with OH radicals was found to dominate the nitrate production after nitrate chemistry was reset by the precipitation events. These results suggest the importance of high-time-resolved observations of Δ 17 O( $$\rm{NO}_{3}^{-}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mrow><mml:mi>NO</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow><mml:mrow><mml:mo>−</mml:mo></mml:mrow></mml:msubsup></mml:math> ) for exploring dynamic variations in reactive nitrogen chemistry.

Abstract The climatological characteristics of total aerosol optical thickness (AOT) together with fine and coarse mode AOT (fAOT and cAOT) and fine mode fraction (FMF = fAOT/AOT) over East and South Asia are presented here for the period March 2005 to October 2013. The characteristics are retrieved from POLDER/PARASOL measurements using recently developed aerosol component module of GRASP algorithm. The satellite retrievals were validated and presented a good agreement with the AERONET products (e.g., R of ~0.8–0.9 for AOT, fAOT, Ångström exponent, and FMF). The results show a seasonal cycle and strong relation to the emission sources. For example, FMF has a peak of nearly 1.0 in March in the Indo‐China Peninsula region, reaching a minimum of about 0.4 in April in Northwestern China region. These patterns can be explained by dominance of anthropogenic pollution or desert dust emissions. Maps of fine, coarse, and total AOT, as well as of FMF for the East and South Asia region, are presented and analyzed in scope of seasonal and interannual variabilities.

Based on LMDZ4 daily temperature dataset, equidistant cumulative distribution function matching method (EDCDFm) and cumulative distribution function-transform method (CDF-t) are used to evaluate the ability of models in simulating extreme temperature over central and eastern China. The future temperature change is then projected. The results show that the EDCDFm and CDF-t methods function effectively correct the spatial distribution of daily mean temperature and extreme temperature, significantly reduce the biases of the model simulation and effectively improve the capacity of models for spatial pattern of extreme temperature. However, the cold bias of the CDF-t method in winter is obviously higher than that of the EDCDFm method, and the temperature change curve of the EDCDFm method is closer to the observation than that of the CDF-t method. The projection based on the EDCDFm method shows that under the RCP4.5 emission scenario, the temperature in the study area shows a warming trend. Relative to 1986–2005, the mean temperature is projected to increase by 0.76, 1.84, and 2.10 °C during 2017–2036, 2046–2065, and 2080–2099, respectively. The spatial change for the mean, maximum, and minimum temperature in the three future periods have good consistency; warming in northern China is higher than that in the south. Uncertainties in temperature projection are large in the Tibetan Plateau and Sichuan Basin. Frost days decrease significantly, especially in the Tibetan Plateau, and the frost days in the three periods decrease by more than 15, 30, and 40 d, respectively. The variation of heat wave indice is the smallest; the increase of heat wave is mainly in eastern China, and the increase in South China is more than 2 d. Besides, under the global warming of 1.5 °C and 2 °C, the response characteristics of extreme temperature over central and eastern China are also analyzed. The results show that the mean temperature, maximum temperature and minimum temperature in the study area increase by more than 0.75 °C under 1.5 °C target and over 1.25 °C under 2 °C target, especially in the northwestern China and the Tibetan Plateau, relative to 1986–2005. Additionally, comparing two warming targets, the difference of three temperature indices in parts of northeastern China is over 1.5 °C, while more than 3 d for heat wave.

The effects of 8 typhoons which passed by coldcore eddy (CCE) areas in the South China Sea (SCS) from 1997 to 2009 were observed and evaluated. The changes in the preexisting CCE acted upon by typhoons were described by eddy kinetic energy (EKE) and eddy available gravitational potential energy (EAGPE). The mechanical energy of CCE was estimated from a two-layer reduced gravity model. Comparing with the scenario that typhoon passes by the region without CCEs, the preexisting CCE area plays an important role in the increase of chlorophyll-a (chl-a) concentration in the CCEs impacted by the typhoons. The preexisting chl-a in CCE is about 25%~45% (8%~25%) of postexisting chl-a in CCE for higher (slower) transit speed typhoons. If the EAGPE of CCE increases greatly after typhoon passing by with slow transit speed, so does the chl-a in the CCE area. The EKE (EAGPE) changes of the preexisting CCE are in the order of O(10 14 ~10 15 J). EKE and EAGPE of CCE are dominantly enhanced by typhoon with slow transit speed (&lt;3 m/s) and the posttyphoon EAGPE is always larger than posttyphoon EKE for 8 cases. The maximum EAGPE change of the preexisting CCE reaches<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mn>5.11</mml:mn><mml:mo>×</mml:mo><mml:msup><mml:mrow><mml:mn>10</mml:mn></mml:mrow><mml:mrow><mml:mn>15</mml:mn></mml:mrow></mml:msup></mml:math> J, which was induced by typhoon Hagibis.

