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  • Author or Editor: Florian Pappenberger x
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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


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.

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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
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Will Pozzi, Justin Sheffield, Robert Stefanski, Douglas Cripe, Roger Pulwarty, Jürgen V. Vogt, Richard R. Heim Jr., Michael J. Brewer, Mark Svoboda, Rogier Westerhoff, Albert I. J. M. van Dijk, Benjamin Lloyd-Hughes, Florian Pappenberger, Micha Werner, Emanuel Dutra, Fredrik Wetterhall, Wolfgang Wagner, Siegfried Schubert, Kingtse Mo, Margaret Nicholson, Lynette Bettio, Liliana Nunez, Rens van Beek, Marc Bierkens, Luis Gustavo Goncalves de Goncalves, João Gerd Zell de Mattos, and Richard Lawford

Drought is a global problem that has far-reaching impacts, especially on vulnerable populations in developing regions. This paper highlights the need for a Global Drought Early Warning System (GDEWS), the elements that constitute its underlying framework (GDEWF), and the recent progress made toward its development. Many countries lack drought monitoring systems, as well as the capacity to respond via appropriate political, institutional, and technological frameworks, and these have inhibited the development of integrated drought management plans or early warning systems. The GDEWS will provide a source of drought tools and products via the GDEWF for countries and regions to develop tailored drought early warning systems for their own users. A key goal of a GDEWS is to maximize the lead time for early warning, allowing drought managers and disaster coordinators more time to put mitigation measures in place to reduce the vulnerability to drought. To address this, the GDEWF will take both a top-down approach to provide global realtime drought monitoring and seasonal forecasting, and a bottom-up approach that builds upon existing national and regional systems to provide continental-to-global coverage. A number of challenges must be overcome, however, before a GDEWS can become a reality, including the lack of in situ measurement networks and modest seasonal forecast skill in many regions, and the lack of infrastructure to translate data into useable information. A set of international partners, through a series of recent workshops and evolving collaborations, has made progress toward meeting these challenges and developing a global system.

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