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F. Martin Ralph
,
Forest Cannon
,
Vijay Tallapragada
,
Christopher A. Davis
,
James D. Doyle
,
Florian Pappenberger
,
Aneesh Subramanian
,
Anna M. Wilson
,
David A. Lavers
,
Carolyn A. Reynolds
,
Jennifer S. Haase
,
Luca Centurioni
,
Bruce Ingleby
,
Jonathan J. Rutz
,
Jason M. Cordeira
,
Minghua Zheng
,
Chad Hecht
,
Brian Kawzenuk
, and
Luca Delle Monache
Full access
Alison Cobb
,
F. Martin Ralph
,
Vijay Tallapragada
,
Anna M. Wilson
,
Christopher A. Davis
,
Luca Delle Monache
,
James D. Doyle
,
Florian Pappenberger
,
Carolyn A. Reynolds
,
Aneesh Subramanian
,
Peter G. Black
,
Forest Cannon
,
Chris Castellano
,
Jason M. Cordeira
,
Jennifer S. Haase
,
Chad Hecht
,
Brian Kawzenuk
,
David A. Lavers
,
Michael J. Murphy Jr.
,
Jack Parrish
,
Ryan Rickert
,
Jonathan J. Rutz
,
Ryan Torn
,
Xingren Wu
, and
Minghua Zheng

Abstract

Atmospheric River Reconnaissance (AR Recon) is a targeted campaign that complements other sources of observational data, forming part of a diverse observing system. AR Recon 2021 operated for ten weeks from January 13 to March 22, with 29.5 Intensive Observation Periods (IOPs), 45 flights and 1142 successful dropsondes deployed in the northeast Pacific. With the availability of two WC-130J aircraft operated by the 53rd Weather Reconnaissance Squadron (53 WRS), Air Force Reserve Command (AFRC) and one National Oceanic and Atmospheric Administration (NOAA) Aircraft Operations Center (AOC) G-IVSP aircraft, six sequences were accomplished, in which the same synoptic system was sampled over several days.

The principal aim was to gather observations to improve forecasts of landfalling atmospheric rivers on the U.S. West Coast. Sampling of other meteorological phenomena forecast to have downstream impacts over the U.S. was also considered. Alongside forecast improvement, observations were also gathered to address important scientific research questions, as part of a Research and Operations Partnership.

Targeted dropsonde observations were focused on essential atmospheric structures, primarily atmospheric rivers. Adjoint and ensemble sensitivities, mainly focusing on predictions of U.S. West Coast precipitation, provided complementary information on locations where additional observations may help to reduce the forecast uncertainty. Additionally, Airborne Radio Occultation (ARO) and tail radar were active during some flights, 30 drifting buoys were distributed, and 111 radiosondes were launched from four locations in California. Dropsonde, radiosonde and buoy data were available for assimilation in real-time into operational forecast models. Future work is planned to examine the impact of AR Recon 2021 data on model forecasts.

Full access
F. Martin Ralph
,
Forest Cannon
,
Vijay Tallapragada
,
Christopher A. Davis
,
James D. Doyle
,
Florian Pappenberger
,
Aneesh Subramanian
,
Anna M. Wilson
,
David A. Lavers
,
Carolyn A. Reynolds
,
Jennifer S. Haase
,
Luca Centurioni
,
Bruce Ingleby
,
Jonathan J. Rutz
,
Jason M. Cordeira
,
Minghua Zheng
,
Chad Hecht
,
Brian Kawzenuk
, and
Luca Delle Monache

Abstract

Water management and flood control are major challenges in the western United States. They are heavily influenced by atmospheric river (AR) storms that produce both beneficial water supply and hazards; for example, 84% of all flood damages in the West (up to 99% in key areas) are associated with ARs. However, AR landfall forecast position errors can exceed 200 km at even 1-day lead time and yet many watersheds are <100 km across, which contributes to issues such as the 2017 Oroville Dam spillway incident and regularly to large flood forecast errors. Combined with the rise of wildfires and deadly post-wildfire debris flows, such as Montecito (2018), the need for better AR forecasts is urgent. Atmospheric River Reconnaissance (AR Recon) was developed as a research and operations partnership to address these needs. It combines new observations, modeling, data assimilation, and forecast verification methods to improve the science and predictions of landfalling ARs. ARs over the northeast Pacific are measured using dropsondes from up to three aircraft simultaneously. Additionally, airborne radio occultation is being tested, and drifting buoys with pressure sensors are deployed. AR targeting and data collection methods have been developed, assimilation and forecast impact experiments are ongoing, and better understanding of AR dynamics is emerging. AR Recon is led by the Center for Western Weather and Water Extremes and NWS/NCEP. The effort’s core partners include the U.S. Navy, U.S. Air Force, NCAR, ECMWF, and multiple academic institutions. AR Recon is included in the “National Winter Season Operations Plan” to support improved outcomes for emergency preparedness and water management in the West.

