Report to the CAS/WWRP/SSC7 on the activities of the SDS-WAS for the period July 2013 October 2014; presented by Slobodan Nickovic

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1 Report to the CAS/WWRP/SSC7 on the activities of the SDS-WAS for the period July 2013 October 2014; presented by Slobodan Nickovic General The objective of the Sand and Dust Storm Warning Advisory and Assessment System (SDS-WAS) is to develop, refine and provide a basis for distributing to the global community products that are useful in reducing the adverse impacts of SDS and to assess impacts of the SDS process on society and nature. The SDS-WAS activities are realized through three regional nodes, with intention to also establish collaboration and coordination at global scale in the future. The SDS-WAS activities were focussed on performing several research studies/projects, on continuing systematic validation of quasi-operational dust model products, and on increasing capacities of interested WMO Members to better monitor, predict and reduce negative impacts from SDS. During 2014, a part of the research SDS-WAS products were transferred to CBS operations. Current research studies Dust forecast model intercomparison: Case study of the Dust Cloud of April 2011 As a part of the SDS-WAS North Africa Middle East Europe (NAMEE) regional activities, this study performed four state-of-the-art dust forecast models to predict an intense Saharan dust outbreak transporting dust over Western Europe up to Scandinavia, developed between 5th and 11th April The following models were used: three regional models - BSC-DREAM8b, NMMB/BSC-Dust (BSC) and DREAM-NMME-MACC (Serbian HM Service); two global models MetUMTM (UK MetOffice) and MACC-II (ECMWF). Each model is compared against a set of different observations: surface concentrations (Spanish Research Council IDAEA-CSIC network), aerosol optical depth (AOD) from the GAW contributing network AERONET, AOD from NASA/MODIS, and vertical profiles of dust aerosol from NASA/CALIPSO, wind at 10m and wind profiles. In addition to the model validation, the comprehensive inter-comparison of the models reveal strengths and weaknesses of individual forecasts and provide an assessment of uncertainties in simulating the atmospheric dust cycle. The study allowed investigating the capacity of the models to predict a dust event with a higher temporal resolution.

2 The models are successful in predicting the onset and evolution of the dust cloud in terms of AOD for all three analyzed lead-times, namely 24, 48 and 72 hours. All the models reproduce the major features of the evolution when compared to both AERONET and MODIS. The main differences are in terms of magnitude of the simulated AOD; while AOD at the source region is both over and underestimated by the models, the AOD in northern Europe is underestimated by all models. The former suggest that emissions might be underestimated but misrepresentation of the size distribution cannot be excluded as source if this bias. In spite of the good performance in reproducing the AOD, the models have more difficulties in predicting the surface concentrations in the Iberian Peninsula. Furthermore, comparison against profiles of extinction coefficient from the CALIPSO.CALIOP satellite data reveals that the models have difficulties in reproducing the vertical dust distribution suggesting that the models simulate a too weak vertical mixing or have difficulties in reproducing the processes responsible for the vertical propagation. Dust model evaluation against lidar data Currently, one of the least known features in dust modelling is the vertical structure of dust patterns, since there is yet no assimilation of vertical profiles in the operational dust forecasts. Vertical profiling for dust is needed since this can be also used as a bridge between in-situ observations and satellite observations (WMO/CAS Technical Conference, November 2013). Latest technology developments allow automated lidar and ceilometer systems for continuous operation which could be remotely controlled. This might fill gaps of dust vertical distribution in remote areas, thus achieving a balance between research and operational observations. To response to the problem of dust vertical profiling, in this project the ability of models to reproduce vertical dust distribution was explored. A potential of continental scale remote sensing networks for model evaluation and, in the future, assimilation was considered. Finally, the project aimed to understand the capabilities and limitations of current observational techniques and algorithms and suggest directions of developments in order to support future lidar data assimilation. For the period January 2011 June 2013, ten lidar stations from the GAW GALION/EARLINET, co-located with AERONET photometers were selected and used for the evaluation of the following models: BSC-DREAM8bV2 (BSC, Barcelona), NMMB/BSC-Dust (BSC, Barcelona), DREAMABOL (ISAC-CNR, Bologna) and DREAM8-NMME-MACC (Serbian

