Evaluation of high-resolution satellite precipitation data over the Mediterranean Region

2022 ◽  
pp. 159-175
Author(s):  
Adrianos Retalis ◽  
Dimitrios Katsanos ◽  
Silas Michaelides ◽  
Filippos Tymvios
Keyword(s):  
High Resolution ◽  
Mediterranean Region ◽  
Precipitation Data ◽  
Satellite Precipitation ◽  
The Mediterranean

North Atlantic Oscillation-related impacts on precipitation over the Italian Peninsula during the 1979-2020 period

2021 ◽  
Author(s):  
Paula Lorenzo Sánchez ◽  
Leonardo Aragão
Keyword(s):  
High Resolution ◽  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Mediterranean Region ◽  
Italian Peninsula ◽  
The North ◽  
Nao Index ◽  
The North Atlantic ◽  
The Mediterranean ◽  
Resolution Dataset

<p>The North Atlantic Oscillation (NAO) has been widely recognized as one of the main patterns of atmospheric variability over the northern hemisphere, helping to understand variations on the North Atlantic Jet (NAJ) position and its influence on storm-tracks, atmospheric blocking and Rossby Wave breaking. Among several relevant teleconnection patterns identified through different timescales, the most prominent ones are found for northern Europe during winter months, when positive (negative) phases of NAO are related to wetter (drier) conditions. Although it is not well defined yet, an opposite connection is observed for the Mediterranean region, where negative NAO values are often associated with high precipitation. Therefore, the main goal of this study is to identify which regions and periods of the year are the most susceptible to abundant NAO-related precipitation throughout the Italian Peninsula. For doing so, the last 42 years period (1979-2020) was analysed using the Fifth Generation ECMWF Atmospheric ReAnalysis of the Global Climate (ERA5). The NAO index was calculated using the Mean Sea Level Pressure (MSLP) extracted from the nearest gridpoints to Reykjavik, Ponta Delgada, Lisbon and Gibraltar, with a time resolution of one hour and horizontal spatial resolution of 0.25ºx0.25º. Both NAO index and MSLP time series were validated for different timescales (hourly, daily, monthly and seasonal) using the Automated Surface Observing System data and the Climatic Research Unit (CRU) high-resolution dataset (based on measured data). High correlations, ranging from 0.92 to 0.98, were found for all stations, timescales and evaluated parameters. To quantify the influence of NAO over the Mediterranean region, the monthly averaged ERA5 ‘total precipitation’ data over the Italian Peninsula [35-48º N; 5-20º E] were used. As expected, the results concerning NAO x Precipitation presented the best correlations when analysed monthly, confirming some of the already known NAO signatures over the Italian Peninsula: higher correlations during winter and over the Tyrrhenian coast, and lower correlations during summer and over the Apennines, the Adriatic Sea and the Ionian Sea. On the other hand, the precipitation over the Alps and the Tunisian coast presented a remarkable signature of positive NAO values that, despite a lower statistical significance (85-90%), is in agreement with recent findings of observational studies. In addition, significant negative correlations were identified for the spring and autumn months over the Tyrrhenian area. Among those, the high correlations found during May are particularly interesting, as they follow the behaviour described in recent studies performed using the same high-resolution dataset (ERA5), which have identified an increased number of cyclones over the Mediterranean during this month. This connection suggests that NAO could also be used to explore the potential penetration of the North Atlantic depressions into the Mediterranean Basin. </p><p>Keywords: NAO; Teleconnections; ERA5; ReAnalysis; Mediterranean; Climatology.</p>

scholarly journals Two case studies of severe storms in the Mediterranean using AMSU

2007 ◽  
Vol 12 ◽  
pp. 19-26 ◽  
Author(s):  
B. M. Funatsu ◽  
C. Claud ◽  
J.-P. Chaboureau
Keyword(s):  
Mediterranean Region ◽  
Detection Method ◽  
Precipitation Data ◽  
Severe Storms ◽  
Rainfall Events ◽  
Microwave Sounding Unit ◽  
Microwave Sounding ◽  
The Mediterranean ◽  
Upper Level ◽  
Good Agreement

