Will the South Asian monsoon overturning circulation stabilize any further?

Understanding the response of the South Asian monsoon (SAM) system to global climate change is an interesting scientific problem that has enormous implications from the societal viewpoint. While the CMIP3 projections of future changes in monsoon precipitation used in the IPCC AR4 show major uncertainties, there is a growing recognition that the rapid increase of moisture in a warming climate can potentially enhance the stability of the large-scale tropical circulations. In this work, the authors have examined the stability of the SAM circulation based on diagnostic analysis of climate datasets over the past half century; and addressed the issue of likely future changes in the SAM in response to global warming using simulations from an ultrahigh resolution (20 km) global climate model. Additional sensitivity experiments using a simplified atmospheric model have been presented to supplement the overall findings. The results here suggest that the intensity of the boreal summer monsoon overturning circulation and the associated southwesterly monsoon flow have significantly weakened during the past 50-years. The weakening trend of the monsoon circulation is further corroborated by a significant decrease in the frequency of moderate-to-heavy monsoon rainfall days and upward vertical velocities particularly over the narrow mountain ranges of the Western Ghats. Based on simulations from the 20-km ultra high-resolution model, it is argued that a stabilization (weakening) of the summer monsoon Hadley-type circulation in response to global warming can potentially lead to a weakened large-scale monsoon flow thereby resulting in weaker vertical velocities and reduced orographic precipitation over the narrow Western Ghat mountains by the end of the twenty-first century. Supplementary experiments using a simplified atmospheric model indicate a high sensitivity of the large-scale monsoon circulation to atmospheric stability in comparison with the effects of condensational heating.

Reduction in Northward Incursions of the South Asian Monsoon Since ~1400 AD Inferred from a Mt. Everest Ice Core

A highly resolved Mt. Everest ice core reveals a decrease in marine and increase in continental air masses related to relatively high summer surface pressure over Mongolia, and reduction in northward incursions of the summer South Asian monsoon since similar to 1400 AD. Previously published proxy records from lower sites south of the Himalayas indicate strengthening of the monsoon since this time. These regional differences are consistent with a south north seesaw in convective activity in the Asian monsoon region, and reflect a southward shift in the mean summer position of the monsoon trough since similar to 1400 AD. The change in monsoonal circulation at 1400 AD is synchronous with a reduction in solar irradiance and the onset of the LIA. This demonstrates a hemispheric scale circulation reorganization at this time, and the potential for future large shifts in monsoonal circulation.

Declaration signed by Harvard students to not speak in the vernacular for one year, 1712 August 23

The declaration, handwritten in Latin and signed by members of the junior and sophomore classes (Harvard Classes of 1714 and 1715), promises that the undersigned will not use the vernacular but instead "whenever, at meals, at banquets,...in our rooms, in all our gatherings, wherever and whenever" will speak in Latin, Greek, or Hebrew through the next May. Additional Latin text appears on both the front and back of the document. The original is accompanied by a typed transcription and two partial handwritten translations. Note at top of original: "Script. Leonardo Dowding, Composit. a Tho. Foxcroft."

A copy of the general map the most part compiled from the actual survey by order of the commisioners appointed to settle the partition line between the provinces of New York and New Jersey : manuscript map, 1769

Map showing the whole of New Jersey and its borders with as well as part of Pennsylvania and New York. Map is drawn in black ink with green, pink, and yellow watercolors used to show features such as waterways, borders, and places of interest. Notes on map concern border disputes between New Jersey and New York.

Plea in the case of Hamilton v. Saunders, 1763

Plea in response to the plaintiff's declaration. Signed: (Charles) Pinckney, defendant's attorney, and John Rutledge (plaintiff's attorney?). Note on verso: Filed 4th May 1763.

Notes of cases decided in the Superior and Supreme Judicial Courts of Massachusetts from 1772 to 1789: taken by the Hon. William Cushing, one of the judges during that period and most of the time Chief Justice

Notes of cases taken by Judge William Cushing during his tenure on the Massachusetts superior and supreme courts. (Formerly MS 2141.)

Letter to Samuel Dexter, 13 November 1796

Letter regarding a bankruptcy case, later heard by the U.S. Supreme Court in 1797 (3 Dallas 369; Emory v. Greenough) and the upcoming national election.

Letter to John Worthington: 13 August 1791

Letter to Worhtington, a Springfield, Massachusetts lawyer, regarding tax on a meeting house near Pittsfield, Massachusetts and public support for ministers.

Capt. Weeks his answers to interogatorys on oath ... ca. 1738

Weeks (of Greenland, N.H.) was accused of concealing and embezzling items from his late son's estate. Document is signed: William Parker reg.

[ Order to the sheriff of Bucks County], 1731

An order to the sheriff of Bucks County, Pennsylvania, for twelve men to serve on a jury in the trial of John Borrowes, for an unspecified crime. Signed: Jeremiah Langhorne (justice of the peace); dated 14 June 1731. With seal. With this document (originally attached) is the list of jurors chosen to serve at the trial.

Docket book, 1774-1800

Contains list of names of parties in legal disputes arranged chronologically. Little information is given about the nature of disputes.

The royal charter of King Charles the Second to William Penn, esquire, proprietor of the province of Pennsylvania, 1701

A copy of the charter giving William Penn land in the colonies. Also contains Penn's "Frame of the Government of Pennsylvania in America", the laws he established, and the charter of the city of Philadelphia.

An act for granting to His Majesty the sum of fifty-five thousand pounds, and for striking the same in bills of credit, in the manner herein after directed..., 1764

Contains an act for collection of taxes to pay the debt by establishing a set fee of fifteen shillings per head and household.

Short nomenclator or vocabular in English and Hebrew: composed alphabetically for the use and benefit of my pupils in particular and for the advantage of those who are desirous to obtain the knowledge of the Hebrew tongue in general, which may be that great help to understand not only ye sacred oracles in their original, but even any Jewish author (so far as concern owns) as also it may give great insight in ye tongue to those, as to compose it, a work altogether new, [ca. 1735]

Headed on the first page with the words "Nomenclatura hebraica," this handwritten volume is a vocabulary with the Hebrew word in the left column, and the English translation on the right. While the book is arranged in sections by letter, individual entries do not appear in strict alphabetical order. The small vocabulary varies greatly and includes entries like enigma, excommunication, and martyr, as well as cucumber and maggot. There are translations of the astrological signs at the end of the volume. Poem written at the bottom of the last page in different hand: "Women when good the best of saints/ that bright seraphick lovely/ she, who nothing of an angel/ wants but truth & immortality./ Verse 2: Who silken limbs & charming/ face. Keeps nature warm."

An Act of Assembly of Barbadoes to regulate sales at outcry and the proceedings of persons executing the office of Provost Marshall General ofthe said island and their under officers, 1763

An Act of Assembly of Barbadoes to regulate sales at outcry and the proceedings of persons executing the office of Provost Marshall General of the said island and their under officers (leaf 1) ; A state of some matters relative to the office of Provost Marshall, and to the passing of this bill (leaf 9) ; Observations drawn up by Jonathan Blenman Esq. his Majestys Atty. Gen. in Barbadoes ... on the Act as it had been first brought in 1761 (leaf 13) ; and two leaves laid in ; Power of attorney, granted to Christopher Scandrett, signed by Francis Reynolds and his son Thomas (25 April 1766) ; Petition of Francis Reynolds to the Lords Commissioners of Trade and Plantations (1766).