Severe Sand Storms Research Articles

Dominant circulation pattern and moving path of the Mongolian Cyclone for the severe sand and dust storm in China

Severe sand and dust storm (SDS) is one of the major meteorological disasters in northern China. During 2000–2023, a total of 37 severe SDS events were monitored by the China Meteorological Administration and 34 of them occurred in the boreal spring (March to May). In this study, the 34 cases are analyzed to reveal their spatio-temporal features. The results indicate that there are two high-frequency centers. One is located in the Tarim Basin in northwestern China and the other is located in the central-western part of Inner Mongolia in northern China. In the 21st century, the duration of the severe SDS shows a clear interannual variation with an average of 3.5 days in 2000–2006, 2.7 days in 2007–2015 and 4.6 days in 2016–2023, respectively. Moreover, it occurs mainly in early spring in the third period, whereas it can occur throughout spring in the first and second periods. The composition of the general circulations for these 34 cases indicates that the simultaneous dominant pattern is a “positive-negative-positive” wave structure in the mid-high latitudes of Asia, with a cyclonic circulation (a deep trough) over the southern part of Russia to Mongolia, a major anticyclonic circulation (a ridge) over the eastern Europe to the west of Central Asia and a secondary anticyclonic center over northeastern China to the Korea Peninsula and Japan. The “positive-negative-positive” pattern enhanced the Mongolian Cyclone by increasing the zonal pressure gradients to both its west and east sides. Both the composition and typical case studies indicate that the eastward movement of the Mongolian Cyclone plays a dominant role in causing the severe SDS.

A super sandstorm altered the abundance and composition of airborne bacteria in Beijing

Sandstorm, which injects generous newly emerging microbes into the atmosphere covering cities, adversely affects the air quality in built environments. However, few studies have examined the change of airborne bacteria during severe sandstorm events. In this work, we analyzed the airborne bacteria during one of the strongest sandstorms in East Asia on March 15th, 2021, which affected large areas of China and Mongolia. The characteristics of the sandstorm were compared with those of the subsequent clean and haze days. The composition of the bacterial community of air samples was investigated using quantitative polymerase chain reaction (qPCR) and high-throughput sequencing technology. During the sandstorm, the particulate matter (PM) concentration and bacterial richness were extremely high (PM2.5: 207 µg/m3; PM10: 1630 µg/m3; 5700 amplicon sequence variants/m3). In addition, the sandstorm brought 10 pathogenic bacterial genera to the atmosphere, posing a grave hazard to human health. As the sandstorm subsided, small bioaerosols (0.65–1.1 µm) with a similar bacterial community remained suspended in the atmosphere, bringing possible long-lasting health risks.

Classification and sources of extremely severe sandstorms mixed with haze pollution in Beijing

Air quality has significantly improved in China; however, new challenges emerge when dust weather is combined with haze pollution during spring in northern China. On March 15, 2021, an extremely severe sandstorm occurred in Beijing, with hourly maximum PM10 and PM2.5 concentrations reaching 5267.7 μg m−3 and 963.9 μg m−3, respectively. Continuous sandstorm events usually lead to complicated pollution status in spring. Three pollution types were identified disregarding the time sequence throughout March. The secondary formation type was dominant, with high ratios of PM2.5/PM10 (mean 74%) and PM1/PM2.5 (mean 52%). This suggests that secondary transformations are the primary cause of heavy pollution, even during the dry seasons. Sandstorm type resulted in dramatic PM10 levels, with a noticeable decrease in PM2.5/PM10 levels (27%), although PM2.5 levels remain high. The transitional pollution type was distinguished by an independent increase in PM10 levels, although PM2.5 and PM1 levels differed from the PM10 levels. Throughout March, the sulfur oxidation rate varied considerably, with high levels during most periods (mean 0.52). A strong correlation indicated that relative humidity was the primary variable promoting the formation of secondary sulfate. Sandstorms promote heterogeneous reactions by providing abundant reaction surfaces from mineral particles, therefore aggravating secondary pollution. The sandstorm air mass from the northwest passing through the sand sources of Mongolia carried not only crustal matter but also organic components, such as bioaerosols, resulting in a sharp increase in the organic carbon in PM2.5.

