Quantitative study of atmospheric rivers in the Indian subcontinent

2021 ◽  
Author(s):  
Rosa V. Lyngwa ◽  
Munir Ahmad Nayak
Keyword(s):  
Water Vapor ◽  
Indian Subcontinent ◽  
Temporal Distribution ◽  
Large Degree ◽  
Water Vapor Transport ◽  
Boreal Summer ◽  
Atmospheric Rivers ◽  
Wind Speeds ◽  
Minimum Requirements ◽  
Spatio Temporal

<p>The principal sources of freshwater in India include precipitation, glaciers, and snowmelt. The former dominates the country’s annual river water contribution, which is important for agriculture and livelihood of the residents, and the latter two sources contribute at a much lower fraction in comparison to precipitation to even meet the minimum requirements. However, there is a large degree of variations in their spatio-temporal distribution throughout the country. India receives a major portion of its annual precipitation during the boreal summer (June – September). The well-known but relatively unexplored contributors to precipitation in India are atmospheric rivers (ARs). This study aims to understand the main climatological and dynamical differences between the Indian summer monsoon (ISM) and ARs in boreal summer. Zonal (‘u’) and meridional (‘v’) wind speeds, integrated water vapor transport (IVT), and integrated water vapor (IWV) are used to identify distinct features in ARs in the Indian sub-continent that can be used to distinguish them from ISM. The major differences between the two synoptic features were found in the increased zonal wind speed and moisture inputs during AR events, which often result in extreme precipitation and floods. Besides understanding them, the identification of ARs in this region and accounting for their existential contribution to moisture during peak rainfall seasons is critical for further hydrological impacts studies.</p>

scholarly journals Atmospheric Rivers over the Northwestern Pacific: Climatology and Interannual Variability

2017 ◽  
Vol 30 (15) ◽  
pp. 5605-5619 ◽  
Author(s):  
Youichi Kamae ◽  
Wei Mei ◽  
Shang-Ping Xie ◽  
Moeka Naoi ◽  
Hiroaki Ueda
Keyword(s):  
Water Vapor ◽  
Interannual Variability ◽  
El Niño ◽  
El Nino ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Boreal Summer ◽  
Northwestern Pacific ◽  
Atmospheric Rivers ◽  
Low Level

Atmospheric rivers (ARs), conduits of intense water vapor transport in the midlatitudes, are critically important for water resources and heavy rainfall events over the west coast of North America, Europe, and Africa. ARs are also frequently observed over the northwestern Pacific (NWP) during boreal summer but have not been studied comprehensively. Here the climatology, seasonal variation, interannual variability, and predictability of NWP ARs (NWPARs) are examined by using a large ensemble, high-resolution atmospheric general circulation model (AGCM) simulation and a global atmospheric reanalysis. The AGCM captures general characteristics of climatology and variability compared to the reanalysis, suggesting a strong sea surface temperature (SST) effect on NWPARs. The summertime NWPAR occurrences are tightly related to El Niño–Southern Oscillation (ENSO) in the preceding winter through Indo–western Pacific Ocean capacitor (IPOC) effects. An enhanced East Asian summer monsoon and a low-level anticyclonic anomaly over the tropical western North Pacific in the post–El Niño summer reinforce low-level water vapor transport from the tropics with increased occurrence of NWPARs. The strong coupling with ENSO and IPOC indicates a high predictability of anomalous summertime NWPAR activity.

Extreme Surface Winds During Landfalling Atmospheric Rivers: The Modulating Role of Near-Surface Stability

2021 ◽  
Author(s):  
Terence J. Pagano ◽  
Duane E. Waliser ◽  
Bin Guan ◽  
Hengchun Ye ◽  
F. Martin Ralph ◽  
...  
Keyword(s):  
Water Vapor ◽  
Static Stability ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Surface Winds ◽  
Near Surface ◽  
Extreme Surface ◽  
Atmospheric Rivers ◽  
Explained Variance

