Melvin G. Marcus

SNOW ACCUMULATION IN THE ICEFIELD RANGES, ST. ELIAS MOUNTAINS, YUKON

Snowpack characteristics in the St. Elias Mountains were examined as part of the Icefield Ranges Project for 1961 to 1965, emphasizing particularly the 1964-65 glacier balance year, together with reconstructions for 1953 to 1961. Analysis was carried out along a hydrological traverse on the Kaskawulsh, Hubbard, and Seward-Malaspina glaciers, and at a single location through a period of time. The data obtained are summarized in graphs and tables. The relationships between precipitation, elevation, and topography, and effects of continentality and exposure are considered. In neither case are the relationships clearly defined but it is evident that elevation is a critical factor in the maintenance of continental slope glaciers and spring runoff. Fluctuations in net accumulation are determined and evaluated; a stable period is indicated for the late 1950s, followed by an increase of 200 to 300 mm in the early 1960s and a minimum in 1964-65 and 1965-66 of winter nourishment and mass balance. Climatic implications are drawn from the snow accumulation data.

JULY TEMPERATURES IN KASHMIR AND LADAKH, INDIA: COMPARISONS OF OBSERVATIONS AND GENERAL CIRCULATION MODEL SIMULATIONS

The Himalayan mountain region represents a challenging laboratory to refine general circulation model simulations and to compare them with climate observations at regional and local geographical scales. This paper includes an analysis of July tem- peratures in the Great Himalaya Range of northern India. Five sources of data are analyzed: (1) coarse-scale model simulations for present climate (1 x CO2 runs), (2) regression model predictions of temperature versus elevation (after Lambert and Chitrakar, 1989), (3) spatially-interpolated observed data for the region (after Legates and Willmott, 1990), (4) individual station records in the region, and (5) local-scale field data taken in summer, 1988. As expected, July temperature simulations from general circulation models tend to generalize temperature/elevation relationships and do not appear to account for landscape surface feedbacks on air temperatures at a regional and local scale. Cautious use of climate model predictions of temperature and moisture for climate change scenario analyses is strongly encouraged. For mountain areas, field verification and weather station analyses for regional and local scales are essential for interpreting results from general circulation models.

RECENT TRENDS IN THE LEMON CREEK GLACIER, ALASKA

This paper reports the 1989 re-mapping of Lemon Creek Glacier, Alaska, and, in conjunction with 1948 and 1957 maps of the glacier, calculation of 9-year and 32-year changes of glacier mass and terminal position. As in the earlier maps, the new map is at a scale of 1:10,000 with a 5-m contour interval for the glacier surface. Changes between 1957 and 1989 were determined by use of the geodetic method for determining mass balance. Net water equivalent change was -118.71 × 106 m3. The glaciers respective 1957–1989 area and volume losses were 0.878 × 106 m2 and -131.90 × 106 m3 (14.6%). The terminus retreated an average 700 m.

LONGWAVE RADIATION IN THE HIMALAYAS OF CENTRAL NEPAL AND NORTHWEST INDIA

Short-term climatic field data taken in high elevations of Nepal and Kashmir-Ladakh, India, are used to evaluate incoming, outgoing, and net longwave radiation changes with elevation. Sky brightness temperatures were monitored and converted to equivalent IR, full hemisphere sky emittance values. Surface temperatures were also recorded. Calculated sky radiant IR fluxes are compared to several models of longwave incoming radiation. The model of Brutsaert compares favorably with instrument-derived longwave incoming radiation values in comparison to other empirical equations tested. Elevational gradients of longwave incoming radiation were found to range from -34 W/m2 per km (Kashmir-Ladakh) to -49 W/m2 per km (India-Nepal) and are consistent, in a regional climate context, with the few available analyses of longwave components for some other mountain locales at similar latitudes. Net longwave radiation becomes increasingly more negative at high elevations and patterns of net longwave radiation are strongly c...

ENVIRONMENTAL EFFECTS ON RADIATION FLUXES DURING THE PRE-MONSOON, 4,170-5,525 m, ANNAPURNA REGION, NEPAL

This paper addresses the net radiation balance as it is affected by high elevation, topography, and variable surface materials and surface conditions in the Annapurna region of central Nepal. Emphasis is given to shortwave radiation components. Heat flux data were collected during the pre-monsoon period at four sites north of Annapurna Himal at elevations of 4,170; 5,019; 5,200; and 5,526 m. Results from this and other investigations of radiation in the Himalaya confirm remarkably consistent high transmissiv- ities with low atmospheric turbidities. Seasonal cloudiness, elevation, and solar position appear to be the primary cause of changing global radiation in the region. Beam/diffuse ratios, in addition to expected cloud effects, are strongly influenced by slope, aspect, and surface material. For example, wall-originated diffuse radiation represented 15% of total global radiation at the 5,019 m Tilicho Lake site. Changes of local weather at Tilicho Lake, accompanied by snow flurries and subsequent snow melts, resulted in constantly changing albedos and highly variable longwave and net radiation values throughout most days.