The effect of volcanic eruptions on global precipitation

Abstract

[1] We examine robust features of the global precipitation response to 18 large low-latitude volcanic eruptions using an ensemble of last millennium simulations from the climate model HadCM3. We then test whether these features can be detected in observational land precipitation data following five twentieth century eruptions. The millennium simulations show a significant reduction in global mean precipitation following eruptions, in agreement with previous studies. Further, we find that the response over ocean remains significant for around 5 years and matches the timescale of the near-surface air temperature response. In contrast, the land precipitation response remains significant for 3 years and reacts faster than land temperature, correlating with aerosol optical depth and a reduction in land-ocean temperature contrast. In the tropics, areas experiencing posteruption drying coincide well with climatologically wet regions, while dry regions get wetter on average, but there changes are spatially heterogeneous. This pattern is of opposite sign to, but physically consistent with, projections under global warming. A significant reduction in global mean and wet tropical land regions precipitation is also found in response to twentieth century eruptions in both the observations and model masked to replicate observational coverage, although this is not significant for the observed wet regions response in boreal summer. In boreal winter, the magnitude of this global response is significantly underestimated by the model; the discrepancy originating from the wet tropical regions although removing the influence of ENSO improves agreement. The modeled precipitation response is detectable in the observations in boreal winter but marginal in summer.

Assessing the Impact of a Future Volcanic Eruption on Decadal Predictions

“…2). This is in agreement with previous studies (Iles et al, 2013;Joseph and Zeng, 2011). In the global precipitation-maps, we see a reduction of precipitation for both experiments through the volcanic aerosol in most regions in the first four prediction years (Fig.…”

“…In the first four prediction years, the magnitude of the reduction is about 0.025mm/day. This behavior is in agreement with previous studies which examined historical volcanic eruptions (Gu and Adler, 2011;Iles et al, 2013;Robock and Mao, 1992). The effect decreases with prediction time, but stays significant for all lead-times.…”

“…While the reduction of land precipitation is a direct feedback to the increased AOD, the precipitation changes over the ocean area temperature feedback (Iles et al, 2013). 30 Similar behavior has been found in CMIP5 model simulations, but it turned out that the precipitation changes are (Iles et al, 2013;Iles and Hegerl, 2014;Paik and Min, 2017). The latter suggest that this underestimation is connected to the underestimated latent heat flux in climate models.…”

“…The precipitation reduction over land is only significant until prediction years 2-5, whereas the decline over the ocean remains significant until years 5-8 in the 2014 experiment or even over the whole simulation period as in the 2012 experiment. While the reduction of land precipitation is a direct feedback to the increased AOD, the precipitation changes over the ocean area temperature feedback (Iles et al, 2013). 30 Similar behavior has been found in CMIP5 model simulations, but it turned out that the precipitation changes are (Iles et al, 2013;Iles and Hegerl, 2014;Paik and Min, 2017).…”

The Role of Volcanic Activity in Climate and Global Change

“…In contrast with these results, Anchukaitis et al [88] used well-validated proxy reconstructions of Asian droughts and pluvials to reveal significantly wetter conditions in the year of an eruption over mainland southeast Asia and drier conditions in central Asia. A recent study [89] employed both the model output and observations to examine robust features of the global precipitation response. In agreement with our results they found that the response over oceans remains significant for five years (compare with Fig.…”