Loew, A.

Petrova, I.

English

MPG.PuRe

  Structural Interrelationships between Evaporation and Precipitation:  Application of Complex Networks to Satellite based Fields   I. Petrova 1,2 and A. Loew 1  1 Max Planck Institute for Meteorology, MPI-M, www.mpimet.mpg.de 2 SICCS, KlimaCampus, University of Hamburg, Germany  Irina.Petrova@zmaw.de In attempt to get closer to real climate systems and associated with them system of interactions a concept of coupled climate networks was introduced by                               Donges et al., 2011. Investigating topology of interacting networks conclusions on dominant connectivity “tunnels”, spatial and temporal dependence variability and                          vulnerability of one filed relative to another can be done.  Analyzing coupled topology of evaporation (E) and precipitation (P) fields the conclusions on major teleconnections, topological and dynamical features, temporal and                spatial connectivity variability of the observed and modeled E/ P networks, as well as similarity measures were carried out. Motivation : Studying and understanding complex interactions and system of feedbacks between E and P Connectivity features of observed E and P from the HOAPS-3 product  Improvement / validation of the numerical simulation schemes  Objectives : Analyze topology of single/ coupled precipitation and evaporation networks Investigate prominent global teleconnection patterns in the constructed networks  Identify physical properties within the climate network fields Compare observed (HOAPS) and modelled (MPI-ESM) network features Observed HOAPS-3 and modelled MPI - ESM Data :  Construction of any network strictly depends on the knowledge (collected) data to be used. Imperfect retrieval algorithms and data merging of the atmospheric parameters fields cause uncertainties and lower quality of the final product.  Global Teleconnections :  Area Weighted Connectivity (AWC) fields reveal ENSO and NAO related connectivity patterns and associated teleconnections over western coast of USA, Pakistan, South to Madagascar and the area of NAO– influence over Greenland.   Method of Complex Networks (CCN) :  The information stored in a node of a climate network reflects the physical state of corre-sponding spatial grid-point. Thus, depending on the spatial and temporal scale under research the connections or links between these nodes will represent certain (non-) linear interactions between each other. In order to exclude unwanted and insignificant connections between the vertices, a preprocessing of the knowledge data should be done. Vertices = grid points Edges    = (non) linear             interactions between vertices  Criterion = Spearman Rank Correlation (zero lag) Fixed Link Density = 0.04 Fig 1. Main steps to construct Climate Network (left) and principle idea of Coupled Network                     Connectivity (right)  Combined HOAPS-S and GPCC:  In order to obtain consistent and representative evaporation and precipitation fields the fully satellite-based HOAPS-3 (Hamburg Ocean Atmosphere                         Parameters and Fluxes from Satellite Data,                                 (www.hoaps.org) and combined HOAPS-3 / GPCC     (G loba l  P rec ip i t a t ion  C l ima to logy  Cen te r,                              (www.gpcc.dwd.de) datasets were used.  Earth System Model of MPI-M :  A fully coupled MPI-ESM model is composed of the               atmospheric module (ECHAM6, Stevens et al., 2012), ocean (MPIOM, Jungclaus et al., 2012) and land (JSBACH, Raddatz et al., 2007; Brovkin et al., 2009) components.  Fig 2.  Climatological annual means of Precipitation (upper) and              Evaporation (lower), and corresponding zonal means Fig 3. AWC of the Precipitation Network from HOAPS / GPCC  Fig 5. Correlation Values of source-point neighbours in HOAPS and  MPI-ESM based Evapora-tion and Precipitation Networks  What does degree see?  Where the areas of high connectivity are located?  Super nodes?  What reveals the mis-match of model and observed networks?  North Atlantic Coupled Networks :  High connectivity areas of the Coupled CCN lie around 20°N and 60°N, and can be partly explained by the NAO variability. SVD/ EOF Analysis and Complex Networks :  The EOF approach investigates the covariance structure of a parameter evolving in time which makes it being similar to the correlation based method of CCN, especially to the Degree. Joint variability of two fields can be assessed using SVD analysis. Potential (dis-) similarities   between Coupled Networks and SVD were analyzed.  Fig 6. SVD analysis (mode2, 21%) and Cross Degree Centrality of HOAPS E and P fields References: Donges, J. F. , et al. (2011): Investigating the topology of interacting networks Theory and application to coupled climate subnetworks. The      European Physical Journal B - Condensed Matter and Complex Systems, Volume 84, Number 4, 635-651, DOI: 10.1140/epjb/e2011-10795-8. Stevens, B., et al. (2012): The atmospheric component of the MPI Earth System Model: ECHAM6, JAMES, in preparation. Jungclaus, J. H., et al. (2012): Characteristics of the ocean simulations in the MPI Earth System Model, JAMES, in preparation. Brovkin, V., T. Raddatz, C. H. Reick, M. Claussen, and V. Gayler (2009), Global biogeophysical interactions between forest and climate,        Geophys. Res. Letters, 36, L07 405, doi:10.1029/2009GL037543, 2009. Cross- Betweenness and Closeness centralities designate areas of major importance for cross –           functionality and informational transport between the   networks.  The downstream source feature of High DC          indicates the source area of precipitation within the evaporation field. It is consistent with the wind fields and prominent for the whole high connectivity region. Conclusions : E/ P Network structure resembles major teleconnection patterns High DC area of coupled E/ P Networks reveal spatial source-receptor feature  Uncertainties in E/ P variability associated to NAO/ ENSO in amip and historical       experiments of MPI-ESM model were identified (Dis-)similarities between SVD and cross DC were investigated 

Structural interrelationships between evaporation and precipitation: Application of complex networks to satellite based fields

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