Coupling Effects of Sandstorm and Dust from Coal Bases on the Atmospheric Environment of Northwest China

The coupling effects of sandstorm and dust from coal bases themselves can have a major impact on the atmospheric environment as well as on human health. The typical coal resource city of Wuhai in Inner Mongolia was selected in order to study these impacts during a severe sandstorm event in March 2021. Particulate matter (PM1, PM2.5 and PM10) and total suspended particulate matter (TSP) samples were collected during the sandstorm event of 15–19 March 2021 and non-sandstorm weather (11–13 March 2021) and analyzed for their chemical composition. The concentrations of PM1, PM2.5, PM10 and TSP in Wuhai city during the sandstorm were 2.2, 2.6, 4.8 and 6.0 times higher than during non-sandstorm days, respectively. Trace metals concentrations in particles of different sizes generally increased during the sandstorm, while water-soluble ions decreased. Positive matrix fraction (PMF) results showed that the main sources of particles during both sandstorm and non-sandstorm days were industrial emissions, traffic emissions, combustion sources and dust. The proportion of industrial emissions and combustion sources increased compared with non-sandstorm days, while traffic emissions and dust decreased. The backward trajectory analysis results showed that airflows were mainly transported over short distances during non-sandstorm days, and high concentration contribution source areas were from southern Ningxia, southeast Gansu and western Shaanxi. The airflow was mainly transported over long distances during the sandstorm event, and high concentration contribution source areas were from northwestern Inner Mongolia, southern Russia, northern and southwestern Mongolia, and northern Xinjiang. A health risk analysis showed that the risk to human health during sandstorm days related to the chemical composition of particles was generally 1.2–13.1 times higher than during non-sandstorm days. Children were more susceptible to health risks, about 2–6.3 times more vulnerable than adults to the risks from heavy metals in the particles under both weather conditions.

A cautionary signal from the Red Sea on the impact of increased dust activity on marine microbiota

BackgroundGlobal climate change together with growing desertification is leading to increased dust emissions to the atmosphere, drawing attention to possible impacts on marine ecosystems receiving dust deposition. Since microorganisms play important roles in maintaining marine homeostasis through nutrient cycling and carbon flow, detrimental changes in the composition of marine microbiota in response to increased dust input could negatively impact marine health, particularly so in seas located within the Global Dust Belt. Due to its strategic location between two deserts and unique characteristics, the Red Sea provides an attractive semi-enclosed “megacosm” to examine the impacts of large dust deposition on the vastly diverse microbiota in its exceptionally warm oligotrophic waters.ResultsWe used culture-independent metagenomic approaches to assess temporal changes in the Red Sea microbiota in response to two severe sandstorms, one originated in the Nubian Desert in the summer 2016 and a second one originated in the Libyan Desert in the spring 2017. Despite differences in sandstorm origin and meteorological conditions, both sandstorms shifted bacterial and Archaeal groups in a similar mode. In particular, the relative abundance of autotrophic bacteria declined while those of heterotrophic bacteria, particularly Bacteroidetes, and Archaea increased. The changes peaked within six days from the start of sandstorms, and the community recovered the original assemblage within one month.ConclusionOur results suggest that increased dust emission with expanding desertification could lead to undesirable impacts in ocean function, enhancing heterotrophic processes while reducing autotrophic ones, thereby affecting the marine food web in seas receiving dust deposition.

Experimental study and discrete element analysis on lateral resistance of windblown sand railway

The lateral resistance of ballast bed is an important parameter to prevent track expansion and maintain track stability. The invasion of sand particles can cause the change of lateral resistance of ballast bed and affect the stability of track structure, but little attention has been paid to the change characteristics of nonlinear lateral resistance of sandy ballast bed. In this paper, the field tests on the lateral resistance of windblown sand ballast bed were carried out to establish a multiscale three-dimensional discrete element model of sleeper-ballast bed. A systematic analysis on the evolution of lateral resistance, resistance to lateral deformation, micro-contact characteristics and lateral stability of ballast bed is performed. The results show that sand intrusion can increase the lateral resistance of ballast bed, which is approximately 40 % higher than that of clean ballast bed. In nonlinear strengthening stage and yield stage, the enhancement effect of sand particles on the lateral resistance of ballast bed is relatively weaker in comparison with the linear growth stage. With the increase in sand intrusion depth, the lateral resistance and resistance work of ballast bed both gradually go up, and the contribution of ballast shoulder to lateral resistance tends to play a leading role. Sand intrusion can increase the lateral stiffness of ballast bed and reduce the elasticity of track structure. Therefore, the maintenance operation should be carried out in time for the section with severe sandstorm.

