Intercomparing the quality of recent reanalyses for offshore wind farm planning in Germany's exclusive economic zone of the North Sea

Author(s):
Spangehl, T.; Borsche, M.; Niermann, D.; Kaspar, F.; Schimanke, S.; Brienen, S.; Möller, T.; Brast, M.
Publication title: Advances in Science and Research
2023
 | Volume: 20
2023
DOI: 10.5194/asr-20-109-2023
Abstract:
In order to facilitate offshore wind farm tenders, Deutscher Wetterdienst (DWD, Germany's national meteorological service) provides reanalysis data an… In order to facilitate offshore wind farm tenders, Deutscher Wetterdienst (DWD, Germany's national meteorological service) provides reanalysis data and quality assessments to Bundesamt für Seeschifffahrt und Hydrographie (BSH, Federal Maritime and Hydrographic Agency). The regional reanalysis COSMO-REA6 is used besides the global reanalysis ERA5. New reanalyses and derived products getting available are (i) the regional reanalysis CERRA (C3S), (ii) COSMO-R6G2, a successor of COSMO-REA6 which is currently produced by DWD and (iii) HoKliSim-De, a convection-permitting climate simulation for Germany with COSMO-CLM as a regional downscaling of ERA5. In the present study, the quality of the different data sets for offshore wind energy application is compared using in-situ measurements of the wind speed and wind direction from the top anemometer and vane of the FINO1 research platform and satellite-based data of the near-surface wind speed from the Copernicus Marine Environment Monitoring Service (CMEMS) and the EUMETSAT Satellite Application Facility on Climate Monitoring (CM SAF). Evaluation at FINO1 focuses on the time period prior to the installation of nearby wind farms to avoid wake effects. COSMO-REA6, CERRA and HoKliSim-De show only small biases and resemble the observed distribution of the wind speed at FINO1 whereas ERA5 shows slightly lower values of the wind speed at 100gm. All model-based products tend to slightly underestimate the occurrence of south-westerly wind directions and overestimate wind directions from West to Northwest. Smallest directional biases are analysed for COSMO-REA6. Analysis of the windstorm CHRISTIAN suggests that ensemble information is required for the representation of individual extreme events. Evaluation of the near-surface wind speed using satellite-based data is performed for an area around the German Exclusive Economic Zone (EEZ) of the North Sea. The median bias of ERA5 and COSMO-REA6 is close to zero. CERRA shows a systematic overestimation of the near-surface wind speed compared to the satellite-based reference datasets. By contrast, a slight underestimation is analysed for HoKliSim-De. The bias distribution analysed for a first simulation stream of COSMO-R6G2 is similar to COSMO-REA6 which provides initial indication for the applicability of the new product. © 2023 Thomas Spangehl et al. more
Atmosphere CM-SAF Climate Data Records Ocean

Introducing hydrometeor orientation into all-sky microwave and submillimeter assimilation

Author(s):
Barlakas, V.; Geer, A.J.; Eriksson, P.
Publication title: Atmospheric Measurement Techniques
2021
 | Volume: 14 | Issue: 5
2021
DOI: 10.5194/amt-14-3427-2021
Abstract:
Numerical weather prediction systems still employ many simplifications when assimilating microwave radiances under all-sky conditions (clear sky, clou… Numerical weather prediction systems still employ many simplifications when assimilating microwave radiances under all-sky conditions (clear sky, cloudy, and precipitation). For example, the orientation of ice hydrometeors is ignored, along with the polarization that this causes. We present a simple approach for approximating hydrometeor orientation, requiring minor adaption of software and no additional calculation burden. The approach is introduced in the RTTOV (Radiative Transfer for TOVS) forward operator and tested in the Integrated Forecast System (IFS) of the European Centre for Medium-Range Weather Forecasts (ECMWF). For the first time within a data assimilation (DA) context, this represents the ice-induced brightness temperature differences between vertical (V) and horizontal (H) polarization-the polarization difference (PD). The discrepancies in PD between observations and simulations decrease by an order of magnitude at 166.5 GHz, with maximum reductions of 10-15 K. The error distributions, which were previously highly skewed and therefore problematic for DA, are now roughly symmetrical. The approach is based on rescaling the extinction in V and H channels, which is quantified by the polarization ratio. Using dual-polarization observations from the Global Precipitation Mission microwave imager (GMI), suitable values for were found to be 1.5 and 1.4 at 89.0 and 166.5 GHz, respectively. The scheme was used for all the conical scanners assimilated at ECMWF, with a broadly neutral impact on the forecast but with an increased physical consistency between instruments that employ different polarizations. This opens the way towards representing hydrometeor orientation for cross-track sounders and at frequencies above 183.0 GHz where the polarization can be even stronger. © 2021 Author(s). more
Atmosphere Method NWP-SAF Software for CDR development

