Review of manuscript entitled “A global scale evaluation of extreme events in the eartH2Observe project” by Marthews et al.

Abstract. Climate extremes can affect the functioning of terrestrial ecosystems, for instance via a reduction of the photosynthetic capacity or alterations of respiratory processes. Yet the dominant regional and seasonal effects of hydrometeorological extremes are still not well documented. Here we quantify and characterize the role of large spatiotemporal extreme events in gross primary production (GPP) as triggers of continental anomalies. We also investigate seasonal dynamics of extreme impacts on continental GPP anomalies. We find that the 50 largest positive (increase in uptake) and negative extremes (decrease in uptake) on each continent can explain most of the continental variation in GPP, which is in line with previous results obtained at the global scale. We show that negative extremes are larger than positive ones and demonstrate that this asymmetry is particularly strong in South America and Europe. Most extremes in GPP start in early summer. Our analysis indicates that the overall impacts and the spatial extents of GPP extremes are power law distributed with exponents that vary little across continents. Moreover, we show that on all continents and for all data sets the spatial extents play a more important role than durations or maximal GPP anomaly when it comes to the overall impact of GPP extremes. An analysis of possible causes implies that across continents most extremes in GPP can best be explained by water scarcity rather than by extreme temperatures. However, for Europe, South America and Oceania we identify also fire as an important driver. Our findings are consistent with remote sensing products. An independent validation against a literature survey on specific extreme events supports our results to a large extent.

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Global Assessment of Spatiotemporal Variability of Wet, Normal and Dry Conditions using Multiscale Entropy-based Approach

10.21203/rs.3.rs-1178420/v1 ◽

2021 ◽

Author(s):

Vijay Sreeparva ◽

V.V Srini

Keyword(s):

Climate Change ◽

Extreme Events ◽

Winter Season ◽

Global Scale ◽

Spatiotemporal Variability ◽

Multiscale Entropy ◽

Spatiotemporal Trends ◽

Decadal Scale ◽

Dry Conditions ◽

Dry And Wet Conditions

Abstract In recent decades, human-induced climate change has caused a worldwide increase in the frequency/intensity/duration of extreme events, resulting in enormous disruptions to life and property. Hence, a comprehensive understanding of global-scale spatiotemporal trends and variability of extreme events at different intensity levels (e.g., moderate/severe/extreme) and durations (e.g., short-term/long-term) of normal, dry and wet conditions is essential in predicting/forecasting/mitigating future extreme events. This article analyses these aspects using estimates of a non-stationary standardized precipitation evapotranspiration index corresponding to different accumulation periods for 0.5˚ CRU resolution grids at globe-scale. Results are analyzed with respect to changes in land-use/landcover and location/geographic (latitude, longitude, elevation) indicators at different time scales (decadal/annual/seasonal/monthly) for each continent. The analysis showed an (i) increasing trend in the frequency/count of both dry and wet conditions and variability of dry conditions, and (ii) contrasting (decreasing) trend in the variability of wet conditions, possibly due to climate change-induced variations in atmospheric circulations. Globally, the highest variability in the wet and dry conditions is found during the Northern hemisphere's winter season. The decadal-scale analysis showed that change in variability in dry and wet conditions has been predominant from the 1930s and 1950s, respectively and is found to be increasing in recent decades.

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Global-scale evaluation of SMAP, SMOS and ASCAT soil moisture products using triple collocation

Remote Sensing of Environment ◽

10.1016/j.rse.2018.05.008 ◽

2018 ◽

Vol 214 ◽

pp. 1-13 ◽

Cited By ~ 47

Author(s):

Fan Chen ◽

Wade T. Crow ◽

Rajat Bindlish ◽

Andreas Colliander ◽

Mariko S. Burgin ◽

...

Keyword(s):

Soil Moisture ◽

Global Scale ◽

Scale Evaluation

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Extreme events in gross primary production: a characterization across continents

Biogeosciences ◽

10.5194/bg-11-2909-2014 ◽

2014 ◽

Vol 11 (11) ◽

pp. 2909-2924 ◽

Cited By ~ 56

Author(s):

J. Zscheischler ◽

M. Reichstein ◽

S. Harmeling ◽

A. Rammig ◽

E. Tomelleri ◽

...

Keyword(s):

South America ◽

Primary Production ◽

Extreme Events ◽

Gross Primary Production ◽

Climate Extremes ◽

Terrestrial Ecosystems ◽

Global Scale ◽

Seasonal Effects ◽

Carbon Uptake ◽

Uptake Rates

Abstract. Climate extremes can affect the functioning of terrestrial ecosystems, for instance via a reduction of the photosynthetic capacity or alterations of respiratory processes. Yet the dominant regional and seasonal effects of hydrometeorological extremes are still not well documented and in the focus of this paper. Specifically, we quantify and characterize the role of large spatiotemporal extreme events in gross primary production (GPP) as triggers of continental anomalies. We also investigate seasonal dynamics of extreme impacts on continental GPP anomalies. We find that the 50 largest positive extremes (i.e., statistically unusual increases in carbon uptake rates) and negative extremes (i.e., statistically unusual decreases in carbon uptake rates) on each continent can explain most of the continental variation in GPP, which is in line with previous results obtained at the global scale. We show that negative extremes are larger than positive ones and demonstrate that this asymmetry is particularly strong in South America and Europe. Our analysis indicates that the overall impacts and the spatial extents of GPP extremes are power-law distributed with exponents that vary little across continents. Moreover, we show that on all continents and for all data sets the spatial extents play a more important role for the overall impact of GPP extremes compared to the durations or maximal GPP. An analysis of possible causes across continents indicates that most negative extremes in GPP can be attributed clearly to water scarcity, whereas extreme temperatures play a secondary role. However, for Europe, South America and Oceania we also identify fire as an important driver. Our findings are consistent with remote sensing products. An independent validation against a literature survey on specific extreme events supports our results to a large extent.

Download Full-text