Simulation of a Severe Sand and Dust Storm Event in March 2021 in Northern China: Dust Emission Schemes Comparison and the Role of Gusty Wind

Northern China experienced a severe sand and dust storm (SDS) on 14/15 March 2021. It was difficult to simulate this severe SDS event accurately. This study compared the performances of three dust-emission schemes on simulating PM10 concentration during this SDS event by implementing three vertical dust flux parameterizations in the Comprehensive Air-Quality Model with Extensions (CAMx) model. Additionally, a statistical gusty-wind model was implemented in the dust-emission scheme, and it was used to quantify the gusty-wind contribution to dust emissions and peak PM10 concentration. As a result, the LS scheme (Lu and Shao 1999) produced the minimum errors for peak PM10 concentrations, the MB scheme (Marticorena and Bergametti 1995) underestimated the PM10 concentrations by 70–90%, and the KOK scheme (Kok et al. 2014) overestimated PM10 concentrations by 10–50% in most areas. The gusty-wind model could reasonably reproduce the probability density function of 2-min wind speeds. There were 5–40% more dust-emission flux and 5–40% more peak PM10 concentrations generated by the gusty wind than the hourly wind in the dust-source regions. The increase of peak PM10 concentration caused by gusty wind in the non-dust-source regions was higher than in the dust-source regions, with 10–50%. Implementing the gusty-wind model could help improve the LS scheme’s performance in simulating PM10 concentrations of this severe SDS event. More work is still needed to investigate the reliability of the gusty-wind model and LS scheme on various SDS events.

The performance of a soiled CSP system in Inner Mongolia under various weather conditions

Sand/dust storms (SDSs) are a common natural phenomenon occurring in the spring in arid and semi-arid areas. To investigate the influence of sand/dust on the performance of concentrating solar power systems, the effects of four SDS events and four natural dust deposition (NDD) periods were tested from March 7 to June 11, 2021, and were compared with the performance of the clean state. The results reveal that the sand/dust concentration on the mirror increased significantly after the occurrence of SDS events. In particular, after a severe sandstorm, the dust density was found to have reached 6.177 g/m2, which was 2.09 times that under the NDD exposure period of 40 days. With the increase in the dust density by 1 g/m2 after the occurrence of the four SDS events, the average reflectivity, energy flux density, and thermal efficiency were found to be decreased by 12.1%, 11.9%, and 12.5%, respectively, whereas they are decreased by 13.7%, 10.5%, and 13.7% under the four NDD periods.

Monitoring of Land Degradation in Alluvial Plain in Iraq by Using Geomatics Techniques

Iraq faces a major environmental problem represented by severe deterioration, which threatens its food security. Many natural and human factors combine to make it, and it has dire environmental, economic, social and cultural consequences, most notably the loss of productive lands, the movement of sand dunes, severe sand and dust storms, and the resulting increase in air pollution. This study attempts to identify the development of the problem, analyze its causes and consequences, and propose a number of solutions to address it. In this article Remote Sensing techniques have been used to monitoring land degradation in ( Alluvial Plain ) of Iraq for the stage (1976 - 2021) using different sources of data such as satellite images (Landsat 1-5 MSS 1976, Landsat 5 1996 TM, Landsat8 2016 and sentinel 2 2021), also more than one software was used such as ENVI 5.3 and Erdas image 2015 to extract information from above images, Erdas imagine 2015 was use to sub set area of study, layer stack, merge resolution and classification stage, Arc GIS 10.7 use to make database and maps production), the article used supervise and unsupervised classification techniques to obtain the results, the article indicated that there is a big problem in the year 1976, this problem almost disappeared in the second station of work 1996, but it returned back after that through the results for the years 2016 and 2021. Finally, the article found a deterioration in the soil class during the stages from 2016 (988.547 Km2) to 2021(1342.398 Km2) and a decrease in the area of vegetation cover from (1931.596 Km2) in (2016) to (1632.695 Km2) in (2021).

