Neue Veröffentlichung:

Huo, W., Spiegl, T., Wahl, S., Matthes, K., Langematz, U., Pohlmann, H., Kröger, J. (2025) "Assessment of the 11-year solar cycle signals in the middle atmosphere during boreal winter with multiple-model ensemble simulations." Atmospheric Chemistry and Physics, 25 (4), 2589–2612, https://doi.org/10.5194/acp-25-2589-2025

Summary:
To better understand possible reasons for the diverse modeling results and large discrepancies of the detected solar fingerprints, we took one step back and assessed the “initial” solar signals in the middle atmosphere based on a set of ensemble historical simulations with multiple climate models – the Flexible Ocean Climate Infrastructure (FOCI), the ECHAM/MESSy Atmospheric Chemistry (EMAC), and the Max Planck Institute for Meteorology Earth System Model in high-resolution configuration (MPI-ESM-HR). Consistent with previous work, we find that the 11-year solar cycle signals in the shortwave heating rate (SWHR) and ozone anomalies are robust and statistically significant in all three models. These initial solar cycle signals in the SWHR, ozone, and temperature anomalies are sensitive to the strength of the solar forcing. Correlation coefficients of the solar cycle with the SWHR, ozone, and temperature anomalies linearly increase along with the enhancement of the solar cycle amplitude. This reliance becomes more complex when the solar cycle amplitude – indicated by the standard deviation of the December–January–February mean F10.7 – is larger than 40. In addition, the cold bias in the tropical stratopause of EMAC dampens the subsequent results of the initial solar signal. The warm pole bias in MPI-ESM-HR leads to a weak polar night jet (PNJ), which may limit the top-down propagation of the initial solar signal. Although FOCI simulated a so-called top-down response as revealed in previous studies in a period with large solar cycle amplitudes, its warm bias in the tropical upper stratosphere results in a positive bias in PNJ and can lead to a “reversed” response in some extreme cases. We suggest a careful interpretation of the single model result and further re-examination of the solar signal based on more climate models.

M207 cruise:

M207 expedition on the RV METEOR took a place from January 4 to February 11, 2025, from Belem, Brazil to Mindelo, Cabo Verde.

The EXPORT is the part of the WARD Tropics expedition, which focused on the trans-Atlantic transport of mineral dust. With this aim the new portable meteorological observatory for desert-dust transport was installed on board of the ship. Dust particles can affect climate in many different ways, from affecting radiative forcing to playing a role of nutrient supplier. During the expedition we had an opportunity to measure the Saharan dust, transported far away from the source along tropical Atlantic. Several instruments were installed on board of METEOR, like ceilometer, flat plate aerosol sampler, high volume sampler, disdrometer, solar radiation measurement station and also different sun photometers to record the aerosol optical depth were used.

neue Veröffentlichung:

Mu, F., Fiedler, S. How much do atmospheric depressions and Mongolian cyclones contribute to spring dust activities in East Asia?. npj Clim Atmos Sci 8, 51 (2025). doi.org/10.1038/s41612-025-00929-w

Summary:
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.