Contrasting biosphere responses to hydrometeorological extremes: revisiting the 2010 western Russian heatwave

Abstract

Abstract. Combined droughts and heatwaves are among those compound extreme events that induce severe impacts on the terrestrial biosphere and human health. A record breaking hot and dry compound event hit western Russia in summer 2010 (Russian heatwave, RHW). Events of this kind are relevant from a hydrometeorological perspective, but are also interesting from a biospheric point of view because of their impacts on ecosystems, e.g., reductions in the terrestrial carbon storage. Integrating both perspectives might facilitate our knowledge about the RHW. We revisit the RHW from both a biospheric and a hydrometeorological perspective. We apply a recently developed multivariate anomaly detection approach to a set of hydrometeorological variables, and then to multiple biospheric variables relevant to describe the RHW. One main finding is that the extreme event identified in the hydrometeorological variables leads to multidirectional responses in biospheric variables, e.g., positive and negative anomalies in gross primary production (GPP). In particular, the region of reduced summer ecosystem production does not match the area identified as extreme in the hydrometeorological variables. The reason is that forest-dominated ecosystems in the higher latitudes respond with unusually high productivity to the RHW. Furthermore, the RHW was preceded by an anomalously warm spring, which leads annually integrated to a partial compensation of 54 % (36 % in the preceding spring, 18 % in summer) of the reduced GPP in southern agriculturally dominated ecosystems. Our results show that an ecosystem-specific and multivariate perspective on extreme events can reveal multiple facets of extreme events by simultaneously integrating several data streams irrespective of impact direction and the variables' domain. Our study exemplifies the need for robust multivariate analytic approaches to detect extreme events in both hydrometeorological conditions and associated biosphere responses to fully characterize the effects of extremes, including possible compensatory effects in space and time.

Scaling carbon fluxes from eddy covariance sites to globe: synthesis and evaluation of the FLUXCOM approach

“…It has been shown that despite the local dominance, water-related NEE anomalies largely cancel spatially in RS+METEO and TRENDY, resulting in the dominance of temperature-related NEE anomalies in globally integrated land sink IAV , but see Humphrey et al, 2018, for a different perspective). Studies on effects of water availability on spatial GPP anomalies using the RS data yielded highly plausible patterns that were consistent with independent data (Flach et al, 2018;Orth et al, 2019;Walther Figure 7. Mean seasonal variations in net land carbon release for the period 2008-2010 over TRANSCOM regions.…”

“…Nevertheless, various studies have shown that SIF is currently the best proxy for photosynthesis that can be remotely sensed directly, in particular at seasonal timescale, and over regions with strong seasonal cycles. This is supported by strong empirical relationships between GPP and SIF across different satellites and retrieval methods as well as from EC data, crop inventories and datadriven GPP methods (Frankenberg et al, 2011;Guanter et al, 2014;Joiner et al, 2018;Sun et al, 2017;Walther et al, 2016). This gives us confidence in using SIF as an independent data stream for photosynthesis to evaluate FLUXCOM products.…”

“…For the RS+METEO setup, three ma-chine learning methods with five global climate forcing data sets (Table 1) yielded products with daily temporal and 0.5 • spatial resolution and time periods depending on the meteorological data. The meteorological data included WATCH Forcing Data applied to ERA-Interim (WFDEI; Weedon et al, 2014), Global Soil Wetness Project 3 forcing data (GSWP3, Kim, 2017), CRU JRA version 1.1 (Harris, 2019), ERA5 (C3S, 2017, and a combination of observation-based radiation from CERES (Doelling et al, 2013) and precipitation from GPCP (Huffman et al, 2001) (CERES-GPCP) resampled to 0.5 • . The wide range of data sources from reanalysis to station measurements to satellite observation is intentional and is meant to bracket potential uncertainties in meteorological forcing.…”

“…Exploiting the massive space-based column CO 2 data in the future will hopefully facilitate improvements on this aspect. Despite large uncertainties and apparent knowledge gaps in NEE IAV from both an observational and modelling perspective, there are promising indications of improved capability to track IAV patterns with FLUXCOM such as the good correspondence of RS+METEO with inversions at the global scale and independent verifications of GPP IAV of RS at least outside the wet tropics (Flach et al, 2018;Joiner et al, 2018;Orth et al, 2019;Walther et al, 2019).…”

A monitoring and prediction system for compound dry and hot events

“…compound dry and hot events) (Seneviratne et al 2012, Leonard et al 2014, Liu et al 2017, Miralles et al 2018. Recent decades have witnessed multiple compound dry and hot events in different regions, such as Europe (2003), China (2006), Russia (2010), southern US (2011), and southern Africa (2015-2016) (Barriopedro et al 2011, Hoerling et al 2013, Flach et al 2018, Herring et al 2018, Wu et al 2019. The compound dry and hot event may lead to impacts larger than the sum of impacts from individual extremes and has attracted increased attention in recent decades (Seneviratne et al 2012, Kopp et al 2017.…”