Abstract. Mediterranean storms and their associated upper level features are diagnosed here using Advanced Microwave Sounding Unit (AMSU) observations. AMSU-A channel 8 is used to identify upper-level intrusions of stratospheric air, which are often present upstream of heavy precipitating areas, while a combination of AMSU-B channels 3 and 5 is chosen to discriminate moderate to heavily precipitating areas. This precipitation detection method provides results that are in good agreement with TRMM rainfall product and independent ground-based precipitation data. These tools allow us to follow the concomitant evolution of two severe rainfall events in the Mediterranean region and associated upper-level features.

scholarly journals The Slab Puzzle of the Alpine-Mediterranean Region: Insights from a new, High-Resolution, Shear-Wave Velocity Model of the Upper Mantle

2020 ◽  
Author(s):  
Amr El-Sharkawy ◽  
Thomas Meier ◽  
Sergei Lebedev ◽  
Jan Behrmann ◽  
Mona Hamada ◽  
...  
Keyword(s):  
High Resolution ◽  
Phase Velocity ◽  
Rayleigh Wave ◽  
Upper Mantle ◽  
Mediterranean Region ◽  
Subduction Zones ◽  
Velocity Model ◽  
Large Set ◽  
Depth Range ◽  
The Mediterranean

<p>The fascinatingly complex tectonic make-up of the Mediterranean region comprises small, strongly-curved retreating subduction zones, associated back-arc basins, and the continental collisions along the northern and eastern margins of the Adriatic microplate. It remains a challenge to resolve the geometry of the subducted slabs in the Mediterranean upper mantle. Here, we present new evidence for the location and lateral and vertical extent of slab segments from a new, high-resolution, Rayleigh-wave tomography. The tomographic model spans the depth range from the crust down to 300 km and is complemented by intermediate-deep seismicity data in the circum-Mediterranean region.</p><p>An automated procedure to measure inter-station Rayleigh wave phase velocities is applied to a large, heterogeneous dataset from all publically available stations around the Mediterranean in the time period from 1990 to 2015. Furthermore, for the first time, data from the Egyptian National Seismological Network (ENSN) are used regional seismic tomography. The resulting large set of about 200,000 inter-station phase velocity measurements is inverted for a set of phase-velocity maps spanning a very broad period range (8 - 350 s). The maps are then inverted, point by point, for a 3D, S-velocity model using a stochastic, particle-swarm-optimization inversion.</p><p>We distinguish between attached slab segments reaching down to the bottom of the model and shallow slabs of shorter length or detached slab segments resulting both from horizontal tearing. We discuss evidence for continental subduction east of Cyprus, for continuous NE-dipping subduction in the Antalyan region and NW dipping subduction in the SE Aegean in the area of Rhodes. An attached slab is imaged beneath the Hellenides reaching down to at least 300 km depth whereas beneath the Dinarides a short slab is found down to about 150 km depth above a slab tear. The slab in the southern Carpathians seems to be partly detached. A south-dipping slab is imaged in the central Alps but shallow bivergent subduction is favoured in the eastern Alps. In the western Alps, a shallow slab east-dipping Eurasian slab segment is in close proximity to the nearly vertically dipping attached slab segment beneath the northern Apennines and the southern Po plain. In the central Apennines a slab gap is found whereas the NE-dipping Calabrian Slab seems to partly detached along the northern Sicilian coast. The Kabylides Slab that appears to be attached along the North African coast but detached along the margin of the shelf in the Sicily Channel, is clearly separated from the Calabrian Slab in the NE and the Alboran-Betics Slab in the west. According to our model, the latter slab consists of two segments: a shallow Alboran one and a detached Betics slab segment. We summarize our interpretations in a map of the Mediterranean slab segments and indicate open questions.</p>

scholarly journals Specific climate classification for Mediterranean hydrology and future evolution under Med-CORDEX regional climate model scenarios

2020 ◽  
Vol 24 (9) ◽  
pp. 4503-4521 ◽  
Author(s):  
Antoine Allam ◽  
Roger Moussa ◽  
Wajdi Najem ◽  
Claude Bocquillon
Keyword(s):  
High Resolution ◽  
Water Resources ◽  
Mediterranean Region ◽  
Regional Climate ◽  
Flow Regimes ◽  
The South ◽  
Climatic Indices ◽  
The North ◽  
Seasonality Index ◽  
The Mediterranean

