Search Results

You are looking at 1 - 10 of 61 items for

  • Author or Editor: William H. Klein x
  • Refine by Access: All Content x
Clear All Modify Search
William H. Klein

Abstract

Multiple regression equations relating surface temperature to the mid-tropospheric circulation pattern are tested on observed 30-day mean 700-mb heights. The equations are found to specify monthly mean temperatures within one class out of five about 90 per cent of the time. This is better than results obtained by use of 5-day mean data from which the equations were originally derived.

Full access
William H. Klein

Abstract

The “perfect prog” method of combining numerical and statistical weather prediction is applied to develop an automated system for forecasting the probability of precipitation at 108 cities on the mainland of the United States during daytime and nighttime periods from 12–60 hr in advance. Multiple regression equations are derived from a 4–5 year sample of data by seasons for each city by screening twice-daily geographical arrays of the following predictors: initial 850-mb height, initial 850–700 mb mean dew-point spread, and previous 12-hr precipitation at the network of surface stations. Each of the three predictor fields contributes about equally toward explaining the variance of the observed precipitation, but considerable geographical variation is exhibited by the equations. The forecast system is applied in an iterative fashion in 12-hr time steps by using as input numerical predictions of height and moisture at standard grid points as well as prior values of precipitation. The resulting computerized forecasts of precipitation probability, when applied on an operational basis in real time, may offer valuable guidance to the local weather forecaster.

Full access
William H. Klein

Abstract

Full access
William H. Klein

Abstract

An objective method of forecasting surface temperature at 39 cities in the United States for 1, 2 and 3 days in advance has been developed and tested under operational conditions. This method utilizes daily input to multiple regression equations derived previously for predicting 5-day mean temperature from fields of 700-mb height and surface temperature. Comparative verification shows that the objective method produces forecasts which approximate the skill of subjective predictions made by experienced meteorologists.

Recent experiments are described which indicate that improved forecasts result when 700–1000 mb thickness is included as a predictor. The beneficial synoptic climatology which accrues from these studies is also illustrated.

Full access
William H. Klein

Abstract

No Abstract Available

Full access
William H. Klein

Abstract

Monthly frequencies of occurrence and genesis of migratory cyclones and anticyclones at sea level in the Northern Hemisphere during the period covered by the original Historical Map Series are averaged by 5 deg lat zones. The mean meridional distribution and annual march of these frequencies are summarized by means of four time-latitude sections. These sections are related to a corresponding diagram for the normal zonal circulation of the Northern Hemisphere at the 700-mb level. Additional statistics are presented on the average speed and life span of pressure centers and on the relative frequencies of lows, highs, cyclogenesis, and anticyclogenesis.

Full access
William H. Klein

Abstract

A method of computing the intensities of direct, diffuse, and total solar radiation received on a horizontal surface of the earth is developed by consideration of sky radiation, terrain reflection, and depletion by dry air, water vapor, dust, and clouds in the atmosphere. The calculation is extended aloft, and a general equation is derived expressing the atmospheric transmission coefficient with cloudless sky at any altitude between 300 and 8000 meters as a linear function of solar zenith distance and logarithm of elevation. The contribution of solar radiation to the heat load on man is then evaluated and expressed as an equivalent increment of temperature.

Full access
William H. Klein

The forecast research program of the Techniques Development Laboratory is summarized. This program combines dynamical, statistical, and synoptic techniques in an effort to improve and automate operational weather forecasting. Principal accomplishments of the Laboratory during the five years of its existence are described, and plans for future work are outlined. Weather elements for which forecast techniques are being developed include temperature, precipitation, humidity, wind, ceiling, visibility, severe local storms, wave heights, and storm surges.

Full access
William H. Klein
Full access
William H. Klein

The applied research program of the Techniques Development Laboratory in the field of precipitation prediction is summarized. Current projects are discussed which combine statistical, dynamical, and synoptic techniques and aim at improved and objective forecasts of precipitation probability and amount.

Full access