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Graduate Enrollments in the Atmospheric Sciences

Gabor Vali
,
Richard Anthes
,
Dennis Thomson
,
David Houghton
,
Jack Fellows
, and
Susan Friberg

A recent survey of UCAR member institutions shows reason for concern about a possible decline in the number and quality of applicants entering graduate studies in the atmospheric and related sciences. If reported trends continue, a shortage of qualified Ph.D. graduates in the field in the next decade may be faced.

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Bjorn Stevens
,
Gabor Vali
,
Kimberly Comstock
,
Robert Wood
,
Margreet C. van Zanten
,
Philip H. Austin
,
Christopher S. Bretherton
, and
Donald H. Lenschow

Data from recent field studies in the northeast and southeast Pacific are used to investigate pockets of open cells (POCs) that are embedded in otherwise uniform stratocumulus. The cellular structure within a POC resembles broader regions of open cellular convection typically found further offshore. In both regions, cells are composed of precipitating cell walls and cell interiors with depleted cloud water and even clearing. POCs are long lived and embedded in broader regions of stratocumulus where average droplet sizes are relatively large. In contrast, stratiform, or unbroken, cloud formations tend to be accompanied by less, or no, drizzle, suggesting that precipitation is necessary for the sustenance of the open cellular structure. Because, by definition, open cells are associated with a reduction in cloud cover these observations provide direct evidence of a connection between cloudiness and precipitation—a linchpin of hypotheses that posit a connection between changes in the atmospheric aerosol and climate.

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Paul J. DeMott
,
Ottmar Möhler
,
Olaf Stetzer
,
Gabor Vali
,
Zev Levin
,
Markus D. Petters
,
Masataka Murakami
,
Thomas Leisner
,
Ulrich Bundke
,
Holger Klein
,
Zamin A. Kanji
,
Richard Cotton
,
Hazel Jones
,
Stefan Benz
,
Maren Brinkmann
,
Daniel Rzesanke
,
Harald Saathoff
,
Mathieu Nicolet
,
Atsushi Saito
,
Bjorn Nillius
,
Heinz Bingemer
,
Jonathan Abbatt
,
Karin Ardon
,
Eli Ganor
,
Dimitrios G. Georgakopoulos
, and
Clive Saunders

Understanding cloud and precipitation responses to variations in atmospheric aerosols remains an important research topic for improving the prediction of climate. Knowledge is most uncertain, and the potential impact on climate is largest with regard to how aerosols impact ice formation in clouds. In this paper, we show that research on atmospheric ice nucleation, including the development of new measurement systems, is occurring at a renewed and historically unparalleled level. A historical perspective is provided on the methods and challenges of measuring ice nuclei, and the various factors that led to a lull in research efforts during a nearly 20-yr period centered about 30 yr ago. Workshops played a major role in defining critical needs for improving measurements at that time and helped to guide renewed efforts. Workshops were recently revived for evaluating present research progress. We argue that encouraging progress has been made in the consistency of measurements using the present generation of ice nucleation instruments. Through comparison to laboratory cloud simulations, these ice nuclei measurements have provided increased confidence in our ability to quantify primary ice formation by atmospheric aerosols.

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Bjorn Stevens
,
Donald H. Lenschow
,
Gabor Vali
,
Hermann Gerber
,
A. Bandy
,
B. Blomquist
,
J. -L. Brenguier
,
C. S. Bretherton
,
F. Burnet
,
T. Campos
,
S. Chai
,
I. Faloona
,
D. Friesen
,
S. Haimov
,
K. Laursen
,
D. K. Lilly
,
S. M. Loehrer
,
Szymon P. Malinowski
,
B. Morley
,
M. D. Petters
,
D. C. Rogers
,
L. Russell
,
V. Savic-Jovcic
,
J. R. Snider
,
D. Straub
,
Marcin J. Szumowski
,
H. Takagi
,
D. C. Thornton
,
M. Tschudi
,
C. Twohy
,
M. Wetzel
, and
M. C. van Zanten

The second Dynamics and Chemistry of Marine Stratocumulus (DYCOMS-II) field study is described. The field program consisted of nine flights in marine stratocumulus west-southwest of San Diego, California. The objective of the program was to better understand the physics a n d dynamics of marine stratocumulus. Toward this end special flight strategies, including predominantly nocturnal flights, were employed to optimize estimates of entrainment velocities at cloud-top, large-scale divergence within the boundary layer, drizzle processes in the cloud, cloud microstructure, and aerosol–cloud interactions. Cloud conditions during DYCOMS-II were excellent with almost every flight having uniformly overcast clouds topping a well-mixed boundary layer. Although the emphasis of the manuscript is on the goals and methodologies of DYCOMS-II, some preliminary findings are also presented—the most significant being that the cloud layers appear to entrain less and drizzle more than previous theoretical work led investigators to expect.

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