Abstract. The Mediterranean region is one of the most sensitive regions to anthropogenic and climatic changes, mostly affecting its water resources and related practices. With multiple studies raising serious concerns about climate shifts and aridity expansion in the region, this one aims to establish a new high-resolution classification for hydrology purposes based on Mediterranean-specific climate indices. This classification is useful in following up on hydrological (water resource management, floods, droughts, etc.) and ecohydrological applications such as Mediterranean agriculture. Olive cultivation is the characteristic agricultural practice of the Mediterranean region. The proposed approach includes the use of classic climatic indices and the definition of new climatic indices, mainly precipitation seasonality index Is or evapotranspiration threshold SPET, both in line with river flow regimes, a principal component analysis to reduce the number of indices, K-means classification to distribute them into classes, and finally the construction of a decision tree based on the distances to class kernels to reproduce the classification without having to repeat the whole process. The classification was set and validated by WorldClim-2 at 1 km high-resolution gridded data for the 1970–2000 baseline period and 144 stations' data over 30 to 120 years, both at monthly time steps. Climatic classes coincided with a geographical distribution in the Mediterranean ranging from the most seasonal and driest class 1 in the south to the least seasonal and most humid class 5 in the north, showing the climatic continuity from one place to another and enhancing the visibility of change trends. The MED-CORDEX ALADIN and CCLM historical and projected data at 12 and 50 km resolution simulated under the RCP4.5 and 8.5 scenarios for the 2070–2100 period served to assess the climate change impact on this classification by superimposing the projected changes on the baseline grid-based classification. RCP scenarios increase the seasonality index Is by +80 % and the aridity index IArid by +60 % in the north and IArid by +10 % without Is change in the south, hence causing the wet season shortening and river regime modification with the migration north of moderate and extreme winter regimes instead of early spring regimes. The ALADIN and CCLM regional climate models (RCMs) have demonstrated an evolution of the Mediterranean region towards arid climate. The classes located to the north are slowly evolving towards moderate coastal classes, which might affect hydrologic regimes due to shorter humid seasons and earlier snowmelts. These scenarios might look favourable for Mediterranean cultivation; however, the expected impact on water resources and flow regimes will surely expand and directly hit ecosystems, food, health, and tourism, as risk is interconnected between domains. This kind of classification might be reproduced at the global scale, using the same or other climatic indices specific to each region, highlighting their physiographic characteristics and hydrological responses.

scholarly journals Mapping the Daily Rainfall over an Ungauged Tropical Micro-Watershed: A Downscaling Algorithm Using GPM Data

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1661 ◽  
Author(s):  
Mohd. Rizaludin Mahmud ◽  
Aina Afifah Mohd Yusof ◽  
Mohd Nadzri Mohd Reba ◽  
Mazlan Hashim
Keyword(s):  
High Resolution ◽  
Daily Rainfall ◽  
Rain Gauge ◽  
Rainfall Data ◽  
Precipitation Data ◽  
Rain Gauge Data ◽  
Satellite Precipitation ◽  
Daily Rainfall Data ◽  
Gauge Data

In this study, half-hourly Global Precipitation Mission (GPM) satellite precipitation data were downscaled to produce high-resolution daily rainfall data for tropical coastal micro-watersheds (100–1000 ha) without gauges or with rainfall data conflicts. Currently, daily-scale satellite rainfall downscaling techniques rely on rain gauge data as corrective and controlling factors, making them impractical for ungauged watersheds or watersheds with rainfall data conflicts. Therefore, we used high-resolution local orographic and vertical velocity data as proxies to downscale half-hourly GPM precipitation data (0.1°) to high-resolution daily rainfall data (0.02°). The overall quality of the downscaled product was similar to or better than the quality of the raw GPM data. The downscaled rainfall dataset improved the accuracy of rainfall estimates on the ground, with lower error relative to measured rain gauge data. The average error was reduced from 41 to 27 mm/d and from 16 to 12 mm/d during the wet and dry seasons, respectively. Estimates of localized rainfall patterns were improved from 38% to 73%. The results of this study will be useful for production of high-resolution satellite precipitation data in ungauged tropical micro-watersheds.

Sign in / Sign up

Export Citation Format

Share Document