Intraseasonal and synoptic climate variability of surface solar radiation over South-West Indian Ocean: Regional climate modelling

Author(s):
Li, Peng; Li, Qi
Publication title: INTERNATIONAL JOURNAL OF CLIMATOLOGY
2021
2021
DOI: 10.1002/joc.7476
Abstract:
The abundant surface solar radiation (SSR) over South-West Indian Ocean (SWIO) presents significant temporal variability. To characterize this tempora… The abundant surface solar radiation (SSR) over South-West Indian Ocean (SWIO) presents significant temporal variability. To characterize this temporal variability is important for the application of solar energy, such as photovoltaic industry. This article studied the intraseasonal and synoptic climate variability of SSR by regional climate modelling over SWIO region. The regional climate model, RegCM4's skill is first evaluated through analysing the seasonal mean SSR with the precipitation, near surface temperature and total cloud cover in austral summer and winter. The basic validation of those simulated parameters with the reference data showed model's performance on SSR. The austral summer (November-February) 1999-2008 was chosen to search the Madden-Julian Oscillation patterns and tropical temperate troughs which are the major expression of intraseasonal and synoptic climate variability. The circulation, moisture fluxes, and radiation fluxes have been checked at the beginning for RegCM4's input dataset (ERA-Interim) to find the signals. Then, the output simulation results were taking into account to see if the model can reproduce the intraseasonal and synoptic climate variability or not. SSR from SARAH-E (CM SAF@5 km) as the reference dataset in the end has been used to validate the simulated patterns, which showed that the eastward SSR anomalies propagation and negative SSR anomalies bands can be observed in RegCM4 and the according satellite dataset. These results identified and explained SSR's intraseasonal and synoptic climate variability over SWIO region, which provide a way through RegCM to perform SSR's evaluation and prediction. more
Application Atmosphere CM-SAF Climate Data Records

Intraseasonal and synoptic modulation of diurnal surface solar radiation over Reunion island in the South-West Indian Ocean

Author(s):
Tang, Chao; Mialhe, Pauline; Pohl, Benjamin; Morel, Béatrice; Wild, Martin; Koseki, Shunya; Abiodun, Babatunde; Bessafi, Miloud; Lennard, Chris; Kumar Beeharry, Girish; Lollchund, Roddy; Cunden, Tyagaraja S. M.; Singh, Swati
Publication title: Solar Energy
2023
 | Volume: 262
2023
DOI: 10.1016/j.solener.2023.111856
Abstract:
Understanding the space-time variability of Surface Solar Radiation (SSR) is mandatory for the prediction and, eventually, the skillful forecasting of… Understanding the space-time variability of Surface Solar Radiation (SSR) is mandatory for the prediction and, eventually, the skillful forecasting of photovoltaic energy production. This paper addresses the modulation of local-scale SSR over Reunion, a tropical island in the South-West Indian Ocean, by the leading modes of climate variability influencing both regional-scale and local-scale atmospheric convection and its associated cloud cover. Analyses focus on synoptic (tropical cyclones [TCs], synoptic convective regimes, including Tropical-Temperate Troughs [TTTs]) and intraseasonal (Madden-Julian Oscillation [MJO]) timescales. The SSR intra-daily variability is first assessed by a diurnal classification of SARAH-E satellite SSR data, and it is then related to the climate conditions mentioned above. SSR anomalies are found larger (smaller) on the windward (leeward) side of Reunion and in the summer (winter) season. The island-scale “cloudy” conditions can typically last 1 or 2 days. Nearby TCs can strongly reduce SSR by up to 50% on average, depending on their distances from Reunion, their sizes, and particularly, their longitudinal positions, which is observed for the first time. Nearby TCs are associated with significant negative SSR anomaly when located west of Reunion but with less significant or even positive anomaly when located east of the island. Synoptic convective regimes (the intraseasonal MJO) have a relatively weaker impact on SSR, with a value up to 13% (5%) of the mean value. Potential interactions between these SSR modulators are also investigated to understand better and eventually predict the mechanisms likely to modulate SSR (and thus photovoltaic electricity production) at sub-seasonal timescales. more
Application Atmosphere CM-SAF Climate Data Records

