Abstract. Data collected by two automatic weather stations (AWS) on the Larsen C ice shelf, Antarctica, between 22 January 2009 and 1 February 2011 are analyzed and used as input for a model that computes the surface energy budget (SEB), which includes melt energy. The two AWSs are separated by about 70 km in the north-south direction, and both the near-surface meteorology and the SEB show similarities, although small differences in all components (most notably the melt flux) can be seen. The impact of subsurface absorption of shortwave radiation on melt and snow temperature is significant, and discussed. In winter, longwave cooling of the surface is entirely compensated by a downward turbulent transport of sensible heat. In summer, the positive net radiative flux is compensated by melt, and quite frequently by upward turbulent diffusion of heat and moisture, leading to sublimation and weak convection over the ice shelf. The month of November 2010 is highlighted, when strong westerly flow over the Antarctic Peninsula led to a dry and warm föhn wind over the ice shelf, resulting in warm and sunny conditions. Under these conditions the increase in shortwave and sensible heat fluxes is larger than the decrease of net longwave and latent heat fluxes, providing energy for significant melt.

Data collected by two automatic weather stations (AWS) on the Larsen C ice shelf, Antarctica, between 22 January 2009 and 1 February 2011 are analyzed and used as input for a model that computes the surface energy budget (SEB), including melt energy. The two AWSs are separated by about 70 km in the north-south direction, and both the near-surface meteorology and the SEB show similarities, although small differences in all components (most notably the melt flux) can be seen. The impact of subsurface absorption of shortwave radiation on melt and snow temperature is significant, and discussed. In winter, longwave cooling of the surface is entirely compensated by a downward turbulent transport of sensible heat. In summer, the positive net radiative flux is compensated by melt, and quite frequently by upward turbulent diffusion of heat and moisture, leading to sublimation and weak convection over the ice shelf. The month of November 2010 is highlighted, when strong westerly flow over the Antarctic Peninsula led to a dry and warm föhn wind over the ice shelf, resulting in warm and sunny conditions. Under these conditions the increase in shortwave and sensible heat fluxes is larger than the reduction of net longwave and latent heat fluxes, providing energy for significant melt

The large-scale air-sea interaction over the equatorial Pacific proposed by Bjerknes is investigated. It was found from a study of the Canton Island record that ocean temperature, rainfall, trade wind flow, and equivalent potential temperature are related and undergo long-term variations with periods in excess of a year. Similar changes occur in the high troposphere. Satellite cloud observations, however, indicate important longitudinal variations near the Equator. During the abnormal rainy season of 1965-66 a t Canton Island, the amount of cloudiness remained low over the eastern equatorial Pacific despite above-normal sea-surface temperatures. This suggests a continuation of the widespread subsidence usually present over this region, which is apparently part of a large-scale semipermanent zonal circulation. Satellite observations further show that there are three major "centers of action" (standing eddies) in the vicinity of the Equator. Probably the major part of the condenstion heating necessary for the Hadley circulation occurs in these areas. This study also indicates a possible relation between equatorial rainfall in the central Pacific and the strength of the Northern Hemisphere westerlies as suggested by Bjerknes. I n addition, rainfall appears to vary inversely with the eddy kinetic energy over the Northern Hemisphere suggesting an inverse relation with the large-scale planetary waves in the Northern Hemisphere.

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The purpose of this study is t o evaluate the reliability of locating jet streams by means of certain cloud patterns in TIROS pictures, and to determine the most definitive characteristics of those patterns. It would be very useful omrationally, especially in data-sparse regions, if the jet stream could be accurately located from satellite pictures. Jet stream positions over the United States estimated from TIROS pictures are compared with positions from operational analyses during a 3-month period. The cases are reexamined to determine under which conditions agreement did or did not occur. Jet streams can be accurately located in about 80 percent of the cases whenever clearly defined cloud characteristics occur under favorable viewing conditions. The most definitive cloud characteristics are (1) a n extensive cirrus shield having a sharply defined poleward edge, often outlined by a shadow cast on lower cloud surfaces or on the earth, and (2) transverse banding in the cloud shield. Further, cirrus streaks alone prove to be undependable detectors. The greatest danger exists in confusing frontal cloudiness with jet stream cloudiness. There is the suggestion that operational jet analysis can benefit from satellite pictures even in data-rich areas. Initially agreement is achieved in about half the cases. The jet axis is located on the poleward cloud edge. 127 128 MONTHLY WEATHER REVIEW Vol. 94, No. ' He too has noted the streaked nature of cirrus, which he ological Research Committee, Sept. 1955, 7 pp. 9. P. W. Kadlec, "A Study of Flight Conditions Associated with Jet Stream Cirrus, Atmospheric Temperature Change, and Wind Shear Turbulence," Final Report, Contract NO.