Feifei Mu

According to the International Energy Agency, global wind energy capacity is expected to double between 2024 and 2030. Offshore wind developments are a major driver of this increase, with capacity predicted to quadruple over the period. This rapid development of capacity is driven by governments in Europe and elsewhere to accelerate the transition from fossil fuels to renewable sources, in the face of intensifying climate change.In order to maximize the economic value of these installations, research is needed to understand cost-optimized wind farm layouts and operational strategies. In this context, we present the Microwave Radiometer for the Detection and Assessment of Offshore Wind Resources (MiRadOr) project. MiRadOr assesses the value of use of Microwave Radiometer (MWR) technologies in an operational wind energy context, with a focus on atmospheric stability and offshore applications. The project combines a new months-long MWR observational dataset from the Dutch Meteorological Service’s (KNMI) atmospheric research station in Cabauw, the Netherlands, co-located with supporting observations from a 200 m tall meteorological mast and a Doppler-wind Light Detection and Ranging (LiDAR) system.During the month of March in 2026, the MWR observations were supplemented by a period of intensive observations (IOP), featuring approximately 100 radiosonde ascent profiles, recording temperature, pressure, relative humidity, wind speed and direction. We compare these profiles against those retrieved by the MWR, LiDAR and meteorological mast over the month, including stability-relevant weather events such as cyclones and front systems. In particular, we focus on the observations of Low-level Jets (LLJs): fast moving masses of air, close to the surface (typically within the first 300 m) which are highly relevant to wind energy operations. Additionally, we compare radiosonde and other observations with forecast products from KNMI, DWD (the German Weather Service) and the ECMWF’s integrated forecast system.

East Asian dust storms from the Gobi and the Taklamakan Desert occur frequently in spring. Dust aerosols influence climate through effects on radiation and clouds, and impair air quality with impacts on human health. However, large uncertainties in model simulations of dust aerosols persist. An estimation of the relative contributions of different meteorological drivers to dust activities can help to improve the representation of dust storms in models.Mongolian cyclones, which form East of the Altai-Sayan Mountains, are important for dust-emitting winds in the Gobi Desert. Utilizing an automated detection algorithm of extratropical cyclones and multiple datasets for dust aerosol for 2001–2022, the contribution of Mongolian cyclones to East Asian dust emission and dust optical depth is quantitatively estimated (Mu and Fiedler, in review). The results highlight that springtime dust storms in East Asia are primarily associated with a low-pressure system over Mongolia. Mobile Mongolian cyclones explain almost half of the total spring dust emission amount of the Gobi Desert. The calculated relative contributions of Mongolian cyclones to dust emissions in the Gobi Desert are similar from two different products, despite differences in the physical parameterization schemes for dust emission, number and location of the prescribed potential dust sources, and in the absolute dust emission amount by a factor ten. Dust emissions in the Gobi Desert and dust aerosol optical depth in the region downwind have decreased in the past decades, with Mongolian cyclones contributing to reductions of 10%-18% decade-1 and 11%--15% decade-1, respectively. The reduction of dust emissions and dust aerosol optical depth is at least in part explained by weaker and fewer Mongolian cyclones over time. Mongolian cyclones may also affect the dust activity in the Taklamakan Desert to the west of the Gobi Desert. The passage of the Mongolian cyclone in mid-March 2021 has led to a cold air intrusion into the Taklamakan Desert. The cold air favored the nighttime near-surface temperature inversion. The stable stratification near the surface allows the development of Nocturnal Low-Level Jets (NLLJs). The breakdown of NLLJs results in a strengthening of near-surface winds, which are sufficiently strong for dust emissions in many parts of the Taklamakan Desert (Mu et al., 2023). The Taklamakan dust was elevated by deep mixing and transported eastwards by prevailing mid-level westerlies, impacting air quality primarily in western China. Ongoing work addresses the link of cyclones and NLLJs in the Taklamakan Desert from the climatological perspective.References:Mu, F., Luiz, E.W., Fiedler, S., 2023. On the dynamics and air-quality impact of the exceptional East Asian dust outbreak in mid-March 2021. Atmos. Res. 292, 106846.Mu, F. and Fiedler, S., in review. How much do atmospheric depressions and Mongolian cyclones contribute to East Asian spring dust activities?