Introducing New Metrics for the Atmospheric Pressure Adjustment to Thermal Structures at the Ocean Surface

Author(s):
Meroni, Agostino N.; Desbiolles, Fabien; Pasquero, Claudia
Publication title: JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
2022
 | Volume: 127 | Issue: 16
2022
DOI: 10.1029/2021JD035968
Abstract:
Thermal structures at the sea surface are known to affect the overlying atmospheric dynamics over various spatio-temporal scales, from hourly and sub-… Thermal structures at the sea surface are known to affect the overlying atmospheric dynamics over various spatio-temporal scales, from hourly and sub-kilometric to annual and O(1,000 km). The relevant mechanisms at play are generally identified by means of correlation coefficients (in space or time) or by linear regression analysis using appropriate couples of variables. For fine spatial scales, where sea surface temperature (SST) gradients get stronger, the advection might disrupt these correlations and, thus, mask the action of such mechanisms, just because of the chosen metrics. For example, at the oceanic sub-mesoscale, around 1-10 km and hourly time scales, the standard metrics used to identify the pressure adjustment mechanism (that involves the Laplacian of sea surface temperature, SST, and the wind divergence) may suffer from this issue, even for weak wind conditions. By exploiting high-resolution realistic numerical simulations with ad hoc SST forcing fields, we introduce some new metrics to evaluate the action of the pressure adjustment atmospheric response to the surface oceanic thermal structures. It is found that the most skillful metrics is based on the wind divergence and the SST second spatial derivative evaluated in the across direction of a locally defined background wind field. more
Application Atmosphere Climate Data Records OSI-SAF Ocean

Land Surface Albedo from Geostationary Satelites: A Multiagency Collaboration within SCOPE-CM

Author(s):
Lattanzio, Alessio; Schulz, Jörg; Matthews, Jessica; Okuyama, Arata; Theodore, Bertrand; Bates, John J.; Knapp, Kenneth R.; Kosaka, Yuki; Schüller, Lothar
Publication title: Bulletin of the American Meteorological Society
2013
 | Volume: 94 | Issue: 2
2013
DOI: 10.1175/BAMS-D-11-00230.1
Abstract:
Climate has been recognized to have direct and indirect impact on society and economy, both in the long term and daily life. The challenge of understa… Climate has been recognized to have direct and indirect impact on society and economy, both in the long term and daily life. The challenge of understanding the climate system, with its variability and changes, is enormous and requires a joint long-term international commitment from research and governmental institutions. An important international body to coordinate worldwide climate monitoring efforts is the World Meteorological Organization (WMO). The Global Climate Observing System (GCOS) has the mission to provide coordination and the requirements for global observations and essential climate variables (ECVs) to monitor climate changes. The WMO-led activity on Sustained, Coordinated Processing of Environmental Satellite Data for Climate Monitoring (SCOPE-CM) is responding to these requirements by ensuring a continuous and sustained generation of climate data records (CDRs) from satellite data in compliance with the principles and guidelines of GCOS. SCOPE-CM represents a new partnership between operational space agencies to coordinate the generation of CDRs. To this end, pilot projects for different ECVs, such as surface albedo, cloud properties, water vapor, atmospheric motion winds, and upper-tropospheric humidity, have been initiated. The coordinated activity on land surface albedo involves the operational meteorological satellite agencies in Europe [European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT)], in Japan [the Japan Meteorological Agency (JMA)], and in the United States [National Oceanic and Atmospheric Administration (NOAA)]. This paper presents the first results toward the generation of a unique land surface albedo CDR, involving five different geostationary satellite positions and approximately three decades of data starting in the 1980s, and combining close to 30 different satellite instruments. more
Climate Data Records EUM-Secr Land Validation

Investigating the sensitivity to resolving aerosol interactions in downscaling regional model experiments with WRFv3.8.1 over Europe

