Search Results

You are looking at 101 - 110 of 841 items for :

  • Cloud forcing x
  • Journal of Atmospheric and Oceanic Technology x
  • Refine by Access: All Content x
Clear All
Robert C. Jackson and Greg M. McFarquhar

affects model evolution. For example, Mitchell et al.’s (2008) global model simulations showed that increasing the number of ice crystals with D < 150 μ m induced an upper-tropospheric warming of 3 K and a total cloud forcing of −5 W m 2 in the tropics through an increase of cirrus cloud coverage compared to a control simulation. On the other hand, Boudala et al.’s (2007) simulation, including contributions of crystals with D < 150 μ m, had a net radiative forcing of 2.4 W m −2 greater

Full access
Robin J. Hogan and Anthony J. Illingworth

1. Introduction The importance of ice clouds in the climate system is well recognized ( Stephens et al. 1990 ), and attention recently has focused on ways to measure globally the radiative properties and water content of these clouds using active instruments from space. Brown et al. (1995) analyzed aircraft cloud probe data taken during EUCREX (the European Cloud Radiation Experiment) and CEPEX (the Central Equatorial Pacific Experiment) to determine how accurately a single 94-GHz radar could

Full access
J. G. DeVore, A. T. Stair, A. LePage, D. Rall, J. Atkinson, D. Villanucci, S. A. Rappaport, P. C. Joss, and R. A. McClatchey

1. Introduction An understanding of global, three-dimensional clouds, including particle phase and size distributions of cloud particles, is essential for understanding man-made radiative forcing in the atmosphere (see Forster et al. 2007 ). This paper describes a new ground-based instrument to provide such measurements for clouds with optical depths ranging from 0 to ∼10. A network of such sensors could be used to gain information on the global statistical properties of these optically thin

Full access
Christopher R. Williams, Warner L. Ecklund, and Kenneth S. Gage

shown inFig. 5a.b. Deep convective and shallow convective categories Deep convective and shallow convective precipitatingclouds do not have a melting layer signature as determined by the DVG threshold. The physical processdesired to separate deep convective and shallow convective clouds is the presence of hydrometeors abovethe 0-C isotherm level. Above this altitude, the latentheat associated with freezing and melting of water isimportant in the dynamical forcing of the atmosphere,and the

Full access
Y. Morille, M. Haeffelin, P. Drobinski, and J. Pelon

that 100% of particle layers corresponds to clouds. e. Boundary layer height detection 1)  Method The atmospheric boundary layer (ABL) is the lowest part of the troposphere that is directly influenced by the earth’s surface and responds on short time scales to surface forcing. This is the region that is well mixed due to convectively driven mixing. Several BLH detection methods are described in the literature. Methods using a simple signal threshold (e.g., Melfi et al. 1985 ; Boers et al

Full access
Rasmus Lindstrot, Rene Preusker, and Jürgen Fischer

1. Introduction Satellite observations provide an indispensable contribution to the monitoring of the atmosphere, earth, and ocean. Because it is impossible to operationally perform in situ measurements of cloud properties, the spaceborne remote sensing of clouds is of special importance. The methodologies for the retrieval of cloud properties from satellite data have been constantly advanced during the past decades. In the case of the retrieval of cloud altitude, which is representing one of

Full access
Matthew D. Lebsock and Kentaroh Suzuki

representation of NUBF effects is sensitive to the distribution of cloud horizontal sizes, which is limited by the LES resolution, domain size, and forcing conditions. To explore this limitation, we calculate the distribution of the square root of the cloud horizontal areas, which we term effective diameter. The distribution of effective diameter follows a double power-law distribution with a scale break observed between 400 and 600 m. The scaling exponent for the small clouds is −0.64 and for the large

Full access
Jun Zhou, Hengchi Lei, Lei Ji, and Tuanjie Hou

1. Introduction The spatial distribution of liquid water content (LWC) in clouds plays very important roles in weather forecasting, climate modeling, and weather modification, among other areas. Taking the latter of these, weather modification, as an example, this technique has been widely operated in China but is still in urgent need of scientific guidance and confirmation ( Young 1996 ). The Bergeron–Findeisen mechanism is the theoretical basis for weather modification, including

Full access
Pavlos Kollias, Bruce A. Albrecht, Eugene E. Clothiaux, Mark A. Miller, Karen L. Johnson, and Kenneth P. Moran

. 10.1175/1520-0426(2003)020<0042:POLLSC>2.0.CO;2 Dong, X. , and Mace G G. , 2003b : Artic stratus cloud properties and radiative forcing derived from ground-based data collected at Barrow, Alaska. J. Climate , 16 , 445 – 461 . 10.1175/1520-0442(2003)016<0445:ASCPAR>2.0.CO;2 Doviak, R J. , and Zrnić D S. , 1993 : Doppler Radar and Weather Observations . 2d ed. 562 pp . Frehlich, R G. , and Yadlowsky M J. , 1994 : Performance of mean-frequency estimators for Doppler radar and

Full access
A. V. Korolev, E. F. Emery, J. W. Strapp, S. G. Cober, and G. A. Isaac

1. Introduction Small ice particles may play a significant role in radiation transfer and precipitation formation, and their associated parameterizations have been included in many numerical climate and weather prediction models. Debates around the problem as to whether small ice particles are omnipresent in ice clouds extend well over three decades and began when optical particle size spectrometers ( Knollenberg 1976 ) were commonly adopted for airborne cloud particle sampling in the mid-1970s

Full access