3 HM Service, Belgrade). For each model it was examined how well are represented: the center of mass, the total concentration (dust load), and the peak (maximum) value. The model intercomparison analysis was based on using standard statistical tools. In most cases, the models captured the dust load value although in general there is a certain underestimated bias. Furthermore, models predicted very well the shape of the average vertical dust profile. Specifically, BSC/DREAMB8bV2 and DREAMABOL especially showed high correlation in the structure, but underestimate the actual values of the concentration. In contrast, NMMB-BSC-DUST and DREAM8-NMME-MACC predicted values closer to the observed ones, but at slightly elevated maxima. DREAM8-NMME-MACC over-predicted dust load above 6km not existing in the measurements. In summary, it has been noticed that the absolute dust concentration can be underestimated, but the performance of models is better for strong dust transport events. Future evaluations will include more automatic retrieval algorithms applied over longer time periods. This study provided important information to modelers confirming the usefulness of such observations for the future lidar data assimilation. June 2014 dust storm over Tehran: Process study and modelling The dust forecasting community in general intends to increase the spatial resolution of models, having in mind that small-scale character of dust sources and those typically nonhydrostatic atmospheric conditions are drivers of dust dynamics. This study was proposed by the Regional Steering Group (RSG) for NAMEE during its regular meeting on June 4th, 2014, noting that an extreme dust over Tehran happened the same week was not predicted by any of the eight dust models participating in the SDS-WAS routine intercomparison. Recently published evidence indicated that such dust storms could be predicted only if a model is downscaled below 5km and if sources are described using time dependent information on the land cover. The objectives of the study is: a) to study the process of an extreme dust storm over Tehran and driving atmospheric and environmental conditions, and b) to test capabilities of dust models to predict this event. Collaborating/participating partners expressed interest to participate in the project are: Islamic Republic of Iran Meteorological Organization (Tehran, Iran), Department of the Environment (Tehran, Iran), Indian School of Mines (Dhanbad, India), Egyptian Meteorological Authority (Cairo, Egypt), Regional Maritime University (Accra, Ghana), Agencia Estatal de Meteorología (Madrid, Spain), Republic Hydrometeorological Service of Serbia (Belgrade, Serbia), British Met Office (Exeter,

4 UK), University of Chile (Santiago, Chile), NOAA (Washington, USA), Sharda University, (Greater Noida, India), Leibniz Institute for Tropospheric Research (Leipzig, Germany), Korean Meteorological Service (Seoul, Korea), ISSAC (Bologna, Italy), GFDL (Princeton, USA). The anticipated deadline for performing the study is spring Improving the quantitative estimates of the geographical distribution of the transport and deposition of mineral matter and its content to the ocean This study was performed as a joint WWRP and GAW work with the GESAMP Working group. GESAMP is the Group of Experts on Scientific Aspects of Marine Environmental Protection (GESAMP) established as an advisory body that advises the United Nations (UN) system on the scientific aspects of marine environmental protection. Through the study, GESAMP evalated the state-of-art knowledge and uncertainties regarding the deposition of dust on the ocean and its mineralogical composition provided by models and measurement datasets. The deposition calculations from these global models are frequently used as input for biological productivity calculations. The study concludes that the agreement with individual deposition measurements is within a factor of three at best. At the same time, very few studies have been performed to assess mineralogical composition of dust over the ocean, and thus the associated uncertainties in the mineralogy are even larger than for dust deposition alone. The study report highlights possibilities for a more integrated approach to improve the dust deposition calculations to the ocean using the newest information available from regional and global models and measurements. Finally, the necessary steps are identified regarding models developments and diagnostics concerning the deposition of dust-related nutrients crucial for the marine bio-production. (more in the GAW 203 Technical Note, link The Atmospheric Input of Chemicals to the Ocean ) Management issues Transition to operational activities In September 2012 the Commission for Basic Systems (CBS) recommended designation of the consortium AEMET/BSC to host the first RSMC with activity specialization in Atmospheric Sand and Dust storm Forecasts (RSMC-ASDF) for Northern Africa, Middle East and Europe (NAMEE). In June 2013 The WMO/EC approved the designation, after what the RSMC-ASDF Barcelona Dust Forecast Center started dust forecast operations in March 2014 (dust.aemet.es) and it made the products available on GTS. This was for the first time that a WWRP research project was implemented as an operational one.

5 SDS-WAS Science and Implementation Plan (S&IP) S&IP for the period was drafted and submitted to SSC7 for consideration and approval. The major updates of the document with respect to the previous version are a) developed nomination procedure for membership in the SDS-WAS Steering Committee (global), b) SDS-WAS Trust Fund is proposed to support global coordination, c) the science plan was updated, with the following major research tasks included: High-resolution dust modelling and local phenomena description; Dust observation techniques and methodologies; Improving knowledge of SDS formation mechanisms; Model evaluation and inter-comparisons; Data assimilation and near-real time data processing; Chemical and physical characterization of dust; Dust reanalysis; and direct and indirect dust effects - impacts to weather and climate. Collaboration with GAW All above-mentioned research studies extensively use the GAW-based atmospheric composition (aerosol) observations provided by the GAW networks: the GALION lidar network, and the AERONET contributing network of sun-photometers. These data is used for the monitoring/model validation purposes. In addition, within a WMO/GAW project funded by AEMET, addressed to improving the observational infrastructure in Africa, four AERONET sunphotometer stations are recently established: Quarzazate (Morocco), Tamanrasset (Algeria), Tunis (Tunisia), Cairo (Egypt). These aerosol/dust observations located in the dust source areas partially fill the gap in dust monitoring. Status of the SDS-WAS Regional Nodes activities Among the Regional SDS-WAS nodes, the NAMEE node is the most developed. The corresponding Centre successfully coordinates the regional collaboration: it runs the web site as a one-stop shop for exchange of observations and modelling products, it performs routine intercomparison and validation of eight partner models, coordinates work on several research studies and organizes regular training workshops. The Asian Node, in spite of the substantial capabilities of Korea, China and Japan as the key contributors to SDS-WAS, has still did not achieved the coordination level as in NAMEE. The forthcoming meeting of the regional steering group planned for the beginning of 2015 is expected to accelerate the cooperation in the region. The Pan-American node is still in the phase of establishing the regional activities, slowed down in 2013 because the hosting of the regional centre in the University of Chapman was not able to be realized.