Author(s):
Pavlidis, V.; Katragkou, E.; Prein, A.; Georgoulias, A.K.; Kartsios, S.; Zanis, P.; Karacostas, T.
Publication title: Geoscientific Model Development
2020
 | Volume: 13 | Issue: 6
2020
DOI: 10.5194/gmd-13-2511-2020
Abstract:
In this work we present downscaling experiments with the Weather Research and Forecasting model (WRF) to test the sensitivity to resolving aerosol-rad… In this work we present downscaling experiments with the Weather Research and Forecasting model (WRF) to test the sensitivity to resolving aerosol-radiation and aerosol-cloud interactions on simulated regional climate for the EURO-CORDEX domain. The sensitivities mainly focus on the aerosol-radiation interactions (direct and semi-direct effects) with four different aerosol optical depth datasets (Tegen, MAC-v1, MACC, GOCART) being used and changes to the aerosol absorptivity (single scattering albedo) being examined. Moreover, part of the sensitivities also investigates aerosol-cloud interactions (indirect effect). Simulations have a resolution of 0.44 and are forced by the ERA-Interim reanalysis. A basic evaluation is performed in the context of seasonal-mean comparisons to ground-based (E-OBS) and satellite-based (CM SAF SARAH, CLARA) benchmark observational datasets. The impact of aerosols is calculated by comparing it against a simulation that has no aerosol effects. The implementation of aerosol-radiation interactions reduces the direct component of the incoming surface solar radiation by 20 %-30% in all seasons, due to enhanced aerosol scattering and absorption. Moreover the aerosol-radiation interactions increase the diffuse component of surface solar radiation in both summer (30 %-40 %) and winter (5 %-8 %), whereas the overall downward solar radiation at the surface is attenuated by 3 %-8 %. The resulting aerosol radiative effect is negative and is comprised of the net effect from the combination of the highly negative direct aerosol effect (-17 to-5Wm-2) and the small positive changes in the cloud radiative effect (C5Wm-2), attributed to the semi-direct effect. The aerosol radiative effect is also stronger in summer (-12Wm-2) than in winter (-2Wm-2).We also show that modelling aerosol-radiation and aerosol-cloud interactions can lead to small changes in cloudiness, mainly regarding low-level clouds, and circulation anomalies in the lower and mid-troposphere, which in some cases, mainly close to the Black Sea in autumn, can be of statistical significance. Precipitation is not affected in a consistent pattern throughout the year by the aerosol implementation, and changes do not exceed-5% except for the case of unrealistically absorbing aerosol. Temperature, on the other hand, systematically decreases by-0.1 to-0.5 °C due to aerosol-radiation interactions with regional changes that can be up to-1.5 °C. © 2020 Authors. more
Application Atmosphere CM-SAF Climate Data Records

Joint estimation of sea ice and atmospheric state from microwave imagers in operational weather forecasting

Author(s):
Geer, A.J.
Publication title: Quarterly Journal of the Royal Meteorological Society
2024
 | Volume: 150 | Issue: 763
2024
DOI: 10.1002/qj.4797
Abstract:
Satellite-observed microwave radiances provide information on both surface and atmosphere. For operational weather forecasting, information on atmosph… Satellite-observed microwave radiances provide information on both surface and atmosphere. For operational weather forecasting, information on atmospheric temperature, humidity, cloud, and precipitation is inferred directly using all-sky radiance data assimilation. In contrast, information on the surface state, such as sea-surface temperature (SST) and sea-ice concentration (SIC), is typically provided through third-party retrieval products. Scientifically, this is a sub-optimal use of the observations, and practically it has disadvantages such as time delays of more than 48 h. A better solution is to estimate the surface and atmospheric state jointly from the radiance observations. This has not been possible until now, due to incomplete knowledge of the surface state and the radiative transfer that links this to the observed radiances. A new approach based on an empirical state and an empirical sea-ice surface emissivity model is used here to add sea-ice state estimation, including SIC, to the European Centre for Medium-range Weather Forecasts atmospheric data assimilation system. The sea-ice state is estimated using augmented control variables at the observation locations. The resulting SIC estimates are of good quality and they highlight apparent defects in the existing OCEAN5 sea-ice analysis. The SIC estimates can also be used to track giant icebergs, which may provide a novel maritime application for passive microwave radiances. Further, the SIC estimates should be suitable for onward use in coupled ocean–atmosphere data assimilation. There is also increased coverage of microwave observations in the proximity of sea ice, leading to improved atmospheric forecasts out to day 4 in the Southern Ocean. © 2024 ECMWF. Quarterly Journal of the Royal Meteorological Society published by John Wiley & Sons Ltd on behalf of Royal Meteorological Society. more
Atmosphere Climate Data Records Cryosphere NWP-SAF OSI-SAF Software for CDR development

Land Surface Albedo Derived on a Ten Daily Basis from Meteosat Second Generation Observations: The NRT and Climate Data Record Collections from the EUMETSAT LSA SAF