AbstractAtmospheric rivers (ARs) are long and narrow regions of strong horizontal water vapor transport. Upon landfall, ARs are typically associated with heavy precipitation and strong surface winds. A quantitative understanding of the atmospheric conditions that favor extreme surface winds during ARs has implications for anticipating and managing various impacts associated with these potentially hazardous events. Here, a global AR database (1999–2014) with relevant information from MERRA-2 reanalysis, QuikSCAT and AIRS satellite observations are used to better understand and quantify the role of near-surface static stability in modulating surface winds during landfalling ARs. The temperature difference between the surface and 1 km MSL (ΔT; used here as a proxy for near-surface static stability), and integrated water vapor transport (IVT) are analyzed to quantify their relationships to surface winds using bivariate linear regression. In four regions where AR landfalls are common, the MERRA-2-based results indicate that IVT accounts for 22-38% of the variance in surface wind speed. Combining ΔT with IVT increases the explained variance to 36-52%. Substitution of QuikSCAT surface winds and AIRS ΔT in place of the MERRA-2 data largely preserves this relationship (e.g., 44% compared to 52% explained variance for USA West Coast). Use of an alternate static stability measure–the bulk Richardson number–yields a similar explained variance (47%). Lastly, AR cases within the top and bottom 25% of near-surface static stability indicate that extreme surface winds (gale or higher) are more likely to occur in unstable conditions (5.3%/14.7% during weak/strong IVT) than in stable conditions (0.58%/6.15%).

scholarly journals A daytime climatological distribution of high opaque ice cloud classes over the Indian summer monsoon region observed from 25-year AVHRR data

2009 ◽  
Vol 9 (12) ◽  
pp. 4185-4196 ◽  
Author(s):  
A. Devasthale ◽  
H. Grassl
Keyword(s):  
Summer Monsoon ◽  
Indian Subcontinent ◽  
Deep Convection ◽  
Temporal Distribution ◽  
Radiative Balance ◽  
Ice Cloud ◽  
Brightness Temperatures ◽  
Spatio Temporal ◽  
Very High ◽  
Summer Monsoon Region

Abstract. A daytime climatological spatio-temporal distribution of high opaque ice cloud (HOIC) classes over the Indian subcontinent (0–40° N, 60° E–100° E) is presented using 25-year data from the Advanced Very High Resolution Radiometers (AVHRRs) for the summer monsoon months. The HOICs are important for regional radiative balance, precipitation and troposphere-stratosphere exchange. In this study, HOICs are sub-divided into three classes based on their cloud top brightness temperatures (BT). Class I represents very deep convection (BT<220 K). Class II represents deep convection (220 K

scholarly journals Assessment of Numerical Weather Prediction Model Reforecasts of the Occurrence, Intensity, and Location of Atmospheric Rivers along the West Coast of North America

2018 ◽  
Vol 146 (10) ◽  
pp. 3343-3362 ◽  
Author(s):  
Kyle M. Nardi ◽  
Elizabeth A. Barnes ◽  
F. Martin Ralph
Keyword(s):  
Water Vapor ◽  
North America ◽  
Weather Prediction ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Lead Times ◽  
Model Errors ◽  
The West ◽  
Atmospheric Rivers ◽  
Landfall Location

AbstractAtmospheric rivers (ARs)—narrow corridors of high atmospheric water vapor transport—occur globally and are associated with flooding and maintenance of the water supply. Therefore, it is important to improve forecasts of AR occurrence and characteristics. Although prior work has examined the skill of numerical weather prediction (NWP) models in forecasting atmospheric rivers, these studies only cover several years of reforecasts from a handful of models. Here, we expand this previous work and assess the performance of 10–30 years of wintertime (November–February) AR landfall reforecasts from the control runs of nine operational weather models, obtained from the International Subseasonal to Seasonal (S2S) Project database. Model errors along the west coast of North America at leads of 1–14 days are examined in terms of AR occurrence, intensity, and landfall location. Occurrence-based skill approaches that of climatology at 14 days, while models are, on average, more skillful at shorter leads in California, Oregon, and Washington compared to British Columbia and Alaska. We also find that the average magnitude of landfall integrated water vapor transport (IVT) error stays fairly constant across lead times, although overprediction of IVT is common at later lead times. Finally, we show that northward landfall location errors are favored in California, Oregon, and Washington, although southward errors occur more often than expected from climatology. These results highlight the need for model improvements, while helping to identify factors that cause model errors.

