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Casey D. Burleyson
,
Zhe Feng
,
Samson M. Hagos
,
Jerome Fast
,
Luiz A. T. Machado
, and
Scot T. Martin

Abstract

The isolation of the Amazon rain forest makes it challenging to observe precipitation forming there, but it also creates a natural laboratory to study anthropogenic impacts on clouds and precipitation in an otherwise pristine environment. Observations were collected upwind and downwind of Manaus, Brazil, during the “Observations and Modeling of the Green Ocean Amazon 2014–2015” experiment (GoAmazon2014/5). Besides aircraft, most of the observations were point measurements made in a spatially heterogeneous environment, making it hard to distinguish anthropogenic signals from naturally occurring spatial variability. In this study, 15 years of satellite data are used to examine the spatial and temporal variability of deep convection around the GoAmazon2014/5 sites using cold cloud tops (infrared brightness temperatures colder than 240 K) as a proxy for deep convection. During the rainy season, convection associated with the inland propagation of the previous day’s sea-breeze front is in phase with the diurnal cycle of deep convection near Manaus but is out of phase a few hundred kilometers to the east and west. Convergence between the river breezes and the easterly trade winds generates afternoon convection up to 10% more frequently (on average ~4 mm day−1 more intense rainfall) at the GoAmazon2014/5 sites east of the Negro River (T0e, T0t/k, and T1) relative to the T3 site, which was located west of the river. In general, the annual and diurnal cycles of precipitation during 2014 were similar to climatological values that are based on satellite data from 2000 to 2013.

Full access
Samson Hagos
,
Gregory R. Foltz
,
Chidong Zhang
,
Elizabeth Thompson
,
Hyodae Seo
,
Sue Chen
,
Antonietta Capotondi
,
Kevin A. Reed
,
Charlotte DeMott
, and
Alain Protat
Free access
Effy B. John
,
Karthik Balaguru
,
L. Ruby Leung
,
Gregory R. Foltz
,
Robert D. Hetland
, and
Samson M. Hagos

Abstract

Tropical Cyclone (TC) Sally formed on 11 September 2020, traveled through the Gulf of Mexico (GMX), and intensified rapidly before making landfall on the Alabama coast as a devastating category-2 TC with extensive coastal and inland flooding. In this study, using a combination of observations and idealized numerical model experiments, we demonstrate that the Mississippi River plume played a key role in the intensification of Sally near the northern Gulf Coast. As the storm intensified and its translation slowed before landfall, sea surface cooling was reduced along its track, coincident with a pronounced increase in SSS. Further analysis reveals that TC Sally encountered a warm Loop Current eddy in the northern GMX close to the Mississippi River plume. Besides deepening the thermocline, the eddy advected low-salinity Mississippi River plume water into the storm’s path. This resulted in the development of strong upper-ocean salinity stratification, with a shallow layer of freshwater lying above a deep, warm “barrier layer.” Consequently, TC-induced mixing and the associated sea surface cooling were reduced, aiding Sally’s intensification. These results suggest that the Mississippi River plume and freshwater advection by the Loop Current eddies can play an important role in TC intensification near the U.S. Gulf Coast.

Restricted access
Bryce E. Harrop
,
Michael S. Pritchard
,
Hossein Parishani
,
Andrew Gettelman
,
Samson Hagos
,
Peter H. Lauritzen
,
L. Ruby Leung
,
Jian Lu
,
Kyle G. Pressel
, and
Koichi Sakaguchi

Abstract

For the Community Atmosphere Model version 6 (CAM6), an adjustment is needed to conserve dry air mass. This adjustment exposes an inconsistency in how CAM6’s energy budget incorporates water—in CAM6 water in the vapor phase has energy, but condensed phases of water do not. When water vapor condenses, only its latent energy is retained in the model, while its remaining internal, potential, and kinetic energy are lost. A global fixer is used in the default CAM6 model to maintain global energy conservation, but locally the energy tendency associated with water changing phase violates the divergence theorem. This error in energy tendency is intrinsically tied to the water vapor tendency, and reaches its highest values in regions of heavy rainfall, where the error can be as high as 40 W m−2 annually averaged. Several possible changes are outlined within this manuscript that would allow CAM6 to satisfy the divergence theorem locally. These fall into one of two categories: 1) modifying the surface flux to balance the local atmospheric energy tendency and 2) modifying the local atmospheric tendency to balance the surface plus top-of-atmosphere energy fluxes. To gauge which aspects of the simulated climate are most sensitive to this error, the simplest possible change—where condensed water still does not carry energy and a local energy fixer is used in place of the global one—is implemented within CAM6. Comparing this experiment with the default configuration of CAM6 reveals precipitation, particularly its variability, to be highly sensitive to the energy budget formulation.

