Radiometric Network Research Articles

Assimilation of Precipitable Water Measurements into a Mesoscale Numerical Model

Significant progress has been made over the past decade in the development of remote-sensing instruments to profile wind and temperature. However, the current technology of profiling water vapor remotely is still far from perfect. Although some promising optical research systems, such as the Raman lidar, can provide high vertical resolution profiles of water vapor, it may be years before they are generally available. Currently, there are several systems that can measure the vertically integrated water vapor (i.e., precipitable water) with a high degree of accuracy. In this paper we use a simple method to assimilate precipitable water measurements (possibly from a network of dual-channel ground-based microwave radiometers or a satellite-based system) into a mesoscale model. The basic idea is to relax the predicted precipitable water toward the observed value, while retaining the vertical structure of the model humidity field. We test this method with the special 3-h soundings available from the Severe Environmental Storms and Mesoscale Experiment. The results show that the assimilation of precipitable water into a mesoscale model recovers the vertical structure of water vapor with an accuracy much higher than that from statistical retrieval based on climatology. The improved analysis due to assimilation also leads to improved short-range precipitation forecasts.

Indian programme on middle atmosphere: Some results

We present here an account of the very extensive programme on the middle atmosphere carried out in India since 1982, using three rocket ranges (Thumba, SHAR and Balasore), a high altitude balloon facility at Hyderabad, a Lidar at Thumba, a Laser Heterodyning system at Delhi, a Meteor Radar in Thumba, a network of UVB and multi-wavelength radiometers and a host of conventional ground based facilities scattered over the entire subcontinent spanning a range of latitudes from 8°N to 34°N and largely around the same longitude zone of 75°E. A special nature of the Indian effort is the emphasis on campaign mode operations, knitting special rocket and balloon efforts with more conventional ground based activities around specific themes. Major compaigns carried out included: (i) Indo-Soviet Ozone Intercomparison campaigns in 1983 and 1987 (ii) Aerosol campaign (iii) Ionization and conductivity campaigns (iv) Equatorial Wave Campaign (v) Antarctic Ozone Hole campaign in Dakshin Gangotri. A few of the more important findings are outlined.

Prospecting for Meteorological Energy in Hawaii

Hawaii, with no indigenous fossil fuel resources, is particularly susceptible to oil shortages; hence, surveys have been underway for some time to evaluate the potential of wind and insolation as alternate energy sources. Since numerical modeling of the wind field is inadequate, we have been using fixed and mobile stations to monitor the wind distribution, finding that on parts of each of the main islands average speeds are more than adequate for economic power generation. A radiometer network on Oahu and scattered measurements elsewhere reveal that over most areas sheltered from the trade winds, insolation is as high as anywhere in the continental United States. We are using cloudiness data from weather satellites to refine the insolation maps. On recent field programs, we measured wind, insolation, temperature, humidity, and rainfall, aiming at improving our understanding of physical processes and at developing methods of wind and insolation forecasting.