A Climatological Study of National Weat her Service Watches, Warnings, and Advisories and Landfalling Atmospheric Rivers in the Western U.S. 2006–2018

2021 ◽  
Author(s):  
Samuel M. Bartlett ◽  
Jason M. Cordeira
Keyword(s):  
Water Vapor ◽  
Pacific Northwest ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Synoptic Scale ◽  
Flash Flooding ◽  
Atmospheric Rivers ◽  
The Pacific ◽  
Central Regions ◽  
Heavy Snow

AbstractAtmospheric rivers (ARs) are synoptic-scale phenomena associated with long, narrow corridors of enhanced low-level water vapor transport. Landfalling ARs may produce numerous beneficial (e.g. drought amelioration and watershed recharge) and hazardous (e.g. flash flooding and heavy snow) impacts that may require the National Weather Service (NWS) to issue watches, warnings, and advisories (WWAs) for hazardous weather. Prior research on WWAs and ARs in California found that 50–70% of days with flood-related and 60–80% of days with winter weather-related WWAs occurred on days with landfalling ARs in California. The present study further investigates this relationship for landfalling ARs and WWAs during the cool seasons of 2006–2018 across the entire western U.S. and considers additional dimensions of AR intensity and duration. Across the western U.S., regional maxima of 70–90% of days with WWAs issued for any hazard type were associated with landfalling ARs. In the Pacific Northwest and Central regions, flood-related and wind-related WWAs were also more frequently associated with more intense and longer duration ARs. While a large majority of days with WWAs were associated with landfalling ARs, not all landfalling ARs were necessarily associated with WWAs (i.e., not all ARs are hazardous). For example, regional maxima of only 50–70% of AR days were associated with WWAs issued for any hazard type. However, as landfalling AR intensity and duration increased, the association with a WWA and the “hazard footprint” of WWAs increased quasi-exponentially across the western U.S.

Avalanche Fatalities during Atmospheric River Events in the Western United States

2017 ◽  
Vol 18 (5) ◽  
pp. 1359-1374 ◽  
Author(s):  
Benjamin J. Hatchett ◽  
Susan Burak ◽  
Jonathan J. Rutz ◽  
Nina S. Oakley ◽  
Edward H. Bair ◽  
...  
Keyword(s):  
United States ◽  
Water Vapor ◽  
Snow Water Equivalent ◽  
Vapor Transport ◽  
Western United States ◽  
Snow Avalanche ◽  
Water Vapor Transport ◽  
Atmospheric Rivers ◽  
Avalanche Forecasting ◽  
Snow Water

Abstract The occurrence of atmospheric rivers (ARs) in association with avalanche fatalities is evaluated in the conterminous western United States between 1998 and 2014 using archived avalanche reports, atmospheric reanalysis products, an existing AR catalog, and weather station observations. AR conditions were present during or preceding 105 unique avalanche incidents resulting in 123 fatalities, thus comprising 31% of western U.S. avalanche fatalities. Coastal snow avalanche climates had the highest percentage of avalanche fatalities coinciding with AR conditions (31%–65%), followed by intermountain (25%–46%) and continental snow avalanche climates (&lt;25%). Ratios of avalanche deaths during AR conditions to total AR days increased with distance from the coast. Frequent heavy to extreme precipitation (85th–99th percentile) during ARs favored critical snowpack loading rates with mean snow water equivalent increases of 46 mm. Results demonstrate that there exists regional consistency between snow avalanche climates, derived AR contributions to cool season precipitation, and percentages of avalanche fatalities during ARs. The intensity of water vapor transport and topographic corridors favoring inland water vapor transport may be used to help identify periods of increased avalanche hazard in intermountain and continental snow avalanche climates prior to AR landfall. Several recently developed AR forecast tools applicable to avalanche forecasting are highlighted.

The Inland Penetration of Atmospheric Rivers over Western North America: A Lagrangian Analysis

2015 ◽  
Vol 143 (5) ◽  
pp. 1924-1944 ◽  
Author(s):  
Jonathan J. Rutz ◽  
W. James Steenburgh ◽  
F. Martin Ralph
Keyword(s):  
Water Vapor ◽  
North America ◽  
Pacific Coast ◽  
Water Vapor Transport ◽  
Western North America ◽  
Lagrangian Analysis ◽  
Initial Water ◽  
Atmospheric Rivers ◽  
The Pacific ◽  
Synoptic Conditions

