Precipitation

About: Precipitation is a research topic. Over the lifetime, 32861 publications have been published within this topic receiving 990496 citations. The topic is also known as: rain & rainfall.

Soil as a natural rain gauge: Estimating global rainfall from satellite soil moisture data

Abstract: Measuring precipitation intensity is not straightforward; and over many areas, ground observations are lacking and satellite observations are used to fill this gap. The most common way of retrieving rainfall is by addressing the problem “top-down” by inverting the atmospheric signals reflected or radiated by atmospheric hydrometeors. However, most applications are interested in how much water reaches the ground, a problem that is notoriously difficult to solve from a top-down perspective. In this study, a novel “bottom-up” approach is proposed that, by doing “hydrology backward,” uses variations in soil moisture (SM) sensed by microwave satellite sensors to infer preceding rainfall amounts. In other words, the soil is used as a natural rain gauge. Three different satellite SM data sets from the Advanced SCATterometer (ASCAT), the Advanced Microwave Scanning Radiometer (AMSR-E), and the Microwave Imaging Radiometer with Aperture Synthesis are used to obtain three new daily global rainfall products. The “First Guess Daily” product of the Global Precipitation Climatology Centre (GPCC) is employed as main benchmark in the validation period 2010–2011 for determining the continuous and categorical performance of the SM-derived rainfall products by considering the 5 day accumulated values. The real-time version of the Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis product, i.e., the TRMM-3B42RT, is adopted as a state-of-the-art satellite rainfall product. The SM-derived rainfall products show good Pearson correlation values (R) with the GPCC data set, mainly in areas where SM retrievals are found to be accurate. The global median R values (in the latitude band ±50°) are equal to 0.54, 0.28, and 0.31 for ASCAT-, AMSR-E-, and SMOS-derived products, respectively. For comparison, the median R for the TRMM-3B42RT product is equal to 0.53. Interestingly, the SM-derived products are found to outperform TRMM-3B42RT in terms of average global root-mean-square error statistics and in terms of detection of rainfall events. The regions for which the SM-derived products perform very well are Australia, Spain, South and North Africa, India, China, the Eastern part of South America, and the central part of the United States. The SM-derived products are found to estimate accurately the rainfall accumulated over a 5 day period, an aspect particularly important for their use for hydrological applications, and that address the difficulties of estimating light rainfall from TRMM-3B42RT.

Synoptic aspects of the central chile rainfall variability associated with the southern oscillation

Abstract: Central Chile winter (June, July, August (JJA)) rainfall shows positive anomalies during the developing stage of warm events of the Southern Oscillation. Conversely, cold events correspond quite closely to dry conditions. A synoptic characterization of major storms during the most recent warm events is presented. Dry months during coldevent years are described in terms of average 500-hPa contour anomaly fields. Significant departures from this general behaviour are also discussed. It is found that major winter storms associated with warm events are related to blocking highs frequently located around the Bellingshausen Sea (9OOW) within hemispheric circulation anomaly patterns where zonal wavenumbers 4 and 3 dominate. This phenomenon seems consistent with observed teleconnection wavetrains stemming from the anomalous atmospheric heat source above the equatorial Pacific during ENS0 events. Cold years, often immediately preceding or following a warm event, bring dry conditions in the study area owing to a well-developed south-east subtropical anticyclone with enhanced zonal westerly flow at middle latitudes. Frequency distributions of 500-hPa daily blocking indices (BI) at 90°W, derived from 1980 to 1987 European Centre for Medium Range Weather Forecasts hemispheric analyses, show a significant departure towards positive BI values for the available warm-event winters; the opposite being also true. However, the JJA rainfall variability at Santiago (33.53) also seems to be related to the regional strength of the south-east Pacific anticyclone, as represented by seasonal 500-hPa geopotential anomalies at Puerto Montt, Chile (413"s). The apparent relationship between the phases of the Southern Oscillation (SO) and rainfall anomalies in central Chile (30-35"s) has been reported by several authors. Rubin (1955), while taking into consideration pressure anomalies in the Southern Hemisphere, found that the precipitation in central Chile stays below normal during the positive phase of the SO, namely when the south-east Pacific subtropical anticyclone is stronger than average. The strength and position of the aforementioned anticyclone has also been related by Pittock (1980) to the interannual rainfall variability in the central part of Chile. Quinn and Neal (1983), in an attempt to relate long series of annual precipitation in Santiago (33*5"S, 70.7"W) and in Valparaiso (33.0°S, 71.6"W) with an El Niiio index, obtained a good correspondence of the interannual rainfall variability with area averaged sea-surface temperatures in the south-eastern tropical Pacific. More recently, Aceituno (1987) has correlated the pressure, temperature, wind, and precipitation fields with a Southern Oscillation Index (SOI), concluding that the tendency to positive rainfall anomalies in central Chile during the negative phase of the SO is associated with a weak and northerly displaced southeast Pacific subtropical anticyclone; together with an overall increase in baroclinicity at the subtropical latitudes produced by tropospheric cooling in the southern part of South America and a corresponding warming in tropical latitudes. At present, the Chilean rainfall anomaly seems to have gained a place in the world-wide sequence of major climatic anomalies related 0899-84 1 8/9 1/0 10063-1 4$07.OO 0 1991 by the Royal Meteorological Society