Free access
Emily Shroyer
,
Amit Tandon
,
Debasis Sengupta
,
Harindra J. S. Fernando
,
Andrew J. Lucas
,
J. Thomas Farrar
,
Rajib Chattopadhyay
,
Simon de Szoeke
,
Maria Flatau
,
Adam Rydbeck
,
Hemantha Wijesekera
,
Michael McPhaden
,
Hyodae Seo
,
Aneesh Subramanian
,
R Venkatesan
,
Jossia Joseph
,
S. Ramsundaram
,
Arnold L. Gordon
,
Shannon M. Bohman
,
Jaynise Pérez
,
Iury T. Simoes-Sousa
,
Steven R. Jayne
,
Robert E. Todd
,
G. S. Bhat
,
Matthias Lankhorst
,
Tamara Schlosser
,
Katherine Adams
,
S. U. P Jinadasa
,
Manikandan Mathur
,
M. Mohapatra
,
E. Pattabhi Rama Rao
,
A. K. Sahai
,
Rashmi Sharma
,
Craig Lee
,
Luc Rainville
,
Deepak Cherian
,
Kerstin Cullen
,
Luca R. Centurioni
,
Verena Hormann
,
Jennifer MacKinnon
,
Uwe Send
,
Arachaporn Anutaliya
,
Amy Waterhouse
,
Garrett S. Black
,
Jeremy A. Dehart
,
Kaitlyn M. Woods
,
Edward Creegan
,
Gad Levy
,
Lakshmi H. Kantha
, and
Bulusu Subrahmanyam

Abstract

In the Bay of Bengal, the warm, dry boreal spring concludes with the onset of the summer monsoon and accompanying southwesterly winds, heavy rains, and variable air–sea fluxes. Here, we summarize the 2018 monsoon onset using observations collected through the multinational Monsoon Intraseasonal Oscillations in the Bay of Bengal (MISO-BoB) program between the United States, India, and Sri Lanka. MISO-BoB aims to improve understanding of monsoon intraseasonal variability, and the 2018 field effort captured the coupled air–sea response during a transition from active-to-break conditions in the central BoB. The active phase of the ∼20-day research cruise was characterized by warm sea surface temperature (SST > 30°C), cold atmospheric outflows with intermittent heavy rainfall, and increasing winds (from 2 to 15 m s−1). Accumulated rainfall exceeded 200 mm with 90% of precipitation occurring during the first week. The following break period was both dry and clear, with persistent 10–12 m s−1 wind and evaporation of 0.2 mm h−1. The evolving environmental state included a deepening ocean mixed layer (from ∼20 to 50 m), cooling SST (by ∼1°C), and warming/drying of the lower to midtroposphere. Local atmospheric development was consistent with phasing of the large-scale intraseasonal oscillation. The upper ocean stores significant heat in the BoB, enough to maintain SST above 29°C despite cooling by surface fluxes and ocean mixing. Comparison with reanalysis indicates biases in air–sea fluxes, which may be related to overly cool prescribed SST. Resolution of such biases offers a path toward improved forecasting of transition periods in the monsoon.