Abstract Although atmospheric rivers (ARs) typically weaken following landfall, those that penetrate inland can contribute to heavy precipitation and high-impact weather within the interior of western North America. In this paper, the authors examine the evolution of ARs over western North America using trajectories released at 950 and 700 hPa within cool-season ARs along the Pacific coast. These trajectories are classified as coastal decaying, inland penetrating, or interior penetrating based on whether they remain within an AR upon reaching selected transects over western North America. Interior-penetrating AR trajectories most frequently make landfall along the Oregon coast, but the greatest fraction of landfalling AR trajectories that eventually penetrate into the interior within an AR is found along the Baja Peninsula. In contrast, interior-penetrating AR trajectories rarely traverse the southern “high” Sierra. At landfall, interior-penetrating AR trajectories are associated with a more amplified flow pattern, more southwesterly (vs westerly) flow along the Pacific coast, and larger water vapor transport (qυ). The larger initial qυ of interior-penetrating AR trajectories is due primarily to larger initial water vapor q and wind speed υ for those initiated at 950 and 700 hPa, respectively. Inland- and interior-penetrating AR trajectories maintain large qυ over the interior partially due to increases in υ that offset decreases in q, particularly in the vicinity of topographical barriers. Therefore, synoptic conditions and trajectory pathways favoring larger initial qυ at the coast, limited water vapor depletion by orographic precipitation, and increases in υ over the interior are keys to differentiating interior-penetrating from coastal-decaying ARs.

scholarly journals Horizontal water vapor transport in the lower stratosphere from subtropics to high latitudes during boreal summer

2013 ◽  
Vol 118 (14) ◽  
pp. 8111-8127 ◽  
Author(s):  
F. Ploeger ◽  
G. Günther ◽  
P. Konopka ◽  
S. Fueglistaler ◽  
R. Müller ◽  
...  
Keyword(s):  
Water Vapor ◽  
Lower Stratosphere ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Boreal Summer ◽  
High Latitudes

scholarly journals Image Processing Based Atmospheric River Tracking Method Version 1 (IPART-1)

2020 ◽  
Author(s):  
Guangzhi Xu ◽  
Xiaohui Ma ◽  
Ping Chang ◽  
Lin Wang
Keyword(s):  
Image Processing ◽  
Water Vapor ◽  
Lower Sensitivity ◽  
Image Processing Algorithm ◽  
Water Vapor Flux ◽  
Atmospheric Rivers ◽  
Vapor Flux ◽  
Geographical Distances ◽  
Spatio Temporal ◽  
Modified Hausdorff Distance

Abstract. Automated detection of atmospheric rivers (ARs) has been heavily relying on magnitude thresholding on either the integrated water vapor (IWV) or integrated vapor transport (IVT). Magnitude thresholding approaches can become problematic when detecting ARs in a warming climate, because of the increasing atmospheric moisture. A new AR detection method derived from an image processing algorithm is proposed in this work. Different from conventional thresholding methods, the new algorithm applies threshold to the spatio-temporal scale of ARs to achieve the detection, thus making it magnitude independent and applicable to both IWV- and IVT-based AR detections. Compared with conventional thresholding methods, it displays lower sensitivity to parameters and a greater tolerance to a wider range of water vapor flux intensities. A new method of tracking ARs is also proposed, based on a new AR axis identification method, and a modified Hausdorff distance that gives a measure of the geographical distances of AR axes pairs.

scholarly journals A 142-Year Climatology of Northern California Landslides and Atmospheric Rivers

2019 ◽  
Vol 100 (8) ◽  
pp. 1499-1509 ◽  
Author(s):  
Jason M. Cordeira ◽  
Jonathan Stock ◽  
Michael D. Dettinger ◽  
Allison M. Young ◽  
Julie F. Kalansky ◽  
...  
Keyword(s):  
Water Vapor ◽  
San Francisco ◽  
San Francisco Bay ◽  
San Francisco Bay Area ◽  
Water Vapor Transport ◽  
Atmospheric Conditions ◽  
Sea Level Pressure ◽  
Winter Storms ◽  
Atmospheric Rivers ◽  
Bay Area

AbstractWe compare a novel dataset of San Francisco Bay Area landslides from 1871 to 2012 to corresponding atmospheric conditions commonly associated with Pacific winter storms and landfalling atmospheric rivers (ARs). Landslides in the San Francisco Bay Area occur primarily during winter months, coinciding with enhanced integrated water vapor transport (IVT) magnitudes ≥250 kg m–1 s–1 at the coast 76% of the time and with landfalling ARs over the near-offshore northeast Pacific 82% of the time. Results illustrate that days, or the first in a series of days, with a landslide (i.e., landslide onset days) typically occur in association with NOAA Twentieth Century Reanalysis–derived IVT magnitudes ≥250 kg m–1 s–1 that persist for ∼20 h and temporal maxima in precipitation rates. Composite analyses of sea level pressure, integrated water vapor, and IVT during 3-month periods during September–May on landslide onset days further illustrate that these events coincide with regions of low pressure to the northwest of California and high pressure to the south, synoptic-scale flow conditions associated with strong onshore flow, and water vapor transports in the form of landfalling ARs.

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