ALBERT

Beschreibung: In winter, large interannual fluctuations in the surface temperature are observed over central Europe. Comparing warm February 1990 with cold February 1996, a satellite-retrieved surface (skin) temperature difference of 9.8 K is observed for the region 50-60 degrees N; 5-35 degrees E. Previous studies show that advection from the North Atlantic constitutes the forcing to such fluctuations. The advection is quantified by Index I(sub na), the average of the ocean-surface wind speed over the eastern North Atlantic when the direction is from the southwest (when the wind is from another direction, it counts as a zero speed to the average). Average I(sub na) for February 1990 was 10.6 m/s, but for February 1996 I(sub na) was only 2.4 m/s. A large value of I(sub na) means a strong southwesterly flow which brings warm and moist air into central Europe at low level, producing a steeper tropospheric lapse rate. Strong ascending motions at 700 mb are observed in association with the occurrence of enhanced warm, moist advection from the ocean in February 1990 producing clouds and precipitation. Total precipitable water and cloud-cover fraction have larger values in February 1990 than in 1996. The difference in the greenhouse effect between these two scenarios, this reduction in heat loss to space, can be translated into a virtual radiative heating of 2.6 W/square m above the February 1990 surface/atmosphere system, which contributes to a warming of the surface on the order of 2.6 K. Accepting this estimate as quantitatively meaningful, we evaluate the direct effect, the rise in the surface temperature in Europe as a result of maritime-air inflow, as 7.2 K (9.8 K-2.6 K). Thus, fractional reinforcement by the greenhouse effect is 2.6/7.2, or 36%, a substantial positive feedback.

Beschreibung: In winter, large interannual fluctuations in the surface skin temperature are observed over central Europe: we observe a difference of 9.8 K comparing warm February 1990 with cold February 1996 for the region 50-60 degrees N; 5-35 degrees E. Previous studies show that advection from the North Atlantic constitutes the forcing to such fluctuations. The advection is quantified by Index I(sub na), the average of the ocean-surface wind speed over the eastern North Atlantic when the direction is from the southwest (when the wind is from another direction, it counts as a zero speed to the average). Average Ina for February 1990 was 10.6 in s(exp -1), but for February 1996 I(sub na) was only 2.4 m s(exp -1). A large value of I(sub na) means a strong southwesterly flow which brings warm and moist air into Europe at low level, producing a steeper tropospheric lapse rate. Strong ascending motions result, which we observe in February 1990 at 700 mb. The near-surface moisture rises to higher (and cooler) levels, producing clouds and precipitation. Total preciptable water and cloud-cover fraction have larger values in February 1990 than in 1996. The difference in the greenhouse effect between these two scenarios can be translated into a virtual irradiating source of 2.6 W m(exp -2) above the February 1990 atmosphere, which, as an order of magnitude estimate, contributes to the warming of the surface by 2.6 K. If we accept this estimate as numerically pertinent, the direct effect stands as 7.2 K (9.8 K - 2.6 K), and therefore its greenhouse-effect reinforcement is by 36%. This constitutes a substantial positive feedback to the direct effect, which is the inflow of warm air to the low troposphere over Europe.

Beschreibung: The high resolution laboratory absorption spectrum of the 12 micro band of ethane gas is studied. The data were obtained using the McMath Solar Telescope 1 meter Fourier Transform interferometer at Kitt Peak National Observatory and tunable diode laser spectrometers at the University of Tennessee and NASA/Goddard Space Flight Center. Over 200 individual vibration rotation transitions were analyzed taking into account many higher order effects including torsional splitting. Line positions were reproduced to better than 0.001/cm. Both ground and upper state molecular constants were determined in the analysis. The experimental details, the analysis procedures and the results are addressed. A list of ethane transitions occurring near (14)CO2 laser lines needed for heterodyne searches for C2H6 in extraterrestrial sources is also included. A spectral catalog of the ethane nu sub g fundamental from 765/cm to 900/cm is provided. A high dispersion (1/cm 12 in.) plot of both the Kitt Peak interferometric data and a simulated spectrum with Doppler limited resolution, a table of over 8500 calculated transitions listed quantum number assignments, frequencies and intensities are provided.

Beschreibung: TOVS (Tiros Operational Vertical Sounder) is the suite of infra-red and microwave sounding instruments, including HIRS-2 and MSU, that have flown on the NOAA Polar orbiting operational satellites TIROS-N, NOAA 6-14 from November 1978 to the present day. Data has been analyzed for the entire time period using a consistent methodology to produce twice daily per satellite global fields of surface skin temperature, atmospheric temperature-moisture profile, cloud top pressure, and fractional cloud cover, OLR and clear sky OLR, and precipitation. All parameters were found to depend on the orbit time of observation which differed as a function of time both because of differing initial satellite orbits and orbit drift. This must be accounted for before one can attempt to find trends in the data. Methodology to account for orbit drift will be shown. Trends will then be shown, over the 21 year period 1979-1999, for surface skin temperature and atmospheric temperature profile. There has been global warming near the surface which falls off rapidly with height. Trends will also be shown for values of MSU2R and MSU4 which are computed from the soundings. These will be compared to trends of MSU2R and MSU4 observed by Spencer and Christy. There is generally good agreement between Spencer and Christy MSU2R trends and those computed from the TOVS Pathfinder data set, with the largest differences over the tropics.