The Qinghai-Tibet Plateau (QTP) has the largest extent of high altitude permafrost at the middle and low latitudes in northern hemisphere and is surrounded by dozens of seasonally frozen ground. Rising air temperatures have resulted in frozen ground degradation over QTP since the last century. Based on the daily frozen soil depth, annual mean daily minimum air temperatures and annual mean air temperatures obtained from 19 in-situ observations over QTP, the changes in the thickness, temporal and spatial distributions of frozen ground, as well as the associated attributions, are analyzed for the period of 1960-2019. The results show that the maximum depth of frost penetration, the beginning time of soil freezing and the ending time of soil thawing have changed considerably. On average, the maximum depth of frost penetration (MDFP) has reduced by 0.14~1.71 m at most stations. The annual frozen period has decreased by about 40 days. The changes in seasonal freezing of soils appear to be attributed to the rising of minimum air temperatures in winter, especially at the higher elevations range from 4500 to 5000 m.

Crop type classification with satellite imageries is widely applied in support of crop production management and food security strategy. The abundant supply of these satellite data is accelerating and blooming the application of crop classification as satellite data at 10 m to 30 m spatial resolution have been made accessible easily, widely and free of charge, including optical sensors, the wide field of viewer (WFV) onboard the GaoFen (GF, high resolution in English) series from China, the MultiSpectral Instrument (MSI) onboard Sentinel 2 (S2) from Europe and the Operational Land Imager (OLI) onboard Landsat 8 (L8) from USA, thanks to the implementation of the open data policy. There are more options in using the satellite data as these three data sources are available. This paper explored the different capability of these three data sources for the crop type mapping in the same area and within the same growing season. The study was executed in a flat and irrigated area in Northwest China. Nine types of crop were classified using these three kinds of time series of data sources in 2017 and 2018, respectively. The same suites of the training samples and validation samples were applied for each of the data sources. Random Forest (RF) was used as the classifier for the crop type classification. The confusion error matrix with the OA, Kappa and F1-score was used to evaluate the accuracy of the classifications. The result shows that GF-1 relatively has the lowest accuracy as a consequence of the limited spectral bands, but the accuracy is at 93–94%, which is still excellent and acceptable for crop type classification. S2 achieved the highest accuracy of 96–98%, with 10 available bands for the crop type classification at either 10 m or 20 m. The accuracy of 97–98% for L8 is in the middle but the difference is small in comparison with S2. Any of these satellite data may be used for the crop type classification within the growing season, with a very good accuracy if the training datasets were well tuned.

Abstract Northeast China (NEC) is one of the major agricultural production areas in China, producing about 30% of China’s total maize output. In the past five decades, maize yields in NEC increased rapidly. However, farmer yields still have potential to be increased. Therefore, it is important to quantify the impacts of agronomic factors, including soil physical properties, cultivar selections, and management practices on yield gaps of maize under the changing climate in NEC in order to provide reliable recommendations to narrow down the yield gaps. In this study, the Agricultural Production Systems Simulator (APSIM)-Maize model was used to separate the contributions of soil physical properties, cultivar selections, and management practices to maize yield gaps. The results indicate that approximately 5%, 12%, and 18% of potential yield loss of maize is attributable to soil physical properties, cultivar selection, and management practices. Simulation analyses showed that potential ascensions of yield of maize by improving soil physical properties PAYs, changing to cultivar with longer maturity PAYc, and improving management practices PAYm for the entire region were 0.6, 1.5, and 2.2 ton ha−1 or 9%, 23%, and 34% increases, respectively, in NEC. In addition, PAYc and PAYm varied considerably from location to location (0.4 to 2.2 and 0.9 to 4.5 ton ha−1 respectively), which may be associated with the spatial variation of growing season temperature and precipitation among climate zones in NEC. Therefore, changing to cultivars with longer growing season requirement and improving management practices are the top strategies for improving yield of maize in NEC, especially for the north and west areas.

Timely sowing and harvesting play important roles in agricultural production. The appropriate management decisions are necessary to cope with climate change and ensure high and stable crop yields. This study analyzed the effects of sowing date on the growth process of winter wheat and quantified the effects of climate resources and photothermal potential yield on theoretical yield at different stages of winter wheat. The analysis was based on the data from winter wheat interval sowing experiments conducted at the Hebei Gucheng Agricultural Meteorology National Observation and Research Station (Gucheng station) in north China (115°40′ E, 39°08′ N) during 2017–2019. The results showed that: (1) with the delay in sowing date, the growth process of winter wheat significantly advanced, the proportion of vegetative growth period significantly reduced (0.19% for per day delay), the proportion of reproductive growth period (RGP) significantly increased (0.12% for per day delay), and the prewintering light and temperature resources significantly reduced (12.2 °C·d accumulated temperature and 19.0 MJ·m−2 solar radiation for per day delay); (2) the theoretical yield of winter wheat showed a significant exponential relationship with the photothermal potential yield of the whole growth period: the minimum photothermal potential for yield formation was 26.6 t·ha−1, and the maximum theoretical yield was 12.6 t·ha−1; and (3) the wheat yield and yield stability were highest when the RGP photothermal potential yield was 16.0 t·ha−1 and the prewintering active accumulated temperature was 400 °C·d. This study also proposed a method to estimate the suitable sowing and harvesting dates to achieve high and stable yield of winter wheat, showing that the suitable sowing dates of winter wheat at Gucheng station from 1997 to 2021 ranged from 1 to 15 October, with no significant interannual variation; the suitable harvesting period ranged from 5 June to 10 July and showed a trend of gradual advance with the delay of the year. The results of the study provide a reference for sowing date adjustment of crops to adapt to climate change.