scholarly journals Impact of upstream moisture structure on a back-building convective precipitation system in south-eastern France during HyMeX IOP13

2018 ◽  
Vol 18 (23) ◽  
pp. 16845-16862 ◽  
Author(s):  
Keun-Ok Lee ◽  
Cyrille Flamant ◽  
Fanny Duffourg ◽  
Véronique Ducrocq ◽  
Jean-Pierre Chaboureau
Keyword(s):  
Moisture Content ◽  
Precipitation Amount ◽  
Lower Troposphere ◽  
Precipitation Event ◽  
Total Precipitation ◽  
Mountainous Region ◽  
Southern France ◽  
South Eastern ◽  
Sensitivity Experiments ◽  
Observation Period

Abstract. The present study examines the impact of the environmental moisture structure in the lower troposphere (below 2 km above sea level, a.s.l.) on the precipitation development, observed in southern France during Intensive Observation Period (IOP) 13 of the first Special Observation Period of the Hydrological cycle in the Mediterranean Experiment (HyMeX SOP-1), through a series of sensitivity experiments using the non-hydrostatic mesoscale atmospheric numerical model (Meso-NH). The control simulation (CNTL) and all the other 12 sensitivity experiments examined in this study succeed in reproducing a heavy precipitation event (HPE) in the coastal mountainous region of Var in south-eastern France as observed. The sensitivity experiments are designed to investigate the response of the HPE to the variability of the water vapour content upstream in the moist marine atmospheric boundary layer (MABL) and the drier air above. The comparisons between CNTL and the 12 sensitivity experiments show how the life cycle of precipitation associated with the HPE, but also the upstream flow (over the sea), is modified, even for moisture content changes of only 1 g kg−1 below 2 km a.s.l. Within the low-level wind convergence between southerlies and south-westerlies, a small increase of moisture content in the MABL prolongs moderate precipitation (≥5 mm in 15 min) and enlarges the area of weak precipitation (≥1 mm in 15 min). The moistening in the 1–2 km a.s.l. layer, just above the MABL, prolongs the duration of moderate precipitation, for a similar total precipitation amount as in CNTL. The drier MABL and 1–2 km a.s.l. layer shorten the lifetime of precipitation and reduce the total precipitation amount with respect to CNTL. We also found that the moisture in the MABL has a stronger impact on producing enhanced precipitation (both in terms of amount and intensity) than the moisture just above (1–2 km a.s.l.). Also, it is worth noting that adding moisture in the MABL does not necessarily lead to enhanced precipitation amount. In moistening the MABL, the duration of moderate precipitation increases with increasing moisture as does the area covered by weak precipitation, while the area covered by the intense precipitation (≥30 mm) decreases. Despite a simplified moisture-profile modification approach, this study suggests that moisture structure in the lower troposphere is key for accurate prediction at short-term range of the timing and location of precipitation in the coastal mountainous region in southern France.

scholarly journals Impact of upstream moisture structure on a back-building convective precipitation system in south-eastern France during HyMeX IOP13

2018 ◽  
Author(s):  
Keun-Ok Lee ◽  
Cyrille Flamant ◽  
Fanny Duffourg ◽  
Véronique Ducrocq ◽  
Jean-Pierre Chaboureau
Keyword(s):  
Precipitation Amount ◽  
Lower Troposphere ◽  
Convective Precipitation ◽  
Precipitation Event ◽  
Total Precipitation ◽  
Mountainous Region ◽  
Southern France ◽  
South Eastern ◽  
Sensitivity Experiments ◽  
Observation Period

