Direct Radiative Effects in Haboobs. Issue 21 (27th October 2021)

• Record Type: Journal Article
• Authors: Bukowski, J.; van den Heever, S. C.
• Is Part Of: Journal of geophysical research. Volume 126:Issue 21(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-10-27
• Subjects: mineral dust -- haboobs -- convective dust storm -- dust storm -- dust radiation -- dust feedbacks; Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1029/2021JD034814
• Languages: English
• ISSNs: 2169-897X

Abstract

Abstract: Convective dust storms, or haboobs, form when strong surface winds loft loose soils in convective storm outflow boundaries. Haboobs are a public safety hazard and can cause a near instantaneous loss of visibility, inimical air quality, and contribute significantly to regional dust and radiation budgets. Nevertheless, reliable predictions of convective dust events are inhibited by a lack of understanding regarding the complex and non‐linear interactions between density currents, or convective cold pools, and dust radiative effects. In this study, the Weather Research and Forecasting model coupled with Chemistry (WRF‐Chem) is utilized to simulate the effect dust radiation interactions have on a long‐lived haboob case study that spans three distinct radiative regimes: day (high shortwave), evening (low shortwave), and night [longwave (LW) only]. A sophisticated algorithm is used to track and identify the numerous convective old pool boundaries in the simulations and assemble statistics that represent the impact of dust radiative effects. To first order, dust scattering of shortwave radiation in the day leads to a colder, dustier, and faster moving convective cold pool. In the transition period of early evening, the shortwave effects diminish while LW dust absorption leads to warmer, slower density currents that loft less dust as they propagate. At night, the haboob is again warmer due to dust absorption, but gustier in the more stable nocturnal surface layer, leading to enhanced dust emissions. Plain Language Summary: When rain evaporates below clouds in a thunderstorm, it can produce strong, cold winds at the surface. If the surface is dry and contains loose soils, these strong winds can lift dust into the air, and create a dangerous type of dust storm called a "haboob." The dust inside a haboob can be a safety hazard, but is also a critical contributor to marine ecosystem fertilization, hurricane formation, and the Earth's climate because dust redirects and absorbs incoming energy from both the sun above and the Earth below. Depending on how dust interacts with this energy, it can have opposite effects and either warm or cool the air around it. Therefore, the strong, cold winds from the thunderstorm that created the haboob in the first place can become either colder (stronger, faster) or warmer (weaker, slower). When forecasting and issuing warnings to the public, it is important to know the strength of the haboob and how fast it will move. This study investigates when and how the dust inside a haboob can cool the dust storm and make it stronger, versus when the dust will warm the dust storm and make it weaker. Key Points: Daytime dust scattering leads to colder, stronger density currents with higher windspeeds and dust emissions In the evening, longwave dust absorption leads to a warmer surface and warmer, weaker cold pools with suppressed winds and dust emissions At night, dust absorption leads to less stable and warmer cold pools with higher windspeeds, turbulence, and dust emissions