ARL Weekly News – November 27, 2020
Bruce Hicks and Will Pendergrass coauthored: The North American Solar Eclipse of 2017: Observations on the Surface Biosphere, Time Responses and Persistence in Boundary-Layer Meteorology. The 2017 North American Solar Eclipse offered an opportunity to observe near-surface weather before, during, and after the eclipse, using observations the climate reference network of weather stations deployed across the United States. Since the eclipse was short-lived, the effects were temporary. The changes observed during these short timescales provided a significant opportunity to gather observations on a continental scale to test atmospheric model responses to abrupt changes in solar radiation fluxes. Visibility of the eclipse over the entire conterminous United States (US), allowed its effects to be seen nearly simultaneously in different geographic and climatic regions. The ARL-maintained Climate Reference Network (CRN) stations use a uniform set of highly-accurate instruments to measure air temperature, surface temperature, solar radiation, humidity, precipitation, and more. Complete obscuration, or darkness, occurred at nine CRN stations during the eclipse. An additional 54 stations had at least 75% obscuration, and all but one had at least 50% obscuration.
Hicks, B.B., Pendergrass, W.R., Oetting, J.N. et al. The North American Solar Eclipse of 2017: Observations on the Surface Biosphere, Time Responses and Persistence. Boundary-Layer Meteorol (2020). https://doi.org/10.1007/s10546-020-00582-1
M James Salinger, Howard J Diamond, and James A. Renwick published: Surface temperature trends and variability in New Zealand and surrounding oceans: 1871-2018 in the Meteorological Society of New Zealand’s Weather and Climate. Authors compare homogenized series of maximum, minimum, and mean air temperature averaged over New Zealand (NZ) for the period 1871-2019, to surrounding ocean surface data. Temperatures over the New Zealand Exclusive Economic Zone exhibit an increase (linear trend) of 0.66°C from 1871-2019. As well as the anthropogenic warming signal (identified by CMIP5 simulations), interannual to decadal variability is also examined. Significant volcanic eruptions have caused temporary cooling and the positive trend in the Southern Annular Mode is linked to warming over NZ. All warm years (>+0.45°C above the 1981-2010 normal) occur from 1998 onwards, and all of the nine cold years (<-0.84°C below the 1981-2010 normal) occur prior to 1933. This study illustrates the importance of anthropogenic warming (AGW) as depicted by CMIP5 simulations (the same model used by the IPCC) and the Southern Annular Mode in determining long-term warming in the New Zealand. They conclude that the climate teleconnections that cause interannual to decadal variability (ENSO and IPO) are key factors in these results, beyond the anthropogenic warming signal. Local coverage of the study is published in the New Zealand Herald.
Xinrong Ren and Sarah Benish offer insight into the planetary boundary layer (PBL) production of ozone (O3) over the North China Plain, via the Air chemistry Research in Asia (ARIAs) campaign, which conducted aircraft measurements of air pollutants over Hebei Province, China, between May and June 2016. The authors obtained vertical profiles of trace gas species including O3, nitrogen oxides (NOx), carbon monoxide (CO), and volatile organic compounds (VOCs) and relate to rates of O3 production. Measurements from this airborne platform make a valuable addition to the understanding of one of the most polluted regions in China. The authors conclude that, to improve air quality in Hebei Province, both NOx and VOCs from vehicles and fuel evaporation should be targeted. While VOCs are already targeted for emission reduction in China, the substantial concentrations of O3 observed in this study further confirm the formation of a reactivity-oriented control strategy is urgent.
Benish, S. E., He, H., Ren, X., Roberts, S. J., Salawitch, R. J., Li, Z., Wang, F., Wang, Y., Zhang, F., Shao, M., Lu, S., and Dickerson, R. R.: Measurement report: Aircraft observations of ozone, nitrogen oxides, and volatile organic compounds over Hebei Province, China, Atmos. Chem. Phys., 20, 14523–14545
Xinrong Ren also contributed to a Korea–United States Air Quality (KORUS-AQ) experiment in South Korea and the Air Chemistry Research in Asia (ARIAs) in the North China Plain (NCP), which offers related insights. Authors investigate the bias wherein global coupled chemistry–climate models underestimate carbon monoxide (CO) in the Northern Hemisphere, exhibiting a pervasive negative bias against measurements peaking in late winter and early spring. While this bias has been commonly attributed to underestimation of direct anthropogenic and biomass burning emissions, chemical production and loss via OH reaction from emissions of anthropogenic and biogenic volatile organic compounds (VOCs) play an important role.
Gaubert, B., Emmons, L. K., Raeder, K., Tilmes, S., Miyazaki, K., Arellano Jr., A. F., Elguindi, N., Granier, C., Tang, W., Barré, J., Worden, H. M., Buchholz, R. R., Edwards, D. P., Franke, P., Anderson, J. L., Saunois, M., Schroeder, J., Woo, J.-H., Simpson, I. J., Blake, D. R., Meinardi, S., Wennberg, P. O., Crounse, J., Teng, A., Kim, M., Dickerson, R. R., He, H., Ren, X., Pusede, S. E., and Diskin, G. S.: Correcting model biases of CO in East Asia: impact on oxidant distributions during KORUS-AQ, Atmos. Chem. Phys., 20, 14617–14647,