Abstract. The present study examines the impact of the environmental moisture structure in the lower troposphere (below 2 km above sea level, ASL) on the precipitation development, observed in southern France during intensive observation period 13 of the first Special Observation Period of the Hydrological cycle in the Mediterranean Experiment (HyMeX SOP-1), through a series of sensitivity experiments using the non-hydrostatic numerical model Meso-NH. The control simulation (CNTL) and all the other 12 sensitivity experiments examined in this study succeed in reproducing a heavy precipitation event (HPE) in the coastal mountainous region of Var in south-eastern France as observed. The sensitivity experiments are designed to investigate the response of the variability of the water vapour content upstream in the moist marine atmospheric boundary layer (MABL) and the drier air above on the HPE. The comparisons between CNTL and the 12 sensitivity experiments show how the life cycle of precipitation associated with the HPE, but also the upstream flow (over the sea), is modified, even for moisture contents changes of only 1 g kg−1 below 2 km ASL. Within the low-level wind convergence between southerlies and south-westerlies, a small increase of moisture content in the MABL prolongs moderate precipitation (≥ 5 mm in 15 min) and enlarges the area of weak precipitation (≥ 1 mm in 15 min). The moistening in the 1–2 km ASL layer, just above the MABL, prolongs the duration of moderate precipitation, for a similar total precipitation amount as in CNTL. The drier MABL and 1–2 km ASL layer shorten both the life-time of precipitation and the total precipitation amount with respect to CNTL. We also found that the moisture in the MABL has a stronger impact on producing enhanced precipitation (both in terms of amount and intensity) than the moisture just above (1–2 km ASL). Also it is worth noting that adding moisture in the MABL does not necessarily lead to enhanced precipitation amount. At the same time, the duration of moderate precipitation increases with increasing moisture as does the area covered by weak precipitations, while the area covered by the intense precipitation (≥ 30 mm) decreases. Despite a simplified moisture-profile modification approach, this study suggests that moisture structure in lower troposphere is a key for accurate prediction at short-term range of the timing and location of precipitation in the coastal mountainous region in southern France.

Assessment of Urbanization Impact On Heavy Precipitation in Istanbul, Turkey

2021 ◽  
Author(s):  
Kutay Dönmez ◽  
Berkay Dönmez ◽  
Deniz Diren-Üstün ◽  
Yurdanur Ünal
Keyword(s):  
Land Use ◽  
Precipitation Amount ◽  
Heavy Precipitation ◽  
Heat Fluxes ◽  
Precipitation Event ◽  
Total Precipitation ◽  
Land Use Type ◽  
Start Time ◽  
Heavy Precipitation Event ◽  
The Impact

<p>Cities have undergone a substantial increase in urbanization over the past decades. Whether the change in land-use type and the consequent Urban Heat Island (UHI) affects the extreme precipitation was of interest and has been under investigation for various developing cities. This study pursued a similar purpose and investigated the impact of urbanization on a heavy precipitation incident that took place in Istanbul on 18 July 2017. Two particular land-use scenarios were used to simulate the event by Weather Research and Forecasting Model (WRF). First, the control simulation (WRF-urban) was performed using the default CORINE 2018 land-use dataset. Subsequently, the test simulation (WRF-nourban) was implemented by replacing the urbanized land-use type of Istanbul with the most dominant land use category of arid cultivated area. Comparison of the WRF-urban simulation with station observations and satellite data reveal that the WRF captured the heavy precipitation event reasonably well over Istanbul.  Results showed that urbanization has a notable impact on both the magnitude and timing of heavy rainfall.  Event day total precipitation amount increased considerably over and downstream of Istanbul on the control run. Although the start time and location of the incident reasonably matched for both runs, the test run without urbanization advanced the rainfall quicker, and the heavy precipitation event took place 1 hour earlier than the control run. The most pronounced distinction between the simulations with and without urbanization is detected over the northern coasts of Istanbul as the maximum daily total precipitation amount was approximately 250 mm higher just upstream and downstream of Istanbul Airport (IGA) on the WRF-urban run. Analysis of both vertical cross-sections and sensible heat fluxes on the city revealed that urbanized areas increased the atmospheric instability, thus caused heavier precipitation.</p>

scholarly journals Disaggregative Invariance of Daily Precipitation

1997 ◽  
Vol 36 (6) ◽  
pp. 721-734 ◽  
Author(s):  
Roman Krzysztofowicz ◽  
Thomas A. Pomroy
Keyword(s):  
Empirical Evidence ◽  
Diurnal Cycle ◽  
Daily Precipitation ◽  
Precipitation Amount ◽  
Total Precipitation ◽  
Stochastic Independence ◽  
Precipitation Forecasting ◽  
Precipitation Timing ◽  
Temporal Disaggregation ◽  
Precipitation Records

Abstract Disaggregative invariance refers to stochastic independence between the total precipitation amount and its temporal disaggregation. This property is investigated herein for areal average and point precipitation amounts accumulated over a 24-h period and disaggregated into four 6-h subperiods. Statistical analyses of precipitation records from 1948 to 1993 offer convincing empirical evidence against the disaggregative invariance and in favor of the conditional disaggregative invariance, which arises when the total amount and its temporal disaggregation are conditioned on the timing of precipitation within the diurnal cycle. The property of conditional disaggregative invariance allows the modeler or the forecaster to decompose the problem of quantitative precipitation forecasting into three tasks: (i) forecasting the precipitation timing; (ii) forecasting the total amount, conditional on timing; and (iii) forecasting the temporal disaggregation, conditional on timing. Tasks (ii) and (iii) can be performed independently of one another, and this offers a formidable advantage for applications.