Severe East Asian dust storms occur in spring due to dust-emitting winds in the Gobi Desert associated with Mongolian cyclones. The present study performs the first quantitative assessment of the contributions of Mongolian cyclones to springtime dust activity in East Asia, based on multiple reanalyses and observational datasets for 2001–2022. Atmospheric depressions dominate dust activities in Northern China, explaining ~90–92% of the total dust emissions in the Gobi Desert and ~88–93% of the dust aerosol optical depth (τ) downwind, depending on the dataset. Mongolian cyclones, defined as long-living and mobile atmospheric depressions, explain almost half (~34–47%) of the Gobi’s total dust emissions and τ downwind, and are the primary driver of high-impact dust storms. The number of Mongolian cyclones, along with the dust activity, has decreased since 2001, with a spatial pattern of the dust emission trend that is consistent with the northward shift of cyclone tracks.

Desert-dust aerosols affect the climate, human health, and socio-ecomomic activities. In East Asia, the passage of Mongolian cyclones induce dust-emitting winds in the Gobi Desert. While cyclones are known as driver of dust outbreaks, the relative contribution of Mongolian cyclones to the total East Asian dust emission amount and the dust aerosol optical depth has not been quantified from a climatological perspective. To address this gap in knowledge, the present study systematically assesses the co-occurrence of Mongolian cyclones and dust aerosols in East Asia for 2001 to 2022. This study pairs output of the automated detection algorithm for extra-tropical cyclones in ERA5 re-analysis from the ETH Zürich with data for dust aerosols from multiple sources. Through the use of multiple dust data sets, we account for the substantial data uncertainty for dust aerosols in term of the spatial pattern and the absolute emission magnitudes, which can differ by an order of magnitude. The climatological analysis shows a high frequency and intensity for the occurrence of Mongolian cyclones in the lee of the Altai-Sayan Mountains (100Eo–125Eo and 37No–53No), favouring the seasonal dust activity in the Gobi Desert. The results highlight a tight constraint on the mean Mongolian cyclone contribution to the total dust emission amount of 39-47% in the spatial mean for spring based on data from MERRA-2 and Wu et. al. (2022), despite substantial differences in the absolute emission magnitudes. The dust-laden air from the Gobi Desert during such events typically moves southeastwards over China in the wake of the cyclones affecting the aerosol optical depth. For southern Mongolia and Northeastern China (105Eo–130Eo and 37No–52No), we estimate 34% (MERRA-2) to 43% (CAMS) of the dust aerosol optical depth (DOD) being associated with Mongolian cyclones. A decrease in dust emission fluxes and dust storm frequencies have been reported for Northern China in the past two decades and is thought to be connected to decreasing near-surface winds. Our results point to a negative trend in the dust emission flux and DOD associated with the occurrence of Mongolian cyclones. However, our results also point to the co-occurrence of particularly intense Mongolian cyclones, measured by the 99th percentile of the wind speed, with exceptionally strong dust storms in recent years, e.g., in March 2021, despite a mean negative trend in dust activity. Given the connection of Mongolian cyclone to high-impact dust storms in East Asia, the potential future development of such events should be addressed in future research.

Survival in hyperarid deserts is a major challenge for plant life, requiring the development of evolutionary strategies. The Atacama Desert presents harsh conditions such as limited rainfall, crusted soils, high soil salinity, high altitude, and intense solar radiation. These conditions, together with paleoclimatic variability since the past millions of years, have influenced the genetic structure and connectivity of plant populations, resulting in a diverse flora with high endemism. However, the diversification of most lineages appears to be relatively recent, in contrast to proposed age of the Atacama Desert and the onset, evolution and expansion of hyperarid conditions since the Late Oligocene and Early Miocene. A prominent exception is the Atacama paleoendemic Huidobria chilensis (Loasaceae), which is thought to be adapted to such conditions since the Eocene. Still, the environmental limits and thresholds for life in the Atacama remain poorly understood. To investigate the genetic structure in relation to the history of the Atacama Desert, we studied 186 individuals from 11 populations using genotyping-by-sequencing (GBS). Genome-wide single nucleotide polymorphisms (SNPs) were analyzed for population structure and genetic diversity. We identified three genetic clusters corresponding to geographic regions: the coastal region south of Tocopilla, the Coastal Cordillera around Chañaral, and the Copiapó watershed in the south. These clusters as well as genetic diversity were analyzed alongside rainfall, altitude, and landscape data. Although the genetic data generally supports isolation by distance as a major factor for genetic variation between populations, the study also reveals the influence of the topography on the distribution of H. chilensis and highlights the role of hydrologically connected watersheds and rivers in plant migration and colonization. This shapes the species’ evolutionary trajectory and genetic diversity. Understanding these patterns provides insights into the adaptation and survival strategies of plants in extreme desert environments such as the Atacama.

