EFFECTS OF CLIMATIC CHANGE ON THE THORNTHWAITE MOISTURE INDEX1

ABSTRACT: The Thornthwaite moisture index is a useful indicator of the supply of water (precipitation) in an area relative to the demand for water under prevailing climatic conditions (potential evapotranspiration). This study examines the effects of changes in climate (temperature and precipitation) on the Thornthwaite moisture index in the conterminous United States. Estimates of changes in mean annual temperature and precipitation for doubled-atmospheric CO₂ conditions derived from three general circulation models (GCMs) are used to study the response of the moisture index under steady-state doubled-CO₂ conditions. Results indicate that temperature and precipitation changes under doubled-CO₂ conditions generally will cause the Thornthwaite moisture index to decrease, implying a drier climate for most of the United States. The pattern of expected decrease is consistent among the three GCMs, although the amount of decrease depends on which GCM climatic-change scenario is used. Results also suggest that changes in the moisture index are related mainly to changes in the mean annual potential evapotranspiration as a result of changes in the mean annual temperature, rather than to changes in the mean annual precipitation.     

Hydrology and Water Budget for a Forested Atlantic Coastal Plain Watershed,South Carolina1

Abstract: Increases in timber demand and urban development in the Atlantic Coastal Plain over the past decade have motivated studies on the hydrology, water quality, and sustainable management of coastal plain watersheds. However, studies on baseline water budgets are limited for the low‐lying, forested watersheds of the Atlantic Coastal Plain. The purpose of this study was to document the hydrology and a method to quantify the water budget of a first‐order forested watershed, WS80, located within the USDA Forest Service Santee Experimental Forest northeast of Charleston, South Carolina. Annual Rainfall for the 2003 and 2004 periods were 1,671 mm (300 mm above normal) and 962 mm (over 400 mm below normal), respectively. Runoff coefficients (outflow as a fraction of total rainfall) for the 2003 and 2004 periods were 0.47 and 0.08, respectively, indicating a wide variability of outflows as affected by antecedent conditions. A spreadsheet‐based Thornthwaite monthly water balance model was tested on WS80 using three different potential evapotranspiration estimators [Hamon, Thornthwaite, and Penman‐Monteith (P‐M)]. The Hamon and P‐M‐based methods performed reasonably well with average absolute monthly deviations of 12.6 and 13.9 mm, respectively, between the measured and predicted outflows. Estimated closure errors were all within 9% for the 2003, 2004, and seasonal water budgets. These results may have implications on forest management practices and provide necessary baseline or reference information for Atlantic Coastal Plain watersheds.     

1901—2017年藏西南高原气候及其生产潜力时空变化

研究全球变暖背景下藏西南高原气候及气候生产潜力时空分布,对该区农牧业发展、生态保护和可持续发展等具有重要意义。基于1901—2017年的中国气象再分析数据,利用Miami和Thornthwaite Memorial模型对近117年藏西南高原气候变化、气候生产潜力的时空分布及影响因素进行了分析。结果表明：近117年来藏西南高原年均温呈上升趋势,年均降水量呈下降趋势,并存在明显周期和突变点;温度生产潜力呈增加趋势,空间上自东南向西北递减;降水、蒸散和标准生产潜力呈减小趋势,呈现自南向北递减的空间分布特征;标准生产潜力由降水和温度共同决定,降水是主要限制因子。未来气候若持续“暖干化”变化,将导致藏西南高原气候生产潜力下降。为促进畜牧业发展和生态环境的改善,未来应进一步推进退牧还草、人工种草、舍饲养殖等工程,并选用耐寒耐旱高产草种,提高牧草产量,实现草畜平衡,以推动传统畜牧业向现代牧业转变,实现草原生态保护和可持续发展。     

中亚地区气候生产潜力时空变化特征

根据中亚5 国100 个气象站1901-2000 年月平均温度和降水资料,运用Miami、Thornthwaite Memorial 模型对中亚地区气候生产潜力进行了计算,用气候倾向率、Mann-Kendall 法、并结合ArcGIS 和SPSS 对其时空变化特征及驱动力进行了分析。结果表明：①中亚地区100 a 降水气候生产潜力（Yr）和蒸散气候生产潜力（Ye）均呈逐渐增加的趋势,温度气候生产潜力（Yt）趋势相反,Yr 和Ye 均发生了4 次突变,Yt 没有发生突变;②气候生产潜力区域差异明显,其中,Yt 呈从西南向东北减少的趋势,Yr 和Ye 变化比较复杂,大致具有东部大于西部的规律;③增温增湿的气候变化趋势有利于中亚气候生产潜力的提高,中亚气候生产潜力对增湿的响应更敏感。     

Climate controls on dust storm occurrence in Maowusu Desert, Inner Mongolia, north China

ＩｎｔｒｏｄｕｃｔｉｏｎＤｕｓｔｓｔｏｒｍｓ,ｗｈｉｃｈｒｅｍｏｖｅｌａｒｇｅｑｕａｎｔｉｔｉｅｓｏｆｔｏｐｓｏｉｌ,ｐｌａｙａｍａｉｎｒｏｌｅｉｎｔｈｅｅｖｏｌｕｔｉｏｎｏｆｌａｎｄｓｃａｐｅｓｉｎａｒｉｄａｎｄｓｅｍｉ ａｒｉｄｌａｎｄｓ.Ｏｃｃｕｒｒｅｎｃｅｏｆｄｕｓｔｓｔｏｒｍｄｅｐｅｎｄｓｏｎａｎｕｍｂｅｒｏｆｅｎｖｉｒｏｎｍｅｎｔａｌｆａｃｔｏｒｓ,ｉｎｃｌｕｄｉｎｇｓｅｄｉｍｅｎｔａｖａｉｌａｂｉｌｉｔｙ ,ｓｏｉｌｅｒｏｄｉｂｉｌｉｔｙａｎｄｗｉｎｄｅｒｏｓｉｖｉｔｙ .Ｉｎｒｅｃｅｎｔ…     

Revisiting the Thornthwaite and Mather Water Balance1

Abstract: This technical note clarifies confusion currently present in research using and/or citing the 1955 and 1957 editions of the Thornthwaite and Mather Water Balance (or Budget) resulting from corrections to errant tables in the 1955 edition made by the authors for the 1957 edition. Confusion over the two editions and the formulas used have clouded the results of research, management, and educational publications ever since, resulting in frequent misunderstanding of the method’s utility as well as how its results compare with other frequently used methods for estimating evapotranspiration.