Author(s):
Carrer, Dominique; Moparthy, Suman; Lellouch, Gabriel; Ceamanos, Xavier; Pinault, Florian; Freitas, Sandra; Trigo, Isabel
Publication title: Remote Sensing
2018
 | Volume: 10 | Issue: 8
2018
DOI: 10.3390/rs10081262
Abstract:
Land surface albedo determines the splitting of downwelling solar radiation into components which are either reflected back to the atmosphere or absor… Land surface albedo determines the splitting of downwelling solar radiation into components which are either reflected back to the atmosphere or absorbed by the surface. Land surface albedo is an important variable for the climate community, and therefore was defined by the Global Climate Observing System (GCOS) as an Essential Climate Variable (ECV). Within the scope of the Satellite Application Facility for Land Surface Analysis (LSA SAF) of EUMETSAT (European Organization for the Exploitation of Meteorological Satellites), a near-real time (NRT) daily albedo product was developed in the last decade from observations provided by the Spinning Enhanced Visible and Infrared Imager (SEVIRI) instrument on board the geostationary satellites of the Meteosat Second Generation (MSG) series. In this study we present a new collection of albedo satellite products based on the same satellite data. The MSG Ten-day Albedo (MTAL) product incorporates MSG observations over 31 days with a frequency of NRT production of 10 days. The MTAL collection is more dedicated to climate analysis studies compared to the daily albedo that was initially designed for the weather prediction community. For this reason, a homogeneous reprocessing of MTAL was done in 2018 to generate a climate data record (CDR). The resulting product is called MTAL-R and has been made available to the community in addition to the NRT version of the MTAL product which has been available for several years. The retrieval algorithm behind the MTAL products comprises three distinct modules: One for atmospheric correction, one for daily inversion of a semi-empirical model of the bidirectional reflectance distribution function, and one for monthly composition, that also determines surface albedo values. In this study the MTAL-R CDR is compared to ground surface measurements and concomitant albedo products collected by sensors on-board polar-orbiting satellites (SPOT-VGT and MODIS). We show that MTAL-R meets the quality requirements if MODIS or SPOT-VGT are considered as reference. This work leads to 14 years of production of geostationary land surface albedo products with a guaranteed continuity in the LSA SAF for the future years with the forthcoming third generation of European geostationary satellites. more
Application Climate Data Records LSA-SAF Land Validation

Lessons Learned from the Updated GEWEX Cloud Assessment Database

Author(s):
Stubenrauch, C.J.; Kinne, S.; Mandorli, G.; Rossow, W.B.; Winker, D.M.; Ackerman, S.A.; Chepfer, H.; Di Girolamo, L.; Garnier, A.; Heidinger, A.; Karlsson, K.-G.; Meyer, K.; Minnis, P.; Platnick, S.; Stengel, M.; Sun-Mack, S.; Veglio, P.; Walther, A.; Cai, X.; Young, A.H.; Zhao, G.
Publication title: Surveys in Geophysics
2024
 | Volume: 45 | Issue: 6
2024
DOI: 10.1007/s10712-024-09824-0
Abstract:
Since the first Global Energy and Water Exchanges cloud assessment a decade ago, existing cloud property retrievals have been revised and new retrieva… Since the first Global Energy and Water Exchanges cloud assessment a decade ago, existing cloud property retrievals have been revised and new retrievals have been developed. The new global long-term cloud datasets show, in general, similar results to those of the previous assessment. A notable exception is the reduced cloud amount provided by the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) Science Team, resulting from an improved aerosol–cloud distinction. Height, opacity and thermodynamic phase determine the radiative effect of clouds. Their distributions as well as relative occurrences of cloud types distinguished by height and optical depth are discussed. The similar results of the two assessments indicate that further improvement, in particular on vertical cloud layering, can only be achieved by combining complementary information. We suggest such combination methods to estimate the amount of all clouds within the atmospheric column, including those hidden by clouds aloft. The results compare well with those from CloudSat-CALIPSO radar–lidar geometrical profiles as well as with results from the International Satellite Cloud Climatology Project (ISCCP) corrected by the cloud vertical layer model, which is used for the computation of the ISCCP-derived radiative fluxes. Furthermore, we highlight studies on cloud monitoring using the information from the histograms of the database and give guidelines for: (1) the use of satellite-retrieved cloud properties in climate studies and climate model evaluation and (2) improved retrieval strategies. © The Author(s) 2024. more
Atmosphere CM-SAF Climate Data Records Validation
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