The Gobi and the Taklamakan Desert are the two main dust source regions in East Asia. Extra-tropical cyclones are known as atmospheric driver for severe dust outbreaks in East Asia. Although previous studies show that dust storm frequency in Northern China have decreased associated with a decrease in near-surface wind speed, a severe dust storm occurred in mid-March 2021. This exceptional dust storm was driven by a Mongolian extra-tropical cyclone and had adverse socio-economic and health impacts. The aim of our study is to investigate the atmospheric dynamics, dust-aerosol contributions from the Gobi Desert and the Taklamakan Desert, as well as dust emission mechanisms involved in the event. We use ground-based observations from Chinese observational networks, satellite images from MODIS, data from ERA5 re-analysis, CAMS forecasts, and MERRA-2 re-analysis. The passage of the Mongolian cyclone first induced high dust-emitting winds along its cold front. The maximum wind speeds at 10m a.g.l. over the Gobi Desert exceeded the 99th percentile of the 30-year climatology (1992-2021) for March by around 6 ms−1 . The dust aerosols were emitted by these exceptionally strong near-surface winds and transported southeastwards along with the passage of the frontal system of the Mongolian cyclone from the afternoon of 14th March to the morning of 15th March 2021. Hence, high atmospheric PM10 concentrations were first recorded in Northern China on 15th March. As a consequence of the associated poor air quality caused by the high PM10 concentrations, 19 out of 218 stations recorded the lowest atmospheric visibility for March since the past 30 years. The passage of the Mongolian cyclone then led to a cold air intrusion into the Taklamakan Desert from the afternoon of the 15th onward, which was a few hours after the dust emissions in the Gobi Desert. The cold air intrusion with the associated near-surface temperature inversion was favourable for the formation of Nocturnal Low-Level Jets (NLLJs), which are known as an important mechanism for dust emissions in the dust source regions (e.g., East Asia and North Africa). By comparing the NLLJs from radiosonde observations and an automated detection algorithm applied to ERA5, stronger NLLJs were seen in the Taklamakan Desert in the mornings of 16, 17, and 18 March. The NLLJs breakdown during the morning hours led to sufficiently strong dust-emitting winds in this desert. Consequently, dust emissions are simulated in the mornings of 16, 17, and 18 March 2021 by both CAMS forecasts and MERRA-2 re-analysis. The impacts of the dust aerosols from the Taklamakan Desert were, however, limited to the west of China, supported by spatio-temporal distributions of station observations of the atmospheric PM10 concentrations and visibility.

In mid-March 2021, one of the strongest dust storms of the last decades hit East Asia with adverse impacts on socio-economic activities, and loss of life. The dust storm was associated with a Mongolian extra-tropical cyclone. In this study, we assess the atmospheric dynamics involved in the temporal evolution of this event and quantify contributions from the main dust source regions, namely the Gobi Desert and the Taklamakan Desert. We use the ground-based observations from Chinese observational networks, satellite images from MODIS satellite data, and model data from ERA5 and CAMS of ECMWF. Our results highlight that dust aerosols advected far towards the East primarily originated in the Gobi Desert, where anomalously strong dust-emitting winds were associated with the passage of a cold front embedded in the extra-tropical cyclone over Mongolia. The subsequently formed dust cloud of several hundred kilometers in extent led to sharp increases in the concentration of particulate matter that cause severe deterioration of the air quality across Chinese cities. Also, the Taklamakan Desert contributed to the event, but to a lesser degree than the Gobi, measured by the spatial influence across China. In the Taklamakan Desert, strong low-level easterly winds occurred with the cold air intrusion building up a substantial regional dust burden through the morning breakdown of nocturnal low-level jets. The subsequent directional change in synoptic-scale winds allowed an eastward transport of the dust-laden air from the Taklamakan Desert and increased the dust burden over Western China. Indeed the largest dust burden was seen in the West indicating that the Taklamakan Desert contributed to the dust outbreak, although dust from the Gobi Desert affected larger areas. The dust outbreak has led to record-high hourly concentrations of particulate matter in both the western and eastern cities in China based on data of the past seven years. Our results provide the first evidence for the relative contributions of dust aerosols from different East Asian dust source regions to this unusual event. It remains to be investigated how such dust outbreaks change in a warming world.