Evaluation of the tail of the probability distribution of daily and sub-daily precipitation in CMIP6 models

2021 ◽  
pp. 1-61
Author(s):  
Jesse Norris ◽  
Alex Hall ◽  
J. David Neelin ◽  
Chad W. Thackeray ◽  
Di Chen
Keyword(s):  
General Circulation ◽  
Daily Precipitation ◽  
Precipitation Amount ◽  
Coupled Model ◽  
Lower Troposphere ◽  
General Circulation Models ◽  
Intercomparison Project ◽  
Cloud Tops ◽  
The Tropics ◽  
Fraction Models

AbstractDaily and sub-daily precipitation extremes in historical Coupled-Model-Intercomparison-Project-Phase-6 (CMIP6) simulations are evaluated against satellite-based observational estimates. Extremes are defined as the precipitation amount exceeded every x years, ranging from 0.01–10, encompassing the rarest events that are detectable in the observational record without noisy results. With increasing temporal resolution there is an increased discrepancy between models and observations: for daily extremes the multi-model median underestimates the highest percentiles by about a third, and for 3-hourly extremes by about 75% in the tropics. The novelty of the current study is that, to understand the model spread, we evaluate the 3-D structure of the atmosphere when extremes occur. In midlatitudes, where extremes are simulated predominantly explicitly, the intuitive relationship exists whereby higher-resolution models produce larger extremes (r=–0.49), via greater vertical velocity. In the tropics, the convective fraction (the fraction of precipitation simulated directly from the convective scheme) is more relevant. For models below 60% convective fraction, precipitation amount decreases with convective fraction (r=–0.63), but above 75% convective fraction, this relationship breaks down. In the lower-convective-fraction models, there is more moisture in the lower troposphere, closer to saturation. In the higher-convective-fraction models, there is deeper convection and higher cloud tops, which appears to be more physical. Thus, the low-convective models are mostly closer to the observations of extreme precipitation in the tropics, but likely for the wrong reasons. These inter-model differences in the environment in which extremes are simulated hold clues into how parameterizations could be modified in general circulation models to produce more credible 21st-Century projections.

scholarly journals Sensitivity Experiments on the Orographic Snowfall over the Mountainous Region of Northern Japan

1996 ◽  
Vol 74 (6) ◽  
pp. 797-813 ◽  
Author(s):  
Kazuo Saito ◽  
Masataka Murakami ◽  
Takayo Matsuo ◽  
Hakaru Mizuno
Keyword(s):  
Mountainous Region ◽  
Sensitivity Experiments ◽  
Northern Japan

Utilizing Landsat-8 and ASTER data in geologic mapping of hyper-arid mountainous region: case of Gabal Batoga area, South Eastern Desert of Egypt

2020 ◽  
Vol 79 (5) ◽  
Author(s):  
Mohamed F. Sadek ◽  
Baher A. El-kalioubi ◽  
Mohamed W. Ali-Bik ◽  
Mariam A. El Hefnawi ◽  
Ahmad A. Elnazer
Keyword(s):  
Eastern Desert ◽  
Landsat 8 ◽  
Mountainous Region ◽  
Geologic Mapping ◽  
Aster Data ◽  
South Eastern

Evaluating the applicability of predicting dead fine fuel moisture based on the hourly Fine Fuel Moisture Code in the south-eastern Xing’an Mountains of China

2017 ◽  
Vol 26 (2) ◽  
pp. 167 ◽  
Author(s):  
Jili Zhang ◽  
Xiaoyang Cui ◽  
Rui Wei ◽  
Yan Huang ◽  
Xueying Di
Keyword(s):  
Scots Pine ◽  
Forest Floor ◽  
Loss Rate ◽  
Weather Data ◽  
Fuel Moisture ◽  
The South ◽  
Fire Control ◽  
South Eastern ◽  
Great Xing’An Mountains ◽  
Observation Period