Full access
Ibrahim Hoteit
,
Yasser Abualnaja
,
Shehzad Afzal
,
Boujemaa Ait-El-Fquih
,
Triantaphyllos Akylas
,
Charls Antony
,
Clint Dawson
,
Khaled Asfahani
,
Robert J. Brewin
,
Luigi Cavaleri
,
Ivana Cerovecki
,
Bruce Cornuelle
,
Srinivas Desamsetti
,
Raju Attada
,
Hari Dasari
,
Jose Sanchez-Garrido
,
Lily Genevier
,
Mohamad El Gharamti
,
John A. Gittings
,
Elamurugu Gokul
,
Ganesh Gopalakrishnan
,
Daquan Guo
,
Bilel Hadri
,
Markus Hadwiger
,
Mohammed Abed Hammoud
,
Myrl Hendershott
,
Mohamad Hittawe
,
Ashok Karumuri
,
Omar Knio
,
Armin Köhl
,
Samuel Kortas
,
George Krokos
,
Ravi Kunchala
,
Leila Issa
,
Issam Lakkis
,
Sabique Langodan
,
Pierre Lermusiaux
,
Thang Luong
,
Jingyi Ma
,
Olivier Le Maitre
,
Matthew Mazloff
,
Samah El Mohtar
,
Vassilis P. Papadopoulos
,
Trevor Platt
,
Larry Pratt
,
Naila Raboudi
,
Marie-Fanny Racault
,
Dionysios E. Raitsos
,
Shanas Razak
,
Sivareddy Sanikommu
,
Shubha Sathyendranath
,
Sarantis Sofianos
,
Aneesh Subramanian
,
Rui Sun
,
Edriss Titi
,
Habib Toye
,
George Triantafyllou
,
Kostas Tsiaras
,
Panagiotis Vasou
,
Yesubabu Viswanadhapalli
,
Yixin Wang
,
Fengchao Yao
,
Peng Zhan
, and
George Zodiatis
Full access
Ibrahim Hoteit
,
Yasser Abualnaja
,
Shehzad Afzal
,
Boujemaa Ait-El-Fquih
,
Triantaphyllos Akylas
,
Charls Antony
,
Clint Dawson
,
Khaled Asfahani
,
Robert J. Brewin
,
Luigi Cavaleri
,
Ivana Cerovecki
,
Bruce Cornuelle
,
Srinivas Desamsetti
,
Raju Attada
,
Hari Dasari
,
Jose Sanchez-Garrido
,
Lily Genevier
,
Mohamad El Gharamti
,
John A. Gittings
,
Elamurugu Gokul
,
Ganesh Gopalakrishnan
,
Daquan Guo
,
Bilel Hadri
,
Markus Hadwiger
,
Mohammed Abed Hammoud
,
Myrl Hendershott
,
Mohamad Hittawe
,
Ashok Karumuri
,
Omar Knio
,
Armin Köhl
,
Samuel Kortas
,
George Krokos
,
Ravi Kunchala
,
Leila Issa
,
Issam Lakkis
,
Sabique Langodan
,
Pierre Lermusiaux
,
Thang Luong
,
Jingyi Ma
,
Olivier Le Maitre
,
Matthew Mazloff
,
Samah El Mohtar
,
Vassilis P. Papadopoulos
,
Trevor Platt
,
Larry Pratt
,
Naila Raboudi
,
Marie-Fanny Racault
,
Dionysios E. Raitsos
,
Shanas Razak
,
Sivareddy Sanikommu
,
Shubha Sathyendranath
,
Sarantis Sofianos
,
Aneesh Subramanian
,
Rui Sun
,
Edriss Titi
,
Habib Toye
,
George Triantafyllou
,
Kostas Tsiaras
,
Panagiotis Vasou
,
Yesubabu Viswanadhapalli
,
Yixin Wang
,
Fengchao Yao
,
Peng Zhan
, and
George Zodiatis

Abstract

The Red Sea, home to the second-longest coral reef system in the world, is a vital resource for the Kingdom of Saudi Arabia. The Red Sea provides 90% of the Kingdom’s potable water by desalinization, supporting tourism, shipping, aquaculture, and fishing industries, which together contribute about 10%–20% of the country’s GDP. All these activities, and those elsewhere in the Red Sea region, critically depend on oceanic and atmospheric conditions. At a time of mega-development projects along the Red Sea coast, and global warming, authorities are working on optimizing the harnessing of environmental resources, including renewable energy and rainwater harvesting. All these require high-resolution weather and climate information. Toward this end, we have undertaken a multipronged research and development activity in which we are developing an integrated data-driven regional coupled modeling system. The telescopically nested components include 5-km- to 600-m-resolution atmospheric models to address weather and climate challenges, 4-km- to 50-m-resolution ocean models with regional and coastal configurations to simulate and predict the general and mesoscale circulation, 4-km- to 100-m-resolution ecosystem models to simulate the biogeochemistry, and 1-km- to 50-m-resolution wave models. In addition, a complementary probabilistic transport modeling system predicts dispersion of contaminant plumes, oil spill, and marine ecosystem connectivity. Advanced ensemble data assimilation capabilities have also been implemented for accurate forecasting. Resulting achievements include significant advancement in our understanding of the regional circulation and its connection to the global climate, development, and validation of long-term Red Sea regional atmospheric–oceanic–wave reanalyses and forecasting capacities. These products are being extensively used by academia, government, and industry in various weather and marine studies and operations, environmental policies, renewable energy applications, impact assessment, flood forecasting, and more.

Full access