Coupled spatial variations in precipitation and long-term erosion rates across the Washington Cascades

Abstract: Past studies of tectonically active mountain ranges have suggested strong coupling and feedbacks between climate, tectonics and topography. For example, rock uplift generates topographic relief, thereby enhancing precipitation, which focuses erosion and in turn influences rates and spatial patterns of further rock uplift. Although theoretical links between climate, erosion and uplift have received much attention, few studies have shown convincing correlations between observable indices of these processes on mountain-range scales. Here we show that strongly varying long-term (>10(6)-10(7) yr) erosion rates inferred from apatite (U-Th)/He cooling ages across the Cascades mountains of Washington state closely track modern mean annual precipitation rates. Erosion and precipitation rates vary over an order of magnitude across the range with maxima of 0.33 mm yr(-1) and 3.5 m yr(-1), respectively, with both maxima located 50 km west (windward) of the topographic crest of the range. These data demonstrate a strong coupling between precipitation and long-term erosion rates on the mountain-range scale. If the range is currently in topographic steady state, rock uplift on the west flank is three to ten times faster than elsewhere in the range, possibly in response to climatically focused erosion.

21st century climate change in the Middle East

Abstract: This study examined the performance and future predictions for the Middle East produced by 18 global climate models participating in the Intergovernmental Panel on Climate Change Fourth Assessment Report. Under the Special Report on Emission Scenarios A2 emissions scenario the models predict an overall temperature increase of ~1.4 K by mid-century, increasing to almost 4 K by late-century for the Middle East. In terms of precipitation the southernmost portion of the domain experiences a small increase in precipitation due to the Northward movement of the Inter-Tropical Convergence Zone. The largest change however is a decrease in precipitation that occurs in an area covering the Eastern Mediterranean, Turkey, Syria, Northern Iraq, Northeastern Iran and the Caucasus caused by a decrease in storm track activity over the Eastern Mediterranean. Other changes likely to impact the region include a decrease of over 170,000 km2 in viable rainfed agriculture land by late-century, increases in the length of the dry season that reduces the length of time that the rangelands can be grazed, and changes in the timing of the maximum precipitation in Northern Iran that will impact the growing season, forcing changes in cropping strategy or even crop types.

Terrestrial mechanisms of interannual CO2 variability

Abstract: [1] The interannual variability of atmospheric CO2 growth rate shows remarkable correlation with the El Nino Southern Oscillation (ENSO). Here we present results from mechanistically based terrestrial carbon cycle model VEgetation-Global-Atmosphere-Soil (VEGAS), forced by observed climate fields such as precipitation and temperature. Land is found to explain most of the interannual CO2 variability with a magnitude of about 5 PgC yr−1. The simulated land-atmosphere flux has a detrended correlation of 0.53 (0.6 at the 2–7 year ENSO band) with the CO2 growth rate observed at Mauna Loa from 1965 to 2000. We also present the total ocean flux from the Hamburg Ocean Carbon Cycle Model (HAMOCC) which shows ocean-atmosphere flux variation of about 1 PgC yr−1, and it is largely out of phase with land flux. On land, much of the change comes from the tropical regions such as the Amazon and Indonesia where ENSO related climate anomalies are in the same direction across much of the tropics. The subcontinental variations over North America and Eurasia are comparable to the tropics but the total interannual variability is about 1 PgC yr−1 due to the cancellation from the subregions. This has implication for flux measurement network distribution. The tropical dominance also results from a “conspiracy” between climate and plant/soil physiology, as precipitation and temperature changes drive opposite changes in net primary production (NPP) and heterotrophic respiration (Rh), both contributing to land-atmosphere flux changes in the same direction. However, NPP contributes to about three fourths of the total tropical interannual variation and the rest is from heterotrophic respiration; thus precipitation appears to be a more important factor than temperature on the interannual timescales as tropical wet and dry regimes control vegetation growth. Fire, largely driven by drought, also contributes significantly to the interannual CO2 variability at a rate of about 1 PgC yr−1, and it is not totally in phase with NPP or Rh. The robust variability in tropical fluxes agree well with atmospheric inverse modeling results. Even over North America and Eurasia, where ENSO teleconnection is less robust, the fluxes show general agreement with inversion results, an encouraging sign for fruitful carbon data assimilation.