Since 65 million years ago (Ma), Earth's climate has undergone a significant and complex evolution, the finer details of which are now coming to light through investigations of deep-sea sediment cores. This evolution includes gradual trends of warming and cooling driven by tectonic processes on time scales of 10(5) to 10(7) years, rhythmic or periodic cycles driven by orbital processes with 10(4)- to 10(6)-year cyclicity, and rare rapid aberrant shifts and extreme climate transients with durations of 10(3) to 10(5) years. Here, recent progress in defining the evolution of global climate over the Cenozoic Era is reviewed. We focus primarily on the periodic and anomalous components of variability over the early portion of this era, as constrained by the latest generation of deep-sea isotope records. We also consider how this improved perspective has led to the recognition of previously unforeseen mechanisms for altering climate.

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Trends, Rhythms, and Aberrations in Global Climate 65 Ma to Present

Statistics for Spatial Data.

From a societal, weather, and climate perspective, precipitation intensity, duration, frequency, and phase are as much of concern as total amounts, as these factors determine the disposition of precipitation once it hits the ground and how much runs off. At the extremes of precipitation incidence are the events that give rise to floods and droughts, whose changes in occurrence and severity have an enormous impact on the environment and society. Hence, advancing understanding and the ability to model and predict the character of precipitation is vital but requires new approaches to examining data and models. Various mechanisms, storms and so forth, exist to bring about precipitation. Because the rate of precipitation, conditional on when it falls, greatly exceeds the rate of replenishment of moisture by surface evaporation, most precipitation comes from moisture already in the atmosphere at the time the storm begins, and transport of moisture by the storm-scale circulation into the storm is vital....

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The Changing Character of Precipitation

An overview of model-based geostatistics.- Gaussian models for geostatistical data.- Generalized linear models for geostatistical data.- Classical parameter estimation.- Spatial prediction.- Bayesian inference.- Geostatistical design.

/pdf/model-based-geostatistics-3h5fgto422.pdf

Model-based Geostatistics

Global cooling in the Cenozoic, which led to the growth of large continental ice sheets in both hemispheres, may have been caused by the uplift of the Tibetan plateau and the positive feedbacks initiated by this event. In particular, tectonically driven increases in chemical weathering may have resulted in a decrease of atmospheric C02 concentration over the past 40 Myr.

Tectonic forcing of late Cenozoic climate

Recent studies based on aircraft observations made over ocean by radar and multi-channel passive microwave radiometer, each with a field of view (fov) of a few kilometers, indicate significant problems in relating the radar derived rain rate with the brightness temperature measurements of the microwave radiometer. We arrive at a similar conclusion from extensive observations of rain rate made by ship-borne radars and rain rate deduced from observations of the satellite-borne, multi-channel Special Sensor Microwave Imager (SSM/I) radiometer, which has a much larger fov (∼30 km). The principal reason for these problems is that the signal due to rain drops contained in the radiometer measurements is nonlinearly mixed with that of other hydrometeors that could be present in the radiometer fov. These other hydrometeors include liquid droplets, and dry and melting ice and snow particles of different densities, sizes, and shapes in clouds. Observations made by SSM/I are not adequate to uncouple the rain signal satisfactorily from such a non-linear mix of signals on the scale of the radiometer footprint. These problems are complicated further by meteorological conditions, which can significantly alter the amount and spatial distribution of these other hydrometeors. For these reasons an empirical method is developed to estimate area-average rain rate in a mesoscale region of about 300 x 300 km 2 , based on SSM/I data. One parameter of this empirical method fR relates to the fractional rain area in a mesoscale region, while the second parameter, X, reflects in a weak way the scattering and emission properties of the hydrometeors in that region. This method requires tuning with the help of radar data. Over the TOGA-COARE area, the rain rates retrieved from this method can reproduce the radar observed rain rates with a correlation coefficient of about 0.85. Furthermore, monthly total rainfall estimated from this method for the TOGA-COARE area has an error of about 13 %. This rain retrieval method is applicable to the Tropical Rainfall Measuring Mission (TRMM), in which multi-channel dual-polarization microwave radiometer observations over a 760 km wide swath are overlapped with those of radar, which has a swath of 220 km.

A TRMM microwave radiometer rain retrieval method based on fractional rain area

Volume scan strategies for the WSR-74C in support of Space Launch

The 45th Weather Squadron (45 WS) is replacing the Weather Surveillance Radar, Model 74C (WSR-74C) at Patrick Air Force Base (PAFB), with a Doppler, dual polarization radar, the Radtec 43/250. A new scan strategy is needed for the Radtec 43/250, to provide high vertical resolution data over the Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS) launch pads, while taking advantage of the new radar's advanced capabilities for detecting severe weather phenomena associated with convection within the 45 WS area of responsibility. The Applied Meteorology Unit (AMU) developed several scan strategies customized for the operational needs of the 45 WS. The AMU also developed a plan for evaluating the scan strategies in the period prior to operational acceptance, currently scheduled for November 2008.

/pdf/radar-scan-strategies-for-the-patrick-air-force-base-weather-215rpr8ecc.pdf

Radar Scan Strategies for the Patrick Air Force Base Weather Surveillance Radar, Model-74C, Replacement

A theory is developed which establishes the basis for the use of rainfall areas within present thresholds as a measure of either the instantaneous areawide rain rate of convective storms or the total volume of rain from an individual storm over its lifetime. The method is based upon the existence of a well-behaved pdf of rain rate either from the many storms at one instant or from a single storm during its life. The generality of the instantaneous areawide method was examined by applying it to quantitative radar data sets from the GARP Tropical Atlantic Experiment for South Africa, Texas, and Darwin (Australia). It is shown that the pdf's developed for each of these areas are consistent with the theory.

The estimation of convective rainfall by area integrals. I - The theoretical and empirical basis. II - The height-area rainfall threshold (HART) method

Rainfall products derived from radar data often consume vast amounts of storage space and are time-consuming to analyze. Shipborne radar data collected during the Tropical Ocean Global Atmosphere (TOGA) Coupled Ocean-Atmosphere Response Experiment (COARE) provide an extensive data set to examine rainfall characteristics in the tropical Western Pacific Ocean. TOGA COARE shipborne radar-rainfall products have been organized into a database with efficient storage and access time characteristics. Software for reading and visually browsing the data has been developed and made available to provide users with a convenient method to study the data set.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/1999WR900109

David A. Short

Papers

A TRMM microwave radiometer rain retrieval method based on fractional rain area

Volume scan strategies for the WSR-74C in support of Space Launch

Radar Scan Strategies for the Patrick Air Force Base Weather Surveillance Radar, Model-74C, Replacement

The estimation of convective rainfall by area integrals. I - The theoretical and empirical basis. II - The height-area rainfall threshold (HART) method

Toga coare shipborne radar-rainfall products