Significance Statement

This study examines and explains spurious regional sources and sinks of energy in a widely used climate model. These energy errors result from not tracking energy associated with water after it transitions from the vapor phase to either liquid or ice. Instead, the model used a global fixer to offset the energy tendency related to the energy sources and sinks associated with condensed water species. We replace this global fixer with a local one to examine the model sensitivity to the regional energy error and find a large sensitivity in the simulated hydrologic cycle. This work suggests that the underlying thermodynamic assumptions in the model should be revisited to build confidence in the model-simulated regional-scale water and energy cycles.

Full access
Peter Bissolli
,
Catherine Ganter
,
Tim Li
,
Ademe Mekonnen
,
Ahira Sánchez-Lugo
,
Eric J. Alfaro
,
Lincoln M. Alves
,
Jorge A. Amador
,
B. Andrade
,
Francisco Argeñalso
,
P. Asgarzadeh
,
Julian Baez
,
Reuben Barakiza
,
M. Yu. Bardin
,
Mikhail Bardin
,
Oliver Bochníček
,
Brandon Bukunt
,
Blanca Calderón
,
Jayaka D. Campbell
,
Elise Chandler
,
Ladislaus Chang’a
,
Vincent Y. S. Cheng
,
Leonardo A. Clarke
,
Kris Correa
,
Catalina Cortés
,
Felipe Costa
,
A.P.M.A. Cunha
,
Mesut Demircan
,
K. R. Dhurmea
,
A. Diawara
,
Sarah Diouf
,
Dashkhuu Dulamsuren
,
M. ElKharrim
,
Jhan-Carlo Espinoza
,
A. Fazl-Kazem
,
Chris Fenimore
,
Steven Fuhrman
,
Karin Gleason
,
Charles “Chip” P. Guard
,
Samson Hagos
,
Mizuki Hanafusa
,
H. R. Hasannezhad
,
Richard R. Heim Jr.
,
Hugo G. Hidalgo
,
J. A. Ijampy
,
Gyo Soon Im
,
Annie C. Joseph
,
G. Jumaux
,
K. R. Kabidi
,
P-H. Kamsu-Tamo
,
John Kennedy
,
Valentina Khan
,
Mai Van Khiem
,
Philemon King’uza
,
Natalia N. Korshunova
,
A. C. Kruger
,
Hoang Phuc Lam
,
Mark A. Lander
,
Waldo Lavado-Casimiro
,
Tsz-Cheung Lee
,
Kinson H. Y. Leung
,
Gregor Macara
,
Jostein Mamen
,
José A. Marengo
,
Charlotte McBride
,
Noelia Misevicius
,
Aurel Moise
,
Jorge Molina-Carpio
,
Natali Mora
,
Awatif E. Mostafa
,
Habiba Mtongori
,
Charles Mutai
,
O. Ndiaye
,
Juan José Nieto
,
Latifa Nyembo
,
Patricia Nying’uro
,
Xiao Pan
,
Reynaldo Pascual Ramírez
,
David Phillips
,
Brad Pugh
,
Madhavan Rajeevan
,
M. L. Rakotonirina
,
Andrea M. Ramos
,
M. Robjhon
,
Camino Rodriguez
,
Guisado Rodriguez
,
Josyane Ronchail
,
Benjamin Rösner
,
Roberto Salinas
,
Hirotaka Sato
,
Hitoshi Sato
,
Amal Sayouri
,
Joseph Sebaziga
,
Serhat Sensoy
,
Sandra Spillane
,
Katja Trachte
,
Gerard van der Schrier
,
F. Sima
,
Adam Smith
,