Research on dynamic mechanical behavior of ballast bed in windblown sand railway based on dimensional analysis

Railway operation is faced with windblown sand hazards in desert areas. In order to study the influence of sand intrusion on dynamic mechanical behavior of railway ballast bed, a multi-scale discrete element model of sleeper-ballast bed-surface layer of subgrade has been established with the method of “step filling-particle replacement”. The vibration acceleration of the ballast bed and the dynamic displacement of sleeper field tests in the section with severe sandstorm have carried out to verify the correctness of discrete element analysis model. The scale invariance of the linear contact model and the rationality of the scaling of the sand size are explained by the “dimensional analysis method”. The results show that the sand intrusion reduces the vibration of ballast bed. When the sand content reaches 30%, the vibration and elastic deformation of ballast bed decrease by 94.2% and 63.2% respectively. The invasion of sand can reduce the deformation of the surface layer of subgrade, and the maximum reduction is 53.3%. Therefore, it is necessary to pay attention to the service state of ballast bed with sand content of 30% in windblown sand area, and make the maintenance plan reasonably.

Study on sandstorm in the western section of Hexi Corridor of 2020

A diagnostic analysis of the dust storm weather occurring in the western part of the Hexi Corridor from 27-30 June 2020 was carried out using Jiuquan city’s live data, as well as ECMWF numerical forecasts, and the NCEP reanalysis information was used to draw a theta dust storm model based on the routing principle. The results show that: 1.In the early stage of sandstorm, there was no precipitation in Suzhou and Jinta counties in March and April, which resulted in dry surface and thickened soil layer. These factors created favorable conditions for the occurrence of dust weather. 2.Development of unstable trough eastward in front of the ridge of Mountain Ural at 500 hPa, The cold high pressure is continuously strengthened in the process of moving, which is the large-scale system leading to the sandstorm. Thermal depression in front of ground cold front is the main cause for the outbreak of the severe sandstorm. 3.The beginning and ending time of the sandstorm can be accurately predicted by the simulation chart of sandstorm forecast, which has a good indication significance for the sandstorm forecast in the Hexi area.

Solar PV in Kuwait: The effect of ambient temperature and sandstorms on output variability and uncertainty

Kuwait has a high potential for utilizing meteorologically driven energy resources such as solar PV. However, understanding the extent to which the distinct climatic conditions in Kuwait, reflected in the ambient temperature and occurrence of sandstorms, affect the variability and uncertainty of solar PV output is crucial. This is because it allows power system planners to adopt appropriate measures to accommodate solar PV generation and thus minimize renewable energy curtailment and consequently opportunity costs. In this study, the performance of a 2000 MW solar PV plant operating under the weather conditions in Kuwait is simulated using a Monte Carlo approach. The results show, on average, the power generation is 13% lower in the summer compared with the spring when the temperature is milder and solar production peaks. However, the certainty of production is higher in the summer. Furthermore, the PV generation variability in the summer is of the same magnitude as the demand variability, whereas during winter months, it is approximately twice the demand variability on any given day of the year. Sandstorms with daily average PM10 concentration of less than 300 ppb lead to little to no reduction in daily total irradiation. However, day-long and severe sandstorms (PM10 2700 ppb or greater) reduce daily total irradiation by 57%. Generally, the largest reductions occur when high particulate matter concentrations coincide with peak hourly solar irradiance.

ОБ’ЄДНАНІ АРАБСЬКІ ЕМІРАТИ: ЩО СПРИЧИНИЛО ЕКОНОМІЧНЕ ДИВО?

The United Arab Emirates is situated simultaneously in southern region of the Persian Gulf and on the Coast of the Gulf of Oman next to Saudi Arabia and Oman and remain the closest maritime neighbour of powerful Iran. This fact defines geopolitical importance of the country. But environment here is not conductive for economic development. It is distinguished by some of the highest temperatures in the world during warm season and by extreme humidity because of two surrounding bodies of water. It lacks permanent lakes and rivers and the whole area is prone to severe sandstorms. The native population of the UAE is rather small, what forces Emirati rulers to invite foreign workers in growing numbers. Despite domination of crude oil in foreign trade, the ruling elite took a strategic step towards service economy, what represents an interesting example to follow because of the apparent success of such policy. In this article the author makes an attempt to find out what measures at state level made the UAE the most prosperous country in the Gulf. Key words: UAE, Abu Dhabi, Dubai, airlines, free economic zones, ports, tourism, property.