To evaluate the applicability of the hourly Fine Fuel Moisture Code (FFMC) to the south-eastern Great Xing’an Mountains, dead fine fuel moisture (Mf) was observed under less-sheltered and sheltered conditions in Scots pine (Pinus sylvestris var. mongolica), larch (Larix gmelinii) and oak (Quercus mongolicus) stands during the summer and autumn of 2014. Standard FFMC and locally calibrated FFMC values calculated hourly were tested using Mf observations and weather data, and the results showed that the Mf loss rate in the less-sheltered forest floor was markedly higher than that in the sheltered forest floor (P < 0.05). The standard hourly FFMC underestimated Mf, especially in stands of larch, the dominant species in the Great Xing’an Mountains, and Mf for rainy days in Scots pine and oak stands. However, the calibrated hourly FFMC predicted Mf in all three forest stands very well (R2 ranged from 0.920 to 0.969; mean absolute errorfrom 2.93 to 6.93, and root-mean-squared errorfrom 4.09 to 7.87), which suggested that it was sufficiently robust for those stands around the observation period. This study will improve the accuracy of Mf predictions to aid fire control efforts in the Great Xing’an Mountains and provide a basis for hourly FFMC model calibration.

scholarly journals Statistical analysis of daily precipitation in the Bydgoszcz region

2018 ◽  
Vol 23 ◽  
pp. 00004
Author(s):  
Waldemar Bojar ◽  
Leszek Knopik ◽  
Renata Kuśmierek-Tomaszewska ◽  
Jacek Żarski ◽  
Wojciech Żarski
Keyword(s):  
Statistical Analysis ◽  
Gamma Distribution ◽  
Daily Precipitation ◽  
Precipitation Amount ◽  
City Centre ◽  
Total Precipitation ◽  
Precipitation Frequency ◽  
Potential Variation ◽  
The City ◽  
Daily Total

The aim of the research has been to provide a statistical analysis of precipitation in the Bydgoszcz region based on the results of the measurements taken at the Experiment Station of the UTP University of Science and Technology in Bydgoszcz, located at Mochle, about 20 km away from the city centre. The paper analyses the daily total precipitation throughout 43 years (1971—2013). The analysis demonstrated a high dependence of the indicators studied on the month, confirming the annual pattern typical for the transitional climate of the temperate zone. In general, it shows an advantage of the amount and variation, and less considerably — the daily precipitation frequency in summer months, as compared with the winter months. The distribution of the probability of the daily precipitation amount for each month turned out to be compliant with gamma distribution, which allows for a potential variation in the future.

scholarly journals Spatial relationship between the atmospheric circulation and the precipitation measured in the western Swiss Alps by means of the analogue method

2012 ◽  
Vol 12 (3) ◽  
pp. 777-784 ◽  
Author(s):  
P. Horton ◽  
M. Jaboyedoff ◽  
R. Metzger ◽  
C. Obled ◽  
R. Marty
Keyword(s):  
Atmospheric Circulation ◽  
Precipitation Amount ◽  
Heavy Precipitation ◽  
Swiss Alps ◽  
Precipitation Event ◽  
Circulation Patterns ◽  
Analogue Method ◽  
Western Swiss Alps ◽  
Time Extrapolation ◽  
Precipitation Events

Abstract. An adaptation technique based on the synoptic atmospheric circulation to forecast local precipitation, namely the analogue method, has been implemented for the western Swiss Alps. During the calibration procedure, relevance maps were established for the geopotential height data. These maps highlight the locations were the synoptic circulation was found of interest for the precipitation forecasting at two rain gauge stations (Binn and Les Marécottes) that are located both in the alpine Rhône catchment, at a distance of about 100 km from each other. These two stations are sensitive to different atmospheric circulations. We have observed that the most relevant data for the analogue method can be found where specific atmospheric circulation patterns appear concomitantly with heavy precipitation events. Those skilled regions are coherent with the atmospheric flows illustrated, for example, by means of the back trajectories of air masses. Indeed, the circulation recurrently diverges from the climatology during days with strong precipitation on the southern part of the alpine Rhône catchment. We have found that for over 152 days with precipitation amount above 50 mm at the Binn station, only 3 did not show a trajectory of a southerly flow, meaning that such a circulation was present for 98% of the events. Time evolution of the relevance maps confirms that the atmospheric circulation variables have significantly better forecasting skills close to the precipitation period, and that it seems pointless for the analogue method to consider circulation information days before a precipitation event as a primary predictor. Even though the occurrence of some critical circulation patterns leading to heavy precipitation events can be detected by precursors at remote locations and 1 week ahead (Grazzini, 2007; Martius et al., 2008), time extrapolation by the analogue method seems to be rather poor. This would suggest, in accordance with previous studies (Obled et al., 2002; Bontron and Obled, 2005), that time extrapolation should be done by the Global Circulation Model, which can process atmospheric variables that can be used by the adaptation method.

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