Jacqueline M. Spence
,
O. P. Sreejith
,
A. K. Srivastava
,
José L. Stella
,
Kimberly A. Stephenson
,
Tannecia S. Stephenson
,
S. Supari
,
Sahar Tajbakhsh-Mosalman
,
Gerard Tamar
,
Michael A. Taylor
,
Asaminew Teshome
,
Wassila M. Thiaw
,
Skie Tobin
,
Adrian R. Trotman
,
Cedric J. Van Meerbeeck
,
A. Vazifeh
,
Shunya Wakamatsu
,
Wei Wang
,
Fei Xin
,
F. Zeng
,
Peiqun Zhang
, and
Zhiwei Zhu
Free access
Peter Bissolli
,
Catherine Ganter
,
Ademe Mekonnen
,
Ahira Sánchez-Lugo
,
Zhiwei Zhu
,
A. Abida
,
W. Agyakwah
,
Laura S. Aldeco
,
Eric J. Alfaro
,
Teddy Allen
,
Lincoln M. Alves
,
Jorge A. Amador
,
B. Andrade
,
P. Asgarzadeh
,
Grinia Avalos
,
Julian Baez
,
M. Yu. Bardin
,
E. Bekele
,
Renato Bertalanic
,
Oliver Bochníček
,
Brandon Bukunt
,
Blanca Calderón
,
Jayaka D. Campbell
,
Elise Chandler
,
Candice S Charlton
,
Vincent Y. S. Cheng
,
Leonardo A. Clarke
,
Kris Correa
,
Catalina R. Cortés Salazar
,
Felipe Costa
,
Lenka Crhová
,
Ana Paula Cunha
,
Mesut Demircan
,
K. R. Dhurmea
,
Diana A. Domínguez
,
Dashkhuu Dulamsuren
,
M. ElKharrim
,
Jhan-Carlo Espinoza
,
A. Fazl-Kezemi
,
Nava Fedaeff
,
Chris Fenimore
,
Steven Fuhrman
,
Karin Gleason
,
Charles “Chip” P. Guard
,
Samson Hagos
,
Mizuki Hanafusa
,
Richard R. Heim Jr.
,
John Kennedy
,
Sverker Hellström
,
Hugo G. Hidalgo
,
I. A. Ijampy
,
Gyo Soon Im
,
G. Jumaux
,
K. Kabidi
,
Kenneth Kerr
,
Yelena Khalatyan
,
Valentina Khan
,
Mai Van Khiem
,
Tobias Koch
,
Gerbrand Koren
,
Natalia N. Korshunova
,
A. C. Kruger
,
Mónika Lakatos
,
Jostein Mamen
,
Hoang Phuc Lam
,
Mark A. Lander
,
Waldo Lavado-Casimiro
,
Tsz-Cheung Lee
,
Kinson H. Y. Leung
,
Xuefeng Liu
,
Rui Lu
,
José A. Marengo
,
Mohammadi Marjan
,
Ana E. Martínez
,
Charlotte McBride
,
Mirek Mietus
,
Noelia Misevicius
,
Aurel Moise
,
Jorge Molina-Carpio
,
Natali Mora
,
Awatif E. Mostafa
,
O. Ndiaye
,
Juan J. Nieto
,
Kristin Olafsdottir
,
Reynaldo Pascual Ramírez
,
David Phillips
,
Amos Porat
,
Esteban Rodriguez Guisado
,
Madhavan Rajeevan
,
Andrea M. Ramos
,
Cristina Recalde Coronel
,
Alejandra J. Reyes Kohler
,
M. Robjhon
,
Josyane Ronchail
,
Roberto Salinas
,
Hirotaka Sato
,
Hitoshi Sato
,
Amal Sayouri
,
Serhat Sensoy
,
Amsari Mudzakir Setiawan
,
F. Sima
,
Adam Smith
,
Matthieu Sorel
,
Sandra Spillane
,
Jacqueline M. Spence
,
O. P. Sreejith
,
A. K. Srivastava
,
Tannecia S. Stephenson
,
Kiyotoshi Takahashi
,
Michael A. Taylor
,
Wassila M. Thiaw
,
Skie Tobin
,
Lidia Trescilo
,
Adrian R. Trotman
,
Cedric J. Van Meerbeeck
,
A. Vazifeh
,
Shunya Wakamatsu
,
M. F. Zaheer
,
F. Zeng
, and
Peiqun Zhang
Free access