Detection of New Dust Sources in Central/East Asia and Their Impact on Simulations of a Severe Sand and Dust Storm

AbstractInformation regarding dust concentrations and size distributions is very important for determining air quality and aerosol–radiation–cloud interactions. Only by using a correct erosion database can the sectional dust emission scheme resolve detailed size distributions and determine where and how dust will be emitted. In this paper, the bias and reasons for dust emission in China Meteorological Administration Unified Atmospheric Chemistry Environment–Dust, an operational dust forecasting model, are analyzed using a heavy sand and dust storm episode. We used 18 years of routine sand and dust storm phenomena recorded at meteorological stations to retrieve and update the desertification details in the MBA sectional dust emission scheme adopted in China Meteorological Administration Unified Atmospheric Chemistry Environment–Dust. New desertification details include decreased erodibility in the area adjacent to Uzbekistan, Turkmenistan, and southern Kazakhstan, where Kyzylkum, Karakum, and Aralkum are located in central Asia, and in the Chinese deserts of Onqin Daga, Mu Us, and Gurbantungut. New desertification also results in increased erodibility in northern Mongolia. Comparisons show that the new desertification database decreases overestimation of dust emission in central Asia, including western Mongolia. It improves the underestimation of dust emission in northern Mongolia and the Gobi desert in southeast Mongolia, and the Taklimakan desert in China. Consequently, it corrects the overestimated dust cloud in the source area and in areas impacted by dust transportation. The timing, quantitative mass concentrations, and dust size distributions determined here are all more reasonable and rational than those of the original case.

Climate-induced migration: using mental models to explore aggregate and individual decision-making

The US Dust Bowl of the 1930s (a prolong period of drought experienced in the United States accompanied by severe sand storms) is often described as an abnormal event. However, climate change is likely to increase the frequency and impact of similar occurrences. Because of this, a growing number of scholars have begun to examine multiple facets of climate-induced migration from various disciplinary traditions. Specifically, scholars have called for continued research into individual decision-making processes. Responding to this call, we construct a mental model from historical interviews of those who migrated to California during the US Dust Bowl. Our model provides insight into the migration process with a unique focus on individual decision-making processes of migrants.

Adverse effects of inhaled sand dust particles on the respiratory organs of sheep and goats exposed to severe sand storms in Mongolia.

Sand storms in Mongolia have increased in frequency and scale, resulting in increased exposure of the inhabitants of Asian countries, including Japan and Korea, to Asian sand dust (ASD), which results in adverse effects on the respiratory system. However, there is no information on the health risks of severe sand storms in domestic animals in Mongolia. The aim of the study was to investigate the effects of sand dust particles on the respiratory organs, including the lungs and tracheobronchial lymph nodes, of sheep and goats exposed to severe sand storms in Mongolia. Seven adult sheep and 4 adult goats that had been exposed to sand storms and 3 sheep with no history of exposure were included in this study. Lung tissues and tracheobronchial lymph nodes were subjected to histopathological and immunohistochemical examination. The mineralogical contents of the lungs and lymph nodes were determined using inductively coupled plasma atomic emission spectroscopy. Fibrosis and granulomatous lesions comprising macrophages containing fine sand dust particles were observed exclusively in the lungs of sheep and goats exposed to sand storms. The activity of macrophages was also demonstrated by the presence of IL-6, TNF, and lysozyme. In addition, silicon, which is the major element of ASD (kosa aerosol), was detected exclusively in the lung tissues of the exposed animals. Our findings suggest that exposure to sand dust particles may affect the respiratory systems of domestic animals during their relatively short life span.

Sand-Dust Storm Simulation Model Coupled with PSU/NCAR Mesoscale Model

A sand-dust numerical model coupled with MM5(PSU/NCAR mesoscale model) –CUCSDust (CMA Unified Chemistry System-Dust) is introduced. CUCSDust includes such detail physical processes as dust production, transport, growth, coagulation, dry and wet deposition, which can simulate and forecast the initial and sand-dust concentration of sand and dust storm. A parallel scheme is also designed to reduce the run-time which is most important for real-time forecasting. Based on CUCSDust, a numerical model forecasting system is established in northeast Asia, and is applied to China Meteorological Administration (CMA) for operational prediction of sand and dust storm from March, 2006. A prediction result of severe sand and dust storm occurred in 26–28, March, 2006 is chosen, which shows no difference for sand-dust spatial distribution between model outputs and remote sensing monitoring imagers and indicates that the model system has the capability of real-time forecasting sand and dust storm in northeast Asia.*

The processes and mechanisms of severe sandstorm development in the eastern Hexi Corridor China, during the Last Glacial period

Dust transported by sandstorms has been an important feedback in climate change in the past, and its environmental effects are predicted to have a great impact on future global climatic change. Investigating the grain-size classes and the standard deviations of the modern sandstorm samples, and the samples in the Shagou section (situated in the eastern Hexi Corridor), lead us to suggest that the sand fraction within the range of 275.4–550μm in this section can be used as a sensitive indicator of severe sandstorms. We selected the size range in the L1 stratum of the Shagou loess section as indicative of temporal changes in sandstorm intensity in the eastern Hexi Corridor and found that during the Last Glacial period, severe sandstorms in the eastern Hexi Corridor occurred with high frequency during these periods: I (70–54ka B.P.), II (51–48ka B.P.), III (45–42ka B.P.), IV (38–33ka B.P.), V (31–28ka B.P.) and VI (26–12ka B.P.) In general, the frequency and intensity of dust storms in the early (MIS 4) and late (MIS 2) periods were both high but they were reduced in the middle period (MIS 3). The primary factors controlling severe sandstorms are hydrology and wind power, followed by the expansion of the source extent. Reduced precipitation caused the source region of sandstorms to expand; in addition, wind speeds also increased at this time. These factors may have directly contributed to the abundance of severe sandstorms. Based on the grain size from a loess section (the Shagou section) in the eastern Hexi Corridor, we propose an evolutionary sequence of the severe sandstorms during the Last Glacial period. This sequence is consistent with the dust records in the Arctic, the Antarctic and low-latitude (the central equatorial Pacific) areas. Thus globally synchronous periods of high dust activity occurred in the Last Glacial period. The strong winds proposed here provide a potential explanation for the global consistency of dust flux changes during the Last Glacial period.

Loess record of the evolution history of severe sandstorms in the Tengger Desert during the Last Interglacial Period (MIS5)

The Shagou loess section recorded the evolution information of severe sandstorms in the Tengger Desert during the Last Interglacial (MIS 5). By analyzing the grain size data of the loess samples using the grain size class-standard deviation, we selected the grain size component between 209 and 550 μm to reconstruct the evolution history of the severe sandstorms in the Tengger Desert during the Last Interglacial. The results indicate that there were at least 12 periods of frequently occurring severe sandstorms in that location over this time period. There were two periods in each of S1SS1 and S1SS2, four periods in S1LL1, three periods in S1LL2 and one in S1LL4. The occurrence frequency and intensity of the severe sandstorms presented a characteristic increase from the early to the late period of the Last Interglacial. Combined with the calcium carbonate results, this evidence suggests that climatic change is closely related to sandstorms. A warm and wet climate could restrict the occurrence of severe sandstorms; conversely, a cold and dry climate easily induces severe sandstorms. Meanwhile, with a warm and dry climate background, the relationship between climatic change and the occurrence of sandstorms is quite complex: severe sandstorms are also able to occur in such a climate. A cold and dry climate, however, does not mean a certainty of severe sandstorms.

Removal of Contaminated Pixels from the Desert Target for AVHRR Vicarious Calibration

Abstract Desert-based vicarious calibration plays an important role in generating long-term reliable satellite radiances for the visible and near-infrared channels of the Advanced Very High Resolution Radiometer (AVHRR). Lacking an onboard calibration device, the AVHRR relies on reflected radiances from a target site, for example, a large desert, to calibrate its solar reflective channels. While the radiometric characteristics of the desert may be assumed to be stable, the reflected radiances from the target can occasionally be affected by the presence of clouds, sand storms, vegetation, and wet surfaces. These contaminated pixels must be properly identified and removed to ensure calibration performance. This paper describes an algorithm for removing the contaminated pixels from AVHRR measurements taken over the Libyan Desert based on the characteristics of consistent normalized difference vegetation index (NDVI) land-cover stratification. An NDVI histogram-determined threshold is first applied to screen pixels contaminated with vegetation in each individual AVHRR observation. The resulting analyses show that the vegetation growth inside the desert target has a negligibly small impact on the AVHRR operational calibration results. Two criteria based on the maximum NDVI compositing technique are then employed to remove pixels contaminated with clouds, severe sand storms, and wet sand surfaces. Compared to other cloud-screening methods, this algorithm is capable of not only identifying high-reflectance clouds, but also removing the low reflectance of wet surfaces and the nearly indifferent reflectance of severe dust storms. The use of clear pixels appears to improve AVHRR calibration accuracy